X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/5b02c8a11f0e0d284eff32cfde1fcd2a4b2e659d..3013861102292eb82391e361bee1dc090783c653:/src/png/pngread.c?ds=sidebyside

diff --git a/src/png/pngread.c b/src/png/pngread.c
index 9f57e62f23..92060d2bc6 100644
--- a/src/png/pngread.c
+++ b/src/png/pngread.c
@@ -1,18 +1,24 @@
 
 /* pngread.c - read a PNG file
  *
- * libpng 1.2.6 - August 15, 2004
- * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2004 Glenn Randers-Pehrson
+ * Last changed in libpng 1.4.1 [February 25, 2010]
+ * Copyright (c) 1998-2010 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
+#define PNG_NO_PEDANTIC_WARNINGS
 #include "png.h"
+#ifdef PNG_READ_SUPPORTED
+#include "pngpriv.h"
+
 
 /* Create a PNG structure for reading, and allocate any memory needed. */
 png_structp PNGAPI
@@ -22,10 +28,12 @@ png_create_read_struct(png_const_charp user_png_ver, png_voidp error_ptr,
 
 #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. */
+/* 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,
@@ -33,7 +41,11 @@ png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
 {
 #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
@@ -43,49 +55,45 @@ png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
 
    int i;
 
-   png_debug(1, "in png_create_read_struct\n");
+   png_debug(1, "in png_create_read_struct");
+
 #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 */
-#endif
-#endif /* PNG_1_0_X */
-
-   /* 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;
+   /* 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
 
 #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))
+   if (setjmp(png_jmpbuf(png_ptr))) /* Sets longjmp to match setjmp */
 #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);
-#else
-      png_destroy_struct((png_voidp)png_ptr);
-#endif
-      return (NULL);
-   }
+      PNG_ABORT();
 #ifdef USE_FAR_KEYWORD
-   png_memcpy(png_ptr->jmpbuf,jmpbuf,png_sizeof(jmp_buf));
-#endif
+   png_memcpy(png_jmpbuf(png_ptr), 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);
@@ -93,215 +101,107 @@ 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++]);
-
-   if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
+   if (user_png_ver)
    {
-     /* 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);
+      i = 0;
+      do
+      {
+         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
+       * 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'))
+      {
+#ifdef PNG_STDIO_SUPPORTED
+         char msg[80];
+         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
 #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");
-     }
+         png_warning(png_ptr,
+            "Incompatible libpng version in application and library");
+
+         png_cleanup_needed = 1;
+      }
    }
 
-   /* initialize zbuf - compression buffer */
+   if (!png_cleanup_needed)
+   {
+   /* 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->zbuf = (png_bytep)png_malloc_warn(png_ptr,
+     png_ptr->zbuf_size);
+   if (png_ptr->zbuf == NULL)
+        png_cleanup_needed = 1;
+   }
    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;
-
-   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));
-#else
-   if (setjmp(png_ptr->jmpbuf))
-      PNG_ABORT();
-#endif
-#endif
-   return (png_ptr);
-}
-
-/* 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);
-}
-
-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(png_sizeof(png_struct) > png_struct_size || 
-      png_sizeof(png_info) > png_info_size)
-   {
-      char msg[80];
-      png_ptr->warning_fn=NULL;
-      if (user_png_ver)
+      switch (inflateInit(&png_ptr->zstream))
       {
-        sprintf(msg, "Application was compiled with png.h from libpng-%.20s",
-           user_png_ver);
-        png_warning(png_ptr, msg);
+         case Z_OK: /* Do nothing */ break;
+         case Z_MEM_ERROR:
+         case Z_STREAM_ERROR: png_warning(png_ptr, "zlib memory error");
+            png_cleanup_needed = 1; break;
+         case Z_VERSION_ERROR: png_warning(png_ptr, "zlib version error");
+            png_cleanup_needed = 1; break;
+         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(png_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(png_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, 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;
-     }
-
-   /* reset all variables to 0 */
-   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));
-#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;
+      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);
 }
 
-#ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
+
+#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
@@ -313,13 +213,21 @@ 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");
+   png_debug(1, "in png_read_info");
+ 
+   if (png_ptr == NULL || info_ptr == NULL)
+      return;
+ 
    /* 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;
 
+#ifdef PNG_IO_STATE_SUPPORTED
+      png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
+#endif
+
       png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
       png_ptr->sig_bytes = 8;
 
@@ -335,93 +243,86 @@ png_read_info(png_structp png_ptr, png_infop info_ptr)
          png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
    }
 
