Revert "libpng 1.6.3"

third_party/libpng/pngrutil.c

 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.6.3 [July 18, 2013]
- * Copyright (c) 1998-2013 Glenn Randers-Pehrson
+ * Last changed in libpng 1.2.45 [July 7, 2011]
+ * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  *
  * This file contains routines that are only called from within
  * libpng itself during the course of reading an image.
  */
 
-#include "pngpriv.h"
-
+#define PNG_INTERNAL
+#define PNG_NO_PEDANTIC_WARNINGS
+#include "png.h"
 #ifdef PNG_READ_SUPPORTED
 
-png_uint_32 PNGAPI
-png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
-{
-   png_uint_32 uval = png_get_uint_32(buf);
-
-   if (uval > PNG_UINT_31_MAX)
-      png_error(png_ptr, "PNG unsigned integer out of range");
-
-   return (uval);
-}
-
-#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
-/* The following is a variation on the above for use with the fixed
- * point values used for gAMA and cHRM.  Instead of png_error it
- * issues a warning and returns (-1) - an invalid value because both
- * gAMA and cHRM use *unsigned* integers for fixed point values.
- */
-#define PNG_FIXED_ERROR (-1)
-
-static png_fixed_point /* PRIVATE */
-png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
-{
-   png_uint_32 uval = png_get_uint_32(buf);
-
-   if (uval <= PNG_UINT_31_MAX)
-      return (png_fixed_point)uval; /* known to be in range */
-
-   /* The caller can turn off the warning by passing NULL. */
-   if (png_ptr != NULL)
-      png_warning(png_ptr, "PNG fixed point integer out of range");
-
-   return PNG_FIXED_ERROR;
-}
+#if defined(_WIN32_WCE) && (_WIN32_WCE<0x500)
+#  define WIN32_WCE_OLD
 #endif
 
-#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
-/* NOTE: the read macros will obscure these definitions, so that if
- * PNG_USE_READ_MACROS is set the library will not use them internally,
- * but the APIs will still be available externally.
- *
- * The parentheses around "PNGAPI function_name" in the following three
- * functions are necessary because they allow the macros to co-exist with
- * these (unused but exported) functions.
- */
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+#  ifdef WIN32_WCE_OLD
+/* The strtod() function is not supported on WindowsCE */
+__inline double png_strtod(png_structp png_ptr, PNG_CONST char *nptr,
+    char **endptr)
+{
+   double result = 0;
+   int len;
+   wchar_t *str, *end;
 
+   len = MultiByteToWideChar(CP_ACP, 0, nptr, -1, NULL, 0);
+   str = (wchar_t *)png_malloc(png_ptr, len * png_sizeof(wchar_t));
+   if ( NULL != str )
+   {
+      MultiByteToWideChar(CP_ACP, 0, nptr, -1, str, len);
+      result = wcstod(str, &end);
+      len = WideCharToMultiByte(CP_ACP, 0, end, -1, NULL, 0, NULL, NULL);
+      *endptr = (char *)nptr + (png_strlen(nptr) - len + 1);
+      png_free(png_ptr, str);
+   }
+   return result;
+}
+#  else
+#    define png_strtod(p,a,b) strtod(a,b)
+#  endif
+#endif
+
+png_uint_32 PNGAPI
+png_get_uint_31(png_structp png_ptr, png_bytep buf)
+{
+#ifdef PNG_READ_BIG_ENDIAN_SUPPORTED
+   png_uint_32 i = png_get_uint_32(buf);
+#else
+   /* Avoid an extra function call by inlining the result. */
+   png_uint_32 i = ((png_uint_32)(*buf) << 24) +
+      ((png_uint_32)(*(buf + 1)) << 16) +
+      ((png_uint_32)(*(buf + 2)) << 8) +
+      (png_uint_32)(*(buf + 3));
+#endif
+   if (i > PNG_UINT_31_MAX)
+     png_error(png_ptr, "PNG unsigned integer out of range.");
+   return (i);
+}
+#ifndef PNG_READ_BIG_ENDIAN_SUPPORTED
 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
-png_uint_32 (PNGAPI
-png_get_uint_32)(png_const_bytep buf)
+png_uint_32 PNGAPI
+png_get_uint_32(png_bytep buf)
 {
-   png_uint_32 uval =
-       ((png_uint_32)(*(buf    )) << 24) +
-       ((png_uint_32)(*(buf + 1)) << 16) +
-       ((png_uint_32)(*(buf + 2)) <<  8) +
-       ((png_uint_32)(*(buf + 3))      ) ;
+   png_uint_32 i = ((png_uint_32)(*buf) << 24) +
+      ((png_uint_32)(*(buf + 1)) << 16) +
+      ((png_uint_32)(*(buf + 2)) << 8) +
+      (png_uint_32)(*(buf + 3));
 
-   return uval;
+   return (i);
 }
 
 /* Grab a signed 32-bit integer from a buffer in big-endian format.  The
- * data is stored in the PNG file in two's complement format and there
- * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
- * the following code does a two's complement to native conversion.
+ * data is stored in the PNG file in two's complement format, and it is
+ * assumed that the machine format for signed integers is the same.
  */
-png_int_32 (PNGAPI
-png_get_int_32)(png_const_bytep buf)
+png_int_32 PNGAPI
+png_get_int_32(png_bytep buf)
 {
-   png_uint_32 uval = png_get_uint_32(buf);
-   if ((uval & 0x80000000) == 0) /* non-negative */
-      return uval;
+   png_int_32 i = ((png_int_32)(*buf) << 24) +
+      ((png_int_32)(*(buf + 1)) << 16) +
+      ((png_int_32)(*(buf + 2)) << 8) +
+      (png_int_32)(*(buf + 3));
 
-   uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
-   return -(png_int_32)uval;
+   return (i);
 }
 
 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
-png_uint_16 (PNGAPI
-png_get_uint_16)(png_const_bytep buf)
+png_uint_16 PNGAPI
+png_get_uint_16(png_bytep buf)
 {
-   /* ANSI-C requires an int value to accomodate at least 16 bits so this
-    * works and allows the compiler not to worry about possible narrowing
-    * on 32 bit systems.  (Pre-ANSI systems did not make integers smaller
-    * than 16 bits either.)
-    */
-   unsigned int val =
-       ((unsigned int)(*buf) << 8) +
-       ((unsigned int)(*(buf + 1)));
+   png_uint_16 i = (png_uint_16)(((png_uint_16)(*buf) << 8) +
+      (png_uint_16)(*(buf + 1)));
 
-   return (png_uint_16)val;
+   return (i);
 }
-
-#endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
-
-/* Read and check the PNG file signature */
-void /* PRIVATE */
-png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
-{
-   png_size_t num_checked, num_to_check;
-
-   /* Exit if the user application does not expect a signature. */
-   if (png_ptr->sig_bytes >= 8)
-      return;
-
-   num_checked = png_ptr->sig_bytes;
-   num_to_check = 8 - num_checked;
-
-#ifdef PNG_IO_STATE_SUPPORTED
-   png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
-#endif
-
-   /* The signature must be serialized in a single I/O call. */
-   png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
-   png_ptr->sig_bytes = 8;
-
-   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
-   {
-      if (num_checked < 4 &&
-          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
-         png_error(png_ptr, "Not a PNG file");
-      else
-         png_error(png_ptr, "PNG file corrupted by ASCII conversion");
-   }
-   if (num_checked < 3)
-      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
-}
+#endif /* PNG_READ_BIG_ENDIAN_SUPPORTED */
 
 /* Read the chunk header (length + type name).
  * Put the type name into png_ptr->chunk_name, and return the length.
  */
 png_uint_32 /* PRIVATE */
-png_read_chunk_header(png_structrp png_ptr)
+png_read_chunk_header(png_structp png_ptr)
 {
    png_byte buf[8];
    png_uint_32 length;
 
-#ifdef PNG_IO_STATE_SUPPORTED
-   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
-#endif
-
-   /* Read the length and the chunk name.
-    * This must be performed in a single I/O call.
-    */
+   /* Read the length and the chunk name */
    png_read_data(png_ptr, buf, 8);
    length = png_get_uint_31(png_ptr, buf);
 
-   /* Put the chunk name into png_ptr->chunk_name. */
-   png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
+   /* Put the chunk name into png_ptr->chunk_name */
+   png_memcpy(png_ptr->chunk_name, buf + 4, 4);
 
-   png_debug2(0, "Reading %lx chunk, length = %lu",
-       (unsigned long)png_ptr->chunk_name, (unsigned long)length);
+   png_debug2(0, "Reading %s chunk, length = %lu",
+      png_ptr->chunk_name, length);
 
-   /* Reset the crc and run it over the chunk name. */
+   /* Reset the crc and run it over the chunk name */
    png_reset_crc(png_ptr);
-   png_calculate_crc(png_ptr, buf + 4, 4);
+   png_calculate_crc(png_ptr, png_ptr->chunk_name, 4);
 
-   /* Check to see if chunk name is valid. */
+   /* Check to see if chunk name is valid */
    png_check_chunk_name(png_ptr, png_ptr->chunk_name);
 
-#ifdef PNG_IO_STATE_SUPPORTED
-   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
-#endif
-
    return length;
 }
 
 /* Read data, and (optionally) run it through the CRC. */
 void /* PRIVATE */
-png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
+png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
 {
    if (png_ptr == NULL)
       return;
-
    png_read_data(png_ptr, buf, length);
    png_calculate_crc(png_ptr, buf, length);
 }
 
 /* Optionally skip data and then check the CRC.  Depending on whether we
- * are reading an ancillary or critical chunk, and how the program has set
+ * are reading a ancillary or critical chunk, and how the program has set
  * things up, we may calculate the CRC on the data and print a message.
  * Returns '1' if there was a CRC error, '0' otherwise.
  */
 int /* PRIVATE */
-png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
+png_crc_finish(png_structp png_ptr, png_uint_32 skip)
 {
-   /* The size of the local buffer for inflate is a good guess as to a
-    * reasonable size to use for buffering reads from the application.
-    */
-   while (skip > 0)
+   png_size_t i;
+   png_size_t istop = png_ptr->zbuf_size;
+
+   for (i = (png_size_t)skip; i > istop; i -= istop)
    {
-      png_uint_32 len;
-      png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
-
-      len = (sizeof tmpbuf);
-      if (len > skip)
-         len = skip;
-      skip -= len;
-
-      png_crc_read(png_ptr, tmpbuf, len);
+      png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
+   }
+   if (i)
+   {
+      png_crc_read(png_ptr, png_ptr->zbuf, i);
    }
 
    if (png_crc_error(png_ptr))
    {
-      if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) ?
-          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
-          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
+      if (((png_ptr->chunk_name[0] & 0x20) &&                /* Ancillary */
+          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) ||
+          (!(png_ptr->chunk_name[0] & 0x20) &&             /* Critical  */
+          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE)))
       {
          png_chunk_warning(png_ptr, "CRC error");
       }
-
       else
       {
-         png_chunk_benign_error(png_ptr, "CRC error");
-         return (0);
+         png_chunk_error(png_ptr, "CRC error");
       }
-
       return (1);
    }
 
    return (0);
 }
 
 /* Compare the CRC stored in the PNG file with that calculated by libpng from
  * the data it has read thus far.
  */
 int /* PRIVATE */
-png_crc_error(png_structrp png_ptr)
+png_crc_error(png_structp png_ptr)
 {
    png_byte crc_bytes[4];
    png_uint_32 crc;
    int need_crc = 1;
 
-   if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
+   if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
    {
       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
           (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
          need_crc = 0;
    }
-
-   else /* critical */
+   else                                                    /* critical */
    {
       if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
          need_crc = 0;
    }
 
-#ifdef PNG_IO_STATE_SUPPORTED
-   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
-#endif
-
-   /* The chunk CRC must be serialized in a single I/O call. */
    png_read_data(png_ptr, crc_bytes, 4);
 
    if (need_crc)
    {
       crc = png_get_uint_32(crc_bytes);
       return ((int)(crc != png_ptr->crc));
    }
-
    else
       return (0);
 }
 
-/* Manage the read buffer; this simply reallocates the buffer if it is not small
- * enough (or if it is not allocated).  The routine returns a pointer to the
- * buffer; if an error occurs and 'warn' is set the routine returns NULL, else
- * it will call png_error (via png_malloc) on failure.  (warn == 2 means
- * 'silent').
- */
-static png_bytep
-png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
+#if defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) || \
+    defined(PNG_READ_iCCP_SUPPORTED)
+static png_size_t
+png_inflate(png_structp png_ptr, const png_byte *data, png_size_t size,
+        png_bytep output, png_size_t output_size)
 {
-   png_bytep buffer = png_ptr->read_buffer;
-
-   if (buffer != NULL && new_size > png_ptr->read_buffer_size)
-   {
-      png_ptr->read_buffer = NULL;
-      png_ptr->read_buffer = NULL;
-      png_ptr->read_buffer_size = 0;
-      png_free(png_ptr, buffer);
-      buffer = NULL;
-   }
-
-   if (buffer == NULL)
-   {
-      buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
-
-      if (buffer != NULL)
-      {
-         png_ptr->read_buffer = buffer;
-         png_ptr->read_buffer_size = new_size;
-      }
-
-      else if (warn < 2) /* else silent */
-      {
-#ifdef PNG_WARNINGS_SUPPORTED
-         if (warn)
-             png_chunk_warning(png_ptr, "insufficient memory to read chunk");
+   png_size_t count = 0;
+
+   png_ptr->zstream.next_in = (png_bytep)data; /* const_cast: VALID */
+   png_ptr->zstream.avail_in = size;
+
+   while (1)
+   {
+      int ret, avail;
+
+      /* Reset the output buffer each time round - we empty it
+       * after every inflate call.
+       */
+      png_ptr->zstream.next_out = png_ptr->zbuf;
+      png_ptr->zstream.avail_out = png_ptr->zbuf_size;
+
+      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
+      avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;
+
+      /* First copy/count any new output - but only if we didn't
+       * get an error code.
+       */
+      if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)
+      {
+         if (output != 0 && output_size > count)
+         {
+            png_size_t copy = output_size - count;
+            if ((png_size_t) avail < copy) copy = (png_size_t) avail;
+            png_memcpy(output + count, png_ptr->zbuf, copy);
+         }
+         count += avail;
+      }
+
+      if (ret == Z_OK)
+         continue;
+
+      /* Termination conditions - always reset the zstream, it
+       * must be left in inflateInit state.
+       */
+      png_ptr->zstream.avail_in = 0;
+      inflateReset(&png_ptr->zstream);
+
+      if (ret == Z_STREAM_END)
+         return count; /* NOTE: may be zero. */
+
+      /* Now handle the error codes - the API always returns 0
+       * and the error message is dumped into the uncompressed
+       * buffer if available.
+       */
+      {
+         PNG_CONST char *msg;
+         if (png_ptr->zstream.msg != 0)
+            msg = png_ptr->zstream.msg;
          else
-#endif
-         {
-#ifdef PNG_ERROR_TEXT_SUPPORTED
-             png_chunk_error(png_ptr, "insufficient memory to read chunk");
-#endif
-         }
-      }
-   }
-
-   return buffer;
+         {
+#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
+            char umsg[52];
+
+            switch (ret)
+            {
+               case Z_BUF_ERROR:
+                  msg = "Buffer error in compressed datastream in %s chunk";
+                  break;
+               case Z_DATA_ERROR:
+                  msg = "Data error in compressed datastream in %s chunk";
+                  break;
+               default:
+                  msg = "Incomplete compressed datastream in %s chunk";
+                  break;
+            }
+
+            png_snprintf(umsg, sizeof umsg, msg, png_ptr->chunk_name);
+            msg = umsg;
+#else
+            msg = "Damaged compressed datastream in chunk other than IDAT";
+#endif
+         }
+
+         png_warning(png_ptr, msg);
+      }
+
+      /* 0 means an error - notice that this code simple ignores
+       * zero length compressed chunks as a result.
+       */
+      return 0;
+   }
 }
 
