X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/2b5f62a0b2db198609b45dec622a018dae37008e..8a31648287be0ef976f133de2786b137f1e98340:/src/png/pngread.c

diff --git a/src/png/pngread.c b/src/png/pngread.c
index 31019304c0..7599206bfd 100644
--- a/src/png/pngread.c
+++ b/src/png/pngread.c
@@ -1,85 +1,97 @@
 
 /* pngread.c - read a PNG file
  *
- * libpng 1.2.5rc3 - September 18, 2002
- * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2002 Glenn Randers-Pehrson
+ * Last changed in libpng 1.5.6 [November 3, 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 an application calls directly to
  * read a PNG file or stream.
  */
 
-#define PNG_INTERNAL
-#include "png.h"
+#include "pngpriv.h"
+
+#ifdef 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)
+PNG_FUNCTION(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),PNG_ALLOCATED)
 {
 
 #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));
+       warn_fn, NULL, NULL, 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)
+/* Alternate create PNG structure for reading, and allocate any memory
+ * needed.
+ */
+PNG_FUNCTION(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),PNG_ALLOCATED)
 {
 #endif /* PNG_USER_MEM_SUPPORTED */
 
+#ifdef PNG_SETJMP_SUPPORTED
+   volatile
+#endif
    png_structp png_ptr;
+   volatile int png_cleanup_needed = 0;
 
 #ifdef PNG_SETJMP_SUPPORTED
 #ifdef USE_FAR_KEYWORD
-   jmp_buf jmpbuf;
+   jmp_buf tmp_jmpbuf;
 #endif
 #endif
 
-   int i;
+   png_debug(1, "in png_create_read_struct");
 
-   png_debug(1, "in png_create_read_struct\n");
 #ifdef PNG_USER_MEM_SUPPORTED
    png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
-      (png_malloc_ptr)malloc_fn, (png_voidp)mem_ptr);
+       malloc_fn, mem_ptr);
 #else
    png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
 #endif
    if (png_ptr == NULL)
       return (NULL);
 
-#if !defined(PNG_1_0_X)
-#ifdef PNG_ASSEMBLER_CODE_SUPPORTED
-   png_init_mmx_flags(png_ptr);   /* 1.2.0 addition */
+   /* Added at libpng-1.2.6 */
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
+   png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
+
+#  ifdef PNG_USER_CHUNK_CACHE_MAX
+   /* Added at libpng-1.2.43 and 1.4.0 */
+   png_ptr->user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
+#  endif
+
+#  ifdef PNG_SET_USER_CHUNK_MALLOC_MAX
+   /* Added at libpng-1.2.43 and 1.4.1 */
+   png_ptr->user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
+#  endif
 #endif
-#endif /* PNG_1_0_X */
 
 #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))
-#else
-   if (setjmp(png_ptr->jmpbuf))
-#endif
-   {
-      png_free(png_ptr, png_ptr->zbuf);
-      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);
+   if (setjmp(tmp_jmpbuf))
 #else
-      png_destroy_struct((png_voidp)png_ptr);
+   if (setjmp(png_jmpbuf(png_ptr))) /* Sets longjmp to match setjmp */
 #endif
-      return (NULL);
-   }
+      PNG_ABORT();
 #ifdef USE_FAR_KEYWORD
-   png_memcpy(png_ptr->jmpbuf,jmpbuf,sizeof(jmp_buf));
-#endif
+   png_memcpy(png_jmpbuf(png_ptr), tmp_jmpbuf, png_sizeof(jmp_buf));
 #endif
+#endif /* PNG_SETJMP_SUPPORTED */
 
 #ifdef PNG_USER_MEM_SUPPORTED
    png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
@@ -87,207 +99,76 @@ png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
 
    png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
 
-   i=0;
-   do
-   {
-     if(user_png_ver[i] != png_libpng_ver[i])
-        png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
-   } while (png_libpng_ver[i++]);
+   /* Call the general version checker (shared with read and write code): */
+   if (!png_user_version_check(png_ptr, user_png_ver))
+      png_cleanup_needed = 1;
 
-   if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
+   if (!png_cleanup_needed)
    {
-     /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
-      * we must recompile any applications that use any older library version.
-      * For versions after libpng 1.0, we will be compatible, so we need
-      * only check the first digit.
-      */
-     if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
-         (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||
-         (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
-     {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
-        char msg[80];
-        if (user_png_ver)
-        {
-          sprintf(msg, "Application was compiled with png.h from libpng-%.20s",
-             user_png_ver);
-          png_warning(png_ptr, msg);
-        }
-        sprintf(msg, "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;
-#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_warn(png_ptr, png_ptr->zbuf_size);
+
+   if (png_ptr->zbuf == NULL)
+      png_cleanup_needed = 1;
    }
 
-   /* 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);
    png_ptr->zstream.zalloc = png_zalloc;
    png_ptr->zstream.zfree = png_zfree;
    png_ptr->zstream.opaque = (voidpf)png_ptr;
 
-   switch (inflateInit(&png_ptr->zstream))
+   if (!png_cleanup_needed)
    {
-     case Z_OK: /* Do nothing */ break;
-     case Z_MEM_ERROR:
-     case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory error"); break;
-     case Z_VERSION_ERROR: png_error(png_ptr, "zlib version error"); break;
-     default: png_error(png_ptr, "Unknown zlib error");
-   }
-
-   png_ptr->zstream.next_out = png_ptr->zbuf;
-   png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+      switch (inflateInit(&png_ptr->zstream))
+      {
+         case Z_OK:
+            break; /* Do nothing */
 
-   png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL);
+         case Z_MEM_ERROR:
+            png_warning(png_ptr, "zlib memory error");
+            png_cleanup_needed = 1;
+            break;
 
