Remove the in-tree copy of the libpng source to make way for a newer release.

git-svn-id: http://svn.ghostscript.com/ghostscript/trunk@10696 a1074d23-0009-0410-80fe-cf8c14f379e6

1 files changed, 0 insertions, 3221 deletions

diff --git a/gs/libpng/pngrutil.c b/gs/libpng/pngrutil.c
deleted file mode 100644
index 5fafde6c3..000000000
--- a/gs/libpng/pngrutil.c
+++ /dev/null
@@ -1,3221 +0,0 @@
-
-/* pngrutil.c - utilities to read a PNG file
- *
- * Last changed in libpng 1.2.34 [December 18, 2008]
- * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2008 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
- *
- * This file contains routines that are only called from within
- * libpng itself during the course of reading an image.
- */
-
-#define PNG_INTERNAL
-#include "png.h"
-#if defined(PNG_READ_SUPPORTED)
-
-#if defined(_WIN32_WCE) && (_WIN32_WCE<0x500)
-#  define WIN32_WCE_OLD
-#endif
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-#  if defined(WIN32_WCE_OLD)
-/* strtod() function is not supported on WindowsCE */
-__inline double png_strtod(png_structp png_ptr, PNG_CONST char *nptr, char **endptr)
-{
-   double result = 0;
-   int len;
-   wchar_t *str, *end;
-
-   len = MultiByteToWideChar(CP_ACP, 0, nptr, -1, NULL, 0);
-   str = (wchar_t *)png_malloc(png_ptr, len * png_sizeof(wchar_t));
-   if ( NULL != str )
-   {
-      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);
-      png_free(png_ptr, str);
-   }
-   return result;
-}
-#  else
-#    define png_strtod(p,a,b) strtod(a,b)
-#  endif
-#endif
-
-png_uint_32 PNGAPI
-png_get_uint_31(png_structp png_ptr, png_bytep buf)
-{
-#ifdef PNG_READ_BIG_ENDIAN_SUPPORTED
-   png_uint_32 i = png_get_uint_32(buf);
-#else
-   /* Avoid an extra function call by inlining the result. */
-   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));
-#endif
-   if (i > PNG_UINT_31_MAX)
-     png_error(png_ptr, "PNG unsigned integer out of range.");
-   return (i);
-}
-#ifndef PNG_READ_BIG_ENDIAN_SUPPORTED
-/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
-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));
-
-   return (i);
-}
-
-/* Grab a signed 32-bit integer from a buffer in big-endian format.  The
- * data is stored in the PNG file in two's complement format, and it is
- * assumed that the machine format for signed integers is the same. */
-png_int_32 PNGAPI
-png_get_int_32(png_bytep buf)
-{
-   png_int_32 i = ((png_int_32)(*buf) << 24) +
-      ((png_int_32)(*(buf + 1)) << 16) +
-      ((png_int_32)(*(buf + 2)) << 8) +
-      (png_int_32)(*(buf + 3));
-
-   return (i);
-}
-
-/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
-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)));
-
-   return (i);
-}
-#endif /* PNG_READ_BIG_ENDIAN_SUPPORTED */
-
-/* Read the chunk header (length + type name).
- * Put the type name into png_ptr->chunk_name, and return the length.
- */
-png_uint_32 /* PRIVATE */
-png_read_chunk_header(png_structp png_ptr)
-{
-   png_byte buf[8];
-   png_uint_32 length;
-
-   /* read the length and the chunk name */
-   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);
-
-   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. */
-int /* PRIVATE */
-png_crc_finish(png_structp png_ptr, png_uint_32 skip)
-{
-   png_size_t i;
-   png_size_t istop = png_ptr->zbuf_size;
-
-   for (i = (png_size_t)skip; i > istop; i -= istop)
-   {
-      png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
-   }
-   if (i)
-   {
-      png_crc_read(png_ptr, png_ptr->zbuf, i);
-   }
-
-   if (png_crc_error(png_ptr))
-   {
-      if (((png_ptr->chunk_name[0] & 0x20) &&                /* Ancillary */
-           !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) ||
-          (!(png_ptr->chunk_name[0] & 0x20) &&             /* Critical  */
-          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE)))
-      {
-         png_chunk_warning(png_ptr, "CRC error");
-      }
-      else
-      {
-         png_chunk_error(png_ptr, "CRC error");
-      }
-      return (1);
-   }
-
-   return (0);
-}
-
-/* Compare the CRC stored in the PNG file with that calculated by libpng from
-   the data it has read thus far. */
-int /* PRIVATE */
-png_crc_error(png_structp png_ptr)
-{
-   png_byte crc_bytes[4];
-   png_uint_32 crc;
-   int need_crc = 1;
-
-   if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */
-   {
-      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
-          (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
-         need_crc = 0;
-   }
-   else                                                    /* critical */
-   {
-      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
-         need_crc = 0;
-   }
-
-   png_read_data(png_ptr, crc_bytes, 4);
-
-   if (need_crc)
-   {
-      crc = png_get_uint_32(crc_bytes);
-      return ((int)(crc != png_ptr->crc));
-   }
-   else
-      return (0);
-}
-
-#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).
