Update libpng to 1.2.33.

third_party/libpng/pngread.c

 
 /* pngread.c - read a PNG file
  *
- * Last changed in libpng 1.2.25 [February 18, 2008]
+ * Last changed in libpng 1.2.30 [August 15, 2008]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2008 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 an application calls directly to
  * read a PNG file or stream.
  */
 
 #define PNG_INTERNAL
 #include "png.h"
-
 #if defined(PNG_READ_SUPPORTED)
 
 /* Create a PNG structure for reading, and allocate any memory needed. */
 png_structp PNGAPI
 png_create_read_struct(png_const_charp user_png_ver, png_voidp error_ptr,
    png_error_ptr error_fn, png_error_ptr warn_fn)
 {
 
 #ifdef PNG_USER_MEM_SUPPORTED
    return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
       warn_fn, png_voidp_NULL, png_malloc_ptr_NULL, png_free_ptr_NULL));
 }
 
 /* Alternate create PNG structure for reading, and allocate any memory needed. */
 png_structp PNGAPI
 png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
    png_malloc_ptr malloc_fn, png_free_ptr free_fn)
 {
 #endif /* PNG_USER_MEM_SUPPORTED */
 
+#ifdef PNG_SETJMP_SUPPORTED
+   volatile
+#endif
    png_structp png_ptr;
 
 #ifdef PNG_SETJMP_SUPPORTED
 #ifdef USE_FAR_KEYWORD
    jmp_buf jmpbuf;
 #endif
 #endif
 
    int i;
 
@@ skipping 14 matching lines @@
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
 #ifdef USE_FAR_KEYWORD
    if (setjmp(jmpbuf))
 #else
    if (setjmp(png_ptr->jmpbuf))
 #endif
    {
       png_free(png_ptr, png_ptr->zbuf);
-      png_ptr->zbuf=NULL;
+      png_ptr->zbuf = NULL;
 #ifdef PNG_USER_MEM_SUPPORTED
       png_destroy_struct_2((png_voidp)png_ptr,
          (png_free_ptr)free_fn, (png_voidp)mem_ptr);
 #else
       png_destroy_struct((png_voidp)png_ptr);
 #endif
       return (NULL);
    }
 #ifdef USE_FAR_KEYWORD
-   png_memcpy(png_ptr->jmpbuf,jmpbuf,png_sizeof(jmp_buf));
+   png_memcpy(png_ptr->jmpbuf, jmpbuf, png_sizeof(jmp_buf));
 #endif
 #endif
 
 #ifdef PNG_USER_MEM_SUPPORTED
    png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
 #endif
 
    png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
 
-   if(user_png_ver)
+   if (user_png_ver)
    {
-     i=0;
+     i = 0;
      do
      {
-       if(user_png_ver[i] != png_libpng_ver[i])
+       if (user_png_ver[i] != png_libpng_ver[i])
           png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
      } while (png_libpng_ver[i++]);
    }
    else
         png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
    
 
    if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
    {
      /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
@@ skipping 13 matching lines @@
              "Application was compiled with png.h from libpng-%.20s",
              user_png_ver);
           png_warning(png_ptr, msg);
         }
         png_snprintf(msg, 80,
              "Application  is  running with png.c from libpng-%.20s",
            png_libpng_ver);
         png_warning(png_ptr, msg);
 #endif
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-        png_ptr->flags=0;
+        png_ptr->flags = 0;
 #endif
         png_error(png_ptr,
            "Incompatible libpng version in application and library");
      }
    }
 
    /* initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
      (png_uint_32)png_ptr->zbuf_size);
@@ skipping 15 matching lines @@
 
    png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL);
 
 #ifdef PNG_SETJMP_SUPPORTED
 /* Applications that neglect to set up their own setjmp() and then encounter
    a png_error() will longjmp here.  Since the jmpbuf is then meaningless we
    abort instead of returning. */
 #ifdef USE_FAR_KEYWORD
    if (setjmp(jmpbuf))
       PNG_ABORT();
-   png_memcpy(png_ptr->jmpbuf,jmpbuf,png_sizeof(jmp_buf));
+   png_memcpy(png_ptr->jmpbuf, jmpbuf, png_sizeof(jmp_buf));
 #else
    if (setjmp(png_ptr->jmpbuf))
       PNG_ABORT();
 #endif
 #endif
    return (png_ptr);
 }
 