-/* png_inflate_claim: claim the zstream for some nefarious purpose that involves
- * decompression.  Returns Z_OK on success, else a zlib error code.  It checks
- * the owner but, in final release builds, just issues a warning if some other
- * chunk apparently owns the stream.  Prior to release it does a png_error.
- */
-static int
-png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
-{
-   if (png_ptr->zowner != 0)
-   {
-      char msg[64];
-
-      PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
-      /* So the message that results is "<chunk> using zstream"; this is an
-       * internal error, but is very useful for debugging.  i18n requirements
-       * are minimal.
-       */
-      (void)png_safecat(msg, (sizeof msg), 4, " using zstream");
-#     if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
-         png_chunk_warning(png_ptr, msg);
-         png_ptr->zowner = 0;
-#     else
-         png_chunk_error(png_ptr, msg);
-#     endif
-   }
-
-   /* Implementation note: unlike 'png_deflate_claim' this internal function
-    * does not take the size of the data as an argument.  Some efficiency could
-    * be gained by using this when it is known *if* the zlib stream itself does
-    * not record the number; however, this is an illusion: the original writer
-    * of the PNG may have selected a lower window size, and we really must
-    * follow that because, for systems with with limited capabilities, we
-    * would otherwise reject the application's attempts to use a smaller window
-    * size (zlib doesn't have an interface to say "this or lower"!).
-    *
-    * inflateReset2 was added to zlib 1.2.4; before this the window could not be
-    * reset, therefore it is necessary to always allocate the maximum window
-    * size with earlier zlibs just in case later compressed chunks need it.
-    */
-   {
-      int ret; /* zlib return code */
-#     if PNG_ZLIB_VERNUM >= 0x1240
-
-#        if defined(PNG_SET_OPTION_SUPPORTED) && \
-            defined(PNG_MAXIMUM_INFLATE_WINDOW)
-            int window_bits;
-
-            if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
-               PNG_OPTION_ON)
-               window_bits = 15;
-
-            else
-               window_bits = 0;
-#        else
-#           define window_bits 0
-#        endif
-#     endif
-
-      /* Set this for safety, just in case the previous owner left pointers to
-       * memory allocations.
-       */
-      png_ptr->zstream.next_in = NULL;
-      png_ptr->zstream.avail_in = 0;
-      png_ptr->zstream.next_out = NULL;
-      png_ptr->zstream.avail_out = 0;
-
-      if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
-      {
-#        if PNG_ZLIB_VERNUM < 0x1240
-            ret = inflateReset(&png_ptr->zstream);
-#        else
-            ret = inflateReset2(&png_ptr->zstream, window_bits);
-#        endif
-      }
-
-      else
-      {
-#        if PNG_ZLIB_VERNUM < 0x1240
-            ret = inflateInit(&png_ptr->zstream);
-#        else
-            ret = inflateInit2(&png_ptr->zstream, window_bits);
-#        endif
-
-         if (ret == Z_OK)
-            png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
-      }
-
-      if (ret == Z_OK)
-         png_ptr->zowner = owner;
-
-      else
-         png_zstream_error(png_ptr, ret);
-
-      return ret;
-   }
-
-#  ifdef window_bits
-#     undef window_bits
-#  endif
-}
-
-#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
-/* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
- * allow the caller to do multiple calls if required.  If the 'finish' flag is
- * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
- * be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
- * Z_OK or Z_STREAM_END will be returned on success.
- *
- * The input and output sizes are updated to the actual amounts of data consumed
- * or written, not the amount available (as in a z_stream).  The data pointers
- * are not changed, so the next input is (data+input_size) and the next
- * available output is (output+output_size).
- */
-static int
-png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
-    /* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
-    /* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
-{
-   if (png_ptr->zowner == owner) /* Else not claimed */
-   {
-      int ret;
-      png_alloc_size_t avail_out = *output_size_ptr;
-      png_uint_32 avail_in = *input_size_ptr;
-
-      /* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
-       * can't even necessarily handle 65536 bytes) because the type uInt is
-       * "16 bits or more".  Consequently it is necessary to chunk the input to
-       * zlib.  This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
-       * maximum value that can be stored in a uInt.)  It is possible to set
-       * ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
-       * a performance advantage, because it reduces the amount of data accessed
-       * at each step and that may give the OS more time to page it in.
-       */
-      png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
-      /* avail_in and avail_out are set below from 'size' */
-      png_ptr->zstream.avail_in = 0;
-      png_ptr->zstream.avail_out = 0;
-
-      /* Read directly into the output if it is available (this is set to
-       * a local buffer below if output is NULL).
-       */
-      if (output != NULL)
-         png_ptr->zstream.next_out = output;
-
-      do
-      {
-         uInt avail;
-         Byte local_buffer[PNG_INFLATE_BUF_SIZE];
-
-         /* zlib INPUT BUFFER */
-         /* The setting of 'avail_in' used to be outside the loop; by setting it
-          * inside it is possible to chunk the input to zlib and simply rely on
-          * zlib to advance the 'next_in' pointer.  This allows arbitrary
-          * amounts of data to be passed through zlib at the unavoidable cost of
-          * requiring a window save (memcpy of up to 32768 output bytes)
-          * every ZLIB_IO_MAX input bytes.
-          */
-         avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
-
-         avail = ZLIB_IO_MAX;
-
-         if (avail_in < avail)
-            avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
-
-         avail_in -= avail;
-         png_ptr->zstream.avail_in = avail;
-
-         /* zlib OUTPUT BUFFER */
-         avail_out += png_ptr->zstream.avail_out; /* not written last time */
-
-         avail = ZLIB_IO_MAX; /* maximum zlib can process */
-
-         if (output == NULL)
-         {
-            /* Reset the output buffer each time round if output is NULL and
-             * make available the full buffer, up to 'remaining_space'
-             */
-            png_ptr->zstream.next_out = local_buffer;
-            if ((sizeof local_buffer) < avail)
-               avail = (sizeof local_buffer);
-         }
-
-         if (avail_out < avail)
-            avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
-
-         png_ptr->zstream.avail_out = avail;
-         avail_out -= avail;
-
-         /* zlib inflate call */
-         /* In fact 'avail_out' may be 0 at this point, that happens at the end
-          * of the read when the final LZ end code was not passed at the end of
-          * the previous chunk of input data.  Tell zlib if we have reached the
-          * end of the output buffer.
-          */
-         ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH :
-            (finish ? Z_FINISH : Z_SYNC_FLUSH));
-      } while (ret == Z_OK);
-
-      /* For safety kill the local buffer pointer now */
-      if (output == NULL)
-         png_ptr->zstream.next_out = NULL;
-
-      /* Claw back the 'size' and 'remaining_space' byte counts. */
-      avail_in += png_ptr->zstream.avail_in;
-      avail_out += png_ptr->zstream.avail_out;
-
-      /* Update the input and output sizes; the updated values are the amount
-       * consumed or written, effectively the inverse of what zlib uses.
-       */
-      if (avail_out > 0)
-         *output_size_ptr -= avail_out;
-
-      if (avail_in > 0)
-         *input_size_ptr -= avail_in;
-
-      /* Ensure png_ptr->zstream.msg is set (even in the success case!) */
-      png_zstream_error(png_ptr, ret);
-      return ret;
-   }
-
-   else
-   {
-      /* This is a bad internal error.  The recovery assigns to the zstream msg
-       * pointer, which is not owned by the caller, but this is safe; it's only
-       * used on errors!
-       */
-      png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
-      return Z_STREAM_ERROR;
-   }
-}
-
 /*
- * Decompress trailing data in a chunk.  The assumption is that read_buffer
+ * Decompress trailing data in a chunk.  The assumption is that chunkdata
  * points at an allocated area holding the contents of a chunk with a
  * trailing compressed part.  What we get back is an allocated area
  * holding the original prefix part and an uncompressed version of the
  * trailing part (the malloc area passed in is freed).
  */
-static int
-png_decompress_chunk(png_structrp png_ptr,
-   png_uint_32 chunklength, png_uint_32 prefix_size,
-   png_alloc_size_t *newlength /* must be initialized to the maximum! */,
-   int terminate /*add a '\0' to the end of the uncompressed data*/)
+void /* PRIVATE */
+png_decompress_chunk(png_structp png_ptr, int comp_type,
+    png_size_t chunklength,
+    png_size_t prefix_size, png_size_t *newlength)
 {
-   /* TODO: implement different limits for different types of chunk.
-    *
-    * The caller supplies *newlength set to the maximum length of the
-    * uncompressed data, but this routine allocates space for the prefix and
-    * maybe a '\0' terminator too.  We have to assume that 'prefix_size' is
-    * limited only by the maximum chunk size.
+   /* The caller should guarantee this */
+   if (prefix_size > chunklength)
+   {
+      /* The recovery is to delete the chunk. */
+      png_warning(png_ptr, "invalid chunklength");
+      prefix_size = 0; /* To delete everything */
+   }
+
+   else if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+   {
+      png_size_t expanded_size = png_inflate(png_ptr,
+                (png_bytep)(png_ptr->chunkdata + prefix_size),
+                chunklength - prefix_size,
+                0/*output*/, 0/*output size*/);
+
+      /* Now check the limits on this chunk - if the limit fails the
+       * compressed data will be removed, the prefix will remain.
+       */
+#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+      if (png_ptr->user_chunk_malloc_max &&
+          (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))
+#else
+#  ifdef PNG_USER_CHUNK_MALLOC_MAX
+      if ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
+          prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
+#  endif
+#endif
+         png_warning(png_ptr, "Exceeded size limit while expanding chunk");
+
+      /* If the size is zero either there was an error and a message
+       * has already been output (warning) or the size really is zero
+       * and we have nothing to do - the code will exit through the
+       * error case below.
+       */
+#if defined(PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED) || \
+    defined(PNG_USER_CHUNK_MALLOC_MAX)
+      else
+#endif
+      if (expanded_size > 0)
+      {
+         /* Success (maybe) - really uncompress the chunk. */
+         png_size_t new_size = 0;
+         png_charp text = NULL;
+         /* Need to check for both truncation (64-bit platforms) and integer
+          * overflow.
+          */
+         if (prefix_size + expanded_size > prefix_size &&
+             prefix_size + expanded_size < 0xffffffffU)
+         {
+            text = png_malloc_warn(png_ptr, prefix_size + expanded_size + 1);
+         }
+
+         if (text != NULL)
+         {
+            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+            new_size = png_inflate(png_ptr,
+                (png_bytep)(png_ptr->chunkdata + prefix_size),
+                chunklength - prefix_size,
+                (png_bytep)(text + prefix_size), expanded_size);
+            text[prefix_size + expanded_size] = 0; /* just in case */
+
+            if (new_size == expanded_size)
+            {
+               png_free(png_ptr, png_ptr->chunkdata);
+               png_ptr->chunkdata = text;
+               *newlength = prefix_size + expanded_size;
+               return; /* The success return! */
+            }
+
+            png_warning(png_ptr, "png_inflate logic error");
+            png_free(png_ptr, text);
+         }
+         else
+          png_warning(png_ptr, "Not enough memory to decompress chunk.");
+      }
+   }
+
+   else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */
+   {
+#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
+      char umsg[50];
+
+      png_snprintf(umsg, sizeof umsg, "Unknown zTXt compression type %d",
+          comp_type);
+      png_warning(png_ptr, umsg);
+#else
+      png_warning(png_ptr, "Unknown zTXt compression type");
+#endif
+
+      /* The recovery is to simply drop the data. */
+   }
+
+   /* Generic error return - leave the prefix, delete the compressed
+    * data, reallocate the chunkdata to remove the potentially large
+    * amount of compressed data.
     */
-   png_alloc_size_t limit = PNG_SIZE_MAX;
-
-#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
-      if (png_ptr->user_chunk_malloc_max > 0 &&
-         png_ptr->user_chunk_malloc_max < limit)
-         limit = png_ptr->user_chunk_malloc_max;
-#  elif PNG_USER_CHUNK_MALLOC_MAX > 0
-      if (PNG_USER_CHUNK_MALLOC_MAX < limit)
-         limit = PNG_USER_CHUNK_MALLOC_MAX;
-#  endif
-
-   if (limit >= prefix_size + (terminate != 0))
-   {
-      int ret;
-
-      limit -= prefix_size + (terminate != 0);
-
-      if (limit < *newlength)
-         *newlength = limit;
-
-      /* Now try to claim the stream. */
-      ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
-
-      if (ret == Z_OK)
-      {
-         png_uint_32 lzsize = chunklength - prefix_size;
-
-         ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
-            /* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
-            /* output: */ NULL, newlength);
-
-         if (ret == Z_STREAM_END)
-         {
-            /* Use 'inflateReset' here, not 'inflateReset2' because this
-             * preserves the previously decided window size (otherwise it would
-             * be necessary to store the previous window size.)  In practice
-             * this doesn't matter anyway, because png_inflate will call inflate
-             * with Z_FINISH in almost all cases, so the window will not be
-             * maintained.
-             */
-            if (inflateReset(&png_ptr->zstream) == Z_OK)
-            {
-               /* Because of the limit checks above we know that the new,
-                * expanded, size will fit in a size_t (let alone an
-                * png_alloc_size_t).  Use png_malloc_base here to avoid an
-                * extra OOM message.
-                */
-               png_alloc_size_t new_size = *newlength;
-               png_alloc_size_t buffer_size = prefix_size + new_size +
-                  (terminate != 0);
-               png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
-                  buffer_size));
-
-               if (text != NULL)
-               {
-                  ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
-                     png_ptr->read_buffer + prefix_size, &lzsize,
-                     text + prefix_size, newlength);
-
-                  if (ret == Z_STREAM_END)
-                  {
-                     if (new_size == *newlength)
-                     {
-                        if (terminate)
-                           text[prefix_size + *newlength] = 0;
-
-                        if (prefix_size > 0)
-                           memcpy(text, png_ptr->read_buffer, prefix_size);
-
-                        {
-                           png_bytep old_ptr = png_ptr->read_buffer;
-
-                           png_ptr->read_buffer = text;
-                           png_ptr->read_buffer_size = buffer_size;
-                           text = old_ptr; /* freed below */
-                        }
-                     }
-
-                     else
-                     {
-                        /* The size changed on the second read, there can be no
-                         * guarantee that anything is correct at this point.
-                         * The 'msg' pointer has been set to "unexpected end of
-                         * LZ stream", which is fine, but return an error code
-                         * that the caller won't accept.
-                         */
-                        ret = PNG_UNEXPECTED_ZLIB_RETURN;
-                     }
-                  }
-
-                  else if (ret == Z_OK)
-                     ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
-
-                  /* Free the text pointer (this is the old read_buffer on
-                   * success)
-                   */
-                  png_free(png_ptr, text);
-
-                  /* This really is very benign, but it's still an error because
-                   * the extra space may otherwise be used as a Trojan Horse.
-                   */
-                  if (ret == Z_STREAM_END &&
-                     chunklength - prefix_size != lzsize)
-                     png_chunk_benign_error(png_ptr, "extra compressed data");
-               }
-
-               else
-               {
-                  /* Out of memory allocating the buffer */
-                  ret = Z_MEM_ERROR;
-                  png_zstream_error(png_ptr, Z_MEM_ERROR);
-               }
-            }
-
-            else
-            {
-               /* inflateReset failed, store the error message */
-               png_zstream_error(png_ptr, ret);
-
-               if (ret == Z_STREAM_END)
-                  ret = PNG_UNEXPECTED_ZLIB_RETURN;
-            }
-         }
-
-         else if (ret == Z_OK)
-            ret = PNG_UNEXPECTED_ZLIB_RETURN;
-
-         /* Release the claimed stream */
-         png_ptr->zowner = 0;
-      }
-
-      else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
-         ret = PNG_UNEXPECTED_ZLIB_RETURN;
-
-      return ret;
-   }
-
-   else
-   {
-      /* Application/configuration limits exceeded */
-      png_zstream_error(png_ptr, Z_MEM_ERROR);
-      return Z_MEM_ERROR;
-   }
-}
-#endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
-
-#ifdef PNG_READ_iCCP_SUPPORTED
-/* Perform a partial read and decompress, producing 'avail_out' bytes and
- * reading from the current chunk as required.
- */
-static int
-png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
-   png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
-   int finish)
-{
-   if (png_ptr->zowner == png_ptr->chunk_name)
-   {
-      int ret;
-
-      /* next_in and avail_in must have been initialized by the caller. */
-      png_ptr->zstream.next_out = next_out;
-      png_ptr->zstream.avail_out = 0; /* set in the loop */
-
-      do
-      {
-         if (png_ptr->zstream.avail_in == 0)
-         {
-            if (read_size > *chunk_bytes)
-               read_size = (uInt)*chunk_bytes;
-            *chunk_bytes -= read_size;
-
-            if (read_size > 0)
-               png_crc_read(png_ptr, read_buffer, read_size);
-
-            png_ptr->zstream.next_in = read_buffer;
-            png_ptr->zstream.avail_in = read_size;
-         }
-
-         if (png_ptr->zstream.avail_out == 0)
-         {
-            uInt avail = ZLIB_IO_MAX;
-            if (avail > *out_size)
-               avail = (uInt)*out_size;
-            *out_size -= avail;
-
-            png_ptr->zstream.avail_out = avail;
-         }
-
-         /* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
-          * the available output is produced; this allows reading of truncated
-          * streams.
-          */
-         ret = inflate(&png_ptr->zstream,
-            *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
-      }
-      while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
-
-      *out_size += png_ptr->zstream.avail_out;
-      png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
-
-      /* Ensure the error message pointer is always set: */
-      png_zstream_error(png_ptr, ret);
-      return ret;
-   }
-
-   else
-   {
-      png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
-      return Z_STREAM_ERROR;
-   }
+   {
+      png_charp text = png_malloc_warn(png_ptr, prefix_size + 1);
+      if (text != NULL)
+      {
+         if (prefix_size > 0)
+            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+         png_free(png_ptr, png_ptr->chunkdata);
+         png_ptr->chunkdata = text;
+
+         /* This is an extra zero in the 'uncompressed' part. */
+         *(png_ptr->chunkdata + prefix_size) = 0x00;
+      }
+      /* Ignore a malloc error here - it is safe. */
+   }
+
+   *newlength = prefix_size;
 }
 #endif
 
 /* Read and check the IDHR chunk */
 void /* PRIVATE */
-png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte buf[13];
    png_uint_32 width, height;
    int bit_depth, color_type, compression_type, filter_type;
    int interlace_type;
 
    png_debug(1, "in png_handle_IHDR");
 
    if (png_ptr->mode & PNG_HAVE_IHDR)
-      png_chunk_error(png_ptr, "out of place");
+      png_error(png_ptr, "Out of place IHDR");
 
    /* Check the length */
    if (length != 13)
-      png_chunk_error(png_ptr, "invalid");
+      png_error(png_ptr, "Invalid IHDR chunk");
 
    png_ptr->mode |= PNG_HAVE_IHDR;
 
    png_crc_read(png_ptr, buf, 13);
    png_crc_finish(png_ptr, 0);
 
    width = png_get_uint_31(png_ptr, buf);
    height = png_get_uint_31(png_ptr, buf + 4);
    bit_depth = buf[8];
    color_type = buf[9];
    compression_type = buf[10];
    filter_type = buf[11];
    interlace_type = buf[12];
 
    /* Set internal variables */
    png_ptr->width = width;
    png_ptr->height = height;
    png_ptr->bit_depth = (png_byte)bit_depth;
    png_ptr->interlaced = (png_byte)interlace_type;
    png_ptr->color_type = (png_byte)color_type;
 #ifdef PNG_MNG_FEATURES_SUPPORTED
    png_ptr->filter_type = (png_byte)filter_type;
 #endif
    png_ptr->compression_type = (png_byte)compression_type;
 
    /* Find number of channels */
    switch (png_ptr->color_type)
    {
-      default: /* invalid, png_set_IHDR calls png_error */
       case PNG_COLOR_TYPE_GRAY:
       case PNG_COLOR_TYPE_PALETTE:
          png_ptr->channels = 1;
          break;
 
       case PNG_COLOR_TYPE_RGB:
          png_ptr->channels = 3;
          break;
 
       case PNG_COLOR_TYPE_GRAY_ALPHA:
          png_ptr->channels = 2;
          break;
 
       case PNG_COLOR_TYPE_RGB_ALPHA:
          png_ptr->channels = 4;
          break;
    }
 
    /* Set up other useful info */
    png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
    png_ptr->channels);
    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
    png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
    png_debug1(3, "channels = %d", png_ptr->channels);
-   png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
+   png_debug1(3, "rowbytes = %lu", png_ptr->rowbytes);
    png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
-       color_type, interlace_type, compression_type, filter_type);
+      color_type, interlace_type, compression_type, filter_type);
 }
 
 /* Read and check the palette */
 void /* PRIVATE */
-png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_color palette[PNG_MAX_PALETTE_LENGTH];
    int num, i;
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
    png_colorp pal_ptr;
 #endif
 
    png_debug(1, "in png_handle_PLTE");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
-   /* Moved to before the 'after IDAT' check below because otherwise duplicate
-    * PLTE chunks are potentially ignored (the spec says there shall not be more
-    * than one PLTE, the error is not treated as benign, so this check trumps
-    * the requirement that PLTE appears before IDAT.)
-    */
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      png_chunk_error(png_ptr, "duplicate");
+      png_error(png_ptr, "Missing IHDR before PLTE");
 
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-      /* This is benign because the non-benign error happened before, when an
-       * IDAT was encountered in a color-mapped image with no PLTE.
-       */
+      png_warning(png_ptr, "Invalid PLTE after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      png_error(png_ptr, "Duplicate PLTE chunk");
+
    png_ptr->mode |= PNG_HAVE_PLTE;
 
-   if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
    {
+      png_warning(png_ptr,
+        "Ignoring PLTE chunk in grayscale PNG");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
       return;
    }
-
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
    if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
    {
       png_crc_finish(png_ptr, length);
       return;
    }
 #endif
 
    if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
    {
-      png_crc_finish(png_ptr, length);
-
       if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
-         png_chunk_benign_error(png_ptr, "invalid");
+      {
+         png_warning(png_ptr, "Invalid palette chunk");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
 
       else
-         png_chunk_error(png_ptr, "invalid");
-
-      return;
+      {
+         png_error(png_ptr, "Invalid palette chunk");
+      }
    }
 
-   /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
    num = (int)length / 3;
 
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
    for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
    {
       png_byte buf[3];
 
       png_crc_read(png_ptr, buf, 3);
       pal_ptr->red = buf[0];
       pal_ptr->green = buf[1];
       pal_ptr->blue = buf[2];
    }
 #else
    for (i = 0; i < num; i++)
    {
       png_byte buf[3];
 
       png_crc_read(png_ptr, buf, 3);
       /* Don't depend upon png_color being any order */
       palette[i].red = buf[0];
       palette[i].green = buf[1];
       palette[i].blue = buf[2];
    }
 #endif
 
-   /* If we actually need the PLTE chunk (ie for a paletted image), we do
+   /* If we actually NEED the PLTE chunk (ie for a paletted image), we do
     * whatever the normal CRC configuration tells us.  However, if we
     * have an RGB image, the PLTE can be considered ancillary, so
     * we will act as though it is.
     */
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 #endif
    {
       png_crc_finish(png_ptr, 0);
    }
-
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
    else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
    {
       /* If we don't want to use the data from an ancillary chunk,
-       * we have two options: an error abort, or a warning and we
-       * ignore the data in this chunk (which should be OK, since
-       * it's considered ancillary for a RGB or RGBA image).
-       *
-       * IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
-       * chunk type to determine whether to check the ancillary or the critical
-       * flags.
-       */
+         we have two options: an error abort, or a warning and we
+         ignore the data in this chunk (which should be OK, since
+         it's considered ancillary for a RGB or RGBA image). */
       if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
       {
          if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
          {
-            png_chunk_benign_error(png_ptr, "CRC error");
+            png_chunk_error(png_ptr, "CRC error");
          }
-
          else
          {
             png_chunk_warning(png_ptr, "CRC error");
             return;
          }
       }
-
       /* Otherwise, we (optionally) emit a warning and use the chunk. */
       else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
       {
          png_chunk_warning(png_ptr, "CRC error");
       }
    }
 #endif
 
-   /* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
-    * own copy of the palette.  This has the side effect that when png_start_row
-    * is called (this happens after any call to png_read_update_info) the
-    * info_ptr palette gets changed.  This is extremely unexpected and
-    * confusing.
-    *
-    * Fix this by not sharing the palette in this way.
-    */
    png_set_PLTE(png_ptr, info_ptr, palette, num);
 
-   /* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
-    * IDAT.  Prior to 1.6.0 this was not checked; instead the code merely
-    * checked the apparent validity of a tRNS chunk inserted before PLTE on a
-    * palette PNG.  1.6.0 attempts to rigorously follow the standard and
-    * therefore does a benign error if the erroneous condition is detected *and*
-    * cancels the tRNS if the benign error returns.  The alternative is to
-    * amend the standard since it would be rather hypocritical of the standards
-    * maintainers to ignore it.
-    */
 #ifdef PNG_READ_tRNS_SUPPORTED
-   if (png_ptr->num_trans > 0 ||
-      (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
+   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
-      /* Cancel this because otherwise it would be used if the transforms
-       * require it.  Don't cancel the 'valid' flag because this would prevent
-       * detection of duplicate chunks.
-       */
-      png_ptr->num_trans = 0;
-
-      if (info_ptr != NULL)
-         info_ptr->num_trans = 0;
-
-      png_chunk_benign_error(png_ptr, "tRNS must be after");
+      if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+      {
+         if (png_ptr->num_trans > (png_uint_16)num)
+         {
+            png_warning(png_ptr, "Truncating incorrect tRNS chunk length");
+            png_ptr->num_trans = (png_uint_16)num;
+         }
+         if (info_ptr->num_trans > (png_uint_16)num)
+         {
+            png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");
+            info_ptr->num_trans = (png_uint_16)num;
+         }
+      }
    }
 #endif
 
-#ifdef PNG_READ_hIST_SUPPORTED
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
-      png_chunk_benign_error(png_ptr, "hIST must be after");
-#endif
-
-#ifdef PNG_READ_bKGD_SUPPORTED
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
-      png_chunk_benign_error(png_ptr, "bKGD must be after");
-#endif
 }
 
 void /* PRIVATE */
-png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_debug(1, "in png_handle_IEND");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
-      png_chunk_error(png_ptr, "out of place");
+   {
+      png_error(png_ptr, "No image in file");
+   }
 
    png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
 
+   if (length != 0)
+   {
+      png_warning(png_ptr, "Incorrect IEND chunk length");
+   }
    png_crc_finish(png_ptr, length);
 
-   if (length != 0)
-      png_chunk_benign_error(png_ptr, "invalid");
-
-   PNG_UNUSED(info_ptr)
+   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
 }
 
 #ifdef PNG_READ_gAMA_SUPPORTED
 void /* PRIVATE */
-png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_fixed_point igamma;
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   float file_gamma;
+#endif
    png_byte buf[4];
 
    png_debug(1, "in png_handle_gAMA");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
+      png_error(png_ptr, "Missing IHDR before gAMA");
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid gAMA after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place gAMA chunk");
 
-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
+#ifdef PNG_READ_sRGB_SUPPORTED
+      && !(info_ptr->valid & PNG_INFO_sRGB)
+#endif
+      )
    {
+      png_warning(png_ptr, "Duplicate gAMA chunk");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
    if (length != 4)
    {
+      png_warning(png_ptr, "Incorrect gAMA chunk length");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 4);
-
    if (png_crc_finish(png_ptr, 0))
       return;
 
-   igamma = png_get_fixed_point(NULL, buf);
+   igamma = (png_fixed_point)png_get_uint_32(buf);
+   /* Check for zero gamma */
+   if (igamma == 0)
+      {
+         png_warning(png_ptr,
+           "Ignoring gAMA chunk with gamma=0");
+         return;
+      }
 