-#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,sizeof(jmp_buf));
-#else
-   if (setjmp(png_ptr->jmpbuf))
-      PNG_ABORT();
-#endif
-#endif
-   return (png_ptr);
-}
+         case Z_STREAM_ERROR:
+            png_warning(png_ptr, "zlib stream error");
+            png_cleanup_needed = 1;
+            break;
 
-/* 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 eventually disappear. */
-#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);
-}
+         case Z_VERSION_ERROR:
+            png_warning(png_ptr, "zlib version error");
+            png_cleanup_needed = 1;
+            break;
 
-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 !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
-   if(sizeof(png_struct) > png_struct_size || sizeof(png_info) > png_info_size)
-   {
-      char msg[80];
-      png_ptr->warning_fn=NULL;
-      if (user_png_ver)
-      {
-        sprintf(msg, "Application was compiled with png.h from libpng-%.20s",
-           user_png_ver);
-        png_warning(png_ptr, msg);
+         default: png_warning(png_ptr, "Unknown zlib error");
+            png_cleanup_needed = 1;
       }
-      sprintf(msg, "Application  is  running with png.c from libpng-%.20s",
-         png_libpng_ver);
-      png_warning(png_ptr, msg);
    }
-#endif
-   if(sizeof(png_struct) > png_struct_size)
-     {
-       png_ptr->error_fn=NULL;
-#ifdef PNG_ERROR_NUMBERS_SUPPORTED
-       png_ptr->flags=0;
-#endif
-       png_error(png_ptr,
-       "The png struct allocated by the application for reading is too small.");
-     }
-   if(sizeof(png_info) > png_info_size)
-     {
-       png_ptr->error_fn=NULL;
-#ifdef PNG_ERROR_NUMBERS_SUPPORTED
-       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);
-}
-
-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;
 
-   png_structp png_ptr=*ptr_ptr;
-
-   do
+   if (png_cleanup_needed)
    {
-     if(user_png_ver[i] != png_libpng_ver[i])
-     {
-#ifdef PNG_LEGACY_SUPPORTED
-       png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
+      /* Clean up PNG structure and deallocate any memory. */
+      png_free(png_ptr, png_ptr->zbuf);
+      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_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, sizeof (jmp_buf));
-#endif
-
-   if(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, sizeof (png_struct));
-
-#ifdef PNG_SETJMP_SUPPORTED
-   /* restore jump buffer */
-   png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf));
+      png_destroy_struct((png_voidp)png_ptr);
 #endif
-
-   /* 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);
-   png_ptr->zstream.zalloc = png_zalloc;
-   png_ptr->zstream.zfree = png_zfree;
-   png_ptr->zstream.opaque = (voidpf)png_ptr;
-
-   switch (inflateInit(&png_ptr->zstream))
-   {
-     case Z_OK: /* Do nothing */ break;
-     case Z_MEM_ERROR:
-     case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory"); break;
-     case Z_VERSION_ERROR: png_error(png_ptr, "zlib version"); break;
-     default: png_error(png_ptr, "Unknown zlib error");
+      return (NULL);
    }
 
    png_ptr->zstream.next_out = png_ptr->zbuf;
    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
 
-   png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL);
+   png_set_read_fn(png_ptr, NULL, NULL);
+
+
+   return (png_ptr);
 }
 
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read the information before the actual image data.  This has been
  * 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
@@ -299,228 +180,184 @@ png_read_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,
 void PNGAPI
 png_read_info(png_structp png_ptr, png_infop info_ptr)
 {
-   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_debug(1, "in png_read_info");
 
-      png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
-      png_ptr->sig_bytes = 8;
+   if (png_ptr == NULL || info_ptr == NULL)
+      return;
 
-      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;
-   }
+   /* Read and check the PNG file signature. */
+   png_read_sig(png_ptr, info_ptr);
 