 #if defined(PNG_1_0_X) || defined(PNG_1_2_X)
 /* Initialize PNG structure for reading, and allocate any memory needed.
    This interface is deprecated in favour of the png_create_read_struct(),
    and it will disappear as of libpng-1.3.0. */
 #undef png_read_init
 void PNGAPI
 png_read_init(png_structp png_ptr)
 {
    /* We only come here via pre-1.0.7-compiled applications */
    png_read_init_2(png_ptr, "1.0.6 or earlier", 0, 0);
 }
 
 void PNGAPI
 png_read_init_2(png_structp png_ptr, png_const_charp user_png_ver,
    png_size_t png_struct_size, png_size_t png_info_size)
 {
    /* We only come here via pre-1.0.12-compiled applications */
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
 #if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
-   if(png_sizeof(png_struct) > png_struct_size ||
+   if (png_sizeof(png_struct) > png_struct_size ||
       png_sizeof(png_info) > png_info_size)
    {
       char msg[80];
-      png_ptr->warning_fn=NULL;
+      png_ptr->warning_fn = NULL;
       if (user_png_ver)
       {
         png_snprintf(msg, 80,
            "Application was compiled with png.h from libpng-%.20s",
            user_png_ver);
         png_warning(png_ptr, msg);
       }
       png_snprintf(msg, 80,
          "Application  is  running with png.c from libpng-%.20s",
          png_libpng_ver);
       png_warning(png_ptr, msg);
    }
 #endif
-   if(png_sizeof(png_struct) > png_struct_size)
+   if (png_sizeof(png_struct) > png_struct_size)
      {
-       png_ptr->error_fn=NULL;
+       png_ptr->error_fn = NULL;
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-       png_ptr->flags=0;
+       png_ptr->flags = 0;
 #endif
        png_error(png_ptr,
        "The png struct allocated by the application for reading is too small.");
      }
-   if(png_sizeof(png_info) > png_info_size)
+   if (png_sizeof(png_info) > png_info_size)
      {
-       png_ptr->error_fn=NULL;
+       png_ptr->error_fn = NULL;
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-       png_ptr->flags=0;
+       png_ptr->flags = 0;
 #endif
        png_error(png_ptr,
          "The info struct allocated by application for reading is too small.");
      }
    png_read_init_3(&png_ptr, user_png_ver, png_struct_size);
 }
 #endif /* PNG_1_0_X || PNG_1_2_X */
 
 void PNGAPI
 png_read_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,
    png_size_t png_struct_size)
 {
 #ifdef PNG_SETJMP_SUPPORTED
    jmp_buf tmp_jmp;  /* to save current jump buffer */
 #endif
 
-   int i=0;
+   int i = 0;
 
    png_structp png_ptr=*ptr_ptr;
 
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
 
    do
    {
-     if(user_png_ver[i] != png_libpng_ver[i])
+     if (user_png_ver[i] != png_libpng_ver[i])
      {
 #ifdef PNG_LEGACY_SUPPORTED
        png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
 #else
-       png_ptr->warning_fn=NULL;
+       png_ptr->warning_fn = NULL;
        png_warning(png_ptr,
         "Application uses deprecated png_read_init() and should be recompiled.");
        break;
 #endif
      }
    } while (png_libpng_ver[i++]);
 
    png_debug(1, "in png_read_init_3\n");
 
 #ifdef PNG_SETJMP_SUPPORTED
    /* save jump buffer and error functions */
-   png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof (jmp_buf));
+   png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));
 #endif
 
-   if(png_sizeof(png_struct) > png_struct_size)
-     {
-       png_destroy_struct(png_ptr);
-       *ptr_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
-       png_ptr = *ptr_ptr;
-     }
+   if (png_sizeof(png_struct) > png_struct_size)
+   {
+      png_destroy_struct(png_ptr);
+      *ptr_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
+      png_ptr = *ptr_ptr;
+   }
 