-   png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
-   png_colorspace_sync(png_ptr, info_ptr);
+#ifdef PNG_READ_sRGB_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
+      if (PNG_OUT_OF_RANGE(igamma, 45500L, 500))
+      {
+         png_warning(png_ptr,
+           "Ignoring incorrect gAMA value when sRGB is also present");
+#ifdef PNG_CONSOLE_IO_SUPPORTED
+         fprintf(stderr, "gamma = (%d/100000)", (int)igamma);
+#endif
+         return;
+      }
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   file_gamma = (float)igamma / (float)100000.0;
+#  ifdef PNG_READ_GAMMA_SUPPORTED
+     png_ptr->gamma = file_gamma;
+#  endif
+     png_set_gAMA(png_ptr, info_ptr, file_gamma);
+#endif
+#ifdef PNG_FIXED_POINT_SUPPORTED
+   png_set_gAMA_fixed(png_ptr, info_ptr, igamma);
+#endif
 }
 #endif
 
 #ifdef PNG_READ_sBIT_SUPPORTED
 void /* PRIVATE */
-png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   unsigned int truelen;
+   png_size_t truelen;
    png_byte buf[4];
 
    png_debug(1, "in png_handle_sBIT");
 
    buf[0] = buf[1] = buf[2] = buf[3] = 0;
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+      png_error(png_ptr, "Missing IHDR before sBIT");
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid sBIT after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+   {
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place sBIT chunk");
+   }
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
    {
+      png_warning(png_ptr, "Duplicate sBIT chunk");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       truelen = 3;
-
    else
-      truelen = png_ptr->channels;
+      truelen = (png_size_t)png_ptr->channels;
 
    if (length != truelen || length > 4)
    {
-      png_chunk_benign_error(png_ptr, "invalid");
+      png_warning(png_ptr, "Incorrect sBIT chunk length");
       png_crc_finish(png_ptr, length);
       return;
    }
 
    png_crc_read(png_ptr, buf, truelen);
-
    if (png_crc_finish(png_ptr, 0))
       return;
 
    if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
    {
       png_ptr->sig_bit.red = buf[0];
       png_ptr->sig_bit.green = buf[1];
       png_ptr->sig_bit.blue = buf[2];
       png_ptr->sig_bit.alpha = buf[3];
    }
-
    else
    {
       png_ptr->sig_bit.gray = buf[0];
       png_ptr->sig_bit.red = buf[0];
       png_ptr->sig_bit.green = buf[0];
       png_ptr->sig_bit.blue = buf[0];
       png_ptr->sig_bit.alpha = buf[1];
    }
-
    png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
 }
 #endif
 
 #ifdef PNG_READ_cHRM_SUPPORTED
 void /* PRIVATE */
-png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte buf[32];
-   png_xy xy;
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   float white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y;
+#endif
+   png_fixed_point int_x_white, int_y_white, int_x_red, int_y_red, int_x_green,
+      int_y_green, int_x_blue, int_y_blue;
+
+   png_uint_32 uint_x, uint_y;
 
    png_debug(1, "in png_handle_cHRM");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
-   {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
+      png_error(png_ptr, "Missing IHDR before cHRM");
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid cHRM after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Missing PLTE before cHRM");
+
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)
+#ifdef PNG_READ_sRGB_SUPPORTED
+      && !(info_ptr->valid & PNG_INFO_sRGB)
+#endif
+      )
+   {
+      png_warning(png_ptr, "Duplicate cHRM chunk");
+      png_crc_finish(png_ptr, length);
       return;
    }
 
    if (length != 32)
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
+      png_warning(png_ptr, "Incorrect cHRM chunk length");
+      png_crc_finish(png_ptr, length);
       return;
    }
 
    png_crc_read(png_ptr, buf, 32);
-
    if (png_crc_finish(png_ptr, 0))
       return;
 
-   xy.whitex = png_get_fixed_point(NULL, buf);
-   xy.whitey = png_get_fixed_point(NULL, buf + 4);
-   xy.redx   = png_get_fixed_point(NULL, buf + 8);
-   xy.redy   = png_get_fixed_point(NULL, buf + 12);
-   xy.greenx = png_get_fixed_point(NULL, buf + 16);
-   xy.greeny = png_get_fixed_point(NULL, buf + 20);
-   xy.bluex  = png_get_fixed_point(NULL, buf + 24);
-   xy.bluey  = png_get_fixed_point(NULL, buf + 28);
-
-   if (xy.whitex == PNG_FIXED_ERROR ||
-       xy.whitey == PNG_FIXED_ERROR ||
-       xy.redx   == PNG_FIXED_ERROR ||
-       xy.redy   == PNG_FIXED_ERROR ||
-       xy.greenx == PNG_FIXED_ERROR ||
-       xy.greeny == PNG_FIXED_ERROR ||
-       xy.bluex  == PNG_FIXED_ERROR ||
-       xy.bluey  == PNG_FIXED_ERROR)
-   {
-      png_chunk_benign_error(png_ptr, "invalid values");
-      return;
-   }
-
-   /* If a colorspace error has already been output skip this chunk */
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
-      return;
-
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM)
-   {
-      png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
-      png_colorspace_sync(png_ptr, info_ptr);
-      png_chunk_benign_error(png_ptr, "duplicate");
-      return;
-   }
-
-   png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
-   (void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
-      1/*prefer cHRM values*/);
-   png_colorspace_sync(png_ptr, info_ptr);
+   uint_x = png_get_uint_32(buf);
+   uint_y = png_get_uint_32(buf + 4);
+   int_x_white = (png_fixed_point)uint_x;
+   int_y_white = (png_fixed_point)uint_y;
+
+   uint_x = png_get_uint_32(buf + 8);
+   uint_y = png_get_uint_32(buf + 12);
+   int_x_red = (png_fixed_point)uint_x;
+   int_y_red = (png_fixed_point)uint_y;
+
+   uint_x = png_get_uint_32(buf + 16);
+   uint_y = png_get_uint_32(buf + 20);
+   int_x_green = (png_fixed_point)uint_x;
+   int_y_green = (png_fixed_point)uint_y;
+
+   uint_x = png_get_uint_32(buf + 24);
+   uint_y = png_get_uint_32(buf + 28);
+   int_x_blue = (png_fixed_point)uint_x;
+   int_y_blue = (png_fixed_point)uint_y;
+
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   white_x = (float)int_x_white / (float)100000.0;
+   white_y = (float)int_y_white / (float)100000.0;
+   red_x   = (float)int_x_red   / (float)100000.0;
+   red_y   = (float)int_y_red   / (float)100000.0;
+   green_x = (float)int_x_green / (float)100000.0;
+   green_y = (float)int_y_green / (float)100000.0;
+   blue_x  = (float)int_x_blue  / (float)100000.0;
+   blue_y  = (float)int_y_blue  / (float)100000.0;
+#endif
+
+#ifdef PNG_READ_sRGB_SUPPORTED
+   if ((info_ptr != NULL) && (info_ptr->valid & PNG_INFO_sRGB))
+      {
+      if (PNG_OUT_OF_RANGE(int_x_white, 31270,  1000) ||
+          PNG_OUT_OF_RANGE(int_y_white, 32900,  1000) ||
+          PNG_OUT_OF_RANGE(int_x_red,   64000L, 1000) ||
+          PNG_OUT_OF_RANGE(int_y_red,   33000,  1000) ||
+          PNG_OUT_OF_RANGE(int_x_green, 30000,  1000) ||
+          PNG_OUT_OF_RANGE(int_y_green, 60000L, 1000) ||
+          PNG_OUT_OF_RANGE(int_x_blue,  15000,  1000) ||
+          PNG_OUT_OF_RANGE(int_y_blue,   6000,  1000))
+         {
+            png_warning(png_ptr,
+              "Ignoring incorrect cHRM value when sRGB is also present");
+#ifdef PNG_CONSOLE_IO_SUPPORTED
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+            fprintf(stderr, "wx=%f, wy=%f, rx=%f, ry=%f\n",
+               white_x, white_y, red_x, red_y);
+            fprintf(stderr, "gx=%f, gy=%f, bx=%f, by=%f\n",
+               green_x, green_y, blue_x, blue_y);
+#else
+            fprintf(stderr, "wx=%ld, wy=%ld, rx=%ld, ry=%ld\n",
+               (long)int_x_white, (long)int_y_white,
+               (long)int_x_red, (long)int_y_red);
+            fprintf(stderr, "gx=%ld, gy=%ld, bx=%ld, by=%ld\n",
+               (long)int_x_green, (long)int_y_green,
+               (long)int_x_blue, (long)int_y_blue);
+#endif
+#endif /* PNG_CONSOLE_IO_SUPPORTED */
+         }
+         return;
+      }
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   png_set_cHRM(png_ptr, info_ptr,
+      white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y);
+#endif
+#ifdef PNG_FIXED_POINT_SUPPORTED
+   png_set_cHRM_fixed(png_ptr, info_ptr,
+      int_x_white, int_y_white, int_x_red, int_y_red, int_x_green,
+      int_y_green, int_x_blue, int_y_blue);
+#endif
 }
 #endif
 
 #ifdef PNG_READ_sRGB_SUPPORTED
 void /* PRIVATE */
-png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_byte intent;
+   int intent;
+   png_byte buf[1];
 
    png_debug(1, "in png_handle_sRGB");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
-   {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
+      png_error(png_ptr, "Missing IHDR before sRGB");
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid sRGB after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place sRGB chunk");
+
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
+   {
+      png_warning(png_ptr, "Duplicate sRGB chunk");
+      png_crc_finish(png_ptr, length);
       return;
    }
 
    if (length != 1)
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
-      return;
-   }
-
-   png_crc_read(png_ptr, &intent, 1);
-
+      png_warning(png_ptr, "Incorrect sRGB chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, 1);
    if (png_crc_finish(png_ptr, 0))
       return;
 
-   /* If a colorspace error has already been output skip this chunk */
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
-      return;
-
-   /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
-    * this.
-    */
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT)
-   {
-      png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
-      png_colorspace_sync(png_ptr, info_ptr);
-      png_chunk_benign_error(png_ptr, "too many profiles");
-      return;
-   }
-
-   (void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
-   png_colorspace_sync(png_ptr, info_ptr);
+   intent = buf[0];
+   /* Check for bad intent */
+   if (intent >= PNG_sRGB_INTENT_LAST)
+   {
+      png_warning(png_ptr, "Unknown sRGB intent");
+      return;
+   }
+
+#if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA))
+   {
+   png_fixed_point igamma;
+#ifdef PNG_FIXED_POINT_SUPPORTED
+      igamma=info_ptr->int_gamma;
+#else
+#  ifdef PNG_FLOATING_POINT_SUPPORTED
+      igamma=(png_fixed_point)(info_ptr->gamma * 100000.);
+#  endif
+#endif
+      if (PNG_OUT_OF_RANGE(igamma, 45500L, 500))
+      {
+         png_warning(png_ptr,
+           "Ignoring incorrect gAMA value when sRGB is also present");
+#ifdef PNG_CONSOLE_IO_SUPPORTED
+#  ifdef PNG_FIXED_POINT_SUPPORTED
+         fprintf(stderr, "incorrect gamma=(%d/100000)\n",
+            (int)png_ptr->int_gamma);
+#  else
+#    ifdef PNG_FLOATING_POINT_SUPPORTED
+         fprintf(stderr, "incorrect gamma=%f\n", png_ptr->gamma);
+#    endif
+#  endif
+#endif
+      }
+   }
+#endif /* PNG_READ_gAMA_SUPPORTED */
+
+#ifdef PNG_READ_cHRM_SUPPORTED
+#ifdef PNG_FIXED_POINT_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
+      if (PNG_OUT_OF_RANGE(info_ptr->int_x_white, 31270,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->int_y_white, 32900,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->int_x_red,   64000L, 1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->int_y_red,   33000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->int_x_green, 30000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->int_y_green, 60000L, 1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->int_x_blue,  15000,  1000) ||
+          PNG_OUT_OF_RANGE(info_ptr->int_y_blue,   6000,  1000))
+         {
+            png_warning(png_ptr,
+              "Ignoring incorrect cHRM value when sRGB is also present");
+         }
+#endif /* PNG_FIXED_POINT_SUPPORTED */
+#endif /* PNG_READ_cHRM_SUPPORTED */
+
+   png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);
 }
 #endif /* PNG_READ_sRGB_SUPPORTED */
 
 #ifdef PNG_READ_iCCP_SUPPORTED
 void /* PRIVATE */
-png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
-/* Note: this does not properly handle profiles that are > 64K under DOS */
+png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+/* Note: this does not properly handle chunks that are > 64K under DOS */
 {
-   png_const_charp errmsg = NULL; /* error message output, or no error */
-   int finished = 0; /* crc checked */
+   png_byte compression_type;
+   png_bytep pC;
+   png_charp profile;
+   png_uint_32 skip = 0;
+   png_uint_32 profile_size, profile_length;
+   png_size_t slength, prefix_length, data_length;
 
    png_debug(1, "in png_handle_iCCP");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
-   {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
-      return;
-   }
-
-   /* Consistent with all the above colorspace handling an obviously *invalid*
-    * chunk is just ignored, so does not invalidate the color space.  An
-    * alternative is to set the 'invalid' flags at the start of this routine
-    * and only clear them in they were not set before and all the tests pass.
-    * The minimum 'deflate' stream is assumed to be just the 2 byte header and 4
-    * byte checksum.  The keyword must be one character and there is a
-    * terminator (0) byte and the compression method.
+      png_error(png_ptr, "Missing IHDR before iCCP");
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid iCCP after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place iCCP chunk");
+
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP))
+   {
+      png_warning(png_ptr, "Duplicate iCCP chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+#ifdef PNG_MAX_MALLOC_64K
+   if (length > (png_uint_32)65535L)
+   {
+      png_warning(png_ptr, "iCCP chunk too large to fit in memory");
+      skip = length - (png_uint_32)65535L;
+      length = (png_uint_32)65535L;
+   }
+#endif
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
+   slength = (png_size_t)length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, skip))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   png_ptr->chunkdata[slength] = 0x00;
+
+   for (profile = png_ptr->chunkdata; *profile; profile++)
+      /* Empty loop to find end of name */ ;
+
+   ++profile;
+
+   /* There should be at least one zero (the compression type byte)
+    * following the separator, and we should be on it
     */
-   if (length < 9)
-   {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "too short");
-      return;
-   }
-
-   /* If a colorspace error has already been output skip this chunk */
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
-   {
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
-    * this.
-    */
-   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
-   {
-      uInt read_length, keyword_length;
-      char keyword[81];
-
-      /* Find the keyword; the keyword plus separator and compression method
-       * bytes can be at most 81 characters long.
-       */
-      read_length = 81; /* maximum */
-      if (read_length > length)
-         read_length = (uInt)length;
-
-      png_crc_read(png_ptr, (png_bytep)keyword, read_length);
-      length -= read_length;
-
-      keyword_length = 0;
-      while (keyword_length < 80 && keyword_length < read_length &&
-         keyword[keyword_length] != 0)
-         ++keyword_length;
-
-      /* TODO: make the keyword checking common */
-      if (keyword_length >= 1 && keyword_length <= 79)
-      {
-         /* We only understand '0' compression - deflate - so if we get a
-          * different value we can't safely decode the chunk.
-          */
-         if (keyword_length+1 < read_length &&
-            keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
-         {
-            read_length -= keyword_length+2;
-
-            if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
-            {
-               Byte profile_header[132];
-               Byte local_buffer[PNG_INFLATE_BUF_SIZE];
-               png_alloc_size_t size = (sizeof profile_header);
-
-               png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
-               png_ptr->zstream.avail_in = read_length;
-               (void)png_inflate_read(png_ptr, local_buffer,
-                  (sizeof local_buffer), &length, profile_header, &size,
-                  0/*finish: don't, because the output is too small*/);
-
-               if (size == 0)
-               {
-                  /* We have the ICC profile header; do the basic header checks.
-                   */
-                  const png_uint_32 profile_length =
-                     png_get_uint_32(profile_header);
-
-                  if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
-                     keyword, profile_length))
-                  {
-                     /* The length is apparently ok, so we can check the 132
-                      * byte header.
-                      */
-                     if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
-                        keyword, profile_length, profile_header,
-                        png_ptr->color_type))
-                     {
-                        /* Now read the tag table; a variable size buffer is
-                         * needed at this point, allocate one for the whole
-                         * profile.  The header check has already validated
-                         * that none of these stuff will overflow.
-                         */
-                        const png_uint_32 tag_count = png_get_uint_32(
-                           profile_header+128);
-                        png_bytep profile = png_read_buffer(png_ptr,
-                           profile_length, 2/*silent*/);
-
-                        if (profile != NULL)
-                        {
-                           memcpy(profile, profile_header,
-                              (sizeof profile_header));
-
-                           size = 12 * tag_count;
-
-                           (void)png_inflate_read(png_ptr, local_buffer,
-                              (sizeof local_buffer), &length,
-                              profile + (sizeof profile_header), &size, 0);
-
-                           /* Still expect a a buffer error because we expect
-                            * there to be some tag data!
-                            */
-                           if (size == 0)
-                           {
-                              if (png_icc_check_tag_table(png_ptr,
-                                 &png_ptr->colorspace, keyword, profile_length,
-                                 profile))
-                              {
-                                 /* The profile has been validated for basic
-                                  * security issues, so read the whole thing in.
-                                  */
-                                 size = profile_length - (sizeof profile_header)
-                                    - 12 * tag_count;
-
-                                 (void)png_inflate_read(png_ptr, local_buffer,
-                                    (sizeof local_buffer), &length,
-                                    profile + (sizeof profile_header) +
-                                    12 * tag_count, &size, 1/*finish*/);
-
-                                 if (length > 0 && !(png_ptr->flags &
-                                       PNG_FLAG_BENIGN_ERRORS_WARN))
-                                    errmsg = "extra compressed data";
-
-                                 /* But otherwise allow extra data: */
-                                 else if (size == 0)
-                                 {
-                                    if (length > 0)
-                                    {
-                                       /* This can be handled completely, so
-                                        * keep going.
-                                        */
-                                       png_chunk_warning(png_ptr,
-                                          "extra compressed data");
-                                    }
-
-                                    png_crc_finish(png_ptr, length);
-                                    finished = 1;
-
-#                                   ifdef PNG_sRGB_SUPPORTED
-                                       /* Check for a match against sRGB */
-                                       png_icc_set_sRGB(png_ptr,
-                                          &png_ptr->colorspace, profile,
-                                          png_ptr->zstream.adler);
-#                                   endif
-
-                                    /* Steal the profile for info_ptr. */
-                                    if (info_ptr != NULL)
-                                    {
-                                       png_free_data(png_ptr, info_ptr,
-                                          PNG_FREE_ICCP, 0);
-
-                                       info_ptr->iccp_name = png_voidcast(char*,
-                                          png_malloc_base(png_ptr,
-                                          keyword_length+1));
-                                       if (info_ptr->iccp_name != NULL)
-                                       {
-                                          memcpy(info_ptr->iccp_name, keyword,
-                                             keyword_length+1);
-                                          info_ptr->iccp_proflen =
-                                             profile_length;
-                                          info_ptr->iccp_profile = profile;
-                                          png_ptr->read_buffer = NULL; /*steal*/
-                                          info_ptr->free_me |= PNG_FREE_ICCP;
-                                          info_ptr->valid |= PNG_INFO_iCCP;
-                                       }
-
-                                       else
-                                       {
-                                          png_ptr->colorspace.flags |=
-                                             PNG_COLORSPACE_INVALID;
-                                          errmsg = "out of memory";
-                                       }
-                                    }
-
-                                    /* else the profile remains in the read
-                                     * buffer which gets reused for subsequent
-                                     * chunks.
-                                     */
-
-                                    if (info_ptr != NULL)
-                                       png_colorspace_sync(png_ptr, info_ptr);
-
-                                    if (errmsg == NULL)
-                                    {
-                                       png_ptr->zowner = 0;
-                                       return;
-                                    }
-                                 }
-
-                                 else if (size > 0)
-                                    errmsg = "truncated";
-
-                                 else
-                                    errmsg = png_ptr->zstream.msg;
-                              }
-
-                              /* else png_icc_check_tag_table output an error */
-                           }
-
-                           else /* profile truncated */
-                              errmsg = png_ptr->zstream.msg;
-                        }
-
-                        else
-                           errmsg = "out of memory";
-                     }
-
-                     /* else png_icc_check_header output an error */
-                  }
-
-                  /* else png_icc_check_length output an error */
-               }
-
-               else /* profile truncated */
-                  errmsg = png_ptr->zstream.msg;
-
-               /* Release the stream */
-               png_ptr->zowner = 0;
-            }
-
-            else /* png_inflate_claim failed */
-               errmsg = png_ptr->zstream.msg;
-         }
-
-         else
-            errmsg = "bad compression method"; /* or missing */
-      }
-
-      else
-         errmsg = "bad keyword";
-   }
-
-   else
-      errmsg = "too many profiles";
-
-   /* Failure: the reason is in 'errmsg' */
-   if (!finished)
-      png_crc_finish(png_ptr, length);
-
-   png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
-   png_colorspace_sync(png_ptr, info_ptr);
-   if (errmsg != NULL) /* else already output */
-      png_chunk_benign_error(png_ptr, errmsg);
+   if ( profile >= png_ptr->chunkdata + slength - 1)
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "Malformed iCCP chunk");
+      return;
+   }
+
+   /* Compression_type should always be zero */
+   compression_type = *profile++;
+   if (compression_type)
+   {
+      png_warning(png_ptr, "Ignoring nonzero compression type in iCCP chunk");
+      compression_type = 0x00;  /* Reset it to zero (libpng-1.0.6 through 1.0.8
+                                 wrote nonzero) */
+   }
+
+   prefix_length = profile - png_ptr->chunkdata;
+   png_decompress_chunk(png_ptr, compression_type,
+     slength, prefix_length, &data_length);
+
+   profile_length = data_length - prefix_length;
+
+   if ( prefix_length > data_length || profile_length < 4)
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "Profile size field missing from iCCP chunk");
+      return;
+   }
+
+   /* Check the profile_size recorded in the first 32 bits of the ICC profile */
+   pC = (png_bytep)(png_ptr->chunkdata + prefix_length);
+   profile_size = ((*(pC    ))<<24) |
+                  ((*(pC + 1))<<16) |
+                  ((*(pC + 2))<< 8) |
+                  ((*(pC + 3))    );
+
+   if (profile_size < profile_length)
+      profile_length = profile_size;
+
+   if (profile_size > profile_length)
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "Ignoring truncated iCCP profile.");
+      return;
+   }
+
+   png_set_iCCP(png_ptr, info_ptr, png_ptr->chunkdata,
+     compression_type, png_ptr->chunkdata + prefix_length, profile_length);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
 }
 #endif /* PNG_READ_iCCP_SUPPORTED */
 
