Updates the PNG library to 1.2.37, enables some functionality for O3D

third_party/libpng/pngrutil.c

 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.2.36 [May 7, 2009]
+ * Last changed in libpng 1.2.37 [June 4, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 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 file contains routines that are only called from within
  * libpng itself during the course of reading an image.
  */
 
 #define PNG_INTERNAL
 #include "png.h"
 #if defined(PNG_READ_SUPPORTED)
 
 #if defined(_WIN32_WCE) && (_WIN32_WCE<0x500)
 #  define WIN32_WCE_OLD
 #endif
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 #  if defined(WIN32_WCE_OLD)
-/* strtod() function is not supported on WindowsCE */
+/* 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 )
    {
@@ skipping 34 matching lines @@
    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 (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 it is
- * assumed that the machine format for signed integers is the same. */
+ * assumed that the machine format for signed integers is the same.
+ */
 png_int_32 PNGAPI
 png_get_int_32(png_bytep buf)
 {
    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));
 
    return (i);
 }
@@ skipping 11 matching lines @@
 
 /* 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_structp png_ptr)
 {
    png_byte buf[8];
    png_uint_32 length;
 
-   /* read the length and the chunk name */
+   /* 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 */
+   /* Put the chunk name into png_ptr->chunk_name */
    png_memcpy(png_ptr->chunk_name, buf + 4, 4);
 
    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, 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);
 
    return length;
 }
 
 /* Read data, and (optionally) run it through the CRC. */
 void /* PRIVATE */
 png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
 {
-   if (png_ptr == NULL) return;
+   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 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. */
+ * 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_structp png_ptr, png_uint_32 skip)
 {
    png_size_t i;
    png_size_t istop = png_ptr->zbuf_size;
 
    for (i = (png_size_t)skip; i > istop; i -= istop)
    {
       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_ptr->chunk_name[0] & 0x20) &&                /* Ancillary */
-           !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) ||
+          !(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_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. */
+ * the data it has read thus far.
+ */
 int /* PRIVATE */
 png_crc_error(png_structp png_ptr)
 {
    png_byte crc_bytes[4];
    png_uint_32 crc;
    int need_crc = 1;
 
    if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
    {
       if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
@@ skipping 134 matching lines @@
       }
       if (ret != Z_STREAM_END)
       {
 #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
          char umsg[52];
 
          if (ret == Z_BUF_ERROR)
             png_snprintf(umsg, 52,
                 "Buffer error in compressed datastream in %s chunk",
                 png_ptr->chunk_name);
+
          else if (ret == Z_DATA_ERROR)
             png_snprintf(umsg, 52,
                 "Data error in compressed datastream in %s chunk",
                 png_ptr->chunk_name);
+
          else
             png_snprintf(umsg, 52,
                 "Incomplete compressed datastream in %s chunk",
                 png_ptr->chunk_name);
+
          png_warning(png_ptr, umsg);
 #else
          png_warning(png_ptr,
             "Incomplete compressed datastream in chunk other than IDAT");
 #endif
          text_size = prefix_size;
          if (text ==  NULL)
          {
             text = (png_charp)png_malloc_warn(png_ptr, text_size+1);
             if (text == NULL)
@@ skipping 24 matching lines @@
 #else
       png_warning(png_ptr, "Unknown zTXt compression type");
 #endif
 
       *(png_ptr->chunkdata + prefix_size) = 0x00;
       *newlength = prefix_size;
    }
 }
 #endif
 
-/* read and check the IDHR chunk */
+/* Read and check the IDHR chunk */
 void /* PRIVATE */
 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_error(png_ptr, "Out of place IHDR");
 
-   /* check the length */
+   /* Check the length */
    if (length != 13)
       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 */
+   /* 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;
 #if defined(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 */
+   /* Find number of channels */
    switch (png_ptr->color_type)
    {
       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 */
+   /* 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", png_ptr->rowbytes);
    png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
       color_type, interlace_type, compression_type, filter_type);
 }
 