    /* reset all variables to 0 */
-   png_memset(png_ptr, 0, png_sizeof (png_struct));
+   png_memset(png_ptr, 0, png_sizeof(png_struct));
 
 #ifdef PNG_SETJMP_SUPPORTED
    /* restore jump buffer */
-   png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof (jmp_buf));
+   png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof(jmp_buf));
 #endif
 
    /* added at libpng-1.2.6 */
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
    png_ptr->user_width_max=PNG_USER_WIDTH_MAX;
    png_ptr->user_height_max=PNG_USER_HEIGHT_MAX;
 #endif
 
    /* initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
@@ skipping 23 matching lines @@
  * changed in v0.90 to allow reading a file that already has the magic
  * bytes read from the stream.  You can tell libpng how many bytes have
  * been read from the beginning of the stream (up to the maximum of 8)
  * via png_set_sig_bytes(), and we will only check the remaining bytes
  * here.  The application can then have access to the signature bytes we
  * read if it is determined that this isn't a valid PNG file.
  */
 void PNGAPI
 png_read_info(png_structp png_ptr, png_infop info_ptr)
 {
-   if(png_ptr == NULL || info_ptr == NULL) return;
+   if (png_ptr == NULL || info_ptr == NULL) return;
    png_debug(1, "in png_read_info\n");
    /* If we haven't checked all of the PNG signature bytes, do so now. */
    if (png_ptr->sig_bytes < 8)
    {
       png_size_t num_checked = png_ptr->sig_bytes,
                  num_to_check = 8 - num_checked;
 
       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;
    }
 
-   for(;;)
+   for (;;)
    {
 #ifdef PNG_USE_LOCAL_ARRAYS
       PNG_CONST PNG_IHDR;
       PNG_CONST PNG_IDAT;
       PNG_CONST PNG_IEND;
       PNG_CONST PNG_PLTE;
 #if defined(PNG_READ_bKGD_SUPPORTED)
       PNG_CONST PNG_bKGD;
 #endif
 #if defined(PNG_READ_cHRM_SUPPORTED)
@@ skipping 38 matching lines @@
 #if defined(PNG_READ_tIME_SUPPORTED)
       PNG_CONST PNG_tIME;
 #endif
 #if defined(PNG_READ_tRNS_SUPPORTED)
       PNG_CONST PNG_tRNS;
 #endif
 #if defined(PNG_READ_zTXt_SUPPORTED)
       PNG_CONST PNG_zTXt;
 #endif
 #endif /* PNG_USE_LOCAL_ARRAYS */
-      png_byte chunk_length[4];
-      png_uint_32 length;
-
-      png_read_data(png_ptr, chunk_length, 4);
-      length = png_get_uint_31(png_ptr,chunk_length);
-
-      png_reset_crc(png_ptr);
-      png_crc_read(png_ptr, png_ptr->chunk_name, 4);
-
-      png_debug2(0, "Reading %s chunk, length=%lu.\n", png_ptr->chunk_name,
-         length);
+      png_uint_32 length = png_read_chunk_header(png_ptr);
+      PNG_CONST png_bytep chunk_name = png_ptr->chunk_name;
 
       /* This should be a binary subdivision search or a hash for
        * matching the chunk name rather than a linear search.
        */
-      if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
-        if(png_ptr->mode & PNG_AFTER_IDAT)
+      if (!png_memcmp(chunk_name, png_IDAT, 4))
+        if (png_ptr->mode & PNG_AFTER_IDAT)
           png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
 