- */
-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)
-{
-   static PNG_CONST char msg[] = "Error decoding compressed text";
-   png_charp text;
-   png_size_t text_size;
-
-   if (comp_type == PNG_COMPRESSION_TYPE_BASE)
-   {
-      int ret = Z_OK;
-      png_ptr->zstream.next_in = (png_bytep)(png_ptr->chunkdata + prefix_size);
-      png_ptr->zstream.avail_in = (uInt)(chunklength - prefix_size);
-      png_ptr->zstream.next_out = png_ptr->zbuf;
-      png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-
-      text_size = 0;
-      text = NULL;
-
-      while (png_ptr->zstream.avail_in)
-      {
-         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-         if (ret != Z_OK && ret != Z_STREAM_END)
-         {
-            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;
-
-            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, png_ptr->chunkdata);
-                    png_ptr->chunkdata = NULL;
-                    png_error(png_ptr, "Not enough memory to decompress chunk");
-                 }
-               png_memcpy(text, png_ptr->chunkdata, prefix_size);
-            }
-
-            text[text_size - 1] = 0x00;
-
-            /* Copy what we can of the error message into the text chunk */
-            text_size = (png_size_t)(chunklength -
-              (text - png_ptr->chunkdata) - 1);
-            if (text_size > png_sizeof(msg))
-               text_size = png_sizeof(msg);
-            png_memcpy(text + prefix_size, msg, text_size);
-            break;
-         }
-         if (!png_ptr->zstream.avail_out || ret == Z_STREAM_END)
-         {
-            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, png_ptr->chunkdata);
-                  png_ptr->chunkdata = NULL;
-                  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, png_ptr->chunkdata, prefix_size);
-               *(text + text_size) = 0x00;
-            }
-            else
-            {
-               png_charp tmp;
-
-               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, png_ptr->chunkdata);
-                  png_ptr->chunkdata = NULL;
-                  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
-            {
-               png_ptr->zstream.next_out = png_ptr->zbuf;
-               png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
-            }
-         }
-      }
-      if (ret != Z_STREAM_END)
-      {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
-         char umsg[52];
-
-         if (ret == Z_BUF_ERROR)
-            png_snprintf(umsg, 52,
-                "Buffer error in compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-         else if (ret == Z_DATA_ERROR)
-            png_snprintf(umsg, 52,
-                "Data error in compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-         else
-            png_snprintf(umsg, 52,
-                "Incomplete compressed datastream in %s chunk",
-                png_ptr->chunk_name);
-         png_warning(png_ptr, umsg);
-#else
-         png_warning(png_ptr,
-            "Incomplete compressed datastream in chunk other than IDAT");
-#endif
-         text_size = prefix_size;
-         if (text ==  NULL)
-         {
-            text = (png_charp)png_malloc_warn(png_ptr, text_size+1);
-            if (text == NULL)
-              {
-                png_free(png_ptr, png_ptr->chunkdata);
-                png_ptr->chunkdata = NULL;
-                png_error(png_ptr, "Not enough memory for text.");
-              }
-            png_memcpy(text, png_ptr->chunkdata, prefix_size);
-         }
-         *(text + text_size) = 0x00;
-      }
-
-      inflateReset(&png_ptr->zstream);
-      png_ptr->zstream.avail_in = 0;
-
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = text;
-      *newlength=text_size;
-   }
-   else /* if (comp_type != PNG_COMPRESSION_TYPE_BASE) */
-   {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
-      char umsg[50];
-
-      png_snprintf(umsg, 50, "Unknown zTXt compression type %d", comp_type);
-      png_warning(png_ptr, umsg);
-#else
-      png_warning(png_ptr, "Unknown zTXt compression type");
-#endif
-
-      *(png_ptr->chunkdata + prefix_size) = 0x00;
-      *newlength = prefix_size;
-   }
-}
-#endif
-
-/* read and check the IDHR chunk */
-void /* PRIVATE */
-png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_byte buf[13];
-   png_uint_32 width, height;
-   int bit_depth, color_type, compression_type, filter_type;
-   int interlace_type;
-
-   png_debug(1, "in png_handle_IHDR");
-
-   if (png_ptr->mode & PNG_HAVE_IHDR)
-      png_error(png_ptr, "Out of place IHDR");
-
-   /* check the length */
-   if (length != 13)
-      png_error(png_ptr, "Invalid IHDR chunk");
-
-   png_ptr->mode |= PNG_HAVE_IHDR;
-
-   png_crc_read(png_ptr, buf, 13);
-   png_crc_finish(png_ptr, 0);
-
-   width = png_get_uint_31(png_ptr, buf);
-   height = png_get_uint_31(png_ptr, buf + 4);
-   bit_depth = buf[8];
-   color_type = buf[9];
-   compression_type = buf[10];
-   filter_type = buf[11];
-   interlace_type = buf[12];
-
-   /* set internal variables */
-   png_ptr->width = width;
-   png_ptr->height = height;
-   png_ptr->bit_depth = (png_byte)bit_depth;
-   png_ptr->interlaced = (png_byte)interlace_type;