-   for(;;)
+   for (;;)
    {
-#ifdef PNG_USE_LOCAL_ARRAYS
       PNG_IHDR;
       PNG_IDAT;
       PNG_IEND;
       PNG_PLTE;
-#if defined(PNG_READ_bKGD_SUPPORTED)
+#ifdef PNG_READ_bKGD_SUPPORTED
       PNG_bKGD;
 #endif
-#if defined(PNG_READ_cHRM_SUPPORTED)
+#ifdef PNG_READ_cHRM_SUPPORTED
       PNG_cHRM;
 #endif
-#if defined(PNG_READ_gAMA_SUPPORTED)
+#ifdef PNG_READ_gAMA_SUPPORTED
       PNG_gAMA;
 #endif
-#if defined(PNG_READ_hIST_SUPPORTED)
+#ifdef PNG_READ_hIST_SUPPORTED
       PNG_hIST;
 #endif
-#if defined(PNG_READ_iCCP_SUPPORTED)
+#ifdef PNG_READ_iCCP_SUPPORTED
       PNG_iCCP;
 #endif
-#if defined(PNG_READ_iTXt_SUPPORTED)
+#ifdef PNG_READ_iTXt_SUPPORTED
       PNG_iTXt;
 #endif
-#if defined(PNG_READ_oFFs_SUPPORTED)
+#ifdef PNG_READ_oFFs_SUPPORTED
       PNG_oFFs;
 #endif
-#if defined(PNG_READ_pCAL_SUPPORTED)
+#ifdef PNG_READ_pCAL_SUPPORTED
       PNG_pCAL;
 #endif
-#if defined(PNG_READ_pHYs_SUPPORTED)
+#ifdef PNG_READ_pHYs_SUPPORTED
       PNG_pHYs;
 #endif
-#if defined(PNG_READ_sBIT_SUPPORTED)
+#ifdef PNG_READ_sBIT_SUPPORTED
       PNG_sBIT;
 #endif
-#if defined(PNG_READ_sCAL_SUPPORTED)
+#ifdef PNG_READ_sCAL_SUPPORTED
       PNG_sCAL;
 #endif
-#if defined(PNG_READ_sPLT_SUPPORTED)
+#ifdef PNG_READ_sPLT_SUPPORTED
       PNG_sPLT;
 #endif
-#if defined(PNG_READ_sRGB_SUPPORTED)
+#ifdef PNG_READ_sRGB_SUPPORTED
       PNG_sRGB;
 #endif
-#if defined(PNG_READ_tEXt_SUPPORTED)
+#ifdef PNG_READ_tEXt_SUPPORTED
       PNG_tEXt;
 #endif
-#if defined(PNG_READ_tIME_SUPPORTED)
+#ifdef PNG_READ_tIME_SUPPORTED
       PNG_tIME;
 #endif
-#if defined(PNG_READ_tRNS_SUPPORTED)
+#ifdef PNG_READ_tRNS_SUPPORTED
       PNG_tRNS;
 #endif
-#if defined(PNG_READ_zTXt_SUPPORTED)
+#ifdef 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_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_IHDR, 4))
+      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(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");
@@ -432,9 +333,9 @@ png_read_info(png_structp png_ptr, png_infop info_ptr)
          }
       }
 #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");
@@ -446,94 +347,98 @@ png_read_info(png_structp png_ptr, png_infop info_ptr)
          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 (!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))
+#ifdef PNG_READ_cHRM_SUPPORTED
+      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))
+#ifdef PNG_READ_gAMA_SUPPORTED
+      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))
+#ifdef PNG_READ_hIST_SUPPORTED
+      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))
+#ifdef PNG_READ_oFFs_SUPPORTED
+      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))
+#ifdef PNG_READ_pCAL_SUPPORTED
+      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))
+#ifdef PNG_READ_sCAL_SUPPORTED
+      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))
+#ifdef PNG_READ_pHYs_SUPPORTED
+      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))
+#ifdef PNG_READ_sBIT_SUPPORTED
+      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))
+#ifdef PNG_READ_sRGB_SUPPORTED
+      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))
+#ifdef PNG_READ_iCCP_SUPPORTED
+      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))
+#ifdef PNG_READ_sPLT_SUPPORTED
+      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))
+#ifdef PNG_READ_tEXt_SUPPORTED
+      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))
+#ifdef PNG_READ_tIME_SUPPORTED
+      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))
+#ifdef PNG_READ_tRNS_SUPPORTED
+      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))
+#ifdef PNG_READ_zTXt_SUPPORTED
+      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))
+#ifdef PNG_READ_iTXt_SUPPORTED
+      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 */
+#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");
+   png_debug(1, "in png_read_update_info");
+ 
+   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
+#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.
@@ -542,61 +447,69 @@ 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");
+   png_debug(1, "in png_start_read_image");
+ 
+   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 */
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
-#ifndef PNG_NO_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
+   PNG_CONST int png_pass_dsp_mask[7] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
+      0xff};
+   PNG_CONST int png_pass_mask[7] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
    int ret;
-   png_debug2(1, "in png_read_row (row %lu, pass %d)\n",
-      png_ptr->row_number, png_ptr->pass);
+ 
+   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);
+
    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 */
+   /* 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 */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
       switch (png_ptr->pass)
@@ -676,22 +589,18 @@ 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_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");
          }
@@ -708,7 +617,7 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
       {
          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;
@@ -727,16 +636,15 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
    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) &&
+   png_memcpy(png_ptr->prev_row, png_ptr->row_buf, png_ptr->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 */
@@ -744,19 +652,20 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
    }
 #endif
 