-/* read and check the palette */
+/* Read and check the palette */
 void /* PRIVATE */
 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;
 #ifndef PNG_NO_POINTER_INDEXING
    png_colorp pal_ptr;
 #endif
 
    png_debug(1, "in png_handle_PLTE");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before PLTE");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid PLTE after IDAT");
       png_crc_finish(png_ptr, length);
       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))
    {
       png_warning(png_ptr,
         "Ignoring PLTE chunk in grayscale PNG");
       png_crc_finish(png_ptr, length);
       return;
    }
 #if !defined(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)
    {
       if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
       {
          png_warning(png_ptr, "Invalid palette chunk");
          png_crc_finish(png_ptr, length);
          return;
       }
+
       else
       {
          png_error(png_ptr, "Invalid palette chunk");
       }
    }
 
    num = (int)length / 3;
 
 #ifndef PNG_NO_POINTER_INDEXING
    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 */
+      /* 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
-      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. */
+    * 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.
+    */
 #if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 #endif
    {
       png_crc_finish(png_ptr, 0);
    }
 #if !defined(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,
@@ skipping 54 matching lines @@
    }
 
    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);
 
-   info_ptr = info_ptr; /* quiet compiler warnings about unused info_ptr */
+   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
 }
 
 #if defined(PNG_READ_gAMA_SUPPORTED)
 void /* PRIVATE */
 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
@@ skipping 29 matching lines @@
       png_warning(png_ptr, "Incorrect gAMA chunk length");
       png_crc_finish(png_ptr, length);
       return;
    }
 
    png_crc_read(png_ptr, buf, 4);
    if (png_crc_finish(png_ptr, 0))
       return;
 
    igamma = (png_fixed_point)png_get_uint_32(buf);
-   /* check for zero gamma */
+   /* Check for zero gamma */
    if (igamma == 0)
       {
          png_warning(png_ptr,
            "Ignoring gAMA chunk with gamma=0");
          return;
       }
 
 #if defined(PNG_READ_sRGB_SUPPORTED)
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
       if (PNG_OUT_OF_RANGE(igamma, 45500L, 500))
@@ skipping 243 matching lines @@
       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;
 
    intent = buf[0];
-   /* check for bad intent */
+   /* 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;
@@ skipping 94 matching lines @@
    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 */ ;
+      /* 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  */
+   /* There should be at least one zero (the compression type byte)
+    * following the separator, and we should be on it
+    */
    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 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,
@@ skipping 77 matching lines @@
    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 (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start; entry_start++)
-      /* empty loop to find end of name */ ;
+      /* Empty loop to find end of name */ ;
    ++entry_start;
 
-   /* a sample depth should follow the separator, and we should be on it  */
+   /* A sample depth should follow the separator, and we should be on it  */
    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);
    data_length = (slength - (entry_start - (png_bytep)png_ptr->chunkdata));
 
-   /* integrity-check the data length */
+   /* 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;
    }
 
    new_palette.nentries = (png_int_32) ( data_length / entry_size);
    if ((png_uint_32) new_palette.nentries >
@@ skipping 47 matching lines @@
       {
           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->frequency = png_get_uint_16(entry_start); entry_start += 2;
    }
 #endif
 
-   /* discard all chunk data except the name and stash that */
+   /* Discard all chunk data except the name and stash that */
    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 */
 
@@ skipping 315 matching lines @@
       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
 
 #if defined(PNG_READ_pCAL_SUPPORTED)
-/* read the pCAL chunk (described in the PNG Extensions document) */
+/* Read the pCAL chunk (described in the PNG Extensions document) */
 void /* PRIVATE */
 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_charp buf, units, endptr;
    png_charpp params;
    png_size_t slength;
    int i;
 
@@ skipping 26 matching lines @@
    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_ptr->chunkdata[slength] = 0x00; /* null terminate the last string */
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
    png_debug(3, "Finding end of pCAL purpose string");
    for (buf = png_ptr->chunkdata; *buf; buf++)
-      /* empty loop */ ;
+      /* Empty loop */ ;
 
    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_warning(png_ptr, "Invalid pCAL data");
       png_free(png_ptr, png_ptr->chunkdata);
       png_ptr->chunkdata = NULL;
@@ skipping 62 matching lines @@
    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
 