-   for(;;)
+   for (;;)
    {
-#ifdef PNG_USE_LOCAL_ARRAYS
-      PNG_IHDR;
-      PNG_IDAT;
-      PNG_IEND;
-      PNG_PLTE;
-#if defined(PNG_READ_bKGD_SUPPORTED)
-      PNG_bKGD;
-#endif
-#if defined(PNG_READ_cHRM_SUPPORTED)
-      PNG_cHRM;
-#endif
-#if defined(PNG_READ_gAMA_SUPPORTED)
-      PNG_gAMA;
-#endif
-#if defined(PNG_READ_hIST_SUPPORTED)
-      PNG_hIST;
-#endif
-#if defined(PNG_READ_iCCP_SUPPORTED)
-      PNG_iCCP;
-#endif
-#if defined(PNG_READ_iTXt_SUPPORTED)
-      PNG_iTXt;
-#endif
-#if defined(PNG_READ_oFFs_SUPPORTED)
-      PNG_oFFs;
-#endif
-#if defined(PNG_READ_pCAL_SUPPORTED)
-      PNG_pCAL;
-#endif
-#if defined(PNG_READ_pHYs_SUPPORTED)
-      PNG_pHYs;
-#endif
-#if defined(PNG_READ_sBIT_SUPPORTED)
-      PNG_sBIT;
-#endif
-#if defined(PNG_READ_sCAL_SUPPORTED)
-      PNG_sCAL;
-#endif
-#if defined(PNG_READ_sPLT_SUPPORTED)
-      PNG_sPLT;
-#endif
-#if defined(PNG_READ_sRGB_SUPPORTED)
-      PNG_sRGB;
-#endif
-#if defined(PNG_READ_tEXt_SUPPORTED)
-      PNG_tEXt;
-#endif
-#if defined(PNG_READ_tIME_SUPPORTED)
-      PNG_tIME;
-#endif
-#if defined(PNG_READ_tRNS_SUPPORTED)
-      PNG_tRNS;
-#endif
-#if defined(PNG_READ_zTXt_SUPPORTED)
-      PNG_zTXt;
-#endif
-#endif /* PNG_GLOBAL_ARRAYS */
-      png_byte chunk_length[4];
-      png_uint_32 length;
-
-      png_read_data(png_ptr, chunk_length, 4);
-      length = png_get_uint_32(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);
-
-      if (length > PNG_MAX_UINT)
-         png_error(png_ptr, "Invalid chunk length.");
+      png_uint_32 length = png_read_chunk_header(png_ptr);
+      png_uint_32 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_IHDR, 4))
+      if (chunk_name == png_IDAT)
+         if (png_ptr->mode & PNG_AFTER_IDAT)
+            png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
+
+      if (chunk_name == png_IHDR)
          png_handle_IHDR(png_ptr, info_ptr, length);
-      else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
+
+      else if (chunk_name == png_IEND)
          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_chunk_unknown_handling(png_ptr, chunk_name) !=
+         PNG_HANDLE_CHUNK_AS_DEFAULT)
       {
-         if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+         if (chunk_name == png_IDAT)
             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 (chunk_name == png_PLTE)
             png_ptr->mode |= PNG_HAVE_PLTE;
-         else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+
+         else if (chunk_name == png_IDAT)
          {
             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_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 (chunk_name == png_PLTE)
          png_handle_PLTE(png_ptr, info_ptr, length);
-      else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+
+      else if (chunk_name == png_IDAT)
       {
          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_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))
+
+#ifdef PNG_READ_bKGD_SUPPORTED
+      else if (chunk_name == png_bKGD)
          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))
+
+#ifdef PNG_READ_cHRM_SUPPORTED
+      else if (chunk_name == png_cHRM)
          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))
+
+#ifdef PNG_READ_gAMA_SUPPORTED
+      else if (chunk_name == png_gAMA)
          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))
+
+#ifdef PNG_READ_hIST_SUPPORTED
+      else if (chunk_name == png_hIST)
          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))
+
+#ifdef PNG_READ_oFFs_SUPPORTED
+      else if (chunk_name == png_oFFs)
          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))
+
+#ifdef PNG_READ_pCAL_SUPPORTED
+      else if (chunk_name == png_pCAL)
          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))
+
+#ifdef PNG_READ_sCAL_SUPPORTED
+      else if (chunk_name == png_sCAL)
          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))
+
+#ifdef PNG_READ_pHYs_SUPPORTED
+      else if (chunk_name == png_pHYs)
          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))
+
+#ifdef PNG_READ_sBIT_SUPPORTED
+      else if (chunk_name == png_sBIT)
          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))
+
+#ifdef PNG_READ_sRGB_SUPPORTED
+      else if (chunk_name == png_sRGB)
          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))
+
+#ifdef PNG_READ_iCCP_SUPPORTED
+      else if (chunk_name == png_iCCP)
          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))
+
+#ifdef PNG_READ_sPLT_SUPPORTED
+      else if (chunk_name == png_sPLT)
          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))
+
+#ifdef PNG_READ_tEXt_SUPPORTED
+      else if (chunk_name == png_tEXt)
          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))
+
+#ifdef PNG_READ_tIME_SUPPORTED
+      else if (chunk_name == png_tIME)
          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))
+
+#ifdef PNG_READ_tRNS_SUPPORTED
+      else if (chunk_name == png_tRNS)
          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))
+
+#ifdef PNG_READ_zTXt_SUPPORTED
+      else if (chunk_name == png_zTXt)
          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))
+
+#ifdef PNG_READ_iTXt_SUPPORTED
+      else if (chunk_name == png_iTXt)
          png_handle_iTXt(png_ptr, info_ptr, length);
 #endif
+
       else
          png_handle_unknown(png_ptr, info_ptr, length);
    }
 }
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
-/* optional call to update the users info_ptr structure */
+/* 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->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_debug(1, "in png_read_update_info");
+
+   if (png_ptr == NULL)
+      return;
+
+   png_read_start_row(png_ptr);
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
    png_read_transform_info(png_ptr, info_ptr);
+#else
+   PNG_UNUSED(info_ptr)
+#endif
 }
 
+#ifdef PNG_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.
@@ -529,59 +366,88 @@ png_read_update_info(png_structp png_ptr, png_infop info_ptr)
 void PNGAPI
 png_start_read_image(png_structp png_ptr)
 {
-   png_debug(1, "in png_start_read_image\n");
-   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
-      png_read_start_row(png_ptr);
+   png_debug(1, "in png_start_read_image");
+
+   if (png_ptr != NULL)
+     png_read_start_row(png_ptr);
 }
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
+#ifdef PNG_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_IDAT;
-   const int png_pass_dsp_mask[7] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
-   const int png_pass_mask[7] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
-#endif
    int ret;
-   png_debug2(1, "in png_read_row (row %lu, pass %d)\n",
-      png_ptr->row_number, png_ptr->pass);
+
+   png_row_info row_info;
+
+   if (png_ptr == NULL)
+      return;
+
+   png_debug2(1, "in png_read_row (row %lu, pass %d)",
+       (unsigned long)png_ptr->row_number, png_ptr->pass);
+
+   /* png_read_start_row sets the information (in particular iwidth) for this
+    * interlace pass.
+    */
    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
       png_read_start_row(png_ptr);
+
+   /* 1.5.6: row_info moved out of png_struct to a local here. */
+   row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
+   row_info.color_type = png_ptr->color_type;
+   row_info.bit_depth = png_ptr->bit_depth;
+   row_info.channels = png_ptr->channels;
+   row_info.pixel_depth = png_ptr->pixel_depth;
+   row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
+
    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
    {
-   /* check for transforms that have been set but were defined out */
+   /* 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.");
+      png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
 #endif
+
 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
    if (png_ptr->transformations & PNG_FILLER)
-      png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined.");
+      png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
 #endif
-#if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && !defined(PNG_READ_PACKSWAP_SUPPORTED)
+
+#if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
+    !defined(PNG_READ_PACKSWAP_SUPPORTED)
    if (png_ptr->transformations & PNG_PACKSWAP)
-      png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined.");
+      png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
 #endif
+
 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
    if (png_ptr->transformations & PNG_PACK)
-      png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined.");
+      png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
 #endif
+
 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
    if (png_ptr->transformations & PNG_SHIFT)
-      png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined.");
+      png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
 #endif
+
 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
    if (png_ptr->transformations & PNG_BGR)
-      png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined.");
+      png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
 #endif
+
 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
    if (png_ptr->transformations & PNG_SWAP_BYTES)
-      png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined.");
+      png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
 #endif
    }
 