-      if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
+      if (!png_memcmp(chunk_name, png_IHDR, 4))
          png_handle_IHDR(png_ptr, info_ptr, length);
-      else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
+      else if (!png_memcmp(chunk_name, png_IEND, 4))
          png_handle_IEND(png_ptr, info_ptr, length);
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-      else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))
+      else if (png_handle_as_unknown(png_ptr, chunk_name))
       {
-         if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+         if (!png_memcmp(chunk_name, png_IDAT, 4))
             png_ptr->mode |= PNG_HAVE_IDAT;
          png_handle_unknown(png_ptr, info_ptr, length);
-         if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+         if (!png_memcmp(chunk_name, png_PLTE, 4))
             png_ptr->mode |= PNG_HAVE_PLTE;
-         else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+         else if (!png_memcmp(chunk_name, png_IDAT, 4))
          {
             if (!(png_ptr->mode & PNG_HAVE_IHDR))
                png_error(png_ptr, "Missing IHDR before IDAT");
             else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
                      !(png_ptr->mode & PNG_HAVE_PLTE))
                png_error(png_ptr, "Missing PLTE before IDAT");
             break;
          }
       }
 #endif
-      else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+      else if (!png_memcmp(chunk_name, png_PLTE, 4))
          png_handle_PLTE(png_ptr, info_ptr, length);
-      else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+      else if (!png_memcmp(chunk_name, png_IDAT, 4))
       {
          if (!(png_ptr->mode & PNG_HAVE_IHDR))
             png_error(png_ptr, "Missing IHDR before IDAT");
          else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
                   !(png_ptr->mode & PNG_HAVE_PLTE))
             png_error(png_ptr, "Missing PLTE before IDAT");
 
          png_ptr->idat_size = length;
          png_ptr->mode |= PNG_HAVE_IDAT;
          break;
       }
 #if defined(PNG_READ_bKGD_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
+      else if (!png_memcmp(chunk_name, png_bKGD, 4))
          png_handle_bKGD(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_cHRM_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
+      else if (!png_memcmp(chunk_name, png_cHRM, 4))
          png_handle_cHRM(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_gAMA_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
+      else if (!png_memcmp(chunk_name, png_gAMA, 4))
          png_handle_gAMA(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_hIST_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
+      else if (!png_memcmp(chunk_name, png_hIST, 4))
          png_handle_hIST(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_oFFs_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
+      else if (!png_memcmp(chunk_name, png_oFFs, 4))
          png_handle_oFFs(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_pCAL_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
+      else if (!png_memcmp(chunk_name, png_pCAL, 4))
          png_handle_pCAL(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_sCAL_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
+      else if (!png_memcmp(chunk_name, png_sCAL, 4))
          png_handle_sCAL(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_pHYs_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
+      else if (!png_memcmp(chunk_name, png_pHYs, 4))
          png_handle_pHYs(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_sBIT_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
+      else if (!png_memcmp(chunk_name, png_sBIT, 4))
          png_handle_sBIT(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_sRGB_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
+      else if (!png_memcmp(chunk_name, png_sRGB, 4))
          png_handle_sRGB(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_iCCP_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
+      else if (!png_memcmp(chunk_name, png_iCCP, 4))
          png_handle_iCCP(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_sPLT_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
+      else if (!png_memcmp(chunk_name, png_sPLT, 4))
          png_handle_sPLT(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_tEXt_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
+      else if (!png_memcmp(chunk_name, png_tEXt, 4))
          png_handle_tEXt(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_tIME_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
+      else if (!png_memcmp(chunk_name, png_tIME, 4))
          png_handle_tIME(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_tRNS_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
+      else if (!png_memcmp(chunk_name, png_tRNS, 4))
          png_handle_tRNS(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_zTXt_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
+      else if (!png_memcmp(chunk_name, png_zTXt, 4))
          png_handle_zTXt(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_iTXt_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
+      else if (!png_memcmp(chunk_name, png_iTXt, 4))
          png_handle_iTXt(png_ptr, info_ptr, length);
 #endif
       else
          png_handle_unknown(png_ptr, info_ptr, length);
    }
 }
 #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
 
 /* optional call to update the users info_ptr structure */
 void PNGAPI
 png_read_update_info(png_structp png_ptr, png_infop info_ptr)
 {
    png_debug(1, "in png_read_update_info\n");
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
       png_read_start_row(png_ptr);
    else
       png_warning(png_ptr,
       "Ignoring extra png_read_update_info() call; row buffer not reallocated");
    png_read_transform_info(png_ptr, info_ptr);
 }
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 /* Initialize palette, background, etc, after transformations
  * are set, but before any reading takes place.  This allows
  * the user to obtain a gamma-corrected palette, for example.
  * If the user doesn't call this, we will do it ourselves.
  */
 void PNGAPI
 png_start_read_image(png_structp png_ptr)
 {
    png_debug(1, "in png_start_read_image\n");
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
       png_read_start_row(png_ptr);
 }
 #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 void PNGAPI
 png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_CONST PNG_IDAT;
    PNG_CONST int png_pass_dsp_mask[7] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
-     0xff};
+      0xff};
    PNG_CONST int png_pass_mask[7] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
 #endif
    int ret;
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
    png_debug2(1, "in png_read_row (row %lu, pass %d)\n",
       png_ptr->row_number, png_ptr->pass);
    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
       png_read_start_row(png_ptr);
    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
    {
    /* check for transforms that have been set but were defined out */
 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
    if (png_ptr->transformations & PNG_INVERT_MONO)
       png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined.");
@@ skipping 105 matching lines @@
       png_error(png_ptr, "Invalid attempt to read row data");
 
