X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/5b02c8a11f0e0d284eff32cfde1fcd2a4b2e659d..373a4816d447cbf6da448e139cd577599c866e86:/src/png/pngrutil.c

diff --git a/src/png/pngrutil.c b/src/png/pngrutil.c
index 99455514ea..11e412b729 100644
--- a/src/png/pngrutil.c
+++ b/src/png/pngrutil.c
@@ -1,102 +1,133 @@
+
 /* pngrutil.c - utilities to read a PNG file
  *
- * libpng version 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 1.4.4 [August 26, 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 are only called from within
  * libpng itself during the course of reading an image.
  */
 
-#define PNG_INTERNAL
+#define PNG_NO_PEDANTIC_WARNINGS
 #include "png.h"
+#ifdef PNG_READ_SUPPORTED
+#include "pngpriv.h"
 
-#if defined(_WIN32_WCE)
-/* strtod() function is not supported on WindowsCE */
-#  ifdef PNG_FLOATING_POINT_SUPPORTED
-__inline double strtod(const char *nptr, char **endptr)
-{
-   double result = 0;
-   int len;
-   wchar_t *str, *end;
-
-   len = MultiByteToWideChar(CP_ACP, 0, nptr, -1, NULL, 0);
-   str = (wchar_t *)malloc(len * sizeof(wchar_t));
-   if ( NULL != str )
-   {
-      MultiByteToWideChar(CP_ACP, 0, nptr, -1, str, len);
-      result = wcstod(str, &end);
-      len = WideCharToMultiByte(CP_ACP, 0, end, -1, NULL, 0, NULL, NULL);
-      *endptr = (char *)nptr + (png_strlen(nptr) - len + 1);
-      free(str);
-   }
-   return result;
-}
-#  endif
-#endif
-
-png_uint_32 /* PRIVATE */
+#    define png_strtod(p,a,b) strtod(a,b)
+png_uint_32 PNGAPI
 png_get_uint_31(png_structp png_ptr, png_bytep buf)
 {
    png_uint_32 i = png_get_uint_32(buf);
    if (i > PNG_UINT_31_MAX)
-     png_error(png_ptr, "PNG unsigned integer out of range.\n");
+     png_error(png_ptr, "PNG unsigned integer out of range");
    return (i);
 }
-#ifndef PNG_READ_BIG_ENDIAN_SUPPORTED
+#ifndef PNG_USE_READ_MACROS
 /* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
-png_uint_32 /* PRIVATE */
-png_get_uint_32(png_bytep buf)
+png_uint_32 (PNGAPI
+png_get_uint_32)(png_bytep buf)
 {
-   png_uint_32 i = ((png_uint_32)(*buf) << 24) +
-      ((png_uint_32)(*(buf + 1)) << 16) +
-      ((png_uint_32)(*(buf + 2)) << 8) +
-      (png_uint_32)(*(buf + 3));
+   png_uint_32 i =
+       ((png_uint_32)(*(buf    )) << 24) +
+       ((png_uint_32)(*(buf + 1)) << 16) +
+       ((png_uint_32)(*(buf + 2)) <<  8) +
+       ((png_uint_32)(*(buf + 3))      ) ;
 
    return (i);
 }
 
-#if defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_oFFs_SUPPORTED)
 /* Grab a signed 32-bit integer from a buffer in big-endian format.  The
- * data is stored in the PNG file in two's complement format, and it is
- * assumed that the machine format for signed integers is the same. */
-png_int_32 /* PRIVATE */
-png_get_int_32(png_bytep buf)
+ * data is stored in the PNG file in two's complement format and there
+ * is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
+ * the following code does a two's complement to native conversion.
+ */
+png_int_32 (PNGAPI
+png_get_int_32)(png_bytep buf)
 {
-   png_int_32 i = ((png_int_32)(*buf) << 24) +
-      ((png_int_32)(*(buf + 1)) << 16) +
-      ((png_int_32)(*(buf + 2)) << 8) +
-      (png_int_32)(*(buf + 3));
+   png_uint_32 u = png_get_uint_32(buf);
+   if ((u & 0x80000000) == 0) /* non-negative */
+      return u;
 
-   return (i);
+   u = (u ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
+   return -(png_int_32)u;
 }
-#endif /* PNG_READ_pCAL_SUPPORTED */
 
 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
-png_uint_16 /* PRIVATE */
-png_get_uint_16(png_bytep buf)
+png_uint_16 (PNGAPI
+png_get_uint_16)(png_bytep buf)
 {
-   png_uint_16 i = (png_uint_16)(((png_uint_16)(*buf) << 8) +
-      (png_uint_16)(*(buf + 1)));
+   png_uint_16 i =
+       ((png_uint_32)(*buf) << 8) +
+       ((png_uint_32)(*(buf + 1)));
 
    return (i);
 }
-#endif /* PNG_READ_BIG_ENDIAN_SUPPORTED */
+#endif /* PNG_USE_READ_MACROS */
+
+/* Read the chunk header (length + type name).
+ * Put the type name into png_ptr->chunk_name, and return the length.
+ */
+png_uint_32 /* PRIVATE */
+png_read_chunk_header(png_structp png_ptr)
+{
+   png_byte buf[8];
+   png_uint_32 length;
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   /* Inform the I/O callback that the chunk header is being read.
+    * PNG_IO_CHUNK_HDR requires a single I/O call.
+    */
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
+#endif
+
+   /* Read the length and the chunk name */
+   png_read_data(png_ptr, buf, 8);
+   length = png_get_uint_31(png_ptr, buf);
+
+   /* Put the chunk name into png_ptr->chunk_name */
+   png_memcpy(png_ptr->chunk_name, buf + 4, 4);
+
+   png_debug2(0, "Reading %s chunk, length = %lu",
+      png_ptr->chunk_name, length);
+
+   /* Reset the crc and run it over the chunk name */
+   png_reset_crc(png_ptr);
+   png_calculate_crc(png_ptr, png_ptr->chunk_name, 4);
+
+   /* Check to see if chunk name is valid */
+   png_check_chunk_name(png_ptr, png_ptr->chunk_name);
+
+#ifdef PNG_IO_STATE_SUPPORTED
+   /* Inform the I/O callback that chunk data will (possibly) be read.
+    * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls.
+    */
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
+#endif
+
+   return length;
+}
 
 /* Read data, and (optionally) run it through the CRC. */
 void /* PRIVATE */
 png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
 {
+   if (png_ptr == NULL)
+      return;
    png_read_data(png_ptr, buf, length);
    png_calculate_crc(png_ptr, buf, length);
 }
 
 /* Optionally skip data and then check the CRC.  Depending on whether we
-   are reading a ancillary or critical chunk, and how the program has set
-   things up, we may calculate the CRC on the data and print a message.
-   Returns '1' if there was a CRC error, '0' otherwise. */
+ * are reading a ancillary or critical chunk, and how the program has set
+ * things up, we may calculate the CRC on the data and print a message.
+ * Returns '1' if there was a CRC error, '0' otherwise.
+ */
 int /* PRIVATE */
 png_crc_finish(png_structp png_ptr, png_uint_32 skip)
 {
@@ -115,7 +146,7 @@ png_crc_finish(png_structp png_ptr, png_uint_32 skip)
    if (png_crc_error(png_ptr))
    {
       if (((png_ptr->chunk_name[0] & 0x20) &&                /* Ancillary */
-           !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) ||
+          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) ||
           (!(png_ptr->chunk_name[0] & 0x20) &&             /* Critical  */
           (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE)))
       {
@@ -123,7 +154,8 @@ png_crc_finish(png_structp png_ptr, png_uint_32 skip)
       }
       else
       {
-         png_chunk_error(png_ptr, "CRC error");
+         png_chunk_benign_error(png_ptr, "CRC error");
+         return (0);
       }
       return (1);
    }
@@ -132,7 +164,8 @@ png_crc_finish(png_structp png_ptr, png_uint_32 skip)
 }
 
 /* Compare the CRC stored in the PNG file with that calculated by libpng from
-   the data it has read thus far. */
+ * the data it has read thus far.
+ */
 int /* PRIVATE */
 png_crc_error(png_structp png_ptr)
 {
@@ -152,6 +185,12 @@ png_crc_error(png_structp png_ptr)
          need_crc = 0;
    }
 
+#ifdef PNG_IO_STATE_SUPPORTED
+   /* Inform the I/O callback that the chunk CRC is being read */
+   /* PNG_IO_CHUNK_CRC requires the I/O to be done at once */
+   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
+#endif
+
    png_read_data(png_ptr, crc_bytes, 4);
 
    if (need_crc)
@@ -165,173 +204,218 @@ png_crc_error(png_structp png_ptr)
 
 #if defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) || \
     defined(PNG_READ_iCCP_SUPPORTED)
-/*
- * Decompress trailing data in a chunk.  The assumption is that chunkdata
- * points at an allocated area holding the contents of a chunk with a
- * trailing compressed part.  What we get back is an allocated area
- * holding the original prefix part and an uncompressed version of the
- * trailing part (the malloc area passed in is freed).
- */
-png_charp /* PRIVATE */
-png_decompress_chunk(png_structp png_ptr, int comp_type,
-                              png_charp chunkdata, png_size_t chunklength,
-                              png_size_t prefix_size, png_size_t *newlength)
+static png_size_t
+png_inflate(png_structp png_ptr, const png_byte *data, png_size_t size,
+        png_bytep output, png_size_t output_size)
 {
-   static char msg[] = "Error decoding compressed text";
-   png_charp text;
-   png_size_t text_size;
+   png_size_t count = 0;
+
+   png_ptr->zstream.next_in = (png_bytep)data; /* const_cast: VALID */
+   png_ptr->zstream.avail_in = size;
 
-   if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+   while (1)
    {
-      int ret = Z_OK;
-      png_ptr->zstream.next_in = (png_bytep)(chunkdata + prefix_size);
-      png_ptr->zstream.avail_in = (uInt)(chunklength - prefix_size);
+      int ret, avail;
+
+      /* Reset the output buffer each time round - we empty it
+       * after every inflate call.
+       */
       png_ptr->zstream.next_out = png_ptr->zbuf;
-      png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+      png_ptr->zstream.avail_out = png_ptr->zbuf_size;
 
-      text_size = 0;
-      text = NULL;
+      ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
+      avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;
 
-      while (png_ptr->zstream.avail_in)
+      /* First copy/count any new output - but only if we didn't
+       * get an error code.
+       */
+      if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)
       {
-         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-         if (ret != Z_OK && ret != Z_STREAM_END)
+         if (output != 0 && output_size > count)
          {
-            if (png_ptr->zstream.msg != NULL)
-               png_warning(png_ptr, png_ptr->zstream.msg);
-            else
-               png_warning(png_ptr, msg);
-            inflateReset(&png_ptr->zstream);
-            png_ptr->zstream.avail_in = 0;
+            int copy = output_size - count;
+            if (avail < copy) copy = avail;
+            png_memcpy(output + count, png_ptr->zbuf, copy);
+         }
+         count += avail;
+      }
 
-            if (text ==  NULL)
-            {
-               text_size = prefix_size + png_sizeof(msg) + 1;
-               text = (png_charp)png_malloc_warn(png_ptr, text_size);
-               if (text ==  NULL)
-                 {
-                    png_free(png_ptr,chunkdata);
-                    png_error(png_ptr,"Not enough memory to decompress chunk");
-                 }
-               png_memcpy(text, chunkdata, prefix_size);
-            }
+      if (ret == Z_OK)
+         continue;
+
+      /* Termination conditions - always reset the zstream, it
+       * must be left in inflateInit state.
+       */
+      png_ptr->zstream.avail_in = 0;
+      inflateReset(&png_ptr->zstream);
 