 #ifdef PNG_READ_sPLT_SUPPORTED
 void /* PRIVATE */
-png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 {
-   png_bytep entry_start, buffer;
+   png_bytep entry_start;
    png_sPLT_t new_palette;
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
    png_sPLT_entryp pp;
-   png_uint_32 data_length;
-   int entry_size, i;
+#endif
+   int data_length, entry_size, i;
    png_uint_32 skip = 0;
-   png_uint_32 dl;
-   png_size_t max_dl;
+   png_size_t slength;
 
    png_debug(1, "in png_handle_sPLT");
 
 #ifdef PNG_USER_LIMITS_SUPPORTED
+
    if (png_ptr->user_chunk_cache_max != 0)
    {
       if (png_ptr->user_chunk_cache_max == 1)
       {
          png_crc_finish(png_ptr, length);
          return;
       }
-
       if (--png_ptr->user_chunk_cache_max == 1)
       {
          png_warning(png_ptr, "No space in chunk cache for sPLT");
          png_crc_finish(png_ptr, length);
          return;
       }
    }
 #endif
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
+      png_error(png_ptr, "Missing IHDR before sPLT");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid sPLT after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
 
 #ifdef PNG_MAX_MALLOC_64K
-   if (length > 65535U)
+   if (length > (png_uint_32)65535L)
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "too large to fit in memory");
-      return;
+      png_warning(png_ptr, "sPLT chunk too large to fit in memory");
+      skip = length - (png_uint_32)65535L;
+      length = (png_uint_32)65535L;
    }
 #endif
 
-   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
-   if (buffer == NULL)
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
+   slength = (png_size_t)length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, skip))
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of memory");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
+   png_ptr->chunkdata[slength] = 0x00;
 
-   /* WARNING: this may break if size_t is less than 32 bits; it is assumed
-    * that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
-    * potential breakage point if the types in pngconf.h aren't exactly right.
-    */
-   png_crc_read(png_ptr, buffer, length);
-
-   if (png_crc_finish(png_ptr, skip))
-      return;
-
-   buffer[length] = 0;
-
-   for (entry_start = buffer; *entry_start; entry_start++)
+   for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start;
+       entry_start++)
       /* Empty loop to find end of name */ ;
-
    ++entry_start;
 
    /* A sample depth should follow the separator, and we should be on it  */
-   if (entry_start > buffer + length - 2)
+   if (entry_start > (png_bytep)png_ptr->chunkdata + slength - 2)
    {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "malformed sPLT chunk");
       return;
    }
 
    new_palette.depth = *entry_start++;
    entry_size = (new_palette.depth == 8 ? 6 : 10);
-   /* This must fit in a png_uint_32 because it is derived from the original
-    * chunk data length.
-    */
-   data_length = length - (png_uint_32)(entry_start - buffer);
+   data_length = (slength - (entry_start - (png_bytep)png_ptr->chunkdata));
 
    /* Integrity-check the data length */
    if (data_length % entry_size)
    {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "sPLT chunk has bad length");
       return;
    }
 
-   dl = (png_int_32)(data_length / entry_size);
-   max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
-
-   if (dl > max_dl)
+   new_palette.nentries = (png_int_32) ( data_length / entry_size);
+   if ((png_uint_32) new_palette.nentries >
+       (png_uint_32) (PNG_SIZE_MAX / png_sizeof(png_sPLT_entry)))
    {
        png_warning(png_ptr, "sPLT chunk too long");
        return;
    }
-
-   new_palette.nentries = (png_int_32)(data_length / entry_size);
-
    new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
-       png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
-
+       png_ptr, new_palette.nentries * png_sizeof(png_sPLT_entry));
    if (new_palette.entries == NULL)
    {
        png_warning(png_ptr, "sPLT chunk requires too much memory");
        return;
    }
 
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
    for (i = 0; i < new_palette.nentries; i++)
    {
       pp = new_palette.entries + i;
 
       if (new_palette.depth == 8)
       {
-         pp->red = *entry_start++;
-         pp->green = *entry_start++;
-         pp->blue = *entry_start++;
-         pp->alpha = *entry_start++;
+          pp->red = *entry_start++;
+          pp->green = *entry_start++;
+          pp->blue = *entry_start++;
+          pp->alpha = *entry_start++;
       }
-
       else
       {
-         pp->red   = png_get_uint_16(entry_start); entry_start += 2;
-         pp->green = png_get_uint_16(entry_start); entry_start += 2;
-         pp->blue  = png_get_uint_16(entry_start); entry_start += 2;
-         pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
+          pp->red   = png_get_uint_16(entry_start); entry_start += 2;
+          pp->green = png_get_uint_16(entry_start); entry_start += 2;
+          pp->blue  = png_get_uint_16(entry_start); entry_start += 2;
+          pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
       }
-
       pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
    }
 #else
    pp = new_palette.entries;
-
    for (i = 0; i < new_palette.nentries; i++)
    {
 
       if (new_palette.depth == 8)
       {
-         pp[i].red   = *entry_start++;
-         pp[i].green = *entry_start++;
-         pp[i].blue  = *entry_start++;
-         pp[i].alpha = *entry_start++;
+          pp[i].red   = *entry_start++;
+          pp[i].green = *entry_start++;
+          pp[i].blue  = *entry_start++;
+          pp[i].alpha = *entry_start++;
       }
-
       else
       {
-         pp[i].red   = png_get_uint_16(entry_start); entry_start += 2;
-         pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
-         pp[i].blue  = png_get_uint_16(entry_start); entry_start += 2;
-         pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
+          pp[i].red   = png_get_uint_16(entry_start); entry_start += 2;
+          pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
+          pp[i].blue  = png_get_uint_16(entry_start); entry_start += 2;
+          pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
       }
-
-      pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
+      pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
    }
 #endif
 
    /* Discard all chunk data except the name and stash that */
-   new_palette.name = (png_charp)buffer;
+   new_palette.name = png_ptr->chunkdata;
 
    png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
 
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
    png_free(png_ptr, new_palette.entries);
 }
 #endif /* PNG_READ_sPLT_SUPPORTED */
 
 #ifdef PNG_READ_tRNS_SUPPORTED
 void /* PRIVATE */
-png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
 
    png_debug(1, "in png_handle_tRNS");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
+      png_error(png_ptr, "Missing IHDR before tRNS");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid tRNS after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
+      return;
+   }
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+   {
+      png_warning(png_ptr, "Duplicate tRNS chunk");
+      png_crc_finish(png_ptr, length);
       return;
    }
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
-   {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
-      return;
-   }
-
    if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
    {
       png_byte buf[2];
 
       if (length != 2)
       {
+         png_warning(png_ptr, "Incorrect tRNS chunk length");
          png_crc_finish(png_ptr, length);
-         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
 
       png_crc_read(png_ptr, buf, 2);
       png_ptr->num_trans = 1;
-      png_ptr->trans_color.gray = png_get_uint_16(buf);
+      png_ptr->trans_values.gray = png_get_uint_16(buf);
    }
-
    else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
    {
       png_byte buf[6];
 
       if (length != 6)
       {
+         png_warning(png_ptr, "Incorrect tRNS chunk length");
          png_crc_finish(png_ptr, length);
-         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
-
-      png_crc_read(png_ptr, buf, length);
+      png_crc_read(png_ptr, buf, (png_size_t)length);
       png_ptr->num_trans = 1;
-      png_ptr->trans_color.red = png_get_uint_16(buf);
-      png_ptr->trans_color.green = png_get_uint_16(buf + 2);
-      png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
+      png_ptr->trans_values.red = png_get_uint_16(buf);
+      png_ptr->trans_values.green = png_get_uint_16(buf + 2);
+      png_ptr->trans_values.blue = png_get_uint_16(buf + 4);
    }
-
    else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
       if (!(png_ptr->mode & PNG_HAVE_PLTE))
       {
-         /* TODO: is this actually an error in the ISO spec? */
+         /* Should be an error, but we can cope with it. */
+         png_warning(png_ptr, "Missing PLTE before tRNS");
+      }
+      if (length > (png_uint_32)png_ptr->num_palette ||
+          length > PNG_MAX_PALETTE_LENGTH)
+      {
+         png_warning(png_ptr, "Incorrect tRNS chunk length");
          png_crc_finish(png_ptr, length);
-         png_chunk_benign_error(png_ptr, "out of place");
          return;
       }
-
-      if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH ||
-         length == 0)
+      if (length == 0)
       {
+         png_warning(png_ptr, "Zero length tRNS chunk");
          png_crc_finish(png_ptr, length);
-         png_chunk_benign_error(png_ptr, "invalid");
          return;
       }
-
-      png_crc_read(png_ptr, readbuf, length);
+      png_crc_read(png_ptr, readbuf, (png_size_t)length);
       png_ptr->num_trans = (png_uint_16)length;
    }
-
    else
    {
+      png_warning(png_ptr, "tRNS chunk not allowed with alpha channel");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid with alpha channel");
       return;
    }
 
    if (png_crc_finish(png_ptr, 0))
    {
       png_ptr->num_trans = 0;
       return;
    }
 
-   /* TODO: this is a horrible side effect in the palette case because the
-    * png_struct ends up with a pointer to the tRNS buffer owned by the
-    * png_info.  Fix this.
-    */
    png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
-       &(png_ptr->trans_color));
+      &(png_ptr->trans_values));
 }
 #endif
 
 #ifdef PNG_READ_bKGD_SUPPORTED
 void /* PRIVATE */
-png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   unsigned int truelen;
+   png_size_t truelen;
    png_byte buf[6];
-   png_color_16 background;
 
    png_debug(1, "in png_handle_bKGD");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
-   else if ((png_ptr->mode & PNG_HAVE_IDAT) ||
-      (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-       !(png_ptr->mode & PNG_HAVE_PLTE)))
+      png_error(png_ptr, "Missing IHDR before bKGD");
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid bKGD after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-
+   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+            !(png_ptr->mode & PNG_HAVE_PLTE))
+   {
+      png_warning(png_ptr, "Missing PLTE before bKGD");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
    {
+      png_warning(png_ptr, "Duplicate bKGD chunk");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       truelen = 1;
-
    else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
       truelen = 6;
-
    else
       truelen = 2;
 
    if (length != truelen)
    {
+      png_warning(png_ptr, "Incorrect bKGD chunk length");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, truelen);
-
    if (png_crc_finish(png_ptr, 0))
       return;
 
    /* We convert the index value into RGB components so that we can allow
     * arbitrary RGB values for background when we have transparency, and
     * so it is easy to determine the RGB values of the background color
-    * from the info_ptr struct.
-    */
+    * from the info_ptr struct. */
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
-      background.index = buf[0];
-
+      png_ptr->background.index = buf[0];
       if (info_ptr && info_ptr->num_palette)
       {
-         if (buf[0] >= info_ptr->num_palette)
-         {
-            png_chunk_benign_error(png_ptr, "invalid index");
-            return;
-         }
-
-         background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
-         background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
-         background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
+          if (buf[0] >= info_ptr->num_palette)
+          {
+             png_warning(png_ptr, "Incorrect bKGD chunk index value");
+             return;
+          }
+          png_ptr->background.red =
+             (png_uint_16)png_ptr->palette[buf[0]].red;
+          png_ptr->background.green =
+             (png_uint_16)png_ptr->palette[buf[0]].green;
+          png_ptr->background.blue =
+             (png_uint_16)png_ptr->palette[buf[0]].blue;
       }
-
-      else
-         background.red = background.green = background.blue = 0;
-
-      background.gray = 0;
+   }
+   else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
+   {
+      png_ptr->background.red =
+      png_ptr->background.green =
+      png_ptr->background.blue =
+      png_ptr->background.gray = png_get_uint_16(buf);
+   }
+   else
+   {
+      png_ptr->background.red = png_get_uint_16(buf);
+      png_ptr->background.green = png_get_uint_16(buf + 2);
+      png_ptr->background.blue = png_get_uint_16(buf + 4);
    }
 
-   else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
-   {
-      background.index = 0;
-      background.red =
-      background.green =
-      background.blue =
-      background.gray = png_get_uint_16(buf);
-   }
-
-   else
-   {
-      background.index = 0;
-      background.red = png_get_uint_16(buf);
-      background.green = png_get_uint_16(buf + 2);
-      background.blue = png_get_uint_16(buf + 4);
-      background.gray = 0;
-   }
-
-   png_set_bKGD(png_ptr, info_ptr, &background);
+   png_set_bKGD(png_ptr, info_ptr, &(png_ptr->background));
 }
 #endif
 
 #ifdef PNG_READ_hIST_SUPPORTED
 void /* PRIVATE */
-png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    unsigned int num, i;
    png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
 
    png_debug(1, "in png_handle_hIST");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
-   else if ((png_ptr->mode & PNG_HAVE_IDAT) || !(png_ptr->mode & PNG_HAVE_PLTE))
+      png_error(png_ptr, "Missing IHDR before hIST");
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid hIST after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-
+   else if (!(png_ptr->mode & PNG_HAVE_PLTE))
+   {
+      png_warning(png_ptr, "Missing PLTE before hIST");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
    {
+      png_warning(png_ptr, "Duplicate hIST chunk");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    num = length / 2 ;
-
-   if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH)
+   if (num != (unsigned int) png_ptr->num_palette || num >
+      (unsigned int) PNG_MAX_PALETTE_LENGTH)
    {
+      png_warning(png_ptr, "Incorrect hIST chunk length");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    for (i = 0; i < num; i++)
    {
       png_byte buf[2];
 
       png_crc_read(png_ptr, buf, 2);
       readbuf[i] = png_get_uint_16(buf);
    }
 
    if (png_crc_finish(png_ptr, 0))
       return;
 
    png_set_hIST(png_ptr, info_ptr, readbuf);
 }
 #endif
 
 #ifdef PNG_READ_pHYs_SUPPORTED
 void /* PRIVATE */
-png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte buf[9];
    png_uint_32 res_x, res_y;
    int unit_type;
 
    png_debug(1, "in png_handle_pHYs");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
+      png_error(png_ptr, "Missing IHDR before pHYs");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid pHYs after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
    {
+      png_warning(png_ptr, "Duplicate pHYs chunk");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (length != 9)
    {
+      png_warning(png_ptr, "Incorrect pHYs chunk length");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 9);
-
    if (png_crc_finish(png_ptr, 0))
       return;
 
    res_x = png_get_uint_32(buf);
    res_y = png_get_uint_32(buf + 4);
    unit_type = buf[8];
    png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
 }
 #endif
 
 #ifdef PNG_READ_oFFs_SUPPORTED
 void /* PRIVATE */
-png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte buf[9];
    png_int_32 offset_x, offset_y;
    int unit_type;
 
    png_debug(1, "in png_handle_oFFs");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
+      png_error(png_ptr, "Missing IHDR before oFFs");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid oFFs after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
    {
+      png_warning(png_ptr, "Duplicate oFFs chunk");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (length != 9)
    {
+      png_warning(png_ptr, "Incorrect oFFs chunk length");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 9);
-
    if (png_crc_finish(png_ptr, 0))
       return;
 
    offset_x = png_get_int_32(buf);
    offset_y = png_get_int_32(buf + 4);
    unit_type = buf[8];
    png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
 }
 #endif
 
 #ifdef PNG_READ_pCAL_SUPPORTED
 /* Read the pCAL chunk (described in the PNG Extensions document) */
 void /* PRIVATE */
-png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_int_32 X0, X1;
    png_byte type, nparams;
-   png_bytep buffer, buf, units, endptr;
+   png_charp buf, units, endptr;
    png_charpp params;
+   png_size_t slength;
    int i;
 
    png_debug(1, "in png_handle_pCAL");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
+      png_error(png_ptr, "Missing IHDR before pCAL");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid pCAL after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
+      return;
+   }
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
+   {
+      png_warning(png_ptr, "Duplicate pCAL chunk");
+      png_crc_finish(png_ptr, length);
       return;
    }
 
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
+   png_debug1(2, "Allocating and reading pCAL chunk data (%lu bytes)",
+      length + 1);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
+     {
+       png_warning(png_ptr, "No memory for pCAL purpose.");
+       return;
+     }
+   slength = (png_size_t)length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+
+   if (png_crc_finish(png_ptr, 0))
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
-       length + 1);
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
-   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
+   png_debug(3, "Finding end of pCAL purpose string");
+   for (buf = png_ptr->chunkdata; *buf; buf++)
+      /* Empty loop */ ;
 
-   if (buffer == NULL)
+   endptr = png_ptr->chunkdata + slength;
+
+   /* We need to have at least 12 bytes after the purpose string
+      in order to get the parameter information. */
+   if (endptr <= buf + 12)
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of memory");
+      png_warning(png_ptr, "Invalid pCAL data");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   png_crc_read(png_ptr, buffer, length);
-
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   buffer[length] = 0; /* Null terminate the last string */
-
-   png_debug(3, "Finding end of pCAL purpose string");
-   for (buf = buffer; *buf; buf++)
-      /* Empty loop */ ;
-
-   endptr = buffer + length;
-
-   /* We need to have at least 12 bytes after the purpose string
-    * in order to get the parameter information.
-    */
-   if (endptr <= buf + 12)
-   {
-      png_chunk_benign_error(png_ptr, "invalid");
-      return;
-   }
-
    png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
    X0 = png_get_int_32((png_bytep)buf+1);
    X1 = png_get_int_32((png_bytep)buf+5);
    type = buf[9];
    nparams = buf[10];
    units = buf + 11;
 
    png_debug(3, "Checking pCAL equation type and number of parameters");
    /* Check that we have the right number of parameters for known
-    * equation types.
-    */
+      equation types. */
    if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
        (type == PNG_EQUATION_BASE_E && nparams != 3) ||
        (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
        (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
    {
-      png_chunk_benign_error(png_ptr, "invalid parameter count");
+      png_warning(png_ptr, "Invalid pCAL parameters for equation type");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
-
    else if (type >= PNG_EQUATION_LAST)
    {
-      png_chunk_benign_error(png_ptr, "unrecognized equation type");
+      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
    }
 
    for (buf = units; *buf; buf++)
       /* Empty loop to move past the units string. */ ;
 
    png_debug(3, "Allocating pCAL parameters array");
-
-   params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
-       nparams * (sizeof (png_charp))));
-
+   params = (png_charpp)png_malloc_warn(png_ptr,
+      (png_uint_32)(nparams * png_sizeof(png_charp))) ;
    if (params == NULL)
-   {
-      png_chunk_benign_error(png_ptr, "out of memory");
-      return;
-   }
+     {
+       png_free(png_ptr, png_ptr->chunkdata);
+       png_ptr->chunkdata = NULL;
+       png_warning(png_ptr, "No memory for pCAL params.");
+       return;
+     }
 
    /* Get pointers to the start of each parameter string. */
-   for (i = 0; i < nparams; i++)
+   for (i = 0; i < (int)nparams; i++)
    {
       buf++; /* Skip the null string terminator from previous parameter. */
 
       png_debug1(3, "Reading pCAL parameter %d", i);
-
-      for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
+      for (params[i] = buf; buf <= endptr && *buf != 0x00; buf++)
          /* Empty loop to move past each parameter string */ ;
 
       /* Make sure we haven't run out of data yet */
       if (buf > endptr)
       {
+         png_warning(png_ptr, "Invalid pCAL data");
+         png_free(png_ptr, png_ptr->chunkdata);
+         png_ptr->chunkdata = NULL;
          png_free(png_ptr, params);
-         png_chunk_benign_error(png_ptr, "invalid data");
          return;
       }
    }
 
-   png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
-      (png_charp)units, params);
+   png_set_pCAL(png_ptr, info_ptr, png_ptr->chunkdata, X0, X1, type, nparams,
+      units, params);
 
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
    png_free(png_ptr, params);
 }
 #endif
 
 #ifdef PNG_READ_sCAL_SUPPORTED
 /* Read the sCAL chunk */
 void /* PRIVATE */
-png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_bytep buffer;
-   png_size_t i;
-   int state;
+   png_charp ep;
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   double width, height;
+   png_charp vp;
+#else
+#ifdef PNG_FIXED_POINT_SUPPORTED
+   png_charp swidth, sheight;
+#endif
+#endif
+   png_size_t slength;
 
    png_debug(1, "in png_handle_sCAL");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
+      png_error(png_ptr, "Missing IHDR before sCAL");
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
+      png_warning(png_ptr, "Invalid sCAL after IDAT");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of place");
       return;
    }
-
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
    {
+      png_warning(png_ptr, "Duplicate sCAL chunk");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    /* Need unit type, width, \0, height: minimum 4 bytes */
    else if (length < 4)
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
-      return;
-   }
-
-   png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
-      length + 1);
-
-   buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
-
-   if (buffer == NULL)
-   {
-      png_chunk_benign_error(png_ptr, "out of memory");
+      png_warning(png_ptr, "sCAL chunk too short");
       png_crc_finish(png_ptr, length);
       return;
    }
 