-#if defined(PNG_READ_INTERLACING_SUPPORTED)
-   /* if interlaced and we do not need a new row, combine row and return */
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   /* If interlaced and we do not need a new row, combine row and return.
+    * Notice that the pixels we have from previous rows have been transformed
+    * already; we can only combine like with like (transformed or
+    * untransformed) and, because of the libpng API for interlaced images, this
+    * means we must transform before de-interlacing.
+    */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
       switch (png_ptr->pass)
@@ -590,48 +456,51 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
             if (png_ptr->row_number & 0x07)
             {
                if (dsp_row != NULL)
-                  png_combine_row(png_ptr, dsp_row,
-                     png_pass_dsp_mask[png_ptr->pass]);
+                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
                png_read_finish_row(png_ptr);
                return;
             }
             break;
+
          case 1:
             if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
             {
                if (dsp_row != NULL)
-                  png_combine_row(png_ptr, dsp_row,
-                     png_pass_dsp_mask[png_ptr->pass]);
+                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
+
                png_read_finish_row(png_ptr);
                return;
             }
             break;
+
          case 2:
             if ((png_ptr->row_number & 0x07) != 4)
             {
                if (dsp_row != NULL && (png_ptr->row_number & 4))
-                  png_combine_row(png_ptr, dsp_row,
-                     png_pass_dsp_mask[png_ptr->pass]);
+                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
+
                png_read_finish_row(png_ptr);
                return;
             }
             break;
+
          case 3:
             if ((png_ptr->row_number & 3) || png_ptr->width < 3)
             {
                if (dsp_row != NULL)
-                  png_combine_row(png_ptr, dsp_row,
-                     png_pass_dsp_mask[png_ptr->pass]);
+                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
+
                png_read_finish_row(png_ptr);
                return;
             }
             break;
+
          case 4:
             if ((png_ptr->row_number & 3) != 2)
             {
                if (dsp_row != NULL && (png_ptr->row_number & 2))
-                  png_combine_row(png_ptr, dsp_row,
-                     png_pass_dsp_mask[png_ptr->pass]);
+                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
+
                png_read_finish_row(png_ptr);
                return;
             }
@@ -640,12 +509,14 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
             if ((png_ptr->row_number & 1) || png_ptr->width < 2)
             {
                if (dsp_row != NULL)
-                  png_combine_row(png_ptr, dsp_row,
-                     png_pass_dsp_mask[png_ptr->pass]);
+                  png_combine_row(png_ptr, dsp_row, 1/*display*/);
+
                png_read_finish_row(png_ptr);
                return;
             }
             break;
+
+         default:
          case 6:
             if (!(png_ptr->row_number & 1))
             {
@@ -661,26 +532,20 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
       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;
+   png_ptr->zstream.avail_out =
+       (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
+       png_ptr->iwidth) + 1);
+
    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_32(chunk_length);
-
-            if (png_ptr->idat_size > PNG_MAX_UINT)
-              png_error(png_ptr, "Invalid 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_ptr->idat_size = png_read_chunk_header(png_ptr);
+            if (png_ptr->chunk_name != png_IDAT)
                png_error(png_ptr, "Not enough image data");
          }
          png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
@@ -688,86 +553,103 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
          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_size_t)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_error(png_ptr, "Extra compressed data");
+            png_benign_error(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");
+             "Decompression error");
 
    } 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_ptr->row_info.width *
-      (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
-
-   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) &&
-      (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
+   if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
+   {
+      if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
+         png_read_filter_row(&row_info, png_ptr->row_buf + 1,
+            png_ptr->prev_row + 1, png_ptr->row_buf[0]);
+      else
+         png_error(png_ptr, "bad adaptive filter value");
+   }
+
+   /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
+    * 1.5.6, while the buffer really is this big in current versions of libpng
+    * it may not be in the future, so this was changed just to copy the
+    * interlaced count:
+    */
+   png_memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
+
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+   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);
+      png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
    }
 #endif
 
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
    if (png_ptr->transformations)
-      png_do_read_transformations(png_ptr);
+      png_do_read_transformations(png_ptr, &row_info);
+#endif
 
-#if defined(PNG_READ_INTERLACING_SUPPORTED)
-   /* blow up interlaced rows to full size */
+   /* The transformed pixel depth should match the depth now in row_info. */
+   if (png_ptr->transformed_pixel_depth == 0)
+   {
+      png_ptr->transformed_pixel_depth = row_info.pixel_depth;
+      if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
+         png_error(png_ptr, "sequential row overflow");
+   }
+
+   else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
+      png_error(png_ptr, "internal sequential row size calculation error");
+
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   /* Blow up interlaced rows to full size */
    if (png_ptr->interlaced &&
       (png_ptr->transformations & PNG_INTERLACE))
    {
       if (png_ptr->pass < 6)
-/*       old interface (pre-1.0.9):
-         png_do_read_interlace(&(png_ptr->row_info),
-            png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
- */
-         png_do_read_interlace(png_ptr);
+         png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
+            png_ptr->transformations);
 