-            text[text_size - 1] = 0x00;
+      if (ret == Z_STREAM_END)
+         return count; /* NOTE: may be zero. */
 
-            /* Copy what we can of the error message into the text chunk */
-            text_size = (png_size_t)(chunklength - (text - chunkdata) - 1);
-            text_size = png_sizeof(msg) > text_size ? text_size :
-               png_sizeof(msg);
-            png_memcpy(text + prefix_size, msg, text_size + 1);
-            break;
-         }
-         if (!png_ptr->zstream.avail_out || ret == Z_STREAM_END)
+      /* Now handle the error codes - the API always returns 0
+       * and the error message is dumped into the uncompressed
+       * buffer if available.
+       */
+      {
+         PNG_CONST char *msg;
+         if (png_ptr->zstream.msg != 0)
+            msg = png_ptr->zstream.msg;
+         else
          {
-            if (text == NULL)
-            {
-               text_size = prefix_size +
-                   png_ptr->zbuf_size - png_ptr->zstream.avail_out;
-               text = (png_charp)png_malloc_warn(png_ptr, text_size + 1);
-               if (text ==  NULL)
-                 {
-                    png_free(png_ptr,chunkdata);
-                    png_error(png_ptr,"Not enough memory to decompress chunk.");
-                 }
-               png_memcpy(text + prefix_size, png_ptr->zbuf,
-                    text_size - prefix_size);
-               png_memcpy(text, chunkdata, prefix_size);
-               *(text + text_size) = 0x00;
-            }
-            else
-            {
-               png_charp tmp;
+#ifdef PNG_STDIO_SUPPORTED
+            char umsg[52];
 
-               tmp = text;
-               text = (png_charp)png_malloc_warn(png_ptr,
-                  (png_uint_32)(text_size +
-                  png_ptr->zbuf_size - png_ptr->zstream.avail_out + 1));
-               if (text == NULL)
-               {
-                  png_free(png_ptr, tmp);
-                  png_free(png_ptr, chunkdata);
-                  png_error(png_ptr,"Not enough memory to decompress chunk..");
-               }
-               png_memcpy(text, tmp, text_size);
-               png_free(png_ptr, tmp);
-               png_memcpy(text + text_size, png_ptr->zbuf,
-                  (png_ptr->zbuf_size - png_ptr->zstream.avail_out));
-               text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
-               *(text + text_size) = 0x00;
-            }
-            if (ret == Z_STREAM_END)
-               break;
-            else
+            switch (ret)
             {
-               png_ptr->zstream.next_out = png_ptr->zbuf;
-               png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
+               case Z_BUF_ERROR:
+                  msg = "Buffer error in compressed datastream in %s chunk";
+                  break;
+               case Z_DATA_ERROR:
+                  msg = "Data error in compressed datastream in %s chunk";
+                  break;
+               default:
+                  msg = "Incomplete compressed datastream in %s chunk";
+                  break;
             }
+
+            png_snprintf(umsg, sizeof umsg, msg, png_ptr->chunk_name);
+            msg = umsg;
+#else
+            msg = "Damaged compressed datastream in chunk other than IDAT";
+#endif
          }
+
+         png_warning(png_ptr, msg);
       }
-      if (ret != Z_STREAM_END)
-      {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
-         char umsg[50];
 
-         if (ret == Z_BUF_ERROR)
-            sprintf(umsg,"Buffer error in compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-         else if (ret == Z_DATA_ERROR)
-            sprintf(umsg,"Data error in compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-         else
-            sprintf(umsg,"Incomplete compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-         png_warning(png_ptr, umsg);
+      /* 0 means an error - notice that this code simple ignores
+       * zero length compressed chunks as a result.
+       */
+      return 0;
+   }
+}
+
+/*
+ * Decompress trailing data in a chunk.  The assumption is that chunkdata
+ * points at an allocated area holding the contents of a chunk with a
+ * trailing compressed part.  What we get back is an allocated area
+ * holding the original prefix part and an uncompressed version of the
+ * trailing part (the malloc area passed in is freed).
+ */
+void /* PRIVATE */
+png_decompress_chunk(png_structp png_ptr, int comp_type,
+    png_size_t chunklength,
+    png_size_t prefix_size, png_size_t *newlength)
+{
+   /* The caller should guarantee this */
+   if (prefix_size > chunklength)
+   {
+      /* The recovery is to delete the chunk. */
+      png_warning(png_ptr, "invalid chunklength");
+      prefix_size = 0; /* To delete everything */
+   }
+
+   else if (comp_type == PNG_COMPRESSION_TYPE_BASE)
+   {
+      png_size_t expanded_size = png_inflate(png_ptr,
+                (png_bytep)(png_ptr->chunkdata + prefix_size),
+                chunklength - prefix_size,
+                0/*output*/, 0/*output size*/);
+
+      /* Now check the limits on this chunk - if the limit fails the
+       * compressed data will be removed, the prefix will remain.
+       */
+#ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+      if (png_ptr->user_chunk_malloc_max &&
+          (prefix_size + expanded_size >= png_ptr->user_chunk_malloc_max - 1))
 #else
-         png_warning(png_ptr,
-            "Incomplete compressed datastream in chunk other than IDAT");
+#  ifdef PNG_USER_CHUNK_MALLOC_MAX
+      if ((PNG_USER_CHUNK_MALLOC_MAX > 0) &&
+          prefix_size + expanded_size >= PNG_USER_CHUNK_MALLOC_MAX - 1)
+#  endif
+#endif
+         png_warning(png_ptr, "Exceeded size limit while expanding chunk");
+
+      /* If the size is zero either there was an error and a message
+       * has already been output (warning) or the size really is zero
+       * and we have nothing to do - the code will exit through the
+       * error case below.
+       */
+#if defined(PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED) || \
+    defined(PNG_USER_CHUNK_MALLOC_MAX)
+      else
 #endif
-         text_size=prefix_size;
-         if (text ==  NULL)
+      if (expanded_size > 0)
+      {
+         /* Success (maybe) - really uncompress the chunk. */
+         png_size_t new_size = 0;
+         png_charp text = png_malloc_warn(png_ptr,
+                        prefix_size + expanded_size + 1);
+
+         if (text != NULL)
          {
-            text = (png_charp)png_malloc_warn(png_ptr, text_size+1);
-            if (text == NULL)
-              {
-                png_free(png_ptr, chunkdata);
-                png_error(png_ptr,"Not enough memory for text.");
-              }
-            png_memcpy(text, chunkdata, prefix_size);
+            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+            new_size = png_inflate(png_ptr,
+                (png_bytep)(png_ptr->chunkdata + prefix_size),
+                chunklength - prefix_size,
+                (png_bytep)(text + prefix_size), expanded_size);
+            text[prefix_size + expanded_size] = 0; /* just in case */
+
+            if (new_size == expanded_size)
+            {
+               png_free(png_ptr, png_ptr->chunkdata);
+               png_ptr->chunkdata = text;
+               *newlength = prefix_size + expanded_size;
+               return; /* The success return! */
+            }
+
+            png_warning(png_ptr, "png_inflate logic error");
+            png_free(png_ptr, text);
          }
-         *(text + text_size) = 0x00;
+         else
+          png_warning(png_ptr, "Not enough memory to decompress chunk");
       }
-
-      inflateReset(&png_ptr->zstream);
-      png_ptr->zstream.avail_in = 0;
-
-      png_free(png_ptr, chunkdata);
-      chunkdata = text;
-      *newlength=text_size;
    }
+
    else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */
    {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
+#ifdef PNG_STDIO_SUPPORTED
       char umsg[50];
 
-      sprintf(umsg, "Unknown zTXt compression type %d", comp_type);
+      png_snprintf(umsg, sizeof umsg, "Unknown zTXt compression type %d",
+          comp_type);
       png_warning(png_ptr, umsg);
 #else
       png_warning(png_ptr, "Unknown zTXt compression type");
 #endif
 
-      *(chunkdata + prefix_size) = 0x00;
-      *newlength=prefix_size;
+      /* The recovery is to simply drop the data. */
    }
 
-   return chunkdata;
+   /* Generic error return - leave the prefix, delete the compressed
+    * data, reallocate the chunkdata to remove the potentially large
+    * amount of compressed data.
+    */
+   {
+      png_charp text = png_malloc_warn(png_ptr, prefix_size + 1);
+      if (text != NULL)
+      {
+         if (prefix_size > 0)
+            png_memcpy(text, png_ptr->chunkdata, prefix_size);
+         png_free(png_ptr, png_ptr->chunkdata);
+         png_ptr->chunkdata = text;
+
+         /* This is an extra zero in the 'uncompressed' part. */
+         *(png_ptr->chunkdata + prefix_size) = 0x00;
+      }
+      /* Ignore a malloc error here - it is safe. */
+   }
+
+   *newlength = prefix_size;
 }
 #endif
 
-/* read and check the IDHR chunk */
+/* Read and check the IDHR chunk */
 void /* PRIVATE */
 png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -340,12 +424,12 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    int bit_depth, color_type, compression_type, filter_type;
    int interlace_type;
 
-   png_debug(1, "in png_handle_IHDR\n");
+   png_debug(1, "in png_handle_IHDR");
 
    if (png_ptr->mode & PNG_HAVE_IHDR)
       png_error(png_ptr, "Out of place IHDR");
 
-   /* check the length */
+   /* Check the length */
    if (length != 13)
       png_error(png_ptr, "Invalid IHDR chunk");
 
@@ -362,66 +446,71 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    filter_type = buf[11];
    interlace_type = buf[12];
 
-   /* set internal variables */
+   /* Set internal variables */
    png_ptr->width = width;
    png_ptr->height = height;
    png_ptr->bit_depth = (png_byte)bit_depth;
    png_ptr->interlaced = (png_byte)interlace_type;
    png_ptr->color_type = (png_byte)color_type;
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
    png_ptr->filter_type = (png_byte)filter_type;
 #endif
    png_ptr->compression_type = (png_byte)compression_type;
 
-   /* find number of channels */
+   /* Find number of channels */
    switch (png_ptr->color_type)
    {
       case PNG_COLOR_TYPE_GRAY:
       case PNG_COLOR_TYPE_PALETTE:
          png_ptr->channels = 1;
          break;
+
       case PNG_COLOR_TYPE_RGB:
          png_ptr->channels = 3;
          break;
+
       case PNG_COLOR_TYPE_GRAY_ALPHA:
          png_ptr->channels = 2;
          break;
+
       case PNG_COLOR_TYPE_RGB_ALPHA:
          png_ptr->channels = 4;
          break;
    }
 
-   /* set up other useful info */
+   /* Set up other useful info */
    png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
    png_ptr->channels);
-   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth,png_ptr->width);
-   png_debug1(3,"bit_depth = %d\n", png_ptr->bit_depth);
-   png_debug1(3,"channels = %d\n", png_ptr->channels);
-   png_debug1(3,"rowbytes = %lu\n", png_ptr->rowbytes);
+   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
+   png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
+   png_debug1(3, "channels = %d", png_ptr->channels);
+   png_debug1(3, "rowbytes = %lu", png_ptr->rowbytes);
    png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
       color_type, interlace_type, compression_type, filter_type);
 }
 