-   png_crc_read(png_ptr, buffer, length);
-   buffer[length] = 0; /* Null terminate the last string */
+   png_debug1(2, "Allocating and reading sCAL chunk data (%lu bytes)",
+      length + 1);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
+   {
+      png_warning(png_ptr, "Out of memory while processing sCAL chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+   slength = (png_size_t)length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, 0))
-      return;
-
-   /* Validate the unit. */
-   if (buffer[0] != 1 && buffer[0] != 2)
    {
-      png_chunk_benign_error(png_ptr, "invalid unit");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   /* Validate the ASCII numbers, need two ASCII numbers separated by
-    * a '\0' and they need to fit exactly in the chunk data.
-    */
-   i = 1;
-   state = 0;
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
-   if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
-       i >= length || buffer[i++] != 0)
-      png_chunk_benign_error(png_ptr, "bad width format");
+   ep = png_ptr->chunkdata + 1;        /* Skip unit byte */
 
-   else if (!PNG_FP_IS_POSITIVE(state))
-      png_chunk_benign_error(png_ptr, "non-positive width");
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   width = png_strtod(png_ptr, ep, &vp);
+   if (*vp)
+   {
+      png_warning(png_ptr, "malformed width string in sCAL chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+#else
+#ifdef PNG_FIXED_POINT_SUPPORTED
+   swidth = (png_charp)png_malloc_warn(png_ptr, png_strlen(ep) + 1);
+   if (swidth == NULL)
+   {
+      png_warning(png_ptr, "Out of memory while processing sCAL chunk width");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+   png_memcpy(swidth, ep, (png_size_t)png_strlen(ep));
+#endif
+#endif
 
-   else
+   for (ep = png_ptr->chunkdata; *ep; ep++)
+      /* Empty loop */ ;
+   ep++;
+
+   if (png_ptr->chunkdata + slength < ep)
    {
-      png_size_t heighti = i;
+      png_warning(png_ptr, "Truncated sCAL chunk");
+#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
+      png_free(png_ptr, swidth);
+#endif
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
 
-      state = 0;
-      if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
-         i != length)
-         png_chunk_benign_error(png_ptr, "bad height format");
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   height = png_strtod(png_ptr, ep, &vp);
+   if (*vp)
+   {
+      png_warning(png_ptr, "malformed height string in sCAL chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
+      png_free(png_ptr, swidth);
+#endif
+      return;
+   }
+#else
+#ifdef PNG_FIXED_POINT_SUPPORTED
+   sheight = (png_charp)png_malloc_warn(png_ptr, png_strlen(ep) + 1);
+   if (sheight == NULL)
+   {
+      png_warning(png_ptr, "Out of memory while processing sCAL chunk height");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
+      png_free(png_ptr, swidth);
+#endif
+      return;
+   }
+   png_memcpy(sheight, ep, (png_size_t)png_strlen(ep));
+#endif
+#endif
 
-      else if (!PNG_FP_IS_POSITIVE(state))
-         png_chunk_benign_error(png_ptr, "non-positive height");
+   if (png_ptr->chunkdata + slength < ep
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+      || width <= 0. || height <= 0.
+#endif
+      )
+   {
+      png_warning(png_ptr, "Invalid sCAL data");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
+      png_free(png_ptr, swidth);
+      png_free(png_ptr, sheight);
+#endif
+      return;
+   }
 
-      else
-         /* This is the (only) success case. */
-         png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
-            (png_charp)buffer+1, (png_charp)buffer+heighti);
-   }
+
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+   png_set_sCAL(png_ptr, info_ptr, png_ptr->chunkdata[0], width, height);
+#else
+#ifdef PNG_FIXED_POINT_SUPPORTED
+   png_set_sCAL_s(png_ptr, info_ptr, png_ptr->chunkdata[0], swidth, sheight);
+#endif
+#endif
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
+   png_free(png_ptr, swidth);
+   png_free(png_ptr, sheight);
+#endif
 }
 #endif
 
 #ifdef PNG_READ_tIME_SUPPORTED
 void /* PRIVATE */
-png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte buf[7];
    png_time mod_time;
 
    png_debug(1, "in png_handle_tIME");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
-
+      png_error(png_ptr, "Out of place tIME chunk");
    else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
    {
+      png_warning(png_ptr, "Duplicate tIME chunk");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "duplicate");
       return;
    }
 
    if (png_ptr->mode & PNG_HAVE_IDAT)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
    if (length != 7)
    {
+      png_warning(png_ptr, "Incorrect tIME chunk length");
       png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "invalid");
       return;
    }
 
    png_crc_read(png_ptr, buf, 7);
-
    if (png_crc_finish(png_ptr, 0))
       return;
 
    mod_time.second = buf[6];
    mod_time.minute = buf[5];
    mod_time.hour = buf[4];
    mod_time.day = buf[3];
    mod_time.month = buf[2];
    mod_time.year = png_get_uint_16(buf);
 
    png_set_tIME(png_ptr, info_ptr, &mod_time);
 }
 #endif
 
 #ifdef PNG_READ_tEXt_SUPPORTED
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_text  text_info;
-   png_bytep buffer;
+   png_textp text_ptr;
    png_charp key;
    png_charp text;
    png_uint_32 skip = 0;
+   png_size_t slength;
+   int ret;
 
    png_debug(1, "in png_handle_tEXt");
 
 #ifdef PNG_USER_LIMITS_SUPPORTED
    if (png_ptr->user_chunk_cache_max != 0)
    {
       if (png_ptr->user_chunk_cache_max == 1)
       {
          png_crc_finish(png_ptr, length);
          return;
       }
-
       if (--png_ptr->user_chunk_cache_max == 1)
       {
+         png_warning(png_ptr, "No space in chunk cache for tEXt");
          png_crc_finish(png_ptr, length);
-         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 #endif
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
+      png_error(png_ptr, "Missing IHDR before tEXt");
 
    if (png_ptr->mode & PNG_HAVE_IDAT)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
 #ifdef PNG_MAX_MALLOC_64K
-   if (length > 65535U)
+   if (length > (png_uint_32)65535L)
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "too large to fit in memory");
-      return;
+      png_warning(png_ptr, "tEXt chunk too large to fit in memory");
+      skip = length - (png_uint_32)65535L;
+      length = (png_uint_32)65535L;
    }
 #endif
 
-   buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
+   png_free(png_ptr, png_ptr->chunkdata);
 
-   if (buffer == NULL)
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
    {
-     png_chunk_benign_error(png_ptr, "out of memory");
+     png_warning(png_ptr, "No memory to process text chunk.");
      return;
    }
-
-   png_crc_read(png_ptr, buffer, length);
+   slength = (png_size_t)length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, skip))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
+   }
 
-   key = (png_charp)buffer;
-   key[length] = 0;
+   key = png_ptr->chunkdata;
+
+   key[slength] = 0x00;
 
    for (text = key; *text; text++)
       /* Empty loop to find end of key */ ;
 
-   if (text != key + length)
+   if (text != key + slength)
       text++;
 
-   text_info.compression = PNG_TEXT_COMPRESSION_NONE;
-   text_info.key = key;
-   text_info.lang = NULL;
-   text_info.lang_key = NULL;
-   text_info.itxt_length = 0;
-   text_info.text = text;
-   text_info.text_length = strlen(text);
+   text_ptr = (png_textp)png_malloc_warn(png_ptr,
+      (png_uint_32)png_sizeof(png_text));
+   if (text_ptr == NULL)
+   {
+     png_warning(png_ptr, "Not enough memory to process text chunk.");
+     png_free(png_ptr, png_ptr->chunkdata);
+     png_ptr->chunkdata = NULL;
+     return;
+   }
+   text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
+   text_ptr->key = key;
+#ifdef PNG_iTXt_SUPPORTED
+   text_ptr->lang = NULL;
+   text_ptr->lang_key = NULL;
+   text_ptr->itxt_length = 0;
+#endif
+   text_ptr->text = text;
+   text_ptr->text_length = png_strlen(text);
 
-   if (png_set_text_2(png_ptr, info_ptr, &text_info, 1))
-      png_warning(png_ptr, "Insufficient memory to process text chunk");
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+   png_free(png_ptr, text_ptr);
+   if (ret)
+     png_warning(png_ptr, "Insufficient memory to process text chunk.");
 }
 #endif
 
 #ifdef PNG_READ_zTXt_SUPPORTED
 /* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_const_charp errmsg = NULL;
-   png_bytep       buffer;
-   png_uint_32     keyword_length;
+   png_textp text_ptr;
+   png_charp text;
+   int comp_type;
+   int ret;
+   png_size_t slength, prefix_len, data_len;
 
    png_debug(1, "in png_handle_zTXt");
 
 #ifdef PNG_USER_LIMITS_SUPPORTED
    if (png_ptr->user_chunk_cache_max != 0)
    {
       if (png_ptr->user_chunk_cache_max == 1)
       {
          png_crc_finish(png_ptr, length);
          return;
       }
-
       if (--png_ptr->user_chunk_cache_max == 1)
       {
+         png_warning(png_ptr, "No space in chunk cache for zTXt");
          png_crc_finish(png_ptr, length);
-         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 #endif
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
+      png_error(png_ptr, "Missing IHDR before zTXt");
 
    if (png_ptr->mode & PNG_HAVE_IDAT)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
-   buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
+#ifdef PNG_MAX_MALLOC_64K
+   /* We will no doubt have problems with chunks even half this size, but
+      there is no hard and fast rule to tell us where to stop. */
+   if (length > (png_uint_32)65535L)
+   {
+     png_warning(png_ptr, "zTXt chunk too large to fit in memory");
+     png_crc_finish(png_ptr, length);
+     return;
+   }
+#endif
 
-   if (buffer == NULL)
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
    {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of memory");
+     png_warning(png_ptr, "Out of memory processing zTXt chunk.");
+     return;
+   }
+   slength = (png_size_t)length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   if (png_crc_finish(png_ptr, 0))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   png_crc_read(png_ptr, buffer, length);
+   png_ptr->chunkdata[slength] = 0x00;
 
-   if (png_crc_finish(png_ptr, 0))
+   for (text = png_ptr->chunkdata; *text; text++)
+      /* Empty loop */ ;
+
+   /* zTXt must have some text after the chunkdataword */
+   if (text >= png_ptr->chunkdata + slength - 2)
+   {
+      png_warning(png_ptr, "Truncated zTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
-
-   /* TODO: also check that the keyword contents match the spec! */
-   for (keyword_length = 0;
-      keyword_length < length && buffer[keyword_length] != 0;
-      ++keyword_length)
-      /* Empty loop to find end of name */ ;
-
-   if (keyword_length > 79 || keyword_length < 1)
-      errmsg = "bad keyword";
-
-   /* zTXt must have some LZ data after the keyword, although it may expand to
-    * zero bytes; we need a '\0' at the end of the keyword, the compression type
-    * then the LZ data:
-    */
-   else if (keyword_length + 3 > length)
-      errmsg = "truncated";
-
-   else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
-      errmsg = "unknown compression type";
-
+   }
    else
    {
-      png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
+       comp_type = *(++text);
+       if (comp_type != PNG_TEXT_COMPRESSION_zTXt)
+       {
+          png_warning(png_ptr, "Unknown compression type in zTXt chunk");
+          comp_type = PNG_TEXT_COMPRESSION_zTXt;
+       }
+       text++;        /* Skip the compression_method byte */
+   }
+   prefix_len = text - png_ptr->chunkdata;
 
-      /* TODO: at present png_decompress_chunk imposes a single application
-       * level memory limit, this should be split to different values for iCCP
-       * and text chunks.
-       */
-      if (png_decompress_chunk(png_ptr, length, keyword_length+2,
-         &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
-      {
-         png_text text;
+   png_decompress_chunk(png_ptr, comp_type,
+     (png_size_t)length, prefix_len, &data_len);
 
-         /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
-          * for the extra compression type byte and the fact that it isn't
-          * necessarily '\0' terminated.
-          */
-         buffer = png_ptr->read_buffer;
-         buffer[uncompressed_length+(keyword_length+2)] = 0;
+   text_ptr = (png_textp)png_malloc_warn(png_ptr,
+      (png_uint_32)png_sizeof(png_text));
+   if (text_ptr == NULL)
+   {
+     png_warning(png_ptr, "Not enough memory to process zTXt chunk.");
+     png_free(png_ptr, png_ptr->chunkdata);
+     png_ptr->chunkdata = NULL;
+     return;
+   }
+   text_ptr->compression = comp_type;
+   text_ptr->key = png_ptr->chunkdata;
+#ifdef PNG_iTXt_SUPPORTED
+   text_ptr->lang = NULL;
+   text_ptr->lang_key = NULL;
+   text_ptr->itxt_length = 0;
+#endif
+   text_ptr->text = png_ptr->chunkdata + prefix_len;
+   text_ptr->text_length = data_len;
 
-         text.compression = PNG_TEXT_COMPRESSION_zTXt;
-         text.key = (png_charp)buffer;
-         text.text = (png_charp)(buffer + keyword_length+2);
-         text.text_length = uncompressed_length;
-         text.itxt_length = 0;
-         text.lang = NULL;
-         text.lang_key = NULL;
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
 
-         if (png_set_text_2(png_ptr, info_ptr, &text, 1))
-            errmsg = "insufficient memory";
-      }
-
-      else
-         errmsg = png_ptr->zstream.msg;
-   }
-
-   if (errmsg != NULL)
-      png_chunk_benign_error(png_ptr, errmsg);
+   png_free(png_ptr, text_ptr);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+   if (ret)
+     png_error(png_ptr, "Insufficient memory to store zTXt chunk.");
 }
 #endif
 
 #ifdef PNG_READ_iTXt_SUPPORTED
 /* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
-png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_const_charp errmsg = NULL;
-   png_bytep buffer;
-   png_uint_32 prefix_length;
+   png_textp text_ptr;
+   png_charp key, lang, text, lang_key;
+   int comp_flag;
+   int comp_type = 0;
+   int ret;
+   png_size_t slength, prefix_len, data_len;
 
    png_debug(1, "in png_handle_iTXt");
 
 #ifdef PNG_USER_LIMITS_SUPPORTED
    if (png_ptr->user_chunk_cache_max != 0)
    {
       if (png_ptr->user_chunk_cache_max == 1)
       {
          png_crc_finish(png_ptr, length);
          return;
       }
-
       if (--png_ptr->user_chunk_cache_max == 1)
       {
+         png_warning(png_ptr, "No space in chunk cache for iTXt");
          png_crc_finish(png_ptr, length);
-         png_chunk_benign_error(png_ptr, "no space in chunk cache");
          return;
       }
    }
 #endif
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_chunk_error(png_ptr, "missing IHDR");
+      png_error(png_ptr, "Missing IHDR before iTXt");
 