    png_ptr->zstream.next_out = png_ptr->row_buf;
    png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;
    do
    {
       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);
+            png_ptr->idat_size = png_read_chunk_header(png_ptr);
             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_size_t)png_ptr->zstream.avail_in);
          png_ptr->idat_size -= png_ptr->zstream.avail_in;
@@ skipping 15 matching lines @@
    } while (png_ptr->zstream.avail_out);
 
    png_ptr->row_info.color_type = png_ptr->color_type;
    png_ptr->row_info.width = png_ptr->iwidth;
    png_ptr->row_info.channels = png_ptr->channels;
    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
    png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
        png_ptr->row_info.width);
 
-   if(png_ptr->row_buf[0])
+   if (png_ptr->row_buf[0])
    png_read_filter_row(png_ptr, &(png_ptr->row_info),
       png_ptr->row_buf + 1, png_ptr->prev_row + 1,
       (int)(png_ptr->row_buf[0]));
 
    png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,
       png_ptr->rowbytes + 1);
 
 #if defined(PNG_MNG_FEATURES_SUPPORTED)
-   if((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
       (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
    {
       /* Intrapixel differencing */
       png_do_read_intrapixel(&(png_ptr->row_info), png_ptr->row_buf + 1);
    }
 #endif
 
 
    if (png_ptr->transformations || (png_ptr->flags&PNG_FLAG_STRIP_ALPHA))
       png_do_read_transformations(png_ptr);
@@ skipping 59 matching lines @@
 
 void PNGAPI
 png_read_rows(png_structp png_ptr, png_bytepp row,
    png_bytepp display_row, png_uint_32 num_rows)
 {
    png_uint_32 i;
    png_bytepp rp;
    png_bytepp dp;
 
    png_debug(1, "in png_read_rows\n");
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
    rp = row;
    dp = display_row;
    if (rp != NULL && dp != NULL)
       for (i = 0; i < num_rows; i++)
       {
          png_bytep rptr = *rp++;
          png_bytep dptr = *dp++;
 
          png_read_row(png_ptr, rptr, dptr);
       }
-   else if(rp != NULL)
+   else if (rp != NULL)
       for (i = 0; i < num_rows; i++)
       {
          png_bytep rptr = *rp;
          png_read_row(png_ptr, rptr, png_bytep_NULL);
          rp++;
       }
-   else if(dp != NULL)
+   else if (dp != NULL)
       for (i = 0; i < num_rows; i++)
       {
          png_bytep dptr = *dp;
          png_read_row(png_ptr, png_bytep_NULL, dptr);
          dp++;
       }
 }
 #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 /* Read the entire image.  If the image has an alpha channel or a tRNS
  * chunk, and you have called png_handle_alpha()[*], you will need to
  * initialize the image to the current image that PNG will be overlaying.
  * We set the num_rows again here, in case it was incorrectly set in
  * png_read_start_row() by a call to png_read_update_info() or
  * png_start_read_image() if png_set_interlace_handling() wasn't called
  * prior to either of these functions like it should have been.  You can
  * only call this function once.  If you desire to have an image for
  * each pass of a interlaced image, use png_read_rows() instead.
  *
  * [*] png_handle_alpha() does not exist yet, as of this version of libpng
  */
 void PNGAPI
 png_read_image(png_structp png_ptr, png_bytepp image)
 {
-   png_uint_32 i,image_height;
+   png_uint_32 i, image_height;
    int pass, j;
    png_bytepp rp;
 
    png_debug(1, "in png_read_image\n");
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    pass = png_set_interlace_handling(png_ptr);
 #else
    if (png_ptr->interlaced)
       png_error(png_ptr,
         "Cannot read interlaced image -- interlace handler disabled.");
    pass = 1;
 #endif
 