-/* read and check the palette */
+/* Read and check the palette */
 void /* PRIVATE */
 png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_color palette[PNG_MAX_PALETTE_LENGTH];
    int num, i;
-#ifndef PNG_NO_POINTER_INDEXING
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
    png_colorp pal_ptr;
 #endif
 
-   png_debug(1, "in png_handle_PLTE\n");
+   png_debug(1, "in png_handle_PLTE");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before PLTE");
+
    else if (png_ptr->mode & PNG_HAVE_IDAT)
    {
       png_warning(png_ptr, "Invalid PLTE after IDAT");
       png_crc_finish(png_ptr, length);
       return;
    }
+
    else if (png_ptr->mode & PNG_HAVE_PLTE)
       png_error(png_ptr, "Duplicate PLTE chunk");
 
@@ -434,7 +523,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_crc_finish(png_ptr, length);
       return;
    }
-#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
    if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
    {
       png_crc_finish(png_ptr, length);
@@ -450,6 +539,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          png_crc_finish(png_ptr, length);
          return;
       }
+
       else
       {
          png_error(png_ptr, "Invalid palette chunk");
@@ -458,7 +548,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    num = (int)length / 3;
 
-#ifndef PNG_NO_POINTER_INDEXING
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
    for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
    {
       png_byte buf[3];
@@ -474,7 +564,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_byte buf[3];
 
       png_crc_read(png_ptr, buf, 3);
-      /* don't depend upon png_color being any order */
+      /* Don't depend upon png_color being any order */
       palette[i].red = buf[0];
       palette[i].green = buf[1];
       palette[i].blue = buf[2];
@@ -482,16 +572,17 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
 
    /* If we actually NEED the PLTE chunk (ie for a paletted image), we do
-      whatever the normal CRC configuration tells us.  However, if we
-      have an RGB image, the PLTE can be considered ancillary, so
-      we will act as though it is. */
-#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
+    * whatever the normal CRC configuration tells us.  However, if we
+    * have an RGB image, the PLTE can be considered ancillary, so
+    * we will act as though it is.
+    */
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 #endif
    {
       png_crc_finish(png_ptr, 0);
    }
-#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
    else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
    {
       /* If we don't want to use the data from an ancillary chunk,
@@ -502,7 +593,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       {
          if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
          {
-            png_chunk_error(png_ptr, "CRC error");
+            png_chunk_benign_error(png_ptr, "CRC error");
          }
          else
          {
@@ -520,7 +611,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_set_PLTE(png_ptr, info_ptr, palette, num);
 
-#if defined(PNG_READ_tRNS_SUPPORTED)
+#ifdef PNG_READ_tRNS_SUPPORTED
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
       if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
@@ -544,7 +635,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 void /* PRIVATE */
 png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_debug(1, "in png_handle_IEND\n");
+   png_debug(1, "in png_handle_IEND");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
    {
@@ -559,11 +650,10 @@ png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
    png_crc_finish(png_ptr, length);
 
-   if (&info_ptr == NULL) /* quiet compiler warnings about unused info_ptr */
-      return;
+   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
 }
 
-#if defined(PNG_READ_gAMA_SUPPORTED)
+#ifdef PNG_READ_gAMA_SUPPORTED
 void /* PRIVATE */
 png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -573,7 +663,7 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
    png_byte buf[4];
 
-   png_debug(1, "in png_handle_gAMA\n");
+   png_debug(1, "in png_handle_gAMA");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before gAMA");
@@ -588,7 +678,7 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_warning(png_ptr, "Out of place gAMA chunk");
 
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
-#if defined(PNG_READ_sRGB_SUPPORTED)
+#ifdef PNG_READ_sRGB_SUPPORTED
       && !(info_ptr->valid & PNG_INFO_sRGB)
 #endif
       )
@@ -610,7 +700,7 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
 
    igamma = (png_fixed_point)png_get_uint_32(buf);
-   /* check for zero gamma */
+   /* Check for zero gamma */
    if (igamma == 0)
       {
          png_warning(png_ptr,
@@ -618,14 +708,14 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          return;
       }
 
-#if defined(PNG_READ_sRGB_SUPPORTED)
-   if (info_ptr->valid & PNG_INFO_sRGB)
+#ifdef PNG_READ_sRGB_SUPPORTED
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
       if (PNG_OUT_OF_RANGE(igamma, 45500L, 500))
       {
          png_warning(png_ptr,
            "Ignoring incorrect gAMA value when sRGB is also present");
-#ifndef PNG_NO_CONSOLE_IO
-         fprintf(stderr, "gamma = (%d/100000)\n", (int)igamma);
+#ifdef PNG_CONSOLE_IO_SUPPORTED
+         fprintf(stderr, "gamma = (%d/100000)", (int)igamma);
 #endif
          return;
       }
@@ -644,14 +734,14 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif
 
-#if defined(PNG_READ_sBIT_SUPPORTED)
+#ifdef PNG_READ_sBIT_SUPPORTED
 void /* PRIVATE */
 png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_size_t truelen;
    png_byte buf[4];
 
-   png_debug(1, "in png_handle_sBIT\n");
+   png_debug(1, "in png_handle_sBIT");
 
    buf[0] = buf[1] = buf[2] = buf[3] = 0;
 
@@ -710,11 +800,11 @@ png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif
 
-#if defined(PNG_READ_cHRM_SUPPORTED)
+#ifdef PNG_READ_cHRM_SUPPORTED
 void /* PRIVATE */
 png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_byte buf[4];
+   png_byte buf[32];
 #ifdef PNG_FLOATING_POINT_SUPPORTED
    float white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y;
 #endif
@@ -723,7 +813,7 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_uint_32 uint_x, uint_y;
 
-   png_debug(1, "in png_handle_cHRM\n");
+   png_debug(1, "in png_handle_cHRM");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before cHRM");
@@ -738,7 +828,7 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_warning(png_ptr, "Missing PLTE before cHRM");
 
    if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)
-#if defined(PNG_READ_sRGB_SUPPORTED)
+#ifdef PNG_READ_sRGB_SUPPORTED
       && !(info_ptr->valid & PNG_INFO_sRGB)
 #endif
       )
@@ -755,67 +845,27 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   png_crc_read(png_ptr, buf, 4);
-   uint_x = png_get_uint_32(buf);
-
-   png_crc_read(png_ptr, buf, 4);
-   uint_y = png_get_uint_32(buf);
-
-   if (uint_x > 80000L || uint_y > 80000L ||
-      uint_x + uint_y > 100000L)
-   {
-      png_warning(png_ptr, "Invalid cHRM white point");
-      png_crc_finish(png_ptr, 24);
+   png_crc_read(png_ptr, buf, 32);
+   if (png_crc_finish(png_ptr, 0))
       return;
-   }
-   int_x_white = (png_fixed_point)uint_x;
-   int_y_white = (png_fixed_point)uint_y;
 
-   png_crc_read(png_ptr, buf, 4);
    uint_x = png_get_uint_32(buf);
+   uint_y = png_get_uint_32(buf + 4);
+   int_x_white = (png_fixed_point)uint_x;
+   int_y_white = (png_fixed_point)uint_y;
 
-   png_crc_read(png_ptr, buf, 4);
-   uint_y = png_get_uint_32(buf);
-
-   if (uint_x > 80000L || uint_y > 80000L ||
-      uint_x + uint_y > 100000L)
-   {
-      png_warning(png_ptr, "Invalid cHRM red point");
-      png_crc_finish(png_ptr, 16);
-      return;
-   }
+   uint_x = png_get_uint_32(buf + 8);
+   uint_y = png_get_uint_32(buf + 12);
    int_x_red = (png_fixed_point)uint_x;
    int_y_red = (png_fixed_point)uint_y;
 
-   png_crc_read(png_ptr, buf, 4);
-   uint_x = png_get_uint_32(buf);
-
-   png_crc_read(png_ptr, buf, 4);
-   uint_y = png_get_uint_32(buf);
-
-   if (uint_x > 80000L || uint_y > 80000L ||
-      uint_x + uint_y > 100000L)
-   {
-      png_warning(png_ptr, "Invalid cHRM green point");
-      png_crc_finish(png_ptr, 8);
-      return;
-   }
+   uint_x = png_get_uint_32(buf + 16);
+   uint_y = png_get_uint_32(buf + 20);
    int_x_green = (png_fixed_point)uint_x;
    int_y_green = (png_fixed_point)uint_y;
 
-   png_crc_read(png_ptr, buf, 4);
-   uint_x = png_get_uint_32(buf);
-
-   png_crc_read(png_ptr, buf, 4);
-   uint_y = png_get_uint_32(buf);
-
-   if (uint_x > 80000L || uint_y > 80000L ||
-      uint_x + uint_y > 100000L)
-   {
-      png_warning(png_ptr, "Invalid cHRM blue point");
-      png_crc_finish(png_ptr, 0);
-      return;
-   }
+   uint_x = png_get_uint_32(buf + 24);
+   uint_y = png_get_uint_32(buf + 28);
    int_x_blue = (png_fixed_point)uint_x;
    int_y_blue = (png_fixed_point)uint_y;
 
@@ -830,8 +880,8 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    blue_y  = (float)int_y_blue  / (float)100000.0;
 #endif
 
-#if defined(PNG_READ_sRGB_SUPPORTED)
-   if (info_ptr->valid & PNG_INFO_sRGB)
+#ifdef PNG_READ_sRGB_SUPPORTED
+   if ((info_ptr != NULL) && (info_ptr->valid & PNG_INFO_sRGB))
       {
       if (PNG_OUT_OF_RANGE(int_x_white, 31270,  1000) ||
           PNG_OUT_OF_RANGE(int_y_white, 32900,  1000) ||
@@ -842,24 +892,24 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
           PNG_OUT_OF_RANGE(int_x_blue,  15000,  1000) ||
           PNG_OUT_OF_RANGE(int_y_blue,   6000,  1000))
          {
-
             png_warning(png_ptr,
               "Ignoring incorrect cHRM value when sRGB is also present");
-#ifndef PNG_NO_CONSOLE_IO
+#ifdef PNG_CONSOLE_IO_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
-            fprintf(stderr,"wx=%f, wy=%f, rx=%f, ry=%f\n",
+            fprintf(stderr, "wx=%f, wy=%f, rx=%f, ry=%f\n",
                white_x, white_y, red_x, red_y);
-            fprintf(stderr,"gx=%f, gy=%f, bx=%f, by=%f\n",
+            fprintf(stderr, "gx=%f, gy=%f, bx=%f, by=%f\n",
                green_x, green_y, blue_x, blue_y);
 #else
-            fprintf(stderr,"wx=%ld, wy=%ld, rx=%ld, ry=%ld\n",
-               int_x_white, int_y_white, int_x_red, int_y_red);
-            fprintf(stderr,"gx=%ld, gy=%ld, bx=%ld, by=%ld\n",
-               int_x_green, int_y_green, int_x_blue, int_y_blue);
-#endif
-#endif /* PNG_NO_CONSOLE_IO */
+            fprintf(stderr, "wx=%ld, wy=%ld, rx=%ld, ry=%ld\n",
+               (long)int_x_white, (long)int_y_white,
+               (long)int_x_red, (long)int_y_red);
+            fprintf(stderr, "gx=%ld, gy=%ld, bx=%ld, by=%ld\n",
+               (long)int_x_green, (long)int_y_green,
+               (long)int_x_blue, (long)int_y_blue);
+#endif
+#endif /* PNG_CONSOLE_IO_SUPPORTED */
          }
-         png_crc_finish(png_ptr, 0);
          return;
       }
 #endif /* PNG_READ_sRGB_SUPPORTED */
@@ -873,19 +923,17 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       int_x_white, int_y_white, int_x_red, int_y_red, int_x_green,
       int_y_green, int_x_blue, int_y_blue);
 #endif
-   if (png_crc_finish(png_ptr, 0))
-      return;
 }
 #endif
 