 #if defined(PNG_READ_sCAL_SUPPORTED)
-/* read the sCAL chunk */
+/* Read the sCAL chunk */
 void /* PRIVATE */
 png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_charp ep;
 #ifdef PNG_FLOATING_POINT_SUPPORTED
    double width, height;
    png_charp vp;
 #else
 #ifdef PNG_FIXED_POINT_SUPPORTED
    png_charp swidth, sheight;
@@ skipping 29 matching lines @@
    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_ptr->chunkdata[slength] = 0x00; /* null terminate the last string */
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
-   ep = png_ptr->chunkdata + 1;        /* skip unit byte */
+   ep = png_ptr->chunkdata + 1;        /* Skip unit byte */
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
    width = png_strtod(png_ptr, ep, &vp);
    if (*vp)
    {
       png_warning(png_ptr, "malformed width string in sCAL chunk");
       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");
       return;
    }
    png_memcpy(swidth, ep, (png_size_t)png_strlen(ep));
 #endif
 #endif
 
    for (ep = png_ptr->chunkdata; *ep; ep++)
-      /* empty loop */ ;
+      /* Empty loop */ ;
    ep++;
 
    if (png_ptr->chunkdata + slength < ep)
    {
       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);
@@ skipping 143 matching lines @@
       png_free(png_ptr, png_ptr->chunkdata);
       png_ptr->chunkdata = NULL;
       return;
    }
 
    key = png_ptr->chunkdata;
 
    key[slength] = 0x00;
 
    for (text = key; *text; text++)
-      /* empty loop to find end of key */ ;
+      /* Empty loop to find end of key */ ;
 
    if (text != key + slength)
       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);
@@ skipping 14 matching lines @@
 
    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
 
 #if defined(PNG_READ_zTXt_SUPPORTED)
-/* note: this does not correctly handle chunks that are > 64K under DOS */
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
 png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 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");
@@ skipping 28 matching lines @@
    if (png_crc_finish(png_ptr, 0))
    {
       png_free(png_ptr, png_ptr->chunkdata);
       png_ptr->chunkdata = NULL;
       return;
    }
 
    png_ptr->chunkdata[slength] = 0x00;
 
    for (text = png_ptr->chunkdata; *text; text++)
-      /* empty loop */ ;
+      /* 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;
    }
    else
    {
        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 */
+       text++;        /* Skip the compression_method byte */
    }
    prefix_len = text - png_ptr->chunkdata;
 
    png_decompress_chunk(png_ptr, comp_type,
      (png_size_t)length, prefix_len, &data_len);
 
    text_ptr = (png_textp)png_malloc_warn(png_ptr,
       (png_uint_32)png_sizeof(png_text));
    if (text_ptr == NULL)
    {
@@ skipping 16 matching lines @@
 
    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
 
 #if defined(PNG_READ_iTXt_SUPPORTED)
-/* note: this does not correctly handle chunks that are > 64K under DOS */
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
 png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 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;
 
@@ skipping 29 matching lines @@
    if (png_crc_finish(png_ptr, 0))
    {
       png_free(png_ptr, png_ptr->chunkdata);
       png_ptr->chunkdata = NULL;
       return;
    }
 
    png_ptr->chunkdata[slength] = 0x00;
 
    for (lang = png_ptr->chunkdata; *lang; lang++)
-      /* empty loop */ ;
-   lang++;        /* skip NUL separator */
+      /* 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 */
+    * 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;
    }
    else
    {
        comp_flag = *lang++;
        comp_type = *lang++;
    }
 
    for (lang_key = lang; *lang_key; lang_key++)
-      /* empty loop */ ;
-   lang_key++;        /* skip NUL separator */
+      /* Empty loop */ ;
+   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 */
+      /* 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;
 
@@ skipping 41 matching lines @@
    png_uint_32 skip = 0;
 
    png_debug(1, "in png_handle_unknown");
 
 
    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 */
+      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))
    {
 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
       if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
            PNG_HANDLE_CHUNK_ALWAYS
 #if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
            && png_ptr->read_user_chunk_fn == NULL
@@ skipping 23 matching lines @@
        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);
        }
 #if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
        if (png_ptr->read_user_chunk_fn != NULL)
        {
-          /* callback to user unknown chunk handler */
+          /* 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))
                 if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
                      PNG_HANDLE_CHUNK_ALWAYS)
                    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
 #endif
       skip = length;
 
    png_crc_finish(png_ptr, skip);
 