    if (png_ptr->mode & PNG_HAVE_IDAT)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
-   buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
-
-   if (buffer == NULL)
-   {
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "out of memory");
+#ifdef PNG_MAX_MALLOC_64K
+   /* We will no doubt have problems with chunks even half this size, but
+      there is no hard and fast rule to tell us where to stop. */
+   if (length > (png_uint_32)65535L)
+   {
+     png_warning(png_ptr, "iTXt chunk too large to fit in memory");
+     png_crc_finish(png_ptr, length);
+     return;
+   }
+#endif
+
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
+   {
+     png_warning(png_ptr, "No memory to process iTXt chunk.");
+     return;
+   }
+   slength = (png_size_t)length;
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
+   if (png_crc_finish(png_ptr, 0))
+   {
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   png_crc_read(png_ptr, buffer, length);
-
-   if (png_crc_finish(png_ptr, 0))
+   png_ptr->chunkdata[slength] = 0x00;
+
+   for (lang = png_ptr->chunkdata; *lang; lang++)
+      /* Empty loop */ ;
+   lang++;        /* Skip NUL separator */
+
+   /* iTXt must have a language tag (possibly empty), two compression bytes,
+    * translated keyword (possibly empty), and possibly some text after the
+    * keyword
+    */
+
+   if (lang >= png_ptr->chunkdata + slength - 3)
+   {
+      png_warning(png_ptr, "Truncated iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
-
-   /* First the keyword. */
-   for (prefix_length=0;
-      prefix_length < length && buffer[prefix_length] != 0;
-      ++prefix_length)
+   }
+   else
+   {
+       comp_flag = *lang++;
+       comp_type = *lang++;
+   }
+
+   for (lang_key = lang; *lang_key; lang_key++)
       /* Empty loop */ ;
-
-   /* Perform a basic check on the keyword length here. */
-   if (prefix_length > 79 || prefix_length < 1)
-      errmsg = "bad keyword";
-
-   /* Expect keyword, compression flag, compression type, language, translated
-    * keyword (both may be empty but are 0 terminated) then the text, which may
-    * be empty.
-    */
-   else if (prefix_length + 5 > length)
-      errmsg = "truncated";
-
-   else if (buffer[prefix_length+1] == 0 ||
-      (buffer[prefix_length+1] == 1 &&
-      buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
-   {
-      int compressed = buffer[prefix_length+1] != 0;
-      png_uint_32 language_offset, translated_keyword_offset;
-      png_alloc_size_t uncompressed_length = 0;
-
-      /* Now the language tag */
-      prefix_length += 3;
-      language_offset = prefix_length;
-
-      for (; prefix_length < length && buffer[prefix_length] != 0;
-         ++prefix_length)
-         /* Empty loop */ ;
-
-      /* WARNING: the length may be invalid here, this is checked below. */
-      translated_keyword_offset = ++prefix_length;
-
-      for (; prefix_length < length && buffer[prefix_length] != 0;
-         ++prefix_length)
-         /* Empty loop */ ;
-
-      /* prefix_length should now be at the trailing '\0' of the translated
-       * keyword, but it may already be over the end.  None of this arithmetic
-       * can overflow because chunks are at most 2^31 bytes long, but on 16-bit
-       * systems the available allocaton may overflow.
-       */
-      ++prefix_length;
-
-      if (!compressed && prefix_length <= length)
-         uncompressed_length = length - prefix_length;
-
-      else if (compressed && prefix_length < length)
+   lang_key++;        /* Skip NUL separator */
+
+   if (lang_key >= png_ptr->chunkdata + slength)
+   {
+      png_warning(png_ptr, "Truncated iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   for (text = lang_key; *text; text++)
+      /* Empty loop */ ;
+   text++;        /* Skip NUL separator */
+   if (text >= png_ptr->chunkdata + slength)
+   {
+      png_warning(png_ptr, "Malformed iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
+   prefix_len = text - png_ptr->chunkdata;
+
+   key=png_ptr->chunkdata;
+   if (comp_flag)
+       png_decompress_chunk(png_ptr, comp_type,
+         (size_t)length, prefix_len, &data_len);
+   else
+       data_len = png_strlen(png_ptr->chunkdata + prefix_len);
+   text_ptr = (png_textp)png_malloc_warn(png_ptr,
+      (png_uint_32)png_sizeof(png_text));
+   if (text_ptr == NULL)
+   {
+     png_warning(png_ptr, "Not enough memory to process iTXt chunk.");
+     png_free(png_ptr, png_ptr->chunkdata);
+     png_ptr->chunkdata = NULL;
+     return;
+   }
+   text_ptr->compression = (int)comp_flag + 1;
+   text_ptr->lang_key = png_ptr->chunkdata + (lang_key - key);
+   text_ptr->lang = png_ptr->chunkdata + (lang - key);
+   text_ptr->itxt_length = data_len;
+   text_ptr->text_length = 0;
+   text_ptr->key = png_ptr->chunkdata;
+   text_ptr->text = png_ptr->chunkdata + prefix_len;
+
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+
+   png_free(png_ptr, text_ptr);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
+   if (ret)
+     png_error(png_ptr, "Insufficient memory to store iTXt chunk.");
+}
+#endif
+
+/* This function is called when we haven't found a handler for a
+   chunk.  If there isn't a problem with the chunk itself (ie bad
+   chunk name, CRC, or a critical chunk), the chunk is silently ignored
+   -- unless the PNG_FLAG_UNKNOWN_CHUNKS_SUPPORTED flag is on in which
+   case it will be saved away to be written out later. */
+void /* PRIVATE */
+png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   png_uint_32 skip = 0;
+
+   png_debug(1, "in png_handle_unknown");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
       {
-         uncompressed_length = PNG_SIZE_MAX;
-
-         /* TODO: at present png_decompress_chunk imposes a single application
-          * level memory limit, this should be split to different values for
-          * iCCP and text chunks.
-          */
-         if (png_decompress_chunk(png_ptr, length, prefix_length,
-            &uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
-            buffer = png_ptr->read_buffer;
-
-         else
-            errmsg = png_ptr->zstream.msg;
+         png_crc_finish(png_ptr, length);
+         return;
       }
-
-      else
-         errmsg = "truncated";
-
-      if (errmsg == NULL)
+      if (--png_ptr->user_chunk_cache_max == 1)
       {
-         png_text text;
-
-         buffer[uncompressed_length+prefix_length] = 0;
-
-         if (compressed)
-            text.compression = PNG_ITXT_COMPRESSION_NONE;
-
-         else
-            text.compression = PNG_ITXT_COMPRESSION_zTXt;
-
-         text.key = (png_charp)buffer;
-         text.lang = (png_charp)buffer + language_offset;
-         text.lang_key = (png_charp)buffer + translated_keyword_offset;
-         text.text = (png_charp)buffer + prefix_length;
-         text.text_length = 0;
-         text.itxt_length = uncompressed_length;
-
-         if (png_set_text_2(png_ptr, info_ptr, &text, 1))
-            errmsg = "insufficient memory";
+         png_warning(png_ptr, "No space in chunk cache for unknown chunk");
+         png_crc_finish(png_ptr, length);
+         return;
       }
    }
-
+#endif
+
+   if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+#ifdef PNG_USE_LOCAL_ARRAYS
+      PNG_CONST PNG_IDAT;
+#endif
+      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))  /* Not an IDAT */
+         png_ptr->mode |= PNG_AFTER_IDAT;
+   }
+
+   if (!(png_ptr->chunk_name[0] & 0x20))
+   {
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+      if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
+           PNG_HANDLE_CHUNK_ALWAYS
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+           && png_ptr->read_user_chunk_fn == NULL
+#endif
+        )
+#endif
+          png_chunk_error(png_ptr, "unknown critical chunk");
+   }
+
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+   if ((png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+       || (png_ptr->read_user_chunk_fn != NULL)
+#endif
+        )
+   {
+#ifdef PNG_MAX_MALLOC_64K
+       if (length > (png_uint_32)65535L)
+       {
+           png_warning(png_ptr, "unknown chunk too large to fit in memory");
+           skip = length - (png_uint_32)65535L;
+           length = (png_uint_32)65535L;
+       }
+#endif
+       png_memcpy((png_charp)png_ptr->unknown_chunk.name,
+                  (png_charp)png_ptr->chunk_name,
+                  png_sizeof(png_ptr->unknown_chunk.name));
+       png_ptr->unknown_chunk.name[png_sizeof(png_ptr->unknown_chunk.name)-1]
+           = '\0';
+       png_ptr->unknown_chunk.size = (png_size_t)length;
+       if (length == 0)
+         png_ptr->unknown_chunk.data = NULL;
+       else
+       {
+         png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, length);
+         png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, length);
+       }
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+       if (png_ptr->read_user_chunk_fn != NULL)
+       {
+          /* Callback to user unknown chunk handler */
+          int ret;
+          ret = (*(png_ptr->read_user_chunk_fn))
+            (png_ptr, &png_ptr->unknown_chunk);
+          if (ret < 0)
+             png_chunk_error(png_ptr, "error in user chunk");
+          if (ret == 0)
+          {
+             if (!(png_ptr->chunk_name[0] & 0x20))
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+                if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
+                     PNG_HANDLE_CHUNK_ALWAYS)
+#endif
+                   png_chunk_error(png_ptr, "unknown critical chunk");
+             png_set_unknown_chunks(png_ptr, info_ptr,
+               &png_ptr->unknown_chunk, 1);
+          }
+       }
+       else
+#endif
+       png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
+       png_free(png_ptr, png_ptr->unknown_chunk.data);
+       png_ptr->unknown_chunk.data = NULL;
+   }
    else
-      errmsg = "bad compression info";
-
-   if (errmsg != NULL)
-      png_chunk_benign_error(png_ptr, errmsg);
+#endif
+      skip = length;
+
+   png_crc_finish(png_ptr, skip);
+
+#ifndef PNG_READ_USER_CHUNKS_SUPPORTED
+   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
+#endif
 }
-#endif
-
-#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
-/* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
-static int
-png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
+
+/* This function is called to verify that a chunk name is valid.
+   This function can't have the "critical chunk check" incorporated
+   into it, since in the future we will need to be able to call user
+   functions to handle unknown critical chunks after we check that
+   the chunk name itself is valid. */
+
+#define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
+
+void /* PRIVATE */
+png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
 {
-   png_alloc_size_t limit = PNG_SIZE_MAX;
-
-   if (png_ptr->unknown_chunk.data != NULL)
-   {
-      png_free(png_ptr, png_ptr->unknown_chunk.data);
-      png_ptr->unknown_chunk.data = NULL;
-   }
-
-#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
-      if (png_ptr->user_chunk_malloc_max > 0 &&
-         png_ptr->user_chunk_malloc_max < limit)
-         limit = png_ptr->user_chunk_malloc_max;
-
-#  elif PNG_USER_CHUNK_MALLOC_MAX > 0
-      if (PNG_USER_CHUNK_MALLOC_MAX < limit)
-         limit = PNG_USER_CHUNK_MALLOC_MAX;
-#  endif
-
-   if (length <= limit)
-   {
-      PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
-      /* The following is safe because of the PNG_SIZE_MAX init above */
-      png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
-      /* 'mode' is a flag array, only the bottom four bits matter here */
-      png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
-
-      if (length == 0)
-         png_ptr->unknown_chunk.data = NULL;
-
-      else
+   png_debug(1, "in png_check_chunk_name");
+   if (isnonalpha(chunk_name[0]) || isnonalpha(chunk_name[1]) ||
+       isnonalpha(chunk_name[2]) || isnonalpha(chunk_name[3]))
+   {
+      png_chunk_error(png_ptr, "invalid chunk type");
+   }
+}
+
+/* Combines the row recently read in with the existing pixels in the
+   row.  This routine takes care of alpha and transparency if requested.
+   This routine also handles the two methods of progressive display
+   of interlaced images, depending on the mask value.
+   The mask value describes which pixels are to be combined with
+   the row.  The pattern always repeats every 8 pixels, so just 8
+   bits are needed.  A one indicates the pixel is to be combined,
+   a zero indicates the pixel is to be skipped.  This is in addition
+   to any alpha or transparency value associated with the pixel.  If
+   you want all pixels to be combined, pass 0xff (255) in mask.  */
+
+void /* PRIVATE */
+png_combine_row(png_structp png_ptr, png_bytep row, int mask)
+{
+   png_debug(1, "in png_combine_row");
+   if (mask == 0xff)
+   {
+      png_memcpy(row, png_ptr->row_buf + 1,
+         PNG_ROWBYTES(png_ptr->row_info.pixel_depth, png_ptr->width));
+   }
+   else
+   {
+      switch (png_ptr->row_info.pixel_depth)
       {
-         /* Do a 'warn' here - it is handled below. */
-         png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
-            png_malloc_warn(png_ptr, length));
+         case 1:
+         {
+            png_bytep sp = png_ptr->row_buf + 1;
+            png_bytep dp = row;
+            int s_inc, s_start, s_end;
+            int m = 0x80;
+            int shift;
+            png_uint_32 i;
+            png_uint_32 row_width = png_ptr->width;
+
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+            if (png_ptr->transformations & PNG_PACKSWAP)
+            {
+                s_start = 0;
+                s_end = 7;
+                s_inc = 1;
+            }
+            else
+#endif
+            {
+                s_start = 7;
+                s_end = 0;
+                s_inc = -1;
+            }
+
+            shift = s_start;
+
+            for (i = 0; i < row_width; i++)
+            {
+               if (m & mask)
+               {
+                  int value;
+
+                  value = (*sp >> shift) & 0x01;
+                  *dp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
+                  *dp |= (png_byte)(value << shift);
+               }
+
+               if (shift == s_end)
+               {
+                  shift = s_start;
+                  sp++;
+                  dp++;
+               }
+               else
+                  shift += s_inc;
+
+               if (m == 1)
+                  m = 0x80;
+               else
+                  m >>= 1;
+            }
+            break;
+         }
+         case 2:
+         {
+            png_bytep sp = png_ptr->row_buf + 1;
+            png_bytep dp = row;
+            int s_start, s_end, s_inc;
+            int m = 0x80;
+            int shift;
+            png_uint_32 i;
+            png_uint_32 row_width = png_ptr->width;
+            int value;
+
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+            if (png_ptr->transformations & PNG_PACKSWAP)
+            {
+               s_start = 0;
+               s_end = 6;
+               s_inc = 2;
+            }
+            else
+#endif
+            {
+               s_start = 6;
+               s_end = 0;
+               s_inc = -2;
+            }
+
+            shift = s_start;
+
+            for (i = 0; i < row_width; i++)
+            {
+               if (m & mask)
+               {
+                  value = (*sp >> shift) & 0x03;
+                  *dp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
+                  *dp |= (png_byte)(value << shift);
+               }
+
+               if (shift == s_end)
+               {
+                  shift = s_start;
+                  sp++;
+                  dp++;
+               }
+               else
+                  shift += s_inc;
+               if (m == 1)
+                  m = 0x80;
+               else
+                  m >>= 1;
+            }
+            break;
+         }
+         case 4:
+         {
+            png_bytep sp = png_ptr->row_buf + 1;
+            png_bytep dp = row;
+            int s_start, s_end, s_inc;
+            int m = 0x80;
+            int shift;
+            png_uint_32 i;
+            png_uint_32 row_width = png_ptr->width;
+            int value;
+
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+            if (png_ptr->transformations & PNG_PACKSWAP)
+            {
+               s_start = 0;
+               s_end = 4;
+               s_inc = 4;
+            }
+            else
+#endif
+            {
+               s_start = 4;
+               s_end = 0;
+               s_inc = -4;
+            }
+            shift = s_start;
+
+            for (i = 0; i < row_width; i++)
+            {
+               if (m & mask)
+               {
+                  value = (*sp >> shift) & 0xf;
+                  *dp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
+                  *dp |= (png_byte)(value << shift);
+               }
+
+               if (shift == s_end)
+               {
+                  shift = s_start;
+                  sp++;
+                  dp++;
+               }
+               else
+                  shift += s_inc;
+               if (m == 1)
+                  m = 0x80;
+               else
+                  m >>= 1;
+            }
+            break;
+         }
+         default:
+         {
+            png_bytep sp = png_ptr->row_buf + 1;
+            png_bytep dp = row;
+            png_size_t pixel_bytes = (png_ptr->row_info.pixel_depth >> 3);
+            png_uint_32 i;
+            png_uint_32 row_width = png_ptr->width;
+            png_byte m = 0x80;
+
+
+            for (i = 0; i < row_width; i++)
+            {
+               if (m & mask)
+               {
+                  png_memcpy(dp, sp, pixel_bytes);
+               }
+
+               sp += pixel_bytes;
+               dp += pixel_bytes;
+
+               if (m == 1)
+                  m = 0x80;
+               else
+                  m >>= 1;
+            }
+            break;
+         }
       }
    }
-
-   if (png_ptr->unknown_chunk.data == NULL && length > 0)
-   {
-      /* This is benign because we clean up correctly */
-      png_crc_finish(png_ptr, length);
-      png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
-      return 0;
-   }
-
-   else
-   {
-      if (length > 0)
-         png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
-      png_crc_finish(png_ptr, 0);
-      return 1;
-   }
 }
-#endif /* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
-
-/* Handle an unknown, or known but disabled, chunk */
-void /* PRIVATE */
-png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
-   png_uint_32 length, int keep)
-{
-   int handled = 0; /* the chunk was handled */
-
-   png_debug(1, "in png_handle_unknown");
-
-#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
-   /* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
-    * the bug which meant that setting a non-default behavior for a specific
-    * chunk would be ignored (the default was always used unless a user
-    * callback was installed).
-    *
-    * 'keep' is the value from the png_chunk_unknown_handling, the setting for
-    * this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
-    * will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
-    * This is just an optimization to avoid multiple calls to the lookup
-    * function.
-    */
-#  ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-#     ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
-         keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
-#     endif
-#  endif
-
-   /* One of the following methods will read the chunk or skip it (at least one
-    * of these is always defined because this is the only way to switch on
-    * PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
-    */
-#  ifdef PNG_READ_USER_CHUNKS_SUPPORTED
-      /* The user callback takes precedence over the chunk keep value, but the
-       * keep value is still required to validate a save of a critical chunk.
-       */
-      if (png_ptr->read_user_chunk_fn != NULL)
-      {
-         if (png_cache_unknown_chunk(png_ptr, length))
-         {
-            /* Callback to user unknown chunk handler */
-            int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
-               &png_ptr->unknown_chunk);
-
-            /* ret is:
-             * negative: An error occured, png_chunk_error will be called.
-             *     zero: The chunk was not handled, the chunk will be discarded
-             *           unless png_set_keep_unknown_chunks has been used to set
-             *           a 'keep' behavior for this particular chunk, in which
-             *           case that will be used.  A critical chunk will cause an
-             *           error at this point unless it is to be saved.
-             * positive: The chunk was handled, libpng will ignore/discard it.
-             */
-            if (ret < 0)
-               png_chunk_error(png_ptr, "error in user chunk");
-
-            else if (ret == 0)
-            {
-               /* If the keep value is 'default' or 'never' override it, but
-                * still error out on critical chunks unless the keep value is
-                * 'always'  While this is weird it is the behavior in 1.4.12.
-                * A possible improvement would be to obey the value set for the
-                * chunk, but this would be an API change that would probably
-                * damage some applications.
-                *
-                * The png_app_warning below catches the case that matters, where
-                * the application has not set specific save or ignore for this
-                * chunk or global save or ignore.
-                */
-               if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
-               {
-#                 ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
-                     if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
-                     {
-                        png_chunk_warning(png_ptr, "Saving unknown chunk:");
-                        png_app_warning(png_ptr,
-                           "forcing save of an unhandled chunk;"
-                           " please call png_set_keep_unknown_chunks");
-                           /* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
-                     }
-#                 endif
-                  keep = PNG_HANDLE_CHUNK_IF_SAFE;
-               }
-            }
-
-            else /* chunk was handled */
-            {
-               handled = 1;
-               /* Critical chunks can be safely discarded at this point. */
-               keep = PNG_HANDLE_CHUNK_NEVER;
-            }
-         }
-
-         else
-            keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
-      }
-
-      else
-         /* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
-#  endif /* PNG_READ_USER_CHUNKS_SUPPORTED */
-
-#  ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
-      {
-         /* keep is currently just the per-chunk setting, if there was no
-          * setting change it to the global default now (not that this may
-          * still be AS_DEFAULT) then obtain the cache of the chunk if required,
-          * if not simply skip the chunk.
-          */
-         if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
-            keep = png_ptr->unknown_default;
-
-         if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
-            (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
-             PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
-         {
-            if (!png_cache_unknown_chunk(png_ptr, length))
-               keep = PNG_HANDLE_CHUNK_NEVER;
-         }
-
-         else
-            png_crc_finish(png_ptr, length);
-      }
-#  else
-#     ifndef PNG_READ_USER_CHUNKS_SUPPORTED
-#        error no method to support READ_UNKNOWN_CHUNKS
-#     endif
-
-      {
-         /* If here there is no read callback pointer set and no support is
-          * compiled in to just save the unknown chunks, so simply skip this
-          * chunk.  If 'keep' is something other than AS_DEFAULT or NEVER then
-          * the app has erroneously asked for unknown chunk saving when there
-          * is no support.
-          */
-         if (keep > PNG_HANDLE_CHUNK_NEVER)
-            png_app_error(png_ptr, "no unknown chunk support available");
-
-         png_crc_finish(png_ptr, length);
-      }
-#  endif
-
-#  ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
-      /* Now store the chunk in the chunk list if appropriate, and if the limits
-       * permit it.
-       */
-      if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
-         (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
-          PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
-      {
-#     ifdef PNG_USER_LIMITS_SUPPORTED
-         switch (png_ptr->user_chunk_cache_max)
-         {
-            case 2:
-               png_ptr->user_chunk_cache_max = 1;
-               png_chunk_benign_error(png_ptr, "no space in chunk cache");
-               /* FALL THROUGH */
-            case 1:
-               /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
-                * chunk being skipped, now there will be a hard error below.
-                */
-               break;
-
-            default: /* not at limit */
-               --(png_ptr->user_chunk_cache_max);
-               /* FALL THROUGH */
-            case 0: /* no limit */
-#     endif /* PNG_USER_LIMITS_SUPPORTED */
-               /* Here when the limit isn't reached or when limits are compiled
-                * out; store the chunk.
-                */
-               png_set_unknown_chunks(png_ptr, info_ptr,
-                  &png_ptr->unknown_chunk, 1);
-               handled = 1;
-#     ifdef PNG_USER_LIMITS_SUPPORTED
-               break;
-         }
-#     endif
-      }
-#  else /* no store support! */
-      PNG_UNUSED(info_ptr)
-#     error untested code (reading unknown chunks with no store support)
-#  endif
-
-   /* Regardless of the error handling below the cached data (if any) can be
-    * freed now.  Notice that the data is not freed if there is a png_error, but
-    * it will be freed by destroy_read_struct.
-    */
-   if (png_ptr->unknown_chunk.data != NULL)
-      png_free(png_ptr, png_ptr->unknown_chunk.data);
-   png_ptr->unknown_chunk.data = NULL;
-
-#else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
-   /* There is no support to read an unknown chunk, so just skip it. */
-   png_crc_finish(png_ptr, length);
-   PNG_UNUSED(info_ptr)
-   PNG_UNUSED(keep)
-#endif /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
-
-   /* Check for unhandled critical chunks */
-   if (!handled && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
-      png_chunk_error(png_ptr, "unhandled critical chunk");
-}
-
-/* This function is called to verify that a chunk name is valid.
- * This function can't have the "critical chunk check" incorporated
- * into it, since in the future we will need to be able to call user
- * functions to handle unknown critical chunks after we check that
- * the chunk name itself is valid.
- */
-
-/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
- *
- * ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
- */
-
-void /* PRIVATE */
-png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
-{
-   int i;
-
-   png_debug(1, "in png_check_chunk_name");
-
-   for (i=1; i<=4; ++i)
-   {
-      int c = chunk_name & 0xff;
-
-      if (c < 65 || c > 122 || (c > 90 && c < 97))
-         png_chunk_error(png_ptr, "invalid chunk type");
-
-      chunk_name >>= 8;
-   }
-}
-
-/* Combines the row recently read in with the existing pixels in the row.  This
- * routine takes care of alpha and transparency if requested.  This routine also
- * handles the two methods of progressive display of interlaced images,
- * depending on the 'display' value; if 'display' is true then the whole row
- * (dp) is filled from the start by replicating the available pixels.  If
- * 'display' is false only those pixels present in the pass are filled in.
+
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+/* OLD pre-1.0.9 interface:
+void png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
+   png_uint_32 transformations)
  */
 void /* PRIVATE */
-png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
+png_do_read_interlace(png_structp png_ptr)
 {
-   unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
-   png_const_bytep sp = png_ptr->row_buf + 1;
-   png_uint_32 row_width = png_ptr->width;
-   unsigned int pass = png_ptr->pass;
-   png_bytep end_ptr = 0;
-   png_byte end_byte = 0;
-   unsigned int end_mask;
-
-   png_debug(1, "in png_combine_row");
-
-   /* Added in 1.5.6: it should not be possible to enter this routine until at
-    * least one row has been read from the PNG data and transformed.
-    */
-   if (pixel_depth == 0)
-      png_error(png_ptr, "internal row logic error");
-
-   /* Added in 1.5.4: the pixel depth should match the information returned by
-    * any call to png_read_update_info at this point.  Do not continue if we got
-    * this wrong.
-    */
-   if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
-          PNG_ROWBYTES(pixel_depth, row_width))
-      png_error(png_ptr, "internal row size calculation error");
-
-   /* Don't expect this to ever happen: */
-   if (row_width == 0)
-      png_error(png_ptr, "internal row width error");
-
-   /* Preserve the last byte in cases where only part of it will be overwritten,
-    * the multiply below may overflow, we don't care because ANSI-C guarantees
-    * we get the low bits.
-    */
-   end_mask = (pixel_depth * row_width) & 7;
-   if (end_mask != 0)
-   {
-      /* end_ptr == NULL is a flag to say do nothing */
-      end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
-      end_byte = *end_ptr;
-#     ifdef PNG_READ_PACKSWAP_SUPPORTED
-         if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
-            end_mask = 0xff << end_mask;
-
-         else /* big-endian byte */
-#     endif
-         end_mask = 0xff >> end_mask;
-      /* end_mask is now the bits to *keep* from the destination row */
-   }
-
-   /* For non-interlaced images this reduces to a memcpy(). A memcpy()
-    * will also happen if interlacing isn't supported or if the application
-    * does not call png_set_interlace_handling().  In the latter cases the
-    * caller just gets a sequence of the unexpanded rows from each interlace
-    * pass.
-    */
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
-      pass < 6 && (display == 0 ||
-      /* The following copies everything for 'display' on passes 0, 2 and 4. */
-      (display == 1 && (pass & 1) != 0)))
-   {
-      /* Narrow images may have no bits in a pass; the caller should handle
-       * this, but this test is cheap:
-       */
-      if (row_width <= PNG_PASS_START_COL(pass))
-         return;
-
-      if (pixel_depth < 8)
-      {
-         /* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
-          * into 32 bits, then a single loop over the bytes using the four byte
-          * values in the 32-bit mask can be used.  For the 'display' option the
-          * expanded mask may also not require any masking within a byte.  To
-          * make this work the PACKSWAP option must be taken into account - it
-          * simply requires the pixels to be reversed in each byte.
-          *
-          * The 'regular' case requires a mask for each of the first 6 passes,
-          * the 'display' case does a copy for the even passes in the range
-          * 0..6.  This has already been handled in the test above.
-          *
-          * The masks are arranged as four bytes with the first byte to use in
-          * the lowest bits (little-endian) regardless of the order (PACKSWAP or
-          * not) of the pixels in each byte.
-          *
-          * NOTE: the whole of this logic depends on the caller of this function
-          * only calling it on rows appropriate to the pass.  This function only
-          * understands the 'x' logic; the 'y' logic is handled by the caller.
-          *
-          * The following defines allow generation of compile time constant bit
-          * masks for each pixel depth and each possibility of swapped or not
-          * swapped bytes.  Pass 'p' is in the range 0..6; 'x', a pixel index,
-          * is in the range 0..7; and the result is 1 if the pixel is to be
-          * copied in the pass, 0 if not.  'S' is for the sparkle method, 'B'
-          * for the block method.
-          *
-          * With some compilers a compile time expression of the general form:
-          *
-          *    (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
-          *
-          * Produces warnings with values of 'shift' in the range 33 to 63
-          * because the right hand side of the ?: expression is evaluated by
-          * the compiler even though it isn't used.  Microsoft Visual C (various
-          * versions) and the Intel C compiler are known to do this.  To avoid
-          * this the following macros are used in 1.5.6.  This is a temporary
-          * solution to avoid destabilizing the code during the release process.
-          */
-#        if PNG_USE_COMPILE_TIME_MASKS
-#           define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
-#           define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
-#        else
-#           define PNG_LSR(x,s) ((x)>>(s))
-#           define PNG_LSL(x,s) ((x)<<(s))
-#        endif
-#        define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
-           PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
-#        define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
-           PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
-
-         /* Return a mask for pass 'p' pixel 'x' at depth 'd'.  The mask is
-          * little endian - the first pixel is at bit 0 - however the extra
-          * parameter 's' can be set to cause the mask position to be swapped
-          * within each byte, to match the PNG format.  This is done by XOR of
-          * the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
-          */
-#        define PIXEL_MASK(p,x,d,s) \
-            (PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
-
-         /* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
-          */
-#        define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
-#        define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
-
-         /* Combine 8 of these to get the full mask.  For the 1-bpp and 2-bpp
-          * cases the result needs replicating, for the 4-bpp case the above
-          * generates a full 32 bits.
-          */
-#        define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
-
-#        define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
-            S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
-            S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
-
-#        define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
-            B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
-            B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
-
-#if PNG_USE_COMPILE_TIME_MASKS
-         /* Utility macros to construct all the masks for a depth/swap
-          * combination.  The 's' parameter says whether the format is PNG
-          * (big endian bytes) or not.  Only the three odd-numbered passes are
-          * required for the display/block algorithm.
-          */
-#        define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
-            S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
-
-#        define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }
-
-#        define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
-
-         /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
-          * then pass:
-          */
-         static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
-         {
-            /* Little-endian byte masks for PACKSWAP */
-            { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
-            /* Normal (big-endian byte) masks - PNG format */
-            { S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
-         };
-
-         /* display_mask has only three entries for the odd passes, so index by
-          * pass>>1.
-          */
-         static PNG_CONST png_uint_32 display_mask[2][3][3] =
-         {
-            /* Little-endian byte masks for PACKSWAP */
-            { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
-            /* Normal (big-endian byte) masks - PNG format */
-            { B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
-         };
-
-#        define MASK(pass,depth,display,png)\
-            ((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
-               row_mask[png][DEPTH_INDEX(depth)][pass])
-
-#else /* !PNG_USE_COMPILE_TIME_MASKS */
-         /* This is the runtime alternative: it seems unlikely that this will
-          * ever be either smaller or faster than the compile time approach.
-          */
-#        define MASK(pass,depth,display,png)\
-            ((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
-#endif /* !PNG_USE_COMPILE_TIME_MASKS */
-
-         /* Use the appropriate mask to copy the required bits.  In some cases
-          * the byte mask will be 0 or 0xff, optimize these cases.  row_width is
-          * the number of pixels, but the code copies bytes, so it is necessary
-          * to special case the end.
-          */
-         png_uint_32 pixels_per_byte = 8 / pixel_depth;
-         png_uint_32 mask;
-
-#        ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (png_ptr->transformations & PNG_PACKSWAP)
-               mask = MASK(pass, pixel_depth, display, 0);
-
-            else
-#        endif
-            mask = MASK(pass, pixel_depth, display, 1);
-
-         for (;;)
-         {
-            png_uint_32 m;
-
-            /* It doesn't matter in the following if png_uint_32 has more than
-             * 32 bits because the high bits always match those in m<<24; it is,
-             * however, essential to use OR here, not +, because of this.
-             */
-            m = mask;
-            mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
-            m &= 0xff;
-
-            if (m != 0) /* something to copy */
-            {
-               if (m != 0xff)
-                  *dp = (png_byte)((*dp & ~m) | (*sp & m));
-               else
-                  *dp = *sp;
-            }
-
-            /* NOTE: this may overwrite the last byte with garbage if the image
-             * is not an exact number of bytes wide; libpng has always done
-             * this.
-             */
-            if (row_width <= pixels_per_byte)
-               break; /* May need to restore part of the last byte */
-
-            row_width -= pixels_per_byte;
-            ++dp;
-            ++sp;
-         }
-      }
-
-      else /* pixel_depth >= 8 */
-      {
-         unsigned int bytes_to_copy, bytes_to_jump;
-
-         /* Validate the depth - it must be a multiple of 8 */
-         if (pixel_depth & 7)
-            png_error(png_ptr, "invalid user transform pixel depth");
-
-         pixel_depth >>= 3; /* now in bytes */
-         row_width *= pixel_depth;
-
-         /* Regardless of pass number the Adam 7 interlace always results in a
-          * fixed number of pixels to copy then to skip.  There may be a
-          * different number of pixels to skip at the start though.
-          */
-         {
-            unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
-
-            row_width -= offset;
-            dp += offset;
-            sp += offset;
-         }
-
-         /* Work out the bytes to copy. */
-         if (display)
-         {
-            /* When doing the 'block' algorithm the pixel in the pass gets
-             * replicated to adjacent pixels.  This is why the even (0,2,4,6)
-             * passes are skipped above - the entire expanded row is copied.
-             */
-            bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
-
-            /* But don't allow this number to exceed the actual row width. */
-            if (bytes_to_copy > row_width)
-               bytes_to_copy = row_width;
-         }
-
-         else /* normal row; Adam7 only ever gives us one pixel to copy. */
-            bytes_to_copy = pixel_depth;
-
-         /* In Adam7 there is a constant offset between where the pixels go. */
-         bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
-
-         /* And simply copy these bytes.  Some optimization is possible here,
-          * depending on the value of 'bytes_to_copy'.  Special case the low
-          * byte counts, which we know to be frequent.
-          *
-          * Notice that these cases all 'return' rather than 'break' - this
-          * avoids an unnecessary test on whether to restore the last byte
-          * below.
-          */
-         switch (bytes_to_copy)
-         {
-            case 1:
-               for (;;)
-               {
-                  *dp = *sp;
-
-                  if (row_width <= bytes_to_jump)
-                     return;
-
-                  dp += bytes_to_jump;
-                  sp += bytes_to_jump;
-                  row_width -= bytes_to_jump;
-               }
-
-            case 2:
-               /* There is a possibility of a partial copy at the end here; this
-                * slows the code down somewhat.
-                */
-               do
-               {
-                  dp[0] = sp[0], dp[1] = sp[1];
-
-                  if (row_width <= bytes_to_jump)
-                     return;
-
-                  sp += bytes_to_jump;
-                  dp += bytes_to_jump;
-                  row_width -= bytes_to_jump;
-               }
-               while (row_width > 1);
-
-               /* And there can only be one byte left at this point: */
-               *dp = *sp;
-               return;
-
-            case 3:
-               /* This can only be the RGB case, so each copy is exactly one
-                * pixel and it is not necessary to check for a partial copy.
-                */
-               for(;;)
-               {
-                  dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
-
-                  if (row_width <= bytes_to_jump)
-                     return;
-
-                  sp += bytes_to_jump;
-                  dp += bytes_to_jump;
-                  row_width -= bytes_to_jump;
-               }
-
-            default:
-#if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
-               /* Check for double byte alignment and, if possible, use a
-                * 16-bit copy.  Don't attempt this for narrow images - ones that
-                * are less than an interlace panel wide.  Don't attempt it for
-                * wide bytes_to_copy either - use the memcpy there.
-                */
-               if (bytes_to_copy < 16 /*else use memcpy*/ &&
-                  png_isaligned(dp, png_uint_16) &&
-                  png_isaligned(sp, png_uint_16) &&
-                  bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
-                  bytes_to_jump % (sizeof (png_uint_16)) == 0)
-               {
-                  /* Everything is aligned for png_uint_16 copies, but try for
-                   * png_uint_32 first.
-                   */
-                  if (png_isaligned(dp, png_uint_32) &&
-                     png_isaligned(sp, png_uint_32) &&
-                     bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
-                     bytes_to_jump % (sizeof (png_uint_32)) == 0)
-                  {
-                     png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
-                     png_const_uint_32p sp32 = png_aligncastconst(
-                        png_const_uint_32p, sp);
-                     size_t skip = (bytes_to_jump-bytes_to_copy) /
-                        (sizeof (png_uint_32));
-
-                     do
-                     {
-                        size_t c = bytes_to_copy;
-                        do
-                        {
-                           *dp32++ = *sp32++;
-                           c -= (sizeof (png_uint_32));
-                        }
-                        while (c > 0);
-
-                        if (row_width <= bytes_to_jump)
-                           return;
-
-                        dp32 += skip;
-                        sp32 += skip;
-                        row_width -= bytes_to_jump;
-                     }
-                     while (bytes_to_copy <= row_width);
-
-                     /* Get to here when the row_width truncates the final copy.
-                      * There will be 1-3 bytes left to copy, so don't try the
-                      * 16-bit loop below.
-                      */
-                     dp = (png_bytep)dp32;
-                     sp = (png_const_bytep)sp32;
-                     do
-                        *dp++ = *sp++;
-                     while (--row_width > 0);
-                     return;
-                  }
-
-                  /* Else do it in 16-bit quantities, but only if the size is
-                   * not too large.
-                   */
-                  else
-                  {
-                     png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
-                     png_const_uint_16p sp16 = png_aligncastconst(
-                        png_const_uint_16p, sp);
-                     size_t skip = (bytes_to_jump-bytes_to_copy) /
-                        (sizeof (png_uint_16));
-
-                     do
-                     {
-                        size_t c = bytes_to_copy;
-                        do
-                        {
-                           *dp16++ = *sp16++;
-                           c -= (sizeof (png_uint_16));
-                        }
-                        while (c > 0);
-
-                        if (row_width <= bytes_to_jump)
-                           return;
-
-                        dp16 += skip;
-                        sp16 += skip;
-                        row_width -= bytes_to_jump;
-                     }
-                     while (bytes_to_copy <= row_width);
-
-                     /* End of row - 1 byte left, bytes_to_copy > row_width: */
-                     dp = (png_bytep)dp16;
-                     sp = (png_const_bytep)sp16;
-                     do
-                        *dp++ = *sp++;
-                     while (--row_width > 0);
-                     return;
-                  }
-               }
-#endif /* PNG_ALIGN_ code */
-
-               /* The true default - use a memcpy: */
-               for (;;)
-               {
-                  memcpy(dp, sp, bytes_to_copy);
-
-                  if (row_width <= bytes_to_jump)
-                     return;
-
-                  sp += bytes_to_jump;
-                  dp += bytes_to_jump;
-                  row_width -= bytes_to_jump;
-                  if (bytes_to_copy > row_width)
-                     bytes_to_copy = row_width;
-               }
-         }
-
-         /* NOT REACHED*/
-      } /* pixel_depth >= 8 */
-
-      /* Here if pixel_depth < 8 to check 'end_ptr' below. */
-   }
-   else
-#endif
-
-   /* If here then the switch above wasn't used so just memcpy the whole row
-    * from the temporary row buffer (notice that this overwrites the end of the
-    * destination row if it is a partial byte.)
-    */
-   memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
-
-   /* Restore the overwritten bits from the last byte if necessary. */
-   if (end_ptr != NULL)
-      *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
-}
-
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-void /* PRIVATE */
-png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
-   png_uint_32 transformations /* Because these may affect the byte layout */)
-{
+   png_row_infop row_info = &(png_ptr->row_info);
+   png_bytep row = png_ptr->row_buf + 1;
+   int pass = png_ptr->pass;
+   png_uint_32 transformations = png_ptr->transformations;
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
    /* Offset to next interlace block */
-   static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
    png_debug(1, "in png_do_read_interlace");
    if (row != NULL && row_info != NULL)
    {
       png_uint_32 final_width;
 