-#if defined(PNG_READ_sRGB_SUPPORTED)
+#ifdef PNG_READ_sRGB_SUPPORTED
 void /* PRIVATE */
 png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    int intent;
    png_byte buf[1];
 
-   png_debug(1, "in png_handle_sRGB\n");
+   png_debug(1, "in png_handle_sRGB");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before sRGB");
@@ -918,7 +966,7 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
 
    intent = buf[0];
-   /* check for bad intent */
+   /* Check for bad intent */
    if (intent >= PNG_sRGB_INTENT_LAST)
    {
       png_warning(png_ptr, "Unknown sRGB intent");
@@ -926,7 +974,7 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
 #if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
-   if ((info_ptr->valid & PNG_INFO_gAMA))
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA))
    {
    png_fixed_point igamma;
 #ifdef PNG_FIXED_POINT_SUPPORTED
@@ -940,12 +988,13 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       {
          png_warning(png_ptr,
            "Ignoring incorrect gAMA value when sRGB is also present");
-#ifndef PNG_NO_CONSOLE_IO
+#ifdef PNG_CONSOLE_IO_SUPPORTED
 #  ifdef PNG_FIXED_POINT_SUPPORTED
-         fprintf(stderr,"incorrect gamma=(%d/100000)\n",(int)png_ptr->int_gamma);
+         fprintf(stderr, "incorrect gamma=(%d/100000)\n",
+            (int)png_ptr->int_gamma);
 #  else
 #    ifdef PNG_FLOATING_POINT_SUPPORTED
-         fprintf(stderr,"incorrect gamma=%f\n",png_ptr->gamma);
+         fprintf(stderr, "incorrect gamma=%f\n", png_ptr->gamma);
 #    endif
 #  endif
 #endif
@@ -955,7 +1004,7 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 #ifdef PNG_READ_cHRM_SUPPORTED
 #ifdef PNG_FIXED_POINT_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_cHRM)
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
       if (PNG_OUT_OF_RANGE(info_ptr->int_x_white, 31270,  1000) ||
           PNG_OUT_OF_RANGE(info_ptr->int_y_white, 32900,  1000) ||
           PNG_OUT_OF_RANGE(info_ptr->int_x_red,   64000L, 1000) ||
@@ -975,12 +1024,11 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif /* PNG_READ_sRGB_SUPPORTED */
 
-#if defined(PNG_READ_iCCP_SUPPORTED)
+#ifdef PNG_READ_iCCP_SUPPORTED
 void /* PRIVATE */
 png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 {
-   png_charp chunkdata;
    png_byte compression_type;
    png_bytep pC;
    png_charp profile;
@@ -988,7 +1036,7 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_uint_32 profile_size, profile_length;
    png_size_t slength, prefix_length, data_length;
 
-   png_debug(1, "in png_handle_iCCP\n");
+   png_debug(1, "in png_handle_iCCP");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before iCCP");
@@ -1018,93 +1066,129 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 #endif
 
-   chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
    slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)chunkdata, slength);
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, skip))
    {
-      png_free(png_ptr, chunkdata);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   chunkdata[slength] = 0x00;
+   png_ptr->chunkdata[slength] = 0x00;
 
-   for (profile = chunkdata; *profile; profile++)
-      /* empty loop to find end of name */ ;
+   for (profile = png_ptr->chunkdata; *profile; profile++)
+      /* Empty loop to find end of name */ ;
 
    ++profile;
 
-   /* there should be at least one zero (the compression type byte)
-      following the separator, and we should be on it  */
-   if ( profile >= chunkdata + slength)
+   /* There should be at least one zero (the compression type byte)
+    * following the separator, and we should be on it
+    */
+   if ( profile >= png_ptr->chunkdata + slength - 1)
    {
-      png_free(png_ptr, chunkdata);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "Malformed iCCP chunk");
       return;
    }
 
-   /* compression_type should always be zero */
+   /* Compression_type should always be zero */
    compression_type = *profile++;
    if (compression_type)
    {
       png_warning(png_ptr, "Ignoring nonzero compression type in iCCP chunk");
-      compression_type=0x00;  /* Reset it to zero (libpng-1.0.6 through 1.0.8
+      compression_type = 0x00;  /* Reset it to zero (libpng-1.0.6 through 1.0.8
                                  wrote nonzero) */
    }
 
-   prefix_length = profile - chunkdata;
-   chunkdata = png_decompress_chunk(png_ptr, compression_type, chunkdata,
-                                    slength, prefix_length, &data_length);
+   prefix_length = profile - png_ptr->chunkdata;
+   png_decompress_chunk(png_ptr, compression_type,
+     slength, prefix_length, &data_length);
 
    profile_length = data_length - prefix_length;
 
    if ( prefix_length > data_length || profile_length < 4)
    {
-      png_free(png_ptr, chunkdata);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "Profile size field missing from iCCP chunk");
       return;
    }
 
    /* Check the profile_size recorded in the first 32 bits of the ICC profile */
-   pC = (png_bytep)(chunkdata+prefix_length);
-   profile_size = ((*(pC  ))<<24) |
-                  ((*(pC+1))<<16) |
-                  ((*(pC+2))<< 8) |
-                  ((*(pC+3))    );
+   pC = (png_bytep)(png_ptr->chunkdata + prefix_length);
+   profile_size = ((*(pC    ))<<24) |
+                  ((*(pC + 1))<<16) |
+                  ((*(pC + 2))<< 8) |
+                  ((*(pC + 3))    );
 
-   if(profile_size < profile_length)
+   if (profile_size < profile_length)
       profile_length = profile_size;
 
-   if(profile_size > profile_length)
+   if (profile_size > profile_length)
    {
-      png_free(png_ptr, chunkdata);
-      png_warning(png_ptr, "Ignoring truncated iCCP profile.\n");
+#ifdef PNG_STDIO_SUPPORTED
+         char umsg[50];
+#endif
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_warning(png_ptr, "Ignoring truncated iCCP profile");
+#ifdef PNG_STDIO_SUPPORTED
+
+      png_snprintf(umsg, 50, "declared profile size = %lu",
+          (unsigned long)profile_size);
+      png_warning(png_ptr, umsg);
+      png_snprintf(umsg, 50, "actual profile length = %lu",
+          (unsigned long)profile_length);
+      png_warning(png_ptr, umsg);
+#endif
       return;
    }
 
-   png_set_iCCP(png_ptr, info_ptr, chunkdata, compression_type,
-                chunkdata + prefix_length, profile_length);
-   png_free(png_ptr, chunkdata);
+   png_set_iCCP(png_ptr, info_ptr, png_ptr->chunkdata,
+     compression_type, png_ptr->chunkdata + prefix_length, profile_length);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
 }
 #endif /* PNG_READ_iCCP_SUPPORTED */
 
-#if defined(PNG_READ_sPLT_SUPPORTED)
+#ifdef PNG_READ_sPLT_SUPPORTED
 void /* PRIVATE */
 png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 {
-   png_bytep chunkdata;
    png_bytep entry_start;
    png_sPLT_t new_palette;
-#ifdef PNG_NO_POINTER_INDEXING
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
    png_sPLT_entryp pp;
 #endif
    int data_length, entry_size, i;
    png_uint_32 skip = 0;
    png_size_t slength;
 
-   png_debug(1, "in png_handle_sPLT\n");
+   png_debug(1, "in png_handle_sPLT");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for sPLT");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before sPLT");
@@ -1124,45 +1208,50 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 #endif
 
-   chunkdata = (png_bytep)png_malloc(png_ptr, length + 1);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc(png_ptr, length + 1);
    slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)chunkdata, slength);
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, skip))
    {
-      png_free(png_ptr, chunkdata);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   chunkdata[slength] = 0x00;
+   png_ptr->chunkdata[slength] = 0x00;
 
-   for (entry_start = chunkdata; *entry_start; entry_start++)
-      /* empty loop to find end of name */ ;
+   for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start;
+       entry_start++)
+      /* Empty loop to find end of name */ ;
    ++entry_start;
 
-   /* a sample depth should follow the separator, and we should be on it  */
-   if (entry_start > chunkdata + slength)
+   /* A sample depth should follow the separator, and we should be on it  */
+   if (entry_start > (png_bytep)png_ptr->chunkdata + slength - 2)
    {
-      png_free(png_ptr, chunkdata);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "malformed sPLT chunk");
       return;
    }
 
    new_palette.depth = *entry_start++;
    entry_size = (new_palette.depth == 8 ? 6 : 10);
-   data_length = (slength - (entry_start - chunkdata));
+   data_length = (slength - (entry_start - (png_bytep)png_ptr->chunkdata));
 
-   /* integrity-check the data length */
+   /* Integrity-check the data length */
    if (data_length % entry_size)
    {
-      png_free(png_ptr, chunkdata);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       png_warning(png_ptr, "sPLT chunk has bad length");
       return;
    }
 
-   new_palette.nentries = (png_uint_32) (data_length / entry_size);
-   if ((png_uint_32) new_palette.nentries > (png_uint_32) (PNG_SIZE_MAX /
-       png_sizeof(png_sPLT_entry)))
+   new_palette.nentries = (png_int_32) ( data_length / entry_size);
+   if ((png_uint_32) new_palette.nentries >
+       (png_uint_32) (PNG_SIZE_MAX / png_sizeof(png_sPLT_entry)))
    {
        png_warning(png_ptr, "sPLT chunk too long");
        return;
@@ -1175,10 +1264,10 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
        return;
    }
 
-#ifndef PNG_NO_POINTER_INDEXING
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
    for (i = 0; i < new_palette.nentries; i++)
    {
-      png_sPLT_entryp pp = new_palette.entries + i;
+      pp = new_palette.entries + i;
 
       if (new_palette.depth == 8)
       {
@@ -1219,23 +1308,24 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 #endif
 
-   /* discard all chunk data except the name and stash that */
-   new_palette.name = (png_charp)chunkdata;
+   /* Discard all chunk data except the name and stash that */
+   new_palette.name = png_ptr->chunkdata;
 
    png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
 
-   png_free(png_ptr, chunkdata);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
    png_free(png_ptr, new_palette.entries);
 }
 #endif /* PNG_READ_sPLT_SUPPORTED */
 
-#if defined(PNG_READ_tRNS_SUPPORTED)
+#ifdef PNG_READ_tRNS_SUPPORTED
 void /* PRIVATE */
 png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
 