-   if (png_ptr->transformations)
+
+   if (png_ptr->transformations || (png_ptr->flags&PNG_FLAG_STRIP_ALPHA))
       png_do_read_transformations(png_ptr);
 
-#if defined(PNG_READ_INTERLACING_SUPPORTED)
-   /* blow up interlaced rows to full size */
+#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);
- */
+         /* 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);
 
       if (dsp_row != NULL)
@@ -779,9 +688,9 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
    if (png_ptr->read_row_fn != NULL)
       (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
 }
-#endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
-#ifndef PNG_NO_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
@@ -803,7 +712,7 @@ 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 1.2.6
+ * [*] png_handle_alpha() does not exist yet, as of this version of libpng
  */
 
 void PNGAPI
@@ -814,7 +723,10 @@ png_read_rows(png_structp png_ptr, png_bytepp row,
    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)
@@ -825,24 +737,24 @@ 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_NO_SEQUENTIAL_READ_SUPPORTED */
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
-#ifndef PNG_NO_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.
@@ -853,23 +765,26 @@ 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 1.2.6
+ * [*] 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);
 #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
 
@@ -882,14 +797,14 @@ png_read_image(png_structp png_ptr, png_bytepp image)
       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_NO_SEQUENTIAL_READ_SUPPORTED */
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
-#ifndef PNG_NO_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.
@@ -897,185 +812,175 @@ 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\n");
+   png_debug(1, "in png_read_end");
+ 
+   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_IHDR;
       PNG_IDAT;
       PNG_IEND;
       PNG_PLTE;
-#if defined(PNG_READ_bKGD_SUPPORTED)
+#ifdef PNG_READ_bKGD_SUPPORTED
       PNG_bKGD;
 #endif
-#if defined(PNG_READ_cHRM_SUPPORTED)
+#ifdef PNG_READ_cHRM_SUPPORTED
       PNG_cHRM;
 #endif
-#if defined(PNG_READ_gAMA_SUPPORTED)
+#ifdef PNG_READ_gAMA_SUPPORTED
       PNG_gAMA;
 #endif
-#if defined(PNG_READ_hIST_SUPPORTED)
+#ifdef PNG_READ_hIST_SUPPORTED
       PNG_hIST;
 #endif
-#if defined(PNG_READ_iCCP_SUPPORTED)
+#ifdef PNG_READ_iCCP_SUPPORTED
       PNG_iCCP;
 #endif
-#if defined(PNG_READ_iTXt_SUPPORTED)
+#ifdef PNG_READ_iTXt_SUPPORTED
       PNG_iTXt;
 #endif
-#if defined(PNG_READ_oFFs_SUPPORTED)
+#ifdef PNG_READ_oFFs_SUPPORTED
       PNG_oFFs;
 #endif
-#if defined(PNG_READ_pCAL_SUPPORTED)
+#ifdef PNG_READ_pCAL_SUPPORTED
       PNG_pCAL;
 #endif
-#if defined(PNG_READ_pHYs_SUPPORTED)
+#ifdef PNG_READ_pHYs_SUPPORTED
       PNG_pHYs;
 #endif
-#if defined(PNG_READ_sBIT_SUPPORTED)
+#ifdef PNG_READ_sBIT_SUPPORTED
       PNG_sBIT;
 #endif
-#if defined(PNG_READ_sCAL_SUPPORTED)
+#ifdef PNG_READ_sCAL_SUPPORTED
       PNG_sCAL;
 #endif
-#if defined(PNG_READ_sPLT_SUPPORTED)
+#ifdef PNG_READ_sPLT_SUPPORTED
       PNG_sPLT;
 #endif
-#if defined(PNG_READ_sRGB_SUPPORTED)
+#ifdef PNG_READ_sRGB_SUPPORTED
       PNG_sRGB;
 #endif
-#if defined(PNG_READ_tEXt_SUPPORTED)
+#ifdef PNG_READ_tEXt_SUPPORTED
       PNG_tEXt;
 #endif
-#if defined(PNG_READ_tIME_SUPPORTED)
+#ifdef PNG_READ_tIME_SUPPORTED
       PNG_tIME;
 #endif
-#if defined(PNG_READ_tRNS_SUPPORTED)
+#ifdef PNG_READ_tRNS_SUPPORTED
       PNG_tRNS;
 #endif
-#if defined(PNG_READ_zTXt_SUPPORTED)
+#ifdef PNG_READ_zTXt_SUPPORTED
       PNG_zTXt;
 #endif
-#endif /* PNG_GLOBAL_ARRAYS */
-
-      png_read_data(png_ptr, chunk_length, 4);
-      length = png_get_uint_31(png_ptr,chunk_length);
+      png_uint_32 length = png_read_chunk_header(png_ptr);
+      PNG_CONST png_bytep 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 (!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_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 (!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_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 (!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))
+#ifdef PNG_READ_bKGD_SUPPORTED
+      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))
+#ifdef PNG_READ_cHRM_SUPPORTED
+      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))
+#ifdef PNG_READ_gAMA_SUPPORTED
+      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))
+#ifdef PNG_READ_hIST_SUPPORTED
+      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))
+#ifdef PNG_READ_oFFs_SUPPORTED
+      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))
+#ifdef PNG_READ_pCAL_SUPPORTED
+      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))
+#ifdef PNG_READ_sCAL_SUPPORTED
+      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))
+#ifdef PNG_READ_pHYs_SUPPORTED
+      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))
+#ifdef PNG_READ_sBIT_SUPPORTED
+      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))
+#ifdef PNG_READ_sRGB_SUPPORTED
+      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))
+#ifdef PNG_READ_iCCP_SUPPORTED
+      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))
+#ifdef PNG_READ_sPLT_SUPPORTED
+      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))
+#ifdef PNG_READ_tEXt_SUPPORTED
+      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))
+#ifdef PNG_READ_tIME_SUPPORTED
+      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))
+#ifdef PNG_READ_tRNS_SUPPORTED
+      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))
+#ifdef PNG_READ_zTXt_SUPPORTED
+      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))
+#ifdef PNG_READ_iTXt_SUPPORTED
+      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 */
+#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)
@@ -1083,13 +988,21 @@ png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp 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;
-   png_voidp mem_ptr;
+   png_free_ptr free_fn = NULL;
+   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;
@@ -1097,16 +1010,11 @@ 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
 