@@ skipping 14 matching lines @@
 #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 /* Read the end of the PNG file.  Will not read past the end of the
  * file, will verify the end is accurate, and will read any comments
  * or time information at the end of the file, if info is not NULL.
  */
 void PNGAPI
 png_read_end(png_structp png_ptr, png_infop info_ptr)
 {
-   png_byte chunk_length[4];
-   png_uint_32 length;
-
    png_debug(1, "in png_read_end\n");
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
    png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */
 
    do
    {
 #ifdef PNG_USE_LOCAL_ARRAYS
       PNG_CONST PNG_IHDR;
       PNG_CONST PNG_IDAT;
       PNG_CONST PNG_IEND;
       PNG_CONST PNG_PLTE;
 #if defined(PNG_READ_bKGD_SUPPORTED)
@@ skipping 41 matching lines @@
 #if defined(PNG_READ_tIME_SUPPORTED)
       PNG_CONST PNG_tIME;
 #endif
 #if defined(PNG_READ_tRNS_SUPPORTED)
       PNG_CONST PNG_tRNS;
 #endif
 #if defined(PNG_READ_zTXt_SUPPORTED)
       PNG_CONST PNG_zTXt;
 #endif
 #endif /* PNG_USE_LOCAL_ARRAYS */
+      png_uint_32 length = png_read_chunk_header(png_ptr);
+      PNG_CONST png_bytep chunk_name = png_ptr->chunk_name;
 
-      png_read_data(png_ptr, chunk_length, 4);
-      length = png_get_uint_31(png_ptr,chunk_length);
-
-      png_reset_crc(png_ptr);
-      png_crc_read(png_ptr, png_ptr->chunk_name, 4);
-
-      png_debug1(0, "Reading %s chunk.\n", png_ptr->chunk_name);
-
-      if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
+      if (!png_memcmp(chunk_name, png_IHDR, 4))
          png_handle_IHDR(png_ptr, info_ptr, length);
-      else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
+      else if (!png_memcmp(chunk_name, png_IEND, 4))
          png_handle_IEND(png_ptr, info_ptr, length);
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-      else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))
+      else if (png_handle_as_unknown(png_ptr, chunk_name))
       {
-         if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+         if (!png_memcmp(chunk_name, png_IDAT, 4))
          {
             if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
                png_error(png_ptr, "Too many IDAT's found");
          }
          png_handle_unknown(png_ptr, info_ptr, length);
-         if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+         if (!png_memcmp(chunk_name, png_PLTE, 4))
             png_ptr->mode |= PNG_HAVE_PLTE;
       }
 #endif
-      else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+      else if (!png_memcmp(chunk_name, png_IDAT, 4))
       {
          /* Zero length IDATs are legal after the last IDAT has been
           * read, but not after other chunks have been read.
           */
          if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
             png_error(png_ptr, "Too many IDAT's found");
          png_crc_finish(png_ptr, length);
       }
-      else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+      else if (!png_memcmp(chunk_name, png_PLTE, 4))
          png_handle_PLTE(png_ptr, info_ptr, length);
 #if defined(PNG_READ_bKGD_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
+      else if (!png_memcmp(chunk_name, png_bKGD, 4))
          png_handle_bKGD(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_cHRM_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
+      else if (!png_memcmp(chunk_name, png_cHRM, 4))
          png_handle_cHRM(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_gAMA_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
+      else if (!png_memcmp(chunk_name, png_gAMA, 4))
          png_handle_gAMA(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_hIST_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
+      else if (!png_memcmp(chunk_name, png_hIST, 4))
          png_handle_hIST(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_oFFs_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
+      else if (!png_memcmp(chunk_name, png_oFFs, 4))
          png_handle_oFFs(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_pCAL_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
+      else if (!png_memcmp(chunk_name, png_pCAL, 4))
          png_handle_pCAL(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_sCAL_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
+      else if (!png_memcmp(chunk_name, png_sCAL, 4))
          png_handle_sCAL(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_pHYs_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
+      else if (!png_memcmp(chunk_name, png_pHYs, 4))
          png_handle_pHYs(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_sBIT_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
+      else if (!png_memcmp(chunk_name, png_sBIT, 4))
          png_handle_sBIT(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_sRGB_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
+      else if (!png_memcmp(chunk_name, png_sRGB, 4))
          png_handle_sRGB(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_iCCP_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
+      else if (!png_memcmp(chunk_name, png_iCCP, 4))
          png_handle_iCCP(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_sPLT_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
+      else if (!png_memcmp(chunk_name, png_sPLT, 4))
          png_handle_sPLT(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_tEXt_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
+      else if (!png_memcmp(chunk_name, png_tEXt, 4))
          png_handle_tEXt(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_tIME_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
+      else if (!png_memcmp(chunk_name, png_tIME, 4))
          png_handle_tIME(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_tRNS_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
+      else if (!png_memcmp(chunk_name, png_tRNS, 4))
          png_handle_tRNS(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_zTXt_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
+      else if (!png_memcmp(chunk_name, png_zTXt, 4))
          png_handle_zTXt(png_ptr, info_ptr, length);
 #endif
 #if defined(PNG_READ_iTXt_SUPPORTED)
-      else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
+      else if (!png_memcmp(chunk_name, png_iTXt, 4))
          png_handle_iTXt(png_ptr, info_ptr, length);
 #endif
       else
          png_handle_unknown(png_ptr, info_ptr, length);
    } while (!(png_ptr->mode & PNG_HAVE_IEND));
 }
 #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
 