       if (dsp_row != NULL)
-         png_combine_row(png_ptr, dsp_row,
-            png_pass_dsp_mask[png_ptr->pass]);
+         png_combine_row(png_ptr, dsp_row, 1/*display*/);
+
       if (row != NULL)
-         png_combine_row(png_ptr, row,
-            png_pass_mask[png_ptr->pass]);
+         png_combine_row(png_ptr, row, 0/*row*/);
    }
+
    else
 #endif
    {
       if (row != NULL)
-         png_combine_row(png_ptr, row, 0xff);
+         png_combine_row(png_ptr, row, -1/*ignored*/);
+
       if (dsp_row != NULL)
-         png_combine_row(png_ptr, dsp_row, 0xff);
+         png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
    }
    png_read_finish_row(png_ptr);
 
    if (png_ptr->read_row_fn != NULL)
       (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
 }
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read one or more rows of image data.  If the image is interlaced,
  * and png_set_interlace_handling() has been called, the rows need to
  * contain the contents of the rows from the previous pass.  If the
@@ -789,18 +671,22 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
  * not called png_set_interlace_handling(), the display_row buffer will
  * be ignored, so pass NULL to it.
  *
- * [*] png_handle_alpha() does not exist yet, as of libpng version 1.2.5rc3
+ * [*] png_handle_alpha() does not exist yet, as of this version of libpng
  */
 
 void PNGAPI
 png_read_rows(png_structp png_ptr, png_bytepp row,
-   png_bytepp display_row, png_uint_32 num_rows)
+    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");
+   png_debug(1, "in png_read_rows");
+
+   if (png_ptr == NULL)
+      return;
+
    rp = row;
    dp = display_row;
    if (rp != NULL && dp != NULL)
@@ -811,22 +697,26 @@ png_read_rows(png_structp png_ptr, png_bytepp row,
 
          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);
+         png_read_row(png_ptr, rptr, 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);
+         png_read_row(png_ptr, NULL, dptr);
          dp++;
       }
 }
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
+#ifdef PNG_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.
@@ -837,41 +727,69 @@ png_read_rows(png_structp png_ptr, png_bytepp row,
  * 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 libpng version 1.2.5rc3
+ * [*] 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");
+   png_debug(1, "in png_read_image");
+
+   if (png_ptr == NULL)
+      return;
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   pass = png_set_interlace_handling(png_ptr);
+   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
+   {
+      pass = png_set_interlace_handling(png_ptr);
+      /* And make sure transforms are initialized. */
+      png_start_read_image(png_ptr);
+   }
+   else
+   {
+      if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE))
+      {
+         /* Caller called png_start_read_image or png_read_update_info without
+          * first turning on the PNG_INTERLACE transform.  We can fix this here,
+          * but the caller should do it!
+          */
+         png_warning(png_ptr, "Interlace handling should be turned on when "
+            "using png_read_image");
+         /* Make sure this is set correctly */
+         png_ptr->num_rows = png_ptr->height;
+      }
+
+      /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
+       * the above error case.
+       */
+      pass = png_set_interlace_handling(png_ptr);
+   }
 #else
    if (png_ptr->interlaced)
       png_error(png_ptr,
-        "Cannot read interlaced image -- interlace handler disabled.");
+          "Cannot read interlaced image -- interlace handler disabled");
+
    pass = 1;
 #endif
 
-
    image_height=png_ptr->height;
-   png_ptr->num_rows = image_height; /* Make sure this is set correctly */
 
    for (j = 0; j < pass; j++)
    {
       rp = image;
       for (i = 0; i < image_height; i++)
       {
-         png_read_row(png_ptr, *rp, png_bytep_NULL);
+         png_read_row(png_ptr, *rp, NULL);
          rp++;
       }
    }
 }
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
+#ifdef PNG_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.
@@ -879,190 +797,147 @@ png_read_image(png_structp png_ptr, png_bytepp image)
 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");
+
+   if (png_ptr == NULL)
+      return;
 
-   png_debug(1, "in png_read_end\n");
    png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */
 
    do
    {
-#ifdef PNG_USE_LOCAL_ARRAYS
-      PNG_IHDR;
-      PNG_IDAT;
-      PNG_IEND;
-      PNG_PLTE;
-#if defined(PNG_READ_bKGD_SUPPORTED)
-      PNG_bKGD;
-#endif
-#if defined(PNG_READ_cHRM_SUPPORTED)
-      PNG_cHRM;
-#endif
-#if defined(PNG_READ_gAMA_SUPPORTED)
-      PNG_gAMA;
-#endif
-#if defined(PNG_READ_hIST_SUPPORTED)
-      PNG_hIST;
-#endif
-#if defined(PNG_READ_iCCP_SUPPORTED)
-      PNG_iCCP;
-#endif
-#if defined(PNG_READ_iTXt_SUPPORTED)
-      PNG_iTXt;
-#endif
-#if defined(PNG_READ_oFFs_SUPPORTED)
-      PNG_oFFs;
-#endif
-#if defined(PNG_READ_pCAL_SUPPORTED)
-      PNG_pCAL;
-#endif
-#if defined(PNG_READ_pHYs_SUPPORTED)
-      PNG_pHYs;
-#endif
-#if defined(PNG_READ_sBIT_SUPPORTED)
-      PNG_sBIT;
-#endif
-#if defined(PNG_READ_sCAL_SUPPORTED)
-      PNG_sCAL;
-#endif
-#if defined(PNG_READ_sPLT_SUPPORTED)
-      PNG_sPLT;
-#endif
-#if defined(PNG_READ_sRGB_SUPPORTED)
-      PNG_sRGB;
-#endif
-#if defined(PNG_READ_tEXt_SUPPORTED)
-      PNG_tEXt;
-#endif
-#if defined(PNG_READ_tIME_SUPPORTED)
-      PNG_tIME;
-#endif
-#if defined(PNG_READ_tRNS_SUPPORTED)
-      PNG_tRNS;
-#endif
-#if defined(PNG_READ_zTXt_SUPPORTED)
-      PNG_zTXt;
-#endif
-#endif /* PNG_GLOBAL_ARRAYS */
-
-      png_read_data(png_ptr, chunk_length, 4);
-      length = png_get_uint_32(chunk_length);
+      png_uint_32 length = png_read_chunk_header(png_ptr);
+      png_uint_32 chunk_name = png_ptr->chunk_name;
 