@@ -1121,7 +1029,7 @@ 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
@@ -1145,9 +1053,10 @@ 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;
@@ -1159,7 +1068,8 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
    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);
 
@@ -1169,50 +1079,33 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop 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);
-#if defined(PNG_READ_DITHER_SUPPORTED)
+   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);
+   png_free(png_ptr, png_ptr->quantize_index);
 #endif
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
    png_free(png_ptr, png_ptr->gamma_table);
 #endif
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
    png_free(png_ptr, png_ptr->gamma_from_1);
    png_free(png_ptr, png_ptr->gamma_to_1);
 #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)
+#ifdef PNG_READ_GAMMA_SUPPORTED
    if (png_ptr->gamma_16_table != NULL)
    {
       int i;
@@ -1223,7 +1116,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
       }
    png_free(png_ptr, png_ptr->gamma_16_table);
    }
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
    if (png_ptr->gamma_16_from_1 != NULL)
    {
       int i;
@@ -1246,7 +1139,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
    }
 #endif
 #endif
-#if defined(PNG_TIME_RFC1123_SUPPORTED)
+#ifdef PNG_TIME_RFC1123_SUPPORTED
    png_free(png_ptr, png_ptr->time_buffer);
 #endif
 
@@ -1265,7 +1158,7 @@ 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, png_sizeof (jmp_buf));
+   png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));
 #endif
 
    error_fn = png_ptr->error_fn;
@@ -1275,7 +1168,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
    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;
@@ -1285,7 +1178,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
 #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
 
 }
@@ -1293,12 +1186,14 @@ 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;
 }
 
 
-#ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
-#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,
@@ -1306,35 +1201,31 @@ 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)
+      return;
 
    /* 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
+#ifdef 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);
+      png_set_strip_16(png_ptr);
 #endif
 
-#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
+#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)
@@ -1342,41 +1233,41 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
     * 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).
     */
    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:
@@ -1391,25 +1282,41 @@ 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);
 #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
 
    /* We don't handle adding filler bytes */
@@ -1422,32 +1329,33 @@ 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 * png_sizeof(png_bytep));
-#ifdef PNG_FREE_ME_SUPPORTED
+      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;
+   transforms = transforms; /* Quiet compiler warnings */
+   params = params;
 
 }
-#endif
-#endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
+#endif /* PNG_INFO_IMAGE_SUPPORTED */
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+#endif /* PNG_READ_SUPPORTED */