 #if !defined(PNG_READ_USER_CHUNKS_SUPPORTED)
-   info_ptr = info_ptr; /* quiet compiler warnings about unused info_ptr */
+   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
 #endif
 }
 
 /* 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))
@@ skipping 227 matching lines @@
    png_uint_32 transformations)
  */
 void /* PRIVATE */
 png_do_read_interlace(png_structp png_ptr)
 {
    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;
 #ifdef PNG_USE_LOCAL_ARRAYS
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
-   /* offset to next interlace block */
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+   /* Offset to next interlace block */
    PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 #endif
 
    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];
 
@@ skipping 187 matching lines @@
                }
                sp -= pixel_bytes;
             }
             break;
          }
       }
       row_info->width = final_width;
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
    }
 #if !defined(PNG_READ_PACKSWAP_SUPPORTED)
-   transformations = transformations; /* silence compiler warning */
+   transformations = transformations; /* Silence compiler warning */
 #endif
 }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 
 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_debug(1, "in png_read_filter_row");
    png_debug2(2, "row = %lu, filter = %d", png_ptr->row_number, filter);
@@ skipping 63 matching lines @@
          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 */
+         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;
 
@@ skipping 23 matching lines @@
          }
          break;
       }
       default:
          png_warning(png_ptr, "Ignoring bad adaptive filter type");
          *row = 0;
          break;
    }
 }
 
+#ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 void /* PRIVATE */
 png_read_finish_row(png_structp png_ptr)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
-   /* start of interlace block */
+   /* Start of interlace block */
    PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
-   /* offset to next interlace block */
+   /* Offset to next interlace block */
    PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
-   /* start of interlace block in the y direction */
+   /* Start of interlace block in the y direction */
    PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
-   /* offset to next interlace block in the y direction */
+   /* Offset to next interlace block in the y direction */
    PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 #endif
 
    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
@@ skipping 94 matching lines @@
       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_NO_SEQUENTIAL_READ_SUPPORTED */
 
 void /* PRIVATE */
 png_read_start_row(png_structp png_ptr)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
-   /* start of interlace block */
+   /* Start of interlace block */
    PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
-   /* offset to next interlace block */
+   /* Offset to next interlace block */
    PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
-   /* start of interlace block in the y direction */
+   /* Start of interlace block in the y direction */
    PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
-   /* offset to next interlace block in the y direction */
+   /* Offset to next interlace block in the y direction */
    PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
 #endif
 
    int max_pixel_depth;
    png_size_t row_bytes;
 
    png_debug(1, "in png_read_start_row");
    png_ptr->zstream.avail_in = 0;
    png_init_read_transformations(png_ptr);
@@ skipping 116 matching lines @@
 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
      {
        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;
      }
 #endif
 
-   /* align the width on the next larger 8 pixels.  Mainly used
-      for interlacing */
+   /* 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 */
+   /* 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);
 #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 + 64 > png_ptr->old_big_row_buf_size)
    {
      png_free(png_ptr, png_ptr->big_row_buf);
-      png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 64);
+     png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 64);
      if (png_ptr->interlaced)
-       png_memset(png_ptr->big_row_buf, 0, png_ptr->rowbytes + 64);
+       png_memset(png_ptr->big_row_buf, 0, row_bytes + 64);
      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_uint_32)png_ptr->rowbytes + 1 > (png_uint_32)65536L)
+   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)png_ptr->rowbytes > (png_uint_32)(PNG_SIZE_MAX - 1))
+   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.");
 
-   if (png_ptr->rowbytes+1 > png_ptr->old_prev_row_size)
+   if (row_bytes + 1 > png_ptr->old_prev_row_size)
    {
-     png_free(png_ptr, png_ptr->prev_row);
-     png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)(
-        png_ptr->rowbytes + 1));
-     png_ptr->old_prev_row_size = png_ptr->rowbytes+1;
+      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;
    }
 
-   png_memset_check(png_ptr, png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+   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_ptr->irowbytes);
 
    png_ptr->flags |= PNG_FLAG_ROW_INIT;
 }
 #endif /* PNG_READ_SUPPORTED */