       final_width = row_info->width * png_pass_inc[pass];
 
       switch (row_info->pixel_depth)
       {
@@ skipping 10 matching lines @@
 
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (transformations & PNG_PACKSWAP)
             {
                 sshift = (int)((row_info->width + 7) & 0x07);
                 dshift = (int)((final_width + 7) & 0x07);
                 s_start = 7;
                 s_end = 0;
                 s_inc = -1;
             }
-
             else
 #endif
             {
                 sshift = 7 - (int)((row_info->width + 7) & 0x07);
                 dshift = 7 - (int)((final_width + 7) & 0x07);
                 s_start = 0;
                 s_end = 7;
                 s_inc = 1;
             }
 
             for (i = 0; i < row_info->width; i++)
             {
                v = (png_byte)((*sp >> sshift) & 0x01);
                for (j = 0; j < jstop; j++)
                {
-                  unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
-                  tmp |= v << dshift;
-                  *dp = (png_byte)(tmp & 0xff);
-
+                  *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);
+                  *dp |= (png_byte)(v << dshift);
                   if (dshift == s_end)
                   {
                      dshift = s_start;
                      dp--;
                   }
-
                   else
                      dshift += s_inc;
                }
-
                if (sshift == s_end)
                {
                   sshift = s_start;
                   sp--;
                }
-
                else
                   sshift += s_inc;
             }
             break;
          }
-
          case 2:
          {
             png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
             png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
             int sshift, dshift;
             int s_start, s_end, s_inc;
             int jstop = png_pass_inc[pass];
             png_uint_32 i;
 
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (transformations & PNG_PACKSWAP)
             {
                sshift = (int)(((row_info->width + 3) & 0x03) << 1);
                dshift = (int)(((final_width + 3) & 0x03) << 1);
                s_start = 6;
                s_end = 0;
                s_inc = -2;
             }
-
             else
 #endif
             {
                sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
                dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
                s_start = 0;
                s_end = 6;
                s_inc = 2;
             }
 
             for (i = 0; i < row_info->width; i++)
             {
                png_byte v;
                int j;
 
                v = (png_byte)((*sp >> sshift) & 0x03);
                for (j = 0; j < jstop; j++)
                {
-                  unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
-                  tmp |= v << dshift;
-                  *dp = (png_byte)(tmp & 0xff);
-
+                  *dp &= (png_byte)((0x3f3f >> (6 - dshift)) & 0xff);
+                  *dp |= (png_byte)(v << dshift);
                   if (dshift == s_end)
                   {
                      dshift = s_start;
                      dp--;
                   }
-
                   else
                      dshift += s_inc;
                }
-
                if (sshift == s_end)
                {
                   sshift = s_start;
                   sp--;
                }
-
                else
                   sshift += s_inc;
             }
             break;
          }
-
          case 4:
          {
             png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
             png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
             int sshift, dshift;
             int s_start, s_end, s_inc;
             png_uint_32 i;
             int jstop = png_pass_inc[pass];
 
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (transformations & PNG_PACKSWAP)
             {
                sshift = (int)(((row_info->width + 1) & 0x01) << 2);
                dshift = (int)(((final_width + 1) & 0x01) << 2);
                s_start = 4;
                s_end = 0;
                s_inc = -4;
             }
-
             else
 #endif
             {
                sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
                dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
                s_start = 0;
                s_end = 4;
                s_inc = 4;
             }
 
             for (i = 0; i < row_info->width; i++)
             {
-               png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
+               png_byte v = (png_byte)((*sp >> sshift) & 0xf);
                int j;
 
                for (j = 0; j < jstop; j++)
                {
-                  unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
-                  tmp |= v << dshift;
-                  *dp = (png_byte)(tmp & 0xff);
-
+                  *dp &= (png_byte)((0xf0f >> (4 - dshift)) & 0xff);
+                  *dp |= (png_byte)(v << dshift);
                   if (dshift == s_end)
                   {
                      dshift = s_start;
                      dp--;
                   }
-
                   else
                      dshift += s_inc;
                }
-
                if (sshift == s_end)
                {
                   sshift = s_start;
                   sp--;
                }
-
                else
                   sshift += s_inc;
             }
             break;
          }
-
          default:
          {
             png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
-
             png_bytep sp = row + (png_size_t)(row_info->width - 1)
                 * pixel_bytes;
-
             png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
 
             int jstop = png_pass_inc[pass];
             png_uint_32 i;
 
             for (i = 0; i < row_info->width; i++)
             {
-               png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
+               png_byte v[8];
                int j;
 
-               memcpy(v, sp, pixel_bytes);
-
+               png_memcpy(v, sp, pixel_bytes);
                for (j = 0; j < jstop; j++)
                {
-                  memcpy(dp, v, pixel_bytes);
+                  png_memcpy(dp, v, pixel_bytes);
                   dp -= pixel_bytes;
                }
-
                sp -= pixel_bytes;
             }
             break;
          }
       }
-
       row_info->width = final_width;
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
    }
 #ifndef PNG_READ_PACKSWAP_SUPPORTED
-   PNG_UNUSED(transformations)  /* Silence compiler warning */
+   transformations = transformations; /* Silence compiler warning */
 #endif
 }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 
-static void
-png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev_row)
+void /* PRIVATE */
+png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
+   png_bytep prev_row, int filter)
 {
-   png_size_t i;
-   png_size_t istop = row_info->rowbytes;
-   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
-   png_bytep rp = row + bpp;
+   png_debug(1, "in png_read_filter_row");
+   png_debug2(2, "row = %lu, filter = %d", png_ptr->row_number, filter);
+   switch (filter)
+   {
+      case PNG_FILTER_VALUE_NONE:
+         break;
+      case PNG_FILTER_VALUE_SUB:
+      {
+         png_uint_32 i;
+         png_uint_32 istop = row_info->rowbytes;
+         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
+         png_bytep rp = row + bpp;
+         png_bytep lp = row;
 
-   PNG_UNUSED(prev_row)
+         for (i = bpp; i < istop; i++)
+         {
+            *rp = (png_byte)(((int)(*rp) + (int)(*lp++)) & 0xff);
+            rp++;
+         }
+         break;
+      }
+      case PNG_FILTER_VALUE_UP:
+      {
+         png_uint_32 i;
+         png_uint_32 istop = row_info->rowbytes;
+         png_bytep rp = row;
+         png_bytep pp = prev_row;
 
-   for (i = bpp; i < istop; i++)
-   {
-      *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
-      rp++;
+         for (i = 0; i < istop; i++)
+         {
+            *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+            rp++;
+         }
+         break;
+      }
+      case PNG_FILTER_VALUE_AVG:
+      {
+         png_uint_32 i;
+         png_bytep rp = row;
+         png_bytep pp = prev_row;
+         png_bytep lp = row;
+         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
+         png_uint_32 istop = row_info->rowbytes - bpp;
+
+         for (i = 0; i < bpp; i++)
+         {
+            *rp = (png_byte)(((int)(*rp) +
+               ((int)(*pp++) / 2 )) & 0xff);
+            rp++;
+         }
+
+         for (i = 0; i < istop; i++)
+         {
+            *rp = (png_byte)(((int)(*rp) +
+               (int)(*pp++ + *lp++) / 2 ) & 0xff);
+            rp++;
+         }
+         break;
+      }
+      case PNG_FILTER_VALUE_PAETH:
+      {
+         png_uint_32 i;
+         png_bytep rp = row;
+         png_bytep pp = prev_row;
+         png_bytep lp = row;
+         png_bytep cp = prev_row;
+         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
+         png_uint_32 istop=row_info->rowbytes - bpp;
+
+         for (i = 0; i < bpp; i++)
+         {
+            *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+            rp++;
+         }
+
+         for (i = 0; i < istop; i++)   /* Use leftover rp,pp */
+         {
+            int a, b, c, pa, pb, pc, p;
+
+            a = *lp++;
+            b = *pp++;
+            c = *cp++;
+
+            p = b - c;
+            pc = a - c;
+
+#ifdef PNG_USE_ABS
+            pa = abs(p);
+            pb = abs(pc);
+            pc = abs(p + pc);
+#else
+            pa = p < 0 ? -p : p;
+            pb = pc < 0 ? -pc : pc;
+            pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+#endif
+
+            /*
+               if (pa <= pb && pa <= pc)
+                  p = a;
+               else if (pb <= pc)
+                  p = b;
+               else
+                  p = c;
+             */
+
+            p = (pa <= pb && pa <= pc) ? a : (pb <= pc) ? b : c;
+
+            *rp = (png_byte)(((int)(*rp) + p) & 0xff);
+            rp++;
+         }
+         break;
+      }
+      default:
+         png_warning(png_ptr, "Ignoring bad adaptive filter type");
+         *row = 0;
+         break;
    }
 }
 