-   png_debug(1, "in png_handle_tRNS\n");
+   png_debug(1, "in png_handle_tRNS");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before tRNS");
@@ -1265,7 +1355,7 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
       png_crc_read(png_ptr, buf, 2);
       png_ptr->num_trans = 1;
-      png_ptr->trans_values.gray = png_get_uint_16(buf);
+      png_ptr->trans_color.gray = png_get_uint_16(buf);
    }
    else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
    {
@@ -1279,9 +1369,9 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       }
       png_crc_read(png_ptr, buf, (png_size_t)length);
       png_ptr->num_trans = 1;
-      png_ptr->trans_values.red = png_get_uint_16(buf);
-      png_ptr->trans_values.green = png_get_uint_16(buf + 2);
-      png_ptr->trans_values.blue = png_get_uint_16(buf + 4);
+      png_ptr->trans_color.red = png_get_uint_16(buf);
+      png_ptr->trans_color.green = png_get_uint_16(buf + 2);
+      png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
    }
    else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
@@ -1314,21 +1404,24 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    if (png_crc_finish(png_ptr, 0))
+   {
+      png_ptr->num_trans = 0;
       return;
+   }
 
    png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
-      &(png_ptr->trans_values));
+      &(png_ptr->trans_color));
 }
 #endif
 
-#if defined(PNG_READ_bKGD_SUPPORTED)
+#ifdef PNG_READ_bKGD_SUPPORTED
 void /* PRIVATE */
 png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_size_t truelen;
    png_byte buf[6];
 
-   png_debug(1, "in png_handle_bKGD\n");
+   png_debug(1, "in png_handle_bKGD");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before bKGD");
@@ -1377,9 +1470,9 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
    {
       png_ptr->background.index = buf[0];
-      if(info_ptr->num_palette)
+      if (info_ptr && info_ptr->num_palette)
       {
-          if(buf[0] > info_ptr->num_palette)
+          if (buf[0] >= info_ptr->num_palette)
           {
              png_warning(png_ptr, "Incorrect bKGD chunk index value");
              return;
@@ -1410,14 +1503,14 @@ png_handle_bKGD(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif
 
-#if defined(PNG_READ_hIST_SUPPORTED)
+#ifdef PNG_READ_hIST_SUPPORTED
 void /* PRIVATE */
 png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    unsigned int num, i;
    png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
 
-   png_debug(1, "in png_handle_hIST\n");
+   png_debug(1, "in png_handle_hIST");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before hIST");
@@ -1464,7 +1557,7 @@ png_handle_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif
 
-#if defined(PNG_READ_pHYs_SUPPORTED)
+#ifdef PNG_READ_pHYs_SUPPORTED
 void /* PRIVATE */
 png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -1472,7 +1565,7 @@ png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_uint_32 res_x, res_y;
    int unit_type;
 
-   png_debug(1, "in png_handle_pHYs\n");
+   png_debug(1, "in png_handle_pHYs");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before pHYs");
@@ -1507,7 +1600,7 @@ png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif
 
-#if defined(PNG_READ_oFFs_SUPPORTED)
+#ifdef PNG_READ_oFFs_SUPPORTED
 void /* PRIVATE */
 png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -1515,7 +1608,7 @@ png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_int_32 offset_x, offset_y;
    int unit_type;
 
-   png_debug(1, "in png_handle_oFFs\n");
+   png_debug(1, "in png_handle_oFFs");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before oFFs");
@@ -1550,12 +1643,11 @@ png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif
 
-#if defined(PNG_READ_pCAL_SUPPORTED)
-/* read the pCAL chunk (described in the PNG Extensions document) */
+#ifdef PNG_READ_pCAL_SUPPORTED
+/* Read the pCAL chunk (described in the PNG Extensions document) */
 void /* PRIVATE */
 png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_charp purpose;
    png_int_32 X0, X1;
    png_byte type, nparams;
    png_charp buf, units, endptr;
@@ -1563,7 +1655,7 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_size_t slength;
    int i;
 
-   png_debug(1, "in png_handle_pCAL\n");
+   png_debug(1, "in png_handle_pCAL");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before pCAL");
@@ -1580,48 +1672,51 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   png_debug1(2, "Allocating and reading pCAL chunk data (%lu bytes)\n",
+   png_debug1(2, "Allocating and reading pCAL chunk data (%lu bytes)",
       length + 1);
-   purpose = (png_charp)png_malloc_warn(png_ptr, length + 1);
-   if (purpose == NULL)
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
      {
-       png_warning(png_ptr, "No memory for pCAL purpose.");
+       png_warning(png_ptr, "No memory for pCAL purpose");
        return;
      }
    slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)purpose, slength);
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, 0))
    {
-      png_free(png_ptr, purpose);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   purpose[slength] = 0x00; /* null terminate the last string */
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
-   png_debug(3, "Finding end of pCAL purpose string\n");
-   for (buf = purpose; *buf; buf++)
-      /* empty loop */ ;
+   png_debug(3, "Finding end of pCAL purpose string");
+   for (buf = png_ptr->chunkdata; *buf; buf++)
+      /* Empty loop */ ;
 
-   endptr = purpose + slength;
+   endptr = png_ptr->chunkdata + slength;
 
    /* We need to have at least 12 bytes after the purpose string
       in order to get the parameter information. */
    if (endptr <= buf + 12)
    {
       png_warning(png_ptr, "Invalid pCAL data");
-      png_free(png_ptr, purpose);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   png_debug(3, "Reading pCAL X0, X1, type, nparams, and units\n");
+   png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
    X0 = png_get_int_32((png_bytep)buf+1);
    X1 = png_get_int_32((png_bytep)buf+5);
    type = buf[9];
    nparams = buf[10];
    units = buf + 11;
 
-   png_debug(3, "Checking pCAL equation type and number of parameters\n");
+   png_debug(3, "Checking pCAL equation type and number of parameters");
    /* Check that we have the right number of parameters for known
       equation types. */
    if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
@@ -1630,7 +1725,8 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
        (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
    {
       png_warning(png_ptr, "Invalid pCAL parameters for equation type");
-      png_free(png_ptr, purpose);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
    else if (type >= PNG_EQUATION_LAST)
@@ -1641,13 +1737,14 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    for (buf = units; *buf; buf++)
       /* Empty loop to move past the units string. */ ;
 
-   png_debug(3, "Allocating pCAL parameters array\n");
-   params = (png_charpp)png_malloc_warn(png_ptr, (png_uint_32)(nparams
-      *png_sizeof(png_charp))) ;
+   png_debug(3, "Allocating pCAL parameters array");
+   params = (png_charpp)png_malloc_warn(png_ptr,
+      (png_size_t)(nparams * png_sizeof(png_charp)));
    if (params == NULL)
      {
-       png_free(png_ptr, purpose);
-       png_warning(png_ptr, "No memory for pCAL params.");
+       png_free(png_ptr, png_ptr->chunkdata);
+       png_ptr->chunkdata = NULL;
+       png_warning(png_ptr, "No memory for pCAL params");
        return;
      }
 
@@ -1656,34 +1753,36 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    {
       buf++; /* Skip the null string terminator from previous parameter. */
 
-      png_debug1(3, "Reading pCAL parameter %d\n", i);
-      for (params[i] = buf; *buf != 0x00 && buf <= endptr; buf++)
+      png_debug1(3, "Reading pCAL parameter %d", i);
+      for (params[i] = buf; buf <= endptr && *buf != 0x00; buf++)
          /* Empty loop to move past each parameter string */ ;
 
       /* Make sure we haven't run out of data yet */
       if (buf > endptr)
       {
          png_warning(png_ptr, "Invalid pCAL data");
-         png_free(png_ptr, purpose);
+         png_free(png_ptr, png_ptr->chunkdata);
+         png_ptr->chunkdata = NULL;
          png_free(png_ptr, params);
          return;
       }
    }
 
-   png_set_pCAL(png_ptr, info_ptr, purpose, X0, X1, type, nparams,
+   png_set_pCAL(png_ptr, info_ptr, png_ptr->chunkdata, X0, X1, type, nparams,
       units, params);
 
-   png_free(png_ptr, purpose);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
    png_free(png_ptr, params);
 }
 #endif
 
-#if defined(PNG_READ_sCAL_SUPPORTED)
-/* read the sCAL chunk */
+#ifdef PNG_READ_sCAL_SUPPORTED
+/* Read the sCAL chunk */
 void /* PRIVATE */
 png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
-   png_charp buffer, ep;
+   png_charp ep;
 #ifdef PNG_FLOATING_POINT_SUPPORTED
    double width, height;
    png_charp vp;
@@ -1694,7 +1793,7 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
    png_size_t slength;
 
-   png_debug(1, "in png_handle_sCAL\n");
+   png_debug(1, "in png_handle_sCAL");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before sCAL");
@@ -1711,77 +1810,100 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   png_debug1(2, "Allocating and reading sCAL chunk data (%lu bytes)\n",
+   png_debug1(2, "Allocating and reading sCAL chunk data (%lu bytes)",
       length + 1);
-   buffer = (png_charp)png_malloc_warn(png_ptr, length + 1);
-   if (buffer == NULL)
-     {
-       png_warning(png_ptr, "Out of memory while processing sCAL chunk");
-       return;
-     }
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
+   {
+      png_warning(png_ptr, "Out of memory while processing sCAL chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
    slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)buffer, slength);
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, 0))
    {
-      png_free(png_ptr, buffer);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   buffer[slength] = 0x00; /* null terminate the last string */
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
-   ep = buffer + 1;        /* skip unit byte */
+   ep = png_ptr->chunkdata + 1;        /* Skip unit byte */
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
-   width = strtod(ep, &vp);
+   width = png_strtod(png_ptr, ep, &vp);
    if (*vp)
    {
-       png_warning(png_ptr, "malformed width string in sCAL chunk");
-       return;
+      png_warning(png_ptr, "malformed width string in sCAL chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
    }
 #else
 #ifdef PNG_FIXED_POINT_SUPPORTED
    swidth = (png_charp)png_malloc_warn(png_ptr, png_strlen(ep) + 1);
    if (swidth == NULL)
-     {
-       png_warning(png_ptr, "Out of memory while processing sCAL chunk width");
-       return;
-     }
-   png_memcpy(swidth, ep, (png_size_t)png_strlen(ep));
+   {
+      png_warning(png_ptr, "Out of memory while processing sCAL chunk width");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+   png_memcpy(swidth, ep, png_strlen(ep));
 #endif
 #endif
 
-   for (ep = buffer; *ep; ep++)
-      /* empty loop */ ;
+   for (ep = png_ptr->chunkdata; *ep; ep++)
+      /* Empty loop */ ;
    ep++;
 
+   if (png_ptr->chunkdata + slength < ep)
+   {
+      png_warning(png_ptr, "Truncated sCAL chunk");
+#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
+      png_free(png_ptr, swidth);
+#endif
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
+
 #ifdef PNG_FLOATING_POINT_SUPPORTED
-   height = strtod(ep, &vp);
+   height = png_strtod(png_ptr, ep, &vp);
    if (*vp)
    {
-       png_warning(png_ptr, "malformed height string in sCAL chunk");
-       return;
+      png_warning(png_ptr, "malformed height string in sCAL chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
    }
 #else
 #ifdef PNG_FIXED_POINT_SUPPORTED
    sheight = (png_charp)png_malloc_warn(png_ptr, png_strlen(ep) + 1);
-   if (swidth == NULL)
-     {
-       png_warning(png_ptr, "Out of memory while processing sCAL chunk height");
-       return;
-     }
-   png_memcpy(sheight, ep, (png_size_t)png_strlen(ep));
+   if (sheight == NULL)
+   {
+      png_warning(png_ptr, "Out of memory while processing sCAL chunk height");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      png_free(png_ptr, swidth);
+      return;
+   }
+   png_memcpy(sheight, ep, png_strlen(ep));
 #endif
 #endif
 