-      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 (length > PNG_MAX_UINT)
-         png_error(png_ptr, "Invalid chunk length.");
-
-      if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
+      if (chunk_name == png_IHDR)
          png_handle_IHDR(png_ptr, info_ptr, length);
-      else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
+
+      else if (chunk_name == png_IEND)
          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_chunk_unknown_handling(png_ptr, chunk_name) !=
+         PNG_HANDLE_CHUNK_AS_DEFAULT)
       {
-         if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+         if (chunk_name == png_IDAT)
          {
-            if (length > 0 || png_ptr->mode & PNG_AFTER_IDAT)
-               png_error(png_ptr, "Too many IDAT's found");
+            if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
+               png_benign_error(png_ptr, "Too many IDATs found");
          }
-         else
-            png_ptr->mode |= PNG_AFTER_IDAT;
          png_handle_unknown(png_ptr, info_ptr, length);
-         if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+         if (chunk_name == png_PLTE)
             png_ptr->mode |= PNG_HAVE_PLTE;
       }
 #endif
-      else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+
+      else if (chunk_name == png_IDAT)
       {
          /* 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_AFTER_IDAT)
-            png_error(png_ptr, "Too many IDAT's found");
+         if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
+            png_benign_error(png_ptr, "Too many IDATs found");
+
          png_crc_finish(png_ptr, length);
       }
-      else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+      else if (chunk_name == png_PLTE)
          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))
+
+#ifdef PNG_READ_bKGD_SUPPORTED
+      else if (chunk_name == png_bKGD)
          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))
+
+#ifdef PNG_READ_cHRM_SUPPORTED
+      else if (chunk_name == png_cHRM)
          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))
+
+#ifdef PNG_READ_gAMA_SUPPORTED
+      else if (chunk_name == png_gAMA)
          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))
+
+#ifdef PNG_READ_hIST_SUPPORTED
+      else if (chunk_name == png_hIST)
          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))
+
+#ifdef PNG_READ_oFFs_SUPPORTED
+      else if (chunk_name == png_oFFs)
          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))
+
+#ifdef PNG_READ_pCAL_SUPPORTED
+      else if (chunk_name == png_pCAL)
          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))
+
+#ifdef PNG_READ_sCAL_SUPPORTED
+      else if (chunk_name == png_sCAL)
          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))
+
+#ifdef PNG_READ_pHYs_SUPPORTED
+      else if (chunk_name == png_pHYs)
          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))
+
+#ifdef PNG_READ_sBIT_SUPPORTED
+      else if (chunk_name == png_sBIT)
          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))
+
+#ifdef PNG_READ_sRGB_SUPPORTED
+      else if (chunk_name == png_sRGB)
          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))
+
+#ifdef PNG_READ_iCCP_SUPPORTED
+      else if (chunk_name == png_iCCP)
          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))
+
+#ifdef PNG_READ_sPLT_SUPPORTED
+      else if (chunk_name == png_sPLT)
          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))
+
+#ifdef PNG_READ_tEXt_SUPPORTED
+      else if (chunk_name == png_tEXt)
          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))
+
+#ifdef PNG_READ_tIME_SUPPORTED
+      else if (chunk_name == png_tIME)
          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))
+
+#ifdef PNG_READ_tRNS_SUPPORTED
+      else if (chunk_name == png_tRNS)
          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))
+
+#ifdef PNG_READ_zTXt_SUPPORTED
+      else if (chunk_name == png_zTXt)
          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))
+
+#ifdef PNG_READ_iTXt_SUPPORTED
+      else if (chunk_name == png_iTXt)
          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_SEQUENTIAL_READ_SUPPORTED */
 
-/* free all memory used by the read */
+/* 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_infopp end_info_ptr_ptr)
 {
    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL, end_info_ptr = NULL;
@@ -1071,9 +946,17 @@ png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
    png_voidp mem_ptr = NULL;
 #endif
 
-   png_debug(1, "in png_destroy_read_struct\n");
+   png_debug(1, "in png_destroy_read_struct");
+
    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;
@@ -1081,16 +964,11 @@ png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
    if (end_info_ptr_ptr != NULL)
       end_info_ptr = *end_info_ptr_ptr;
 
-#ifdef PNG_USER_MEM_SUPPORTED
-   free_fn = png_ptr->free_fn;
-   mem_ptr = png_ptr->mem_ptr;
-#endif
-
    png_read_destroy(png_ptr, info_ptr, end_info_ptr);
 
    if (info_ptr != NULL)
    {
-#if defined(PNG_TEXT_SUPPORTED)
+#ifdef PNG_TEXT_SUPPORTED
       png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, -1);
 #endif
 
@@ -1105,12 +983,12 @@ png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
 
    if (end_info_ptr != NULL)
    {
-#if defined(PNG_READ_TEXT_SUPPORTED)
+#ifdef PNG_READ_TEXT_SUPPORTED
       png_free_data(png_ptr, end_info_ptr, PNG_FREE_TEXT, -1);
 #endif
 #ifdef PNG_USER_MEM_SUPPORTED
       png_destroy_struct_2((png_voidp)end_info_ptr, (png_free_ptr)free_fn,
-         (png_voidp)mem_ptr);
+          (png_voidp)mem_ptr);
 #else
       png_destroy_struct((png_voidp)end_info_ptr);
 #endif
@@ -1129,112 +1007,64 @@ png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
    }
 }
 
-/* free all memory used by the read (old method) */
+/* 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)
+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;
+#ifdef PNG_WARNINGS_SUPPORTED
    png_error_ptr warning_fn;
+#endif
    png_voidp error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn;
 #endif
 