 /* free all memory used by the read */
 void PNGAPI
 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
    png_infopp end_info_ptr_ptr)
 {
    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL, end_info_ptr = NULL;
 #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn = NULL;
    png_voidp mem_ptr = NULL;
 #endif
 
    png_debug(1, "in png_destroy_read_struct\n");
    if (png_ptr_ptr != NULL)
-   {
       png_ptr = *png_ptr_ptr;
-   }
    if (png_ptr == NULL)
       return;
 
 #ifdef PNG_USER_MEM_SUPPORTED
    free_fn = png_ptr->free_fn;
    mem_ptr = png_ptr->mem_ptr;
 #endif
 
    if (info_ptr_ptr != NULL)
       info_ptr = *info_ptr_ptr;
@@ skipping 25 matching lines @@
 #endif
 #ifdef PNG_USER_MEM_SUPPORTED
       png_destroy_struct_2((png_voidp)end_info_ptr, (png_free_ptr)free_fn,
          (png_voidp)mem_ptr);
 #else
       png_destroy_struct((png_voidp)end_info_ptr);
 #endif
       *end_info_ptr_ptr = NULL;
    }
 
+   if (png_ptr != NULL)
+   {
 #ifdef PNG_USER_MEM_SUPPORTED
-   png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
-       (png_voidp)mem_ptr);
+      png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
+          (png_voidp)mem_ptr);
 #else
-   png_destroy_struct((png_voidp)png_ptr);
+      png_destroy_struct((png_voidp)png_ptr);
 #endif
-   *png_ptr_ptr = NULL;
+      *png_ptr_ptr = NULL;
+   }
 }
 
 /* free all memory used by the read (old method) */
 void /* PRIVATE */
 png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr)
 {
 #ifdef PNG_SETJMP_SUPPORTED
    jmp_buf tmp_jmp;
 #endif
    png_error_ptr error_fn;
    png_error_ptr warning_fn;
    png_voidp error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn;
 #endif
 
    png_debug(1, "in png_read_destroy\n");
    if (info_ptr != NULL)
       png_info_destroy(png_ptr, info_ptr);
 
    if (end_info_ptr != NULL)
       png_info_destroy(png_ptr, end_info_ptr);
 