-   if (buffer + slength < ep
+   if (png_ptr->chunkdata + slength < ep
 #ifdef PNG_FLOATING_POINT_SUPPORTED
       || width <= 0. || height <= 0.
 #endif
       )
    {
       png_warning(png_ptr, "Invalid sCAL data");
-      png_free(png_ptr, buffer);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
 #if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
       png_free(png_ptr, swidth);
       png_free(png_ptr, sheight);
@@ -1791,14 +1913,15 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
-   png_set_sCAL(png_ptr, info_ptr, buffer[0], width, height);
+   png_set_sCAL(png_ptr, info_ptr, png_ptr->chunkdata[0], width, height);
 #else
 #ifdef PNG_FIXED_POINT_SUPPORTED
-   png_set_sCAL_s(png_ptr, info_ptr, buffer[0], swidth, sheight);
+   png_set_sCAL_s(png_ptr, info_ptr, png_ptr->chunkdata[0], swidth, sheight);
 #endif
 #endif
 
-   png_free(png_ptr, buffer);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
 #if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)
    png_free(png_ptr, swidth);
    png_free(png_ptr, sheight);
@@ -1806,14 +1929,14 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif
 
-#if defined(PNG_READ_tIME_SUPPORTED)
+#ifdef PNG_READ_tIME_SUPPORTED
 void /* PRIVATE */
 png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_byte buf[7];
    png_time mod_time;
 
-   png_debug(1, "in png_handle_tIME\n");
+   png_debug(1, "in png_handle_tIME");
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Out of place tIME chunk");
@@ -1849,7 +1972,7 @@ png_handle_tIME(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 }
 #endif
 
-#if defined(PNG_READ_tEXt_SUPPORTED)
+#ifdef PNG_READ_tEXt_SUPPORTED
 /* Note: this does not properly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
 png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
@@ -1861,7 +1984,24 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_size_t slength;
    int ret;
 
-   png_debug(1, "in png_handle_tEXt\n");
+   png_debug(1, "in png_handle_tEXt");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for tEXt");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before tEXt");
@@ -1878,35 +2018,41 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 #endif
 
-   key = (png_charp)png_malloc_warn(png_ptr, length + 1);
-   if (key == NULL)
+   png_free(png_ptr, png_ptr->chunkdata);
+
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
    {
-     png_warning(png_ptr, "No memory to process text chunk.");
+     png_warning(png_ptr, "No memory to process text chunk");
      return;
    }
    slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)key, slength);
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
 
    if (png_crc_finish(png_ptr, skip))
    {
-      png_free(png_ptr, key);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
+   key = png_ptr->chunkdata;
+
    key[slength] = 0x00;
 
    for (text = key; *text; text++)
-      /* empty loop to find end of key */ ;
+      /* Empty loop to find end of key */ ;
 
    if (text != key + slength)
       text++;
 
    text_ptr = (png_textp)png_malloc_warn(png_ptr,
-      (png_uint_32)png_sizeof(png_text));
+      png_sizeof(png_text));
    if (text_ptr == NULL)
    {
-     png_warning(png_ptr, "Not enough memory to process text chunk.");
-     png_free(png_ptr, key);
+     png_warning(png_ptr, "Not enough memory to process text chunk");
+     png_free(png_ptr, png_ptr->chunkdata);
+     png_ptr->chunkdata = NULL;
      return;
    }
    text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
@@ -1919,28 +2065,46 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    text_ptr->text = text;
    text_ptr->text_length = png_strlen(text);
 
-   ret=png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
 
-   png_free(png_ptr, key);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
    png_free(png_ptr, text_ptr);
    if (ret)
-     png_warning(png_ptr, "Insufficient memory to process text chunk.");
+     png_warning(png_ptr, "Insufficient memory to process text chunk");
 }
 #endif
 
-#if defined(PNG_READ_zTXt_SUPPORTED)
-/* note: this does not correctly handle chunks that are > 64K under DOS */
+#ifdef PNG_READ_zTXt_SUPPORTED
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
 png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_textp text_ptr;
-   png_charp chunkdata;
    png_charp text;
    int comp_type;
    int ret;
    png_size_t slength, prefix_len, data_len;
 
-   png_debug(1, "in png_handle_zTXt\n");
+   png_debug(1, "in png_handle_zTXt");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for zTXt");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
+
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before zTXt");
 
@@ -1952,36 +2116,40 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       there is no hard and fast rule to tell us where to stop. */
    if (length > (png_uint_32)65535L)
    {
-     png_warning(png_ptr,"zTXt chunk too large to fit in memory");
+     png_warning(png_ptr, "zTXt chunk too large to fit in memory");
      png_crc_finish(png_ptr, length);
      return;
    }
 #endif
 
-   chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
-   if (chunkdata == NULL)
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
    {
-     png_warning(png_ptr,"Out of memory processing zTXt chunk.");
+     png_warning(png_ptr, "Out of memory processing zTXt chunk");
      return;
    }
    slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)chunkdata, slength);
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
    if (png_crc_finish(png_ptr, 0))
    {
-      png_free(png_ptr, chunkdata);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   chunkdata[slength] = 0x00;
+   png_ptr->chunkdata[slength] = 0x00;
 
-   for (text = chunkdata; *text; text++)
-      /* empty loop */ ;
+   for (text = png_ptr->chunkdata; *text; text++)
+      /* Empty loop */ ;
 
    /* zTXt must have some text after the chunkdataword */
-   if (text == chunkdata + slength)
+   if (text >= png_ptr->chunkdata + slength - 2)
    {
-      comp_type = PNG_TEXT_COMPRESSION_NONE;
-      png_warning(png_ptr, "Zero length zTXt chunk");
+      png_warning(png_ptr, "Truncated zTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
    }
    else
    {
@@ -1991,54 +2159,72 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
           png_warning(png_ptr, "Unknown compression type in zTXt chunk");
           comp_type = PNG_TEXT_COMPRESSION_zTXt;
        }
-       text++;        /* skip the compression_method byte */
+       text++;        /* Skip the compression_method byte */
    }
-   prefix_len = text - chunkdata;
+   prefix_len = text - png_ptr->chunkdata;
 
-   chunkdata = (png_charp)png_decompress_chunk(png_ptr, comp_type, chunkdata,
-                                    (png_size_t)length, prefix_len, &data_len);
+   png_decompress_chunk(png_ptr, comp_type,
+     (png_size_t)length, prefix_len, &data_len);
 
    text_ptr = (png_textp)png_malloc_warn(png_ptr,
-     (png_uint_32)png_sizeof(png_text));
+      png_sizeof(png_text));
    if (text_ptr == NULL)
    {
-     png_warning(png_ptr,"Not enough memory to process zTXt chunk.");
-     png_free(png_ptr, chunkdata);
+     png_warning(png_ptr, "Not enough memory to process zTXt chunk");
+     png_free(png_ptr, png_ptr->chunkdata);
+     png_ptr->chunkdata = NULL;
      return;
    }
    text_ptr->compression = comp_type;
-   text_ptr->key = chunkdata;
+   text_ptr->key = png_ptr->chunkdata;
 #ifdef PNG_iTXt_SUPPORTED
    text_ptr->lang = NULL;
    text_ptr->lang_key = NULL;
    text_ptr->itxt_length = 0;
 #endif
-   text_ptr->text = chunkdata + prefix_len;
+   text_ptr->text = png_ptr->chunkdata + prefix_len;
    text_ptr->text_length = data_len;
 
-   ret=png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
 
    png_free(png_ptr, text_ptr);
-   png_free(png_ptr, chunkdata);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
    if (ret)
-     png_error(png_ptr, "Insufficient memory to store zTXt chunk.");
+     png_error(png_ptr, "Insufficient memory to store zTXt chunk");
 }
 #endif
 
-#if defined(PNG_READ_iTXt_SUPPORTED)
-/* note: this does not correctly handle chunks that are > 64K under DOS */
+#ifdef PNG_READ_iTXt_SUPPORTED
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
 png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_textp text_ptr;
-   png_charp chunkdata;
    png_charp key, lang, text, lang_key;
    int comp_flag;
    int comp_type = 0;
    int ret;
    png_size_t slength, prefix_len, data_len;
 
-   png_debug(1, "in png_handle_iTXt\n");
+   png_debug(1, "in png_handle_iTXt");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for iTXt");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
 
    if (!(png_ptr->mode & PNG_HAVE_IHDR))
       png_error(png_ptr, "Missing IHDR before iTXt");
@@ -2051,40 +2237,45 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       there is no hard and fast rule to tell us where to stop. */
    if (length > (png_uint_32)65535L)
    {
-     png_warning(png_ptr,"iTXt chunk too large to fit in memory");
+     png_warning(png_ptr, "iTXt chunk too large to fit in memory");
      png_crc_finish(png_ptr, length);
      return;
    }
 #endif
 
-   chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
-   if (chunkdata == NULL)
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = (png_charp)png_malloc_warn(png_ptr, length + 1);
+   if (png_ptr->chunkdata == NULL)
    {
-     png_warning(png_ptr, "No memory to process iTXt chunk.");
+     png_warning(png_ptr, "No memory to process iTXt chunk");
      return;
    }
    slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)chunkdata, slength);
+   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
    if (png_crc_finish(png_ptr, 0))
    {
-      png_free(png_ptr, chunkdata);
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
       return;
    }
 
-   chunkdata[slength] = 0x00;
+   png_ptr->chunkdata[slength] = 0x00;
 
-   for (lang = chunkdata; *lang; lang++)
-      /* empty loop */ ;
-   lang++;        /* skip NUL separator */
+   for (lang = png_ptr->chunkdata; *lang; lang++)
+      /* Empty loop */ ;
+   lang++;        /* Skip NUL separator */
 
    /* iTXt must have a language tag (possibly empty), two compression bytes,
-      translated keyword (possibly empty), and possibly some text after the
-      keyword */
+    * translated keyword (possibly empty), and possibly some text after the
+    * keyword
+    */
 
-   if (lang >= chunkdata + slength)
+   if (lang >= png_ptr->chunkdata + slength - 3)
    {
-      comp_flag = PNG_TEXT_COMPRESSION_NONE;
-      png_warning(png_ptr, "Zero length iTXt chunk");
+      png_warning(png_ptr, "Truncated iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
    }
    else
    {
@@ -2093,43 +2284,60 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    for (lang_key = lang; *lang_key; lang_key++)
-      /* empty loop */ ;
-   lang_key++;        /* skip NUL separator */
+      /* Empty loop */ ;
+   lang_key++;        /* Skip NUL separator */
+
+   if (lang_key >= png_ptr->chunkdata + slength)
+   {
+      png_warning(png_ptr, "Truncated iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
 
    for (text = lang_key; *text; text++)
-      /* empty loop */ ;
-   text++;        /* skip NUL separator */
+      /* Empty loop */ ;
+   text++;        /* Skip NUL separator */
+   if (text >= png_ptr->chunkdata + slength)
+   {
+      png_warning(png_ptr, "Malformed iTXt chunk");
+      png_free(png_ptr, png_ptr->chunkdata);
+      png_ptr->chunkdata = NULL;
+      return;
+   }
 
-   prefix_len = text - chunkdata;
+   prefix_len = text - png_ptr->chunkdata;
 