-   png_debug(1, "in png_read_destroy\n");
+   png_debug(1, "in png_read_destroy");
+
    if (info_ptr != NULL)
       png_info_destroy(png_ptr, info_ptr);
 
    if (end_info_ptr != NULL)
       png_info_destroy(png_ptr, end_info_ptr);
 
+#ifdef PNG_READ_GAMMA_SUPPORTED
+   png_destroy_gamma_table(png_ptr);
+#endif
+
    png_free(png_ptr, png_ptr->zbuf);
    png_free(png_ptr, png_ptr->big_row_buf);
-   png_free(png_ptr, png_ptr->prev_row);
-#if defined(PNG_READ_DITHER_SUPPORTED)
+   png_free(png_ptr, png_ptr->big_prev_row);
+   png_free(png_ptr, png_ptr->chunkdata);
+
+#ifdef PNG_READ_QUANTIZE_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);
+   png_free(png_ptr, png_ptr->quantize_index);
 #endif
-#ifdef PNG_FREE_ME_SUPPORTED
+
    if (png_ptr->free_me & PNG_FREE_PLTE)
       png_zfree(png_ptr, png_ptr->palette);
    png_ptr->free_me &= ~PNG_FREE_PLTE;
-#else
-   if (png_ptr->flags & PNG_FLAG_FREE_PLTE)
-      png_zfree(png_ptr, png_ptr->palette);
-   png_ptr->flags &= ~PNG_FLAG_FREE_PLTE;
-#endif
+
 #if defined(PNG_tRNS_SUPPORTED) || \
     defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
-#ifdef PNG_FREE_ME_SUPPORTED
    if (png_ptr->free_me & PNG_FREE_TRNS)
-      png_free(png_ptr, png_ptr->trans);
+      png_free(png_ptr, png_ptr->trans_alpha);
    png_ptr->free_me &= ~PNG_FREE_TRNS;
-#else
-   if (png_ptr->flags & PNG_FLAG_FREE_TRNS)
-      png_free(png_ptr, png_ptr->trans);
-   png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;
 #endif
-#endif
-#if defined(PNG_READ_hIST_SUPPORTED)
-#ifdef PNG_FREE_ME_SUPPORTED
+
+#ifdef PNG_READ_hIST_SUPPORTED
    if (png_ptr->free_me & PNG_FREE_HIST)
       png_free(png_ptr, png_ptr->hist);
    png_ptr->free_me &= ~PNG_FREE_HIST;
-#else
-   if (png_ptr->flags & PNG_FLAG_FREE_HIST)
-      png_free(png_ptr, png_ptr->hist);
-   png_ptr->flags &= ~PNG_FLAG_FREE_HIST;
-#endif
-#endif
-#if defined(PNG_READ_GAMMA_SUPPORTED)
-   if (png_ptr->gamma_16_table != NULL)
-   {
-      int i;
-      int istop = (1 << (8 - png_ptr->gamma_shift));
-      for (i = 0; i < istop; i++)
-      {
-         png_free(png_ptr, png_ptr->gamma_16_table[i]);
-      }
-   png_free(png_ptr, png_ptr->gamma_16_table);
-   }
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
-   if (png_ptr->gamma_16_from_1 != NULL)
-   {
-      int i;
-      int istop = (1 << (8 - png_ptr->gamma_shift));
-      for (i = 0; i < istop; i++)
-      {
-         png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
-      }
-   png_free(png_ptr, png_ptr->gamma_16_from_1);
-   }
-   if (png_ptr->gamma_16_to_1 != NULL)
-   {
-      int i;
-      int istop = (1 << (8 - png_ptr->gamma_shift));
-      for (i = 0; i < istop; i++)
-      {
-         png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
-      }
-   png_free(png_ptr, png_ptr->gamma_16_to_1);
-   }
-#endif
-#endif
-#if defined(PNG_TIME_RFC1123_SUPPORTED)
-   png_free(png_ptr, png_ptr->time_buffer);
 #endif
 
    inflateEnd(&png_ptr->zstream);
+
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    png_free(png_ptr, png_ptr->save_buffer);
 #endif
@@ -1249,27 +1079,31 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
     * being used again.
     */
 #ifdef PNG_SETJMP_SUPPORTED
-   png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf));
+   png_memcpy(tmp_jmp, png_ptr->longjmp_buffer, png_sizeof(jmp_buf));
 #endif
 
    error_fn = png_ptr->error_fn;
+#ifdef PNG_WARNINGS_SUPPORTED
    warning_fn = png_ptr->warning_fn;
+#endif
    error_ptr = png_ptr->error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    free_fn = png_ptr->free_fn;
 #endif
 
-   png_memset(png_ptr, 0, sizeof (png_struct));
+   png_memset(png_ptr, 0, png_sizeof(png_struct));
 
    png_ptr->error_fn = error_fn;
+#ifdef PNG_WARNINGS_SUPPORTED
    png_ptr->warning_fn = warning_fn;
+#endif
    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, sizeof (jmp_buf));
+   png_memcpy(png_ptr->longjmp_buffer, tmp_jmp, png_sizeof(jmp_buf));
 #endif
 
 }
@@ -1277,10 +1111,15 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
 void PNGAPI
 png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn)
 {
+   if (png_ptr == NULL)
+      return;
+
    png_ptr->read_row_fn = read_row_fn;
 }
 
-#if defined(PNG_INFO_IMAGE_SUPPORTED)
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+#ifdef PNG_INFO_IMAGE_SUPPORTED
 void PNGAPI
 png_read_png(png_structp png_ptr, png_infop info_ptr,
                            int transforms,
@@ -1288,70 +1127,87 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
 {
    int row;
 
-#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
+   if (png_ptr == NULL || info_ptr == NULL)
+      return;
 
-   /* The call to png_read_info() gives us all of the information from the
+   /* 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()");
 