    png_free(png_ptr, png_ptr->zbuf);
    png_free(png_ptr, png_ptr->big_row_buf);
    png_free(png_ptr, png_ptr->prev_row);
+   png_free(png_ptr, png_ptr->chunkdata);
 #if defined(PNG_READ_DITHER_SUPPORTED)
    png_free(png_ptr, png_ptr->palette_lookup);
    png_free(png_ptr, png_ptr->dither_index);
 #endif
 #if defined(PNG_READ_GAMMA_SUPPORTED)
    png_free(png_ptr, png_ptr->gamma_table);
 #endif
 #if defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_free(png_ptr, png_ptr->gamma_from_1);
    png_free(png_ptr, png_ptr->gamma_to_1);
@@ skipping 76 matching lines @@
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 #ifdef PNG_TEXT_SUPPORTED
    png_free(png_ptr, png_ptr->current_text);
 #endif /* PNG_TEXT_SUPPORTED */
 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
 
    /* Save the important info out of the png_struct, in case it is
     * being used again.
     */
 #ifdef PNG_SETJMP_SUPPORTED
-   png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof (jmp_buf));
+   png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));
 #endif
 
    error_fn = png_ptr->error_fn;
    warning_fn = png_ptr->warning_fn;
    error_ptr = png_ptr->error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    free_fn = png_ptr->free_fn;
 #endif
 
-   png_memset(png_ptr, 0, png_sizeof (png_struct));
+   png_memset(png_ptr, 0, png_sizeof(png_struct));
 
    png_ptr->error_fn = error_fn;
    png_ptr->warning_fn = warning_fn;
    png_ptr->error_ptr = error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    png_ptr->free_fn = free_fn;
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
-   png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof (jmp_buf));
+   png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof(jmp_buf));
 #endif
 
 }
 
 void PNGAPI
 png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn)
 {
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
    png_ptr->read_row_fn = read_row_fn;
 }
 
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 #if defined(PNG_INFO_IMAGE_SUPPORTED)
 void PNGAPI
 png_read_png(png_structp png_ptr, png_infop info_ptr,
                            int transforms,
                            voidp params)
 {
    int row;
 
-   if(png_ptr == NULL) return;
+   if (png_ptr == NULL) return;
 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
    /* invert the alpha channel from opacity to transparency
     */
    if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
        png_set_invert_alpha(png_ptr);
 #endif
 
    /* png_read_info() gives us all of the information from the
     * PNG file before the first IDAT (image data chunk).
     */
    png_read_info(png_ptr, info_ptr);
    if (info_ptr->height > PNG_UINT_32_MAX/png_sizeof(png_bytep))
-      png_error(png_ptr,"Image is too high to process with png_read_png()");
+      png_error(png_ptr, "Image is too high to process with png_read_png()");
 
    /* -------------- image transformations start here ------------------- */
 
 #if defined(PNG_READ_16_TO_8_SUPPORTED)
    /* tell libpng to strip 16 bit/color files down to 8 bits per color
     */
    if (transforms & PNG_TRANSFORM_STRIP_16)
        png_set_strip_16(png_ptr);
 #endif
 
@@ skipping 86 matching lines @@
     * and update info structure.  REQUIRED if you are expecting libpng to
     * update the palette for you (i.e., you selected such a transform above).
     */
    png_read_update_info(png_ptr, info_ptr);
 
    /* -------------- image transformations end here ------------------- */
 
 #ifdef PNG_FREE_ME_SUPPORTED
    png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
 #endif
-   if(info_ptr->row_pointers == NULL)
+   if (info_ptr->row_pointers == NULL)
    {
       info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
          info_ptr->height * png_sizeof(png_bytep));
 #ifdef PNG_FREE_ME_SUPPORTED
       info_ptr->free_me |= PNG_FREE_ROWS;
 #endif
       for (row = 0; row < (int)info_ptr->height; row++)
       {
          info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr,
             png_get_rowbytes(png_ptr, info_ptr));
       }
    }
 
    png_read_image(png_ptr, info_ptr->row_pointers);
    info_ptr->valid |= PNG_INFO_IDAT;
 
    /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
    png_read_end(png_ptr, info_ptr);
 
    transforms = transforms; /* quiet compiler warnings */
    params = params;
 
 }
 #endif /* PNG_INFO_IMAGE_SUPPORTED */
 #endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
 #endif /* PNG_READ_SUPPORTED */