-   key=chunkdata;
+   key=png_ptr->chunkdata;
    if (comp_flag)
-       chunkdata = png_decompress_chunk(png_ptr, comp_type, chunkdata,
-          (size_t)length, prefix_len, &data_len);
+       png_decompress_chunk(png_ptr, comp_type,
+         (size_t)length, prefix_len, &data_len);
    else
-       data_len=png_strlen(chunkdata + prefix_len);
+       data_len = png_strlen(png_ptr->chunkdata + prefix_len);
    text_ptr = (png_textp)png_malloc_warn(png_ptr,
-      (png_uint_32)png_sizeof(png_text));
+      png_sizeof(png_text));
    if (text_ptr == NULL)
    {
-     png_warning(png_ptr,"Not enough memory to process iTXt chunk.");
-     png_free(png_ptr, chunkdata);
+     png_warning(png_ptr, "Not enough memory to process iTXt chunk");
+     png_free(png_ptr, png_ptr->chunkdata);
+     png_ptr->chunkdata = NULL;
      return;
    }
    text_ptr->compression = (int)comp_flag + 1;
-   text_ptr->lang_key = chunkdata+(lang_key-key);
-   text_ptr->lang = chunkdata+(lang-key);
+   text_ptr->lang_key = png_ptr->chunkdata + (lang_key - key);
+   text_ptr->lang = png_ptr->chunkdata + (lang - key);
    text_ptr->itxt_length = data_len;
    text_ptr->text_length = 0;
-   text_ptr->key = chunkdata;
-   text_ptr->text = chunkdata + prefix_len;
+   text_ptr->key = png_ptr->chunkdata;
+   text_ptr->text = png_ptr->chunkdata + prefix_len;
 
-   ret=png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
+   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
 
    png_free(png_ptr, text_ptr);
-   png_free(png_ptr, chunkdata);
+   png_free(png_ptr, png_ptr->chunkdata);
+   png_ptr->chunkdata = NULL;
    if (ret)
-     png_error(png_ptr, "Insufficient memory to store iTXt chunk.");
+     png_error(png_ptr, "Insufficient memory to store iTXt chunk");
 }
 #endif
 
@@ -2143,25 +2351,38 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
    png_uint_32 skip = 0;
 
-   png_debug(1, "in png_handle_unknown\n");
+   png_debug(1, "in png_handle_unknown");
+
+#ifdef PNG_USER_LIMITS_SUPPORTED
+   if (png_ptr->user_chunk_cache_max != 0)
+   {
+      if (png_ptr->user_chunk_cache_max == 1)
+      {
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+      if (--png_ptr->user_chunk_cache_max == 1)
+      {
+         png_warning(png_ptr, "No space in chunk cache for unknown chunk");
+         png_crc_finish(png_ptr, length);
+         return;
+      }
+   }
+#endif
 
    if (png_ptr->mode & PNG_HAVE_IDAT)
    {
-#ifdef PNG_USE_LOCAL_ARRAYS
       PNG_IDAT;
-#endif
-      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))  /* not an IDAT */
+      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))  /* Not an IDAT */
          png_ptr->mode |= PNG_AFTER_IDAT;
    }
 
-   png_check_chunk_name(png_ptr, png_ptr->chunk_name);
-
    if (!(png_ptr->chunk_name[0] & 0x20))
    {
-#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
-      if(png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+      if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
            PNG_HANDLE_CHUNK_ALWAYS
-#if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
            && png_ptr->read_user_chunk_fn == NULL
 #endif
         )
@@ -2169,11 +2390,13 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
           png_chunk_error(png_ptr, "unknown critical chunk");
    }
 
-#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
-   if (png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+   if ((png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+       || (png_ptr->read_user_chunk_fn != NULL)
+#endif
+        )
    {
-       png_unknown_chunk chunk;
-
 #ifdef PNG_MAX_MALLOC_64K
        if (length > (png_uint_32)65535L)
        {
@@ -2182,30 +2405,45 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
            length = (png_uint_32)65535L;
        }
 #endif
-       png_strcpy((png_charp)chunk.name, (png_charp)png_ptr->chunk_name);
-       chunk.data = (png_bytep)png_malloc(png_ptr, length);
-       chunk.size = (png_size_t)length;
-       png_crc_read(png_ptr, (png_bytep)chunk.data, length);
-#if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
-       if(png_ptr->read_user_chunk_fn != NULL)
+       png_memcpy((png_charp)png_ptr->unknown_chunk.name,
+                  (png_charp)png_ptr->chunk_name,
+                  png_sizeof(png_ptr->unknown_chunk.name));
+       png_ptr->unknown_chunk.name[png_sizeof(png_ptr->unknown_chunk.name)-1]
+           = '\0';
+       png_ptr->unknown_chunk.size = (png_size_t)length;
+       if (length == 0)
+         png_ptr->unknown_chunk.data = NULL;
+       else
+       {
+         png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr, length);
+         png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, length);
+       }
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+       if (png_ptr->read_user_chunk_fn != NULL)
        {
-          /* callback to user unknown chunk handler */
-          if ((*(png_ptr->read_user_chunk_fn)) (png_ptr, &chunk) <= 0)
+          /* Callback to user unknown chunk handler */
+          int ret;
+          ret = (*(png_ptr->read_user_chunk_fn))
+            (png_ptr, &png_ptr->unknown_chunk);
+          if (ret < 0)
+             png_chunk_error(png_ptr, "error in user chunk");
+          if (ret == 0)
           {
              if (!(png_ptr->chunk_name[0] & 0x20))
-                if(png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+                if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
                      PNG_HANDLE_CHUNK_ALWAYS)
-                 {
-                   png_free(png_ptr, chunk.data);
+#endif
                    png_chunk_error(png_ptr, "unknown critical chunk");
-                 }
-             png_set_unknown_chunks(png_ptr, info_ptr, &chunk, 1);
+             png_set_unknown_chunks(png_ptr, info_ptr,
+               &png_ptr->unknown_chunk, 1);
           }
        }
        else
 #endif
-          png_set_unknown_chunks(png_ptr, info_ptr, &chunk, 1);
-       png_free(png_ptr, chunk.data);
+       png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
+       png_free(png_ptr, png_ptr->unknown_chunk.data);
+       png_ptr->unknown_chunk.data = NULL;
    }
    else
 #endif
@@ -2213,9 +2451,8 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    png_crc_finish(png_ptr, skip);
 
-#if !defined(PNG_READ_USER_CHUNKS_SUPPORTED)
-   if (&info_ptr == NULL) /* quiet compiler warnings about unused info_ptr */
-      return;
+#ifndef PNG_READ_USER_CHUNKS_SUPPORTED
+   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
 #endif
 }
 
@@ -2230,7 +2467,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 void /* PRIVATE */
 png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
 {
-   png_debug(1, "in png_check_chunk_name\n");
+   png_debug(1, "in png_check_chunk_name");
    if (isnonalpha(chunk_name[0]) || isnonalpha(chunk_name[1]) ||
        isnonalpha(chunk_name[2]) || isnonalpha(chunk_name[3]))
    {
@@ -2248,11 +2485,11 @@ png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
    a zero indicates the pixel is to be skipped.  This is in addition
    to any alpha or transparency value associated with the pixel.  If
    you want all pixels to be combined, pass 0xff (255) in mask.  */
-#ifndef PNG_HAVE_ASSEMBLER_COMBINE_ROW
+
 void /* PRIVATE */
 png_combine_row(png_structp png_ptr, png_bytep row, int mask)
 {
-   png_debug(1,"in png_combine_row\n");
+   png_debug(1, "in png_combine_row");
    if (mask == 0xff)
    {
       png_memcpy(row, png_ptr->row_buf + 1,
@@ -2272,7 +2509,7 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
             png_uint_32 i;
             png_uint_32 row_width = png_ptr->width;
 
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (png_ptr->transformations & PNG_PACKSWAP)
             {
                 s_start = 0;
@@ -2327,7 +2564,7 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
             png_uint_32 row_width = png_ptr->width;
             int value;
 
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (png_ptr->transformations & PNG_PACKSWAP)
             {
                s_start = 0;
@@ -2379,7 +2616,7 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
             png_uint_32 row_width = png_ptr->width;
             int value;
 
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (png_ptr->transformations & PNG_PACKSWAP)
             {
                s_start = 0;
@@ -2449,10 +2686,8 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
       }
    }
 }
-#endif /* !PNG_HAVE_ASSEMBLER_COMBINE_ROW */
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-#ifndef PNG_HAVE_ASSEMBLER_READ_INTERLACE   /* else in pngvcrd.c, pnggccrd.c */
 /* OLD pre-1.0.9 interface:
 void png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
    png_uint_32 transformations)
@@ -2464,13 +2699,11 @@ png_do_read_interlace(png_structp png_ptr)
    png_bytep row = png_ptr->row_buf + 1;
    int pass = png_ptr->pass;
    png_uint_32 transformations = png_ptr->transformations;
-#ifdef PNG_USE_LOCAL_ARRAYS
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
-   /* offset to next interlace block */
-   const int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
-#endif
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+   /* Offset to next interlace block */
+   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
-   png_debug(1,"in png_do_read_interlace (stock C version)\n");
+   png_debug(1, "in png_do_read_interlace");
    if (row != NULL && row_info != NULL)
    {
       png_uint_32 final_width;
@@ -2490,7 +2723,7 @@ png_do_read_interlace(png_structp png_ptr)
             png_uint_32 i;
             int j;
 
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (transformations & PNG_PACKSWAP)
             {
                 sshift = (int)((row_info->width + 7) & 0x07);
@@ -2543,7 +2776,7 @@ png_do_read_interlace(png_structp png_ptr)
             int jstop = png_pass_inc[pass];
             png_uint_32 i;
 
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (transformations & PNG_PACKSWAP)
             {
                sshift = (int)(((row_info->width + 3) & 0x03) << 1);
@@ -2599,7 +2832,7 @@ png_do_read_interlace(png_structp png_ptr)
             png_uint_32 i;
             int jstop = png_pass_inc[pass];
 
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
             if (transformations & PNG_PACKSWAP)
             {
                sshift = (int)(((row_info->width + 1) & 0x01) << 2);
@@ -2648,7 +2881,8 @@ png_do_read_interlace(png_structp png_ptr)
          default:
          {
             png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
-            png_bytep sp = row + (png_size_t)(row_info->width - 1) * pixel_bytes;
+            png_bytep sp = row + (png_size_t)(row_info->width - 1)
+                * pixel_bytes;
             png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
 
             int jstop = png_pass_inc[pass];
@@ -2671,23 +2905,20 @@ png_do_read_interlace(png_structp png_ptr)
          }
       }
       row_info->width = final_width;
-      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,final_width);
+      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
    }
-#if !defined(PNG_READ_PACKSWAP_SUPPORTED)
-   if (&transformations == NULL) /* silence compiler warning */
-      return;
+#ifndef PNG_READ_PACKSWAP_SUPPORTED
+   transformations = transformations; /* Silence compiler warning */
 #endif
 }
-#endif /* !PNG_HAVE_ASSEMBLER_READ_INTERLACE */
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 
-#ifndef PNG_HAVE_ASSEMBLER_READ_FILTER_ROW
 void /* PRIVATE */
 png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
    png_bytep prev_row, int filter)
 {
-   png_debug(1, "in png_read_filter_row\n");
-   png_debug2(2,"row = %lu, filter = %d\n", png_ptr->row_number, filter);
+   png_debug(1, "in png_read_filter_row");
+   png_debug2(2, "row = %lu, filter = %d", png_ptr->row_number, filter);
    switch (filter)
    {
       case PNG_FILTER_VALUE_NONE:
@@ -2761,7 +2992,7 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
             rp++;
          }
 