    /* -------------- image transformations start here ------------------- */
 
-#if defined(PNG_READ_16_TO_8_SUPPORTED)
-   /* tell libpng to strip 16 bit/color files down to 8 bits/color */
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+   /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
+    */
+   if (transforms & PNG_TRANSFORM_SCALE_16)
+   {
+     /* Added at libpng-1.5.4. "strip_16" produces the same result that it
+      * did in earlier versions, while "scale_16" is now more accurate.
+      */
+      png_set_scale_16(png_ptr);
+   }
+#endif
+
+#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+   /* If both SCALE and STRIP are required pngrtran will effectively cancel the
+    * latter by doing SCALE first.  This is ok and allows apps not to check for
+    * which is supported to get the right answer.
+    */
    if (transforms & PNG_TRANSFORM_STRIP_16)
-       png_set_strip_16(png_ptr);
+      png_set_strip_16(png_ptr);
 #endif
 
-#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
-   /* Strip alpha bytes from the input data without combining with the
-    * background (not recommended).
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+   /* Strip alpha bytes from the input data without combining with
+    * the background (not recommended).
     */
    if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
-       png_set_strip_alpha(png_ptr);
+      png_set_strip_alpha(png_ptr);
 #endif
 
 #if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED)
-   /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
+   /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
     * byte into separate bytes (useful for paletted and grayscale images).
     */
    if (transforms & PNG_TRANSFORM_PACKING)
-       png_set_packing(png_ptr);
+      png_set_packing(png_ptr);
 #endif
 
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
    /* Change the order of packed pixels to least significant bit first
-    * (not useful if you are using png_set_packing). */
+    * (not useful if you are using png_set_packing).
+    */
    if (transforms & PNG_TRANSFORM_PACKSWAP)
-       png_set_packswap(png_ptr);
+      png_set_packswap(png_ptr);
 #endif
 
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
    /* Expand paletted colors into true RGB triplets
     * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
     * Expand paletted or RGB images with transparency to full alpha
     * channels so the data will be available as RGBA quartets.
     */
    if (transforms & PNG_TRANSFORM_EXPAND)
-       if ((png_ptr->bit_depth < 8) ||
-           (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
-           (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
+      if ((png_ptr->bit_depth < 8) ||
+          (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
+          (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
          png_set_expand(png_ptr);
 #endif
 
-   /* We don't handle background color or gamma transformation or dithering. */
+   /* We don't handle background color or gamma transformation or quantizing.
+    */
 
-#if defined(PNG_READ_INVERT_SUPPORTED)
-   /* invert monochrome files to have 0 as white and 1 as black */
+#ifdef PNG_READ_INVERT_SUPPORTED
+   /* Invert monochrome files to have 0 as white and 1 as black
+    */
    if (transforms & PNG_TRANSFORM_INVERT_MONO)
-       png_set_invert_mono(png_ptr);
+      png_set_invert_mono(png_ptr);
 #endif
 
-#if defined(PNG_READ_SHIFT_SUPPORTED)
+#ifdef PNG_READ_SHIFT_SUPPORTED
    /* If you want to shift the pixel values from the range [0,255] or
     * [0,65535] to the original [0,7] or [0,31], or whatever range the
     * colors were originally in:
@@ -1366,26 +1222,51 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
    }
 #endif
 
-#if defined(PNG_READ_BGR_SUPPORTED)
-   /* flip the RGB pixels to BGR (or RGBA to BGRA) */
+#ifdef PNG_READ_BGR_SUPPORTED
+   /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
    if (transforms & PNG_TRANSFORM_BGR)
-       png_set_bgr(png_ptr);
+      png_set_bgr(png_ptr);
 #endif
 
-#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
-   /* swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
+   /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
    if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
-       png_set_swap_alpha(png_ptr);
+      png_set_swap_alpha(png_ptr);
 #endif
 
-#if defined(PNG_READ_SWAP_SUPPORTED)
-   /* swap bytes of 16 bit files to least significant byte first */
+#ifdef PNG_READ_SWAP_SUPPORTED
+   /* Swap bytes of 16-bit files to least significant byte first */
    if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
-       png_set_swap(png_ptr);
+      png_set_swap(png_ptr);
+#endif
+
+/* Added at libpng-1.2.41 */
+#ifdef 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
+
+/* Added at libpng-1.2.41 */
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+   /* Expand grayscale image to RGB */
+   if (transforms & PNG_TRANSFORM_GRAY_TO_RGB)
+      png_set_gray_to_rgb(png_ptr);
+#endif
+
+/* Added at libpng-1.5.4 */
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+   if (transforms & PNG_TRANSFORM_EXPAND_16)
+      png_set_expand_16(png_ptr);
 #endif
 
    /* We don't handle adding filler bytes */
 
+   /* We use png_read_image and rely on that for interlace handling, but we also
+    * call png_read_update_info therefore must turn on interlace handling now:
+    */
+   (void)png_set_interlace_handling(png_ptr);
+
    /* Optional call to gamma correct and add the background to the palette
     * and update info structure.  REQUIRED if you are expecting libpng to
     * update the palette for you (i.e., you selected such a transform above).
@@ -1394,31 +1275,33 @@ png_read_png(png_structp png_ptr, png_infop 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)
    {
+      png_uint_32 iptr;
+
       info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
-         info_ptr->height * sizeof(png_bytep));
-#ifdef PNG_FREE_ME_SUPPORTED
+          info_ptr->height * png_sizeof(png_bytep));
+      for (iptr=0; iptr<info_ptr->height; iptr++)
+         info_ptr->row_pointers[iptr] = NULL;
+
       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 */
+   /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
    png_read_end(png_ptr, info_ptr);
 
-   if(transforms == 0 || params == NULL)
-      /* quiet compiler warnings */ return;
+   PNG_UNUSED(transforms)   /* Quiet compiler warnings */
+   PNG_UNUSED(params)
 
 }
-#endif
+#endif /* PNG_INFO_IMAGE_SUPPORTED */
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+#endif /* PNG_READ_SUPPORTED */