-static void
-png_read_filter_row_up(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev_row)
-{
-   png_size_t i;
-   png_size_t istop = row_info->rowbytes;
-   png_bytep rp = row;
-   png_const_bytep pp = prev_row;
-
-   for (i = 0; i < istop; i++)
-   {
-      *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
-      rp++;
-   }
-}
-
-static void
-png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev_row)
-{
-   png_size_t i;
-   png_bytep rp = row;
-   png_const_bytep pp = prev_row;
-   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
-   png_size_t istop = row_info->rowbytes - bpp;
-
-   for (i = 0; i < bpp; i++)
-   {
-      *rp = (png_byte)(((int)(*rp) +
-         ((int)(*pp++) / 2 )) & 0xff);
-
-      rp++;
-   }
-
-   for (i = 0; i < istop; i++)
-   {
-      *rp = (png_byte)(((int)(*rp) +
-         (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
-
-      rp++;
-   }
-}
-
-static void
-png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev_row)
-{
-   png_bytep rp_end = row + row_info->rowbytes;
-   int a, c;
-
-   /* First pixel/byte */
-   c = *prev_row++;
-   a = *row + c;
-   *row++ = (png_byte)a;
-
-   /* Remainder */
-   while (row < rp_end)
-   {
-      int b, pa, pb, pc, p;
-
-      a &= 0xff; /* From previous iteration or start */
-      b = *prev_row++;
-
-      p = b - c;
-      pc = a - c;
-
-#     ifdef PNG_USE_ABS
-         pa = abs(p);
-         pb = abs(pc);
-         pc = abs(p + pc);
-#     else
-         pa = p < 0 ? -p : p;
-         pb = pc < 0 ? -pc : pc;
-         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
-#     endif
-
-      /* Find the best predictor, the least of pa, pb, pc favoring the earlier
-       * ones in the case of a tie.
-       */
-      if (pb < pa) pa = pb, a = b;
-      if (pc < pa) a = c;
-
-      /* Calculate the current pixel in a, and move the previous row pixel to c
-       * for the next time round the loop
-       */
-      c = b;
-      a += *row;
-      *row++ = (png_byte)a;
-   }
-}
-
-static void
-png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
-   png_const_bytep prev_row)
-{
-   int bpp = (row_info->pixel_depth + 7) >> 3;
-   png_bytep rp_end = row + bpp;
-
-   /* Process the first pixel in the row completely (this is the same as 'up'
-    * because there is only one candidate predictor for the first row).
-    */
-   while (row < rp_end)
-   {
-      int a = *row + *prev_row++;
-      *row++ = (png_byte)a;
-   }
-
-   /* Remainder */
-   rp_end += row_info->rowbytes - bpp;
-
-   while (row < rp_end)
-   {
-      int a, b, c, pa, pb, pc, p;
-
-      c = *(prev_row - bpp);
-      a = *(row - bpp);
-      b = *prev_row++;
-
-      p = b - c;
-      pc = a - c;
-
-#     ifdef PNG_USE_ABS
-         pa = abs(p);
-         pb = abs(pc);
-         pc = abs(p + pc);
-#     else
-         pa = p < 0 ? -p : p;
-         pb = pc < 0 ? -pc : pc;
-         pc = (p + pc) < 0 ? -(p + pc) : p + pc;
-#     endif
-
-      if (pb < pa) pa = pb, a = b;
-      if (pc < pa) a = c;
-
-      c = b;
-      a += *row;
-      *row++ = (png_byte)a;
-   }
-}
-
-static void
-png_init_filter_functions(png_structrp pp)
-   /* This function is called once for every PNG image to set the
-    * implementations required to reverse the filtering of PNG rows.  Reversing
-    * the filter is the first transformation performed on the row data.  It is
-    * performed in place, therefore an implementation can be selected based on
-    * the image pixel format.  If the implementation depends on image width then
-    * take care to ensure that it works correctly if the image is interlaced -
-    * interlacing causes the actual row width to vary.
-    */
-{
-   unsigned int bpp = (pp->pixel_depth + 7) >> 3;
-
-   pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
-   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
-   pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
-   if (bpp == 1)
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
-         png_read_filter_row_paeth_1byte_pixel;
-   else
-      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
-         png_read_filter_row_paeth_multibyte_pixel;
-
-#ifdef PNG_FILTER_OPTIMIZATIONS
-   /* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
-    * call to install hardware optimizations for the above functions; simply
-    * replace whatever elements of the pp->read_filter[] array with a hardware
-    * specific (or, for that matter, generic) optimization.
-    *
-    * To see an example of this examine what configure.ac does when
-    * --enable-arm-neon is specified on the command line.
-    */
-   PNG_FILTER_OPTIMIZATIONS(pp, bpp);
-#endif
-}
-
-void /* PRIVATE */
-png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
-   png_const_bytep prev_row, int filter)
-{
-   /* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
-    * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
-    * implementations.  See png_init_filter_functions above.
-    */
-   if (pp->read_filter[0] == NULL)
-      png_init_filter_functions(pp);
-   if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
-      pp->read_filter[filter-1](row_info, row, prev_row);
-}
-
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 void /* PRIVATE */
-png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
-   png_alloc_size_t avail_out)
-{
-   /* Loop reading IDATs and decompressing the result into output[avail_out] */
-   png_ptr->zstream.next_out = output;
-   png_ptr->zstream.avail_out = 0; /* safety: set below */
-
-   if (output == NULL)
-      avail_out = 0;
-
-   do
-   {
-      int ret;
-      png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
-
-      if (png_ptr->zstream.avail_in == 0)
-      {
-         uInt avail_in;
-         png_bytep buffer;
-
-         while (png_ptr->idat_size == 0)
-         {
-            png_crc_finish(png_ptr, 0);
-
-            png_ptr->idat_size = png_read_chunk_header(png_ptr);
-            /* This is an error even in the 'check' case because the code just
-             * consumed a non-IDAT header.
-             */
-            if (png_ptr->chunk_name != png_IDAT)
-               png_error(png_ptr, "Not enough image data");
-         }
-
-         avail_in = png_ptr->IDAT_read_size;
-
-         if (avail_in > png_ptr->idat_size)
-            avail_in = (uInt)png_ptr->idat_size;
-
-         /* A PNG with a gradually increasing IDAT size will defeat this attempt
-          * to minimize memory usage by causing lots of re-allocs, but
-          * realistically doing IDAT_read_size re-allocs is not likely to be a
-          * big problem.
-          */
-         buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
-
-         png_crc_read(png_ptr, buffer, avail_in);
-         png_ptr->idat_size -= avail_in;
-
-         png_ptr->zstream.next_in = buffer;
-         png_ptr->zstream.avail_in = avail_in;
-      }
-
-      /* And set up the output side. */
-      if (output != NULL) /* standard read */
-      {
-         uInt out = ZLIB_IO_MAX;
-
-         if (out > avail_out)
-            out = (uInt)avail_out;
-
-         avail_out -= out;
-         png_ptr->zstream.avail_out = out;
-      }
-
-      else /* after last row, checking for end */
-      {
-         png_ptr->zstream.next_out = tmpbuf;
-         png_ptr->zstream.avail_out = (sizeof tmpbuf);
-      }
-
-      /* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
-       * process.  If the LZ stream is truncated the sequential reader will
-       * terminally damage the stream, above, by reading the chunk header of the
-       * following chunk (it then exits with png_error).
-       *
-       * TODO: deal more elegantly with truncated IDAT lists.
-       */
-      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
-
-      /* Take the unconsumed output back. */
-      if (output != NULL)
-         avail_out += png_ptr->zstream.avail_out;
-
-      else /* avail_out counts the extra bytes */
-         avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
-
-      png_ptr->zstream.avail_out = 0;
-
-      if (ret == Z_STREAM_END)
-      {
-         /* Do this for safety; we won't read any more into this row. */
-         png_ptr->zstream.next_out = NULL;
-
-         png_ptr->mode |= PNG_AFTER_IDAT;
-         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
-
-         if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
-            png_chunk_benign_error(png_ptr, "Extra compressed data");
-         break;
-      }
-
-      if (ret != Z_OK)
-      {
-         png_zstream_error(png_ptr, ret);
-
-         if (output != NULL)
-            png_chunk_error(png_ptr, png_ptr->zstream.msg);
-
-         else /* checking */
-         {
-            png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
-            return;
-         }
-      }
-   } while (avail_out > 0);
-
-   if (avail_out > 0)
-   {
-      /* The stream ended before the image; this is the same as too few IDATs so
-       * should be handled the same way.
-       */
-      if (output != NULL)
-         png_error(png_ptr, "Not enough image data");
-
-      else /* the deflate stream contained extra data */
-         png_chunk_benign_error(png_ptr, "Too much image data");
-   }
-}
-
-void /* PRIVATE */
-png_read_finish_IDAT(png_structrp png_ptr)
-{
-   /* We don't need any more data and the stream should have ended, however the
-    * LZ end code may actually not have been processed.  In this case we must
-    * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
-    * may still remain to be consumed.
-    */
-   if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
-   {
-      /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
-       * the compressed stream, but the stream may be damaged too, so even after
-       * this call we may need to terminate the zstream ownership.
-       */
-      png_read_IDAT_data(png_ptr, NULL, 0);
-      png_ptr->zstream.next_out = NULL; /* safety */
-
-      /* Now clear everything out for safety; the following may not have been
-       * done.
-       */
-      if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
-      {
-         png_ptr->mode |= PNG_AFTER_IDAT;
-         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
-      }
-   }
-
-   /* If the zstream has not been released do it now *and* terminate the reading
-    * of the final IDAT chunk.
-    */
-   if (png_ptr->zowner == png_IDAT)
-   {
-      /* Always do this; the pointers otherwise point into the read buffer. */
-      png_ptr->zstream.next_in = NULL;
-      png_ptr->zstream.avail_in = 0;
-
-      /* Now we no longer own the zstream. */
-      png_ptr->zowner = 0;
-
-      /* The slightly weird semantics of the sequential IDAT reading is that we
-       * are always in or at the end of an IDAT chunk, so we always need to do a
-       * crc_finish here.  If idat_size is non-zero we also need to read the
-       * spurious bytes at the end of the chunk now.
-       */
-      (void)png_crc_finish(png_ptr, png_ptr->idat_size);
-   }
-}
-
-void /* PRIVATE */
-png_read_finish_row(png_structrp png_ptr)
+png_read_finish_row(png_structp png_ptr)
 {
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
    /* Offset to next interlace block */
-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
    /* Start of interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
    /* Offset to next interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 
    png_debug(1, "in png_read_finish_row");
    png_ptr->row_number++;
    if (png_ptr->row_number < png_ptr->num_rows)
       return;
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
       png_ptr->row_number = 0;
-
-      /* TO DO: don't do this if prev_row isn't needed (requires
-       * read-ahead of the next row's filter byte.
-       */
-      memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
-
+      png_memset_check(png_ptr, png_ptr->prev_row, 0,
+         png_ptr->rowbytes + 1);
       do
       {
          png_ptr->pass++;
-
          if (png_ptr->pass >= 7)
             break;
-
          png_ptr->iwidth = (png_ptr->width +
             png_pass_inc[png_ptr->pass] - 1 -
             png_pass_start[png_ptr->pass]) /
             png_pass_inc[png_ptr->pass];
 
          if (!(png_ptr->transformations & PNG_INTERLACE))
          {
             png_ptr->num_rows = (png_ptr->height +
-                png_pass_yinc[png_ptr->pass] - 1 -
-                png_pass_ystart[png_ptr->pass]) /
-                png_pass_yinc[png_ptr->pass];
+               png_pass_yinc[png_ptr->pass] - 1 -
+               png_pass_ystart[png_ptr->pass]) /
+               png_pass_yinc[png_ptr->pass];
+            if (!(png_ptr->num_rows))
+               continue;
          }
-
          else  /* if (png_ptr->transformations & PNG_INTERLACE) */
-            break; /* libpng deinterlacing sees every row */
-
-      } while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
+            break;
+      } while (png_ptr->iwidth == 0);
 
       if (png_ptr->pass < 7)
          return;
    }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 
-   /* Here after at the end of the last row of the last pass. */
-   png_read_finish_IDAT(png_ptr);
+   if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
+   {
+#ifdef PNG_USE_LOCAL_ARRAYS
+      PNG_CONST PNG_IDAT;
+#endif
+      char extra;
+      int ret;
+
+      png_ptr->zstream.next_out = (Byte *)&extra;
+      png_ptr->zstream.avail_out = (uInt)1;
+      for (;;)
+      {
+         if (!(png_ptr->zstream.avail_in))
+         {
+            while (!png_ptr->idat_size)
+            {
+               png_byte chunk_length[4];
+
+               png_crc_finish(png_ptr, 0);
+
+               png_read_data(png_ptr, chunk_length, 4);
+               png_ptr->idat_size = png_get_uint_31(png_ptr, chunk_length);
+               png_reset_crc(png_ptr);
+               png_crc_read(png_ptr, png_ptr->chunk_name, 4);
+               if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+                  png_error(png_ptr, "Not enough image data");
+
+            }
+            png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
+            png_ptr->zstream.next_in = png_ptr->zbuf;
+            if (png_ptr->zbuf_size > png_ptr->idat_size)
+               png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
+            png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zstream.avail_in);
+            png_ptr->idat_size -= png_ptr->zstream.avail_in;
+         }
+         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
+         if (ret == Z_STREAM_END)
+         {
+            if (!(png_ptr->zstream.avail_out) || png_ptr->zstream.avail_in ||
+               png_ptr->idat_size)
+               png_warning(png_ptr, "Extra compressed data.");
+            png_ptr->mode |= PNG_AFTER_IDAT;
+            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+            break;
+         }
+         if (ret != Z_OK)
+            png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
+                      "Decompression Error");
+
+         if (!(png_ptr->zstream.avail_out))
+         {
+            png_warning(png_ptr, "Extra compressed data.");
+            png_ptr->mode |= PNG_AFTER_IDAT;
+            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
+            break;
+         }
+
+      }
+      png_ptr->zstream.avail_out = 0;
+   }
+
+   if (png_ptr->idat_size || png_ptr->zstream.avail_in)
+      png_warning(png_ptr, "Extra compression data.");
+
+   inflateReset(&png_ptr->zstream);
+
+   png_ptr->mode |= PNG_AFTER_IDAT;
 }
 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
 void /* PRIVATE */
-png_read_start_row(png_structrp png_ptr)
+png_read_start_row(png_structp png_ptr)
 {
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
    /* Offset to next interlace block */
-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
    /* Start of interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
    /* Offset to next interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
 
    int max_pixel_depth;
    png_size_t row_bytes;
 
    png_debug(1, "in png_read_start_row");
-
-#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+   png_ptr->zstream.avail_in = 0;
    png_init_read_transformations(png_ptr);
-#endif
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
       if (!(png_ptr->transformations & PNG_INTERLACE))
          png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
-             png_pass_ystart[0]) / png_pass_yinc[0];
-
+            png_pass_ystart[0]) / png_pass_yinc[0];
       else
          png_ptr->num_rows = png_ptr->height;
 
       png_ptr->iwidth = (png_ptr->width +
-          png_pass_inc[png_ptr->pass] - 1 -
-          png_pass_start[png_ptr->pass]) /
-          png_pass_inc[png_ptr->pass];
+         png_pass_inc[png_ptr->pass] - 1 -
+         png_pass_start[png_ptr->pass]) /
+         png_pass_inc[png_ptr->pass];
    }
-
    else
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
    {
       png_ptr->num_rows = png_ptr->height;
       png_ptr->iwidth = png_ptr->width;
    }
-
    max_pixel_depth = png_ptr->pixel_depth;
 
-   /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of
-    * calculations to calculate the final pixel depth, then
-    * png_do_read_transforms actually does the transforms.  This means that the
-    * code which effectively calculates this value is actually repeated in three
-    * separate places.  They must all match.  Innocent changes to the order of
-    * transformations can and will break libpng in a way that causes memory
-    * overwrites.
-    *
-    * TODO: fix this.
-    */
 #ifdef PNG_READ_PACK_SUPPORTED
    if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
       max_pixel_depth = 8;
 #endif
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
    if (png_ptr->transformations & PNG_EXPAND)
    {
       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       {
          if (png_ptr->num_trans)
             max_pixel_depth = 32;
-
          else
             max_pixel_depth = 24;
       }
-
       else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
       {
          if (max_pixel_depth < 8)
             max_pixel_depth = 8;
-
          if (png_ptr->num_trans)
             max_pixel_depth *= 2;
       }
-
       else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
       {
          if (png_ptr->num_trans)
          {
             max_pixel_depth *= 4;
             max_pixel_depth /= 3;
          }
       }
    }
 #endif
 
-#ifdef PNG_READ_EXPAND_16_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND_16)
-   {
-#     ifdef PNG_READ_EXPAND_SUPPORTED
-         /* In fact it is an error if it isn't supported, but checking is
-          * the safe way.
-          */
-         if (png_ptr->transformations & PNG_EXPAND)
-         {
-            if (png_ptr->bit_depth < 16)
-               max_pixel_depth *= 2;
-         }
-         else
-#     endif
-         png_ptr->transformations &= ~PNG_EXPAND_16;
-   }
-#endif
-
 #ifdef PNG_READ_FILLER_SUPPORTED
    if (png_ptr->transformations & (PNG_FILLER))
    {
-      if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
+      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+         max_pixel_depth = 32;
+      else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
       {
          if (max_pixel_depth <= 8)
             max_pixel_depth = 16;
-
          else
             max_pixel_depth = 32;
       }
-
-      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
-         png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
       {
          if (max_pixel_depth <= 32)
             max_pixel_depth = 32;
-
          else
             max_pixel_depth = 64;
       }
    }
 #endif
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    if (png_ptr->transformations & PNG_GRAY_TO_RGB)
    {
       if (
 #ifdef PNG_READ_EXPAND_SUPPORTED
-          (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
+        (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
 #endif
 #ifdef PNG_READ_FILLER_SUPPORTED
-          (png_ptr->transformations & (PNG_FILLER)) ||
+        (png_ptr->transformations & (PNG_FILLER)) ||
 #endif
-          png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+        png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
       {
          if (max_pixel_depth <= 16)
             max_pixel_depth = 32;
-
          else
             max_pixel_depth = 64;
       }
-
       else
       {
          if (max_pixel_depth <= 8)
-         {
-            if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+           {
+             if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
                max_pixel_depth = 32;
-
-            else
+             else
                max_pixel_depth = 24;
-         }
-
+           }
          else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
             max_pixel_depth = 64;
-
          else
             max_pixel_depth = 48;
       }
    }
 #endif
 
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
-   {
-      int user_pixel_depth = png_ptr->user_transform_depth *
+     {
+       int user_pixel_depth = png_ptr->user_transform_depth*
          png_ptr->user_transform_channels;
-
-      if (user_pixel_depth > max_pixel_depth)
-         max_pixel_depth = user_pixel_depth;
-   }
+       if (user_pixel_depth > max_pixel_depth)
+         max_pixel_depth=user_pixel_depth;
+     }
 #endif
 
-   /* This value is stored in png_struct and double checked in the row read
-    * code.
-    */
-   png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
-   png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
-
    /* Align the width on the next larger 8 pixels.  Mainly used
     * for interlacing
     */
    row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
    /* Calculate the maximum bytes needed, adding a byte and a pixel
     * for safety's sake
     */
    row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
-       1 + ((max_pixel_depth + 7) >> 3);
-
+      1 + ((max_pixel_depth + 7) >> 3);
 #ifdef PNG_MAX_MALLOC_64K
    if (row_bytes > (png_uint_32)65536L)
       png_error(png_ptr, "This image requires a row greater than 64KB");
 #endif
 
-   if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
+   if (row_bytes + 64 > png_ptr->old_big_row_buf_size)
    {
      png_free(png_ptr, png_ptr->big_row_buf);
-     png_free(png_ptr, png_ptr->big_prev_row);
-
      if (png_ptr->interlaced)
         png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
-            row_bytes + 48);
+            row_bytes + 64);
+     else
+        png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr,
+            row_bytes + 64);
+     png_ptr->old_big_row_buf_size = row_bytes + 64;
 
-     else
-        png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
-
-     png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
-
-#ifdef PNG_ALIGNED_MEMORY_SUPPORTED
-     /* Use 16-byte aligned memory for row_buf with at least 16 bytes
-      * of padding before and after row_buf; treat prev_row similarly.
-      * NOTE: the alignment is to the start of the pixels, one beyond the start
-      * of the buffer, because of the filter byte.  Prior to libpng 1.5.6 this
-      * was incorrect; the filter byte was aligned, which had the exact
-      * opposite effect of that intended.
-      */
-     {
-        png_bytep temp = png_ptr->big_row_buf + 32;
-        int extra = (int)((temp - (png_bytep)0) & 0x0f);
-        png_ptr->row_buf = temp - extra - 1/*filter byte*/;
-
-        temp = png_ptr->big_prev_row + 32;
-        extra = (int)((temp - (png_bytep)0) & 0x0f);
-        png_ptr->prev_row = temp - extra - 1/*filter byte*/;
-     }
-
-#else
-     /* Use 31 bytes of padding before and 17 bytes after row_buf. */
-     png_ptr->row_buf = png_ptr->big_row_buf + 31;
-     png_ptr->prev_row = png_ptr->big_prev_row + 31;
-#endif
-     png_ptr->old_big_row_buf_size = row_bytes + 48;
+     /* Use 32 bytes of padding before and after row_buf. */
+     png_ptr->row_buf = png_ptr->big_row_buf + 32;
+     png_ptr->old_big_row_buf_size = row_bytes + 64;
    }
 
 #ifdef PNG_MAX_MALLOC_64K
-   if (png_ptr->rowbytes > 65535)
+   if ((png_uint_32)row_bytes + 1 > (png_uint_32)65536L)
       png_error(png_ptr, "This image requires a row greater than 64KB");
+#endif
+   if ((png_uint_32)row_bytes > (png_uint_32)(PNG_SIZE_MAX - 1))
+      png_error(png_ptr, "Row has too many bytes to allocate in memory.");
 
-#endif
-   if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
-      png_error(png_ptr, "Row has too many bytes to allocate in memory");
-
-   memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
-
-   png_debug1(3, "width = %u,", png_ptr->width);
-   png_debug1(3, "height = %u,", png_ptr->height);
-   png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
-   png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
-   png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
-   png_debug1(3, "irowbytes = %lu",
-       (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
-
-   /* The sequential reader needs a buffer for IDAT, but the progressive reader
-    * does not, so free the read buffer now regardless; the sequential reader
-    * reallocates it on demand.
-    */
-   if (png_ptr->read_buffer)
+   if (row_bytes + 1 > png_ptr->old_prev_row_size)
    {
-      png_bytep buffer = png_ptr->read_buffer;
-
-      png_ptr->read_buffer_size = 0;
-      png_ptr->read_buffer = NULL;
-      png_free(png_ptr, buffer);
+      png_free(png_ptr, png_ptr->prev_row);
+      png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)(
+        row_bytes + 1));
+      png_memset_check(png_ptr, png_ptr->prev_row, 0, row_bytes + 1);
+      png_ptr->old_prev_row_size = row_bytes + 1;
    }
 
-   /* Finally claim the zstream for the inflate of the IDAT data, use the bits
-    * value from the stream (note that this will result in a fatal error if the
-    * IDAT stream has a bogus deflate header window_bits value, but this should
-    * not be happening any longer!)
-    */
-   if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
-      png_error(png_ptr, png_ptr->zstream.msg);
+   png_ptr->rowbytes = row_bytes;
+
+   png_debug1(3, "width = %lu,", png_ptr->width);
+   png_debug1(3, "height = %lu,", png_ptr->height);
+   png_debug1(3, "iwidth = %lu,", png_ptr->iwidth);
+   png_debug1(3, "num_rows = %lu,", png_ptr->num_rows);
+   png_debug1(3, "rowbytes = %lu,", png_ptr->rowbytes);
+   png_debug1(3, "irowbytes = %lu",
+       PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
 
    png_ptr->flags |= PNG_FLAG_ROW_INIT;
 }
 #endif /* PNG_READ_SUPPORTED */