-         for (i = 0; i < istop; i++)   /* use leftover rp,pp */
+         for (i = 0; i < istop; i++)   /* Use leftover rp,pp */
          {
             int a, b, c, pa, pb, pc, p;
 
@@ -2791,7 +3022,7 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
                   p = c;
              */
 
-            p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
+            p = (pa <= pb && pa <= pc) ? a : (pb <= pc) ? b : c;
 
             *rp = (png_byte)(((int)(*rp) + p) & 0xff);
             rp++;
@@ -2800,40 +3031,42 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
       }
       default:
          png_warning(png_ptr, "Ignoring bad adaptive filter type");
-         *row=0;
+         *row = 0;
          break;
    }
 }
-#endif /* !PNG_HAVE_ASSEMBLER_READ_FILTER_ROW */
 
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 void /* PRIVATE */
 png_read_finish_row(png_structp png_ptr)
 {
-#ifdef PNG_USE_LOCAL_ARRAYS
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
-   /* start of interlace block */
-   const int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   /* Start of interlace block */
+   PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
-   /* offset to next interlace block */
-   const int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   /* Offset to next interlace block */
+   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
-   /* start of interlace block in the y direction */
-   const int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   /* Start of interlace block in the y direction */
+   PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
-   /* offset to next interlace block in the y direction */
-   const int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
-#endif
+   /* Offset to next interlace block in the y direction */
+   PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
 
-   png_debug(1, "in png_read_finish_row\n");
+   png_debug(1, "in png_read_finish_row");
    png_ptr->row_number++;
    if (png_ptr->row_number < png_ptr->num_rows)
       return;
 
+#ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
       png_ptr->row_number = 0;
-      png_memset_check(png_ptr, png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+      png_memset(png_ptr->prev_row, 0,
+         png_ptr->rowbytes + 1);
       do
       {
          png_ptr->pass++;
@@ -2844,9 +3077,6 @@ png_read_finish_row(png_structp png_ptr)
             png_pass_start[png_ptr->pass]) /
             png_pass_inc[png_ptr->pass];
 
-         png_ptr->irowbytes = PNG_ROWBYTES(png_ptr->pixel_depth,
-            png_ptr->iwidth) + 1;
-
          if (!(png_ptr->transformations & PNG_INTERLACE))
          {
             png_ptr->num_rows = (png_ptr->height +
@@ -2863,18 +3093,17 @@ png_read_finish_row(png_structp png_ptr)
       if (png_ptr->pass < 7)
          return;
    }
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
 
    if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
    {
-#ifdef PNG_USE_LOCAL_ARRAYS
       PNG_IDAT;
-#endif
       char extra;
       int ret;
 
       png_ptr->zstream.next_out = (Byte *)&extra;
       png_ptr->zstream.avail_out = (uInt)1;
-      for(;;)
+      for (;;)
       {
          if (!(png_ptr->zstream.avail_in))
          {
@@ -2888,7 +3117,7 @@ png_read_finish_row(png_structp png_ptr)
                png_ptr->idat_size = png_get_uint_31(png_ptr, chunk_length);
                png_reset_crc(png_ptr);
                png_crc_read(png_ptr, png_ptr->chunk_name, 4);
-               if (png_memcmp(png_ptr->chunk_name, (png_bytep)png_IDAT, 4))
+               if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
                   png_error(png_ptr, "Not enough image data");
 
             }
@@ -2915,7 +3144,7 @@ png_read_finish_row(png_structp png_ptr)
 
          if (!(png_ptr->zstream.avail_out))
          {
-            png_warning(png_ptr, "Extra compressed data.");
+            png_warning(png_ptr, "Extra compressed data");
             png_ptr->mode |= PNG_AFTER_IDAT;
             png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
             break;
@@ -2932,32 +3161,34 @@ png_read_finish_row(png_structp png_ptr)
 
    png_ptr->mode |= PNG_AFTER_IDAT;
 }
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
 
 void /* PRIVATE */
 png_read_start_row(png_structp png_ptr)
 {
-#ifdef PNG_USE_LOCAL_ARRAYS
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
-   /* start of interlace block */
-   const int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   /* Start of interlace block */
+   PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
-   /* offset to next interlace block */
-   const int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   /* Offset to next interlace block */
+   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
-   /* start of interlace block in the y direction */
-   const int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   /* Start of interlace block in the y direction */
+   PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
-   /* offset to next interlace block in the y direction */
-   const int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   /* Offset to next interlace block in the y direction */
+   PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
 
    int max_pixel_depth;
-   png_uint_32 row_bytes;
+   png_size_t row_bytes;
 
-   png_debug(1, "in png_read_start_row\n");
+   png_debug(1, "in png_read_start_row");
    png_ptr->zstream.avail_in = 0;
    png_init_read_transformations(png_ptr);
+#ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
       if (!(png_ptr->transformations & PNG_INTERLACE))
@@ -2970,27 +3201,21 @@ png_read_start_row(png_structp png_ptr)
          png_pass_inc[png_ptr->pass] - 1 -
          png_pass_start[png_ptr->pass]) /
          png_pass_inc[png_ptr->pass];
-
-         row_bytes = PNG_ROWBYTES(png_ptr->pixel_depth,png_ptr->iwidth) + 1;
-
-         png_ptr->irowbytes = (png_size_t)row_bytes;
-         if((png_uint_32)png_ptr->irowbytes != row_bytes)
-            png_error(png_ptr, "Rowbytes overflow in png_read_start_row");
    }
    else
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
    {
       png_ptr->num_rows = png_ptr->height;
       png_ptr->iwidth = png_ptr->width;
-      png_ptr->irowbytes = png_ptr->rowbytes + 1;
    }
    max_pixel_depth = png_ptr->pixel_depth;
 
-#if defined(PNG_READ_PACK_SUPPORTED)
+#ifdef PNG_READ_PACK_SUPPORTED
    if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
       max_pixel_depth = 8;
 #endif
 
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
    if (png_ptr->transformations & PNG_EXPAND)
    {
       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
@@ -3018,7 +3243,7 @@ png_read_start_row(png_structp png_ptr)
    }
 #endif
 
-#if defined(PNG_READ_FILLER_SUPPORTED)
+#ifdef PNG_READ_FILLER_SUPPORTED
    if (png_ptr->transformations & (PNG_FILLER))
    {
       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
@@ -3040,14 +3265,14 @@ png_read_start_row(png_structp png_ptr)
    }
 #endif
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    if (png_ptr->transformations & PNG_GRAY_TO_RGB)
    {
       if (
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
         (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
 #endif
-#if defined(PNG_READ_FILLER_SUPPORTED)
+#ifdef PNG_READ_FILLER_SUPPORTED
         (png_ptr->transformations & (PNG_FILLER)) ||
 #endif
         png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
@@ -3076,49 +3301,79 @@ png_read_start_row(png_structp png_ptr)
 
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
-   if(png_ptr->transformations & PNG_USER_TRANSFORM)
+   if (png_ptr->transformations & PNG_USER_TRANSFORM)
      {
-       int user_pixel_depth=png_ptr->user_transform_depth*
+       int user_pixel_depth = png_ptr->user_transform_depth*
          png_ptr->user_transform_channels;
-       if(user_pixel_depth > max_pixel_depth)
+       if (user_pixel_depth > max_pixel_depth)
          max_pixel_depth=user_pixel_depth;
      }
 #endif
 
-   /* align the width on the next larger 8 pixels.  Mainly used
-      for interlacing */
+   /* Align the width on the next larger 8 pixels.  Mainly used
+    * for interlacing
+    */
    row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
-   /* calculate the maximum bytes needed, adding a byte and a pixel
-      for safety's sake */
-   row_bytes = PNG_ROWBYTES(max_pixel_depth,row_bytes) +
+   /* Calculate the maximum bytes needed, adding a byte and a pixel
+    * for safety's sake
+    */
+   row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
       1 + ((max_pixel_depth + 7) >> 3);
 #ifdef PNG_MAX_MALLOC_64K
    if (row_bytes > (png_uint_32)65536L)
       png_error(png_ptr, "This image requires a row greater than 64KB");
 #endif
-   png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes+64);
-   png_ptr->row_buf = png_ptr->big_row_buf+32;
-#if defined(PNG_DEBUG) && defined(PNG_USE_PNGGCCRD)
-   png_ptr->row_buf_size = row_bytes;
+
+   if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
+   {
+     png_free(png_ptr, png_ptr->big_row_buf);
+     if (png_ptr->interlaced)
+        png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
+            row_bytes + 48);
+     else
+        png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr,
+            row_bytes + 48);
+     png_ptr->old_big_row_buf_size = row_bytes + 48;
+
+#ifdef PNG_ALIGNED_MEMORY_SUPPORTED
+     /* Use 16-byte aligned memory for row_buf with at least 16 bytes
+      * of padding before and after row_buf.
+      */
+     png_ptr->row_buf = png_ptr->big_row_buf + 32
+         - (((png_alloc_size_t)&(png_ptr->big_row_buf[0]) + 15) % 16);
+     png_ptr->old_big_row_buf_size = row_bytes + 48;
+#else
+     /* Use 32 bytes of padding before and 16 bytes after row_buf. */
+     png_ptr->row_buf = png_ptr->big_row_buf + 32;
 #endif
+     png_ptr->old_big_row_buf_size = row_bytes + 48;
+   }
 
 #ifdef PNG_MAX_MALLOC_64K
    if ((png_uint_32)png_ptr->rowbytes + 1 > (png_uint_32)65536L)
       png_error(png_ptr, "This image requires a row greater than 64KB");
 #endif
-   if ((png_uint_32)png_ptr->rowbytes + 1 > PNG_SIZE_MAX)
-      png_error(png_ptr, "Row has too many bytes to allocate in memory.");
-   png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)(
-      png_ptr->rowbytes + 1));
+   if ((png_uint_32)png_ptr->rowbytes > (png_uint_32)(PNG_SIZE_MAX - 1))
+      png_error(png_ptr, "Row has too many bytes to allocate in memory");
+
+   if (png_ptr->rowbytes + 1 > png_ptr->old_prev_row_size)
+   {
+      png_free(png_ptr, png_ptr->prev_row);
+      png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)(
+        png_ptr->rowbytes + 1));
+      png_ptr->old_prev_row_size = png_ptr->rowbytes + 1;
+   }
 
-   png_memset_check(png_ptr, png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+   png_memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
 
-   png_debug1(3, "width = %lu,\n", png_ptr->width);
-   png_debug1(3, "height = %lu,\n", png_ptr->height);
-   png_debug1(3, "iwidth = %lu,\n", png_ptr->iwidth);
-   png_debug1(3, "num_rows = %lu\n", png_ptr->num_rows);
-   png_debug1(3, "rowbytes = %lu,\n", png_ptr->rowbytes);
-   png_debug1(3, "irowbytes = %lu,\n", png_ptr->irowbytes);
+   png_debug1(3, "width = %lu,", png_ptr->width);
+   png_debug1(3, "height = %lu,", png_ptr->height);
+   png_debug1(3, "iwidth = %lu,", png_ptr->iwidth);
+   png_debug1(3, "num_rows = %lu,", png_ptr->num_rows);
+   png_debug1(3, "rowbytes = %lu,", png_ptr->rowbytes);
+   png_debug1(3, "irowbytes = %lu",
+       PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
 
    png_ptr->flags |= PNG_FLAG_ROW_INIT;
 }
+#endif /* PNG_READ_SUPPORTED */