-   png_ptr->color_type = (png_byte)color_type;
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
-   png_ptr->filter_type = (png_byte)filter_type;
-#endif
-   png_ptr->compression_type = (png_byte)compression_type;
-
-   /* find number of channels */
-   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 */
-   png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
-   png_ptr->channels);
-   png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
-   png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
-   png_debug1(3, "channels = %d", png_ptr->channels);
-   png_debug1(3, "rowbytes = %lu", png_ptr->rowbytes);
-   png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
-      color_type, interlace_type, compression_type, filter_type);
-}
-
-/* read and check the palette */
-void /* PRIVATE */
-png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_color palette[PNG_MAX_PALETTE_LENGTH];
-   int num, i;
-#ifndef PNG_NO_POINTER_INDEXING
-   png_colorp pal_ptr;
-#endif
-
-   png_debug(1, "in png_handle_PLTE");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before PLTE");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid PLTE after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      png_error(png_ptr, "Duplicate PLTE chunk");
-
-   png_ptr->mode |= PNG_HAVE_PLTE;
-
-   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
-   {
-      png_warning(png_ptr,
-        "Ignoring PLTE chunk in grayscale PNG");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
-   if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
-   {
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-#endif
-
-   if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
-   {
-      if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
-      {
-         png_warning(png_ptr, "Invalid palette chunk");
-         png_crc_finish(png_ptr, length);
-         return;
-      }
-      else
-      {
-         png_error(png_ptr, "Invalid palette chunk");
-      }
-   }
-
-   num = (int)length / 3;
-
-#ifndef PNG_NO_POINTER_INDEXING
-   for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
-   {
-      png_byte buf[3];
-
-      png_crc_read(png_ptr, buf, 3);
-      pal_ptr->red = buf[0];
-      pal_ptr->green = buf[1];
-      pal_ptr->blue = buf[2];
-   }
-#else
-   for (i = 0; i < num; i++)
-   {
-      png_byte buf[3];
-
-      png_crc_read(png_ptr, buf, 3);
-      /* don't depend upon png_color being any order */
-      palette[i].red = buf[0];
-      palette[i].green = buf[1];
-      palette[i].blue = buf[2];
-   }
-#endif
-
-   /* If we actually NEED the PLTE chunk (ie for a paletted image), we do
-      whatever the normal CRC configuration tells us.  However, if we
-      have an RGB image, the PLTE can be considered ancillary, so
-      we will act as though it is. */
-#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-#endif
-   {
-      png_crc_finish(png_ptr, 0);
-   }
-#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
-   else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
-   {
-      /* If we don't want to use the data from an ancillary chunk,
-         we have two options: an error abort, or a warning and we
-         ignore the data in this chunk (which should be OK, since
-         it's considered ancillary for a RGB or RGBA image). */
-      if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
-      {
-         if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
-         {
-            png_chunk_error(png_ptr, "CRC error");
-         }
-         else
-         {
-            png_chunk_warning(png_ptr, "CRC error");
-            return;
-         }
-      }
-      /* Otherwise, we (optionally) emit a warning and use the chunk. */
-      else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
-      {
-         png_chunk_warning(png_ptr, "CRC error");
-      }
-   }
-#endif
-
-   png_set_PLTE(png_ptr, info_ptr, palette, num);
-
-#if defined(PNG_READ_tRNS_SUPPORTED)
-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-   {
-      if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
-      {
-         if (png_ptr->num_trans > (png_uint_16)num)
-         {
-            png_warning(png_ptr, "Truncating incorrect tRNS chunk length");
-            png_ptr->num_trans = (png_uint_16)num;
-         }
-         if (info_ptr->num_trans > (png_uint_16)num)
-         {
-            png_warning(png_ptr, "Truncating incorrect info tRNS chunk length");
-            info_ptr->num_trans = (png_uint_16)num;
-         }
-      }
-   }
-#endif
-
-}
-
-void /* PRIVATE */
-png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_debug(1, "in png_handle_IEND");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
-   {
-      png_error(png_ptr, "No image in file");
-   }
-
-   png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
-
-   if (length != 0)
-   {
-      png_warning(png_ptr, "Incorrect IEND chunk length");
-   }
-   png_crc_finish(png_ptr, length);
-
-   info_ptr = info_ptr; /* quiet compiler warnings about unused info_ptr */
-}
-
-#if defined(PNG_READ_gAMA_SUPPORTED)
-void /* PRIVATE */
-png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_fixed_point igamma;
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   float file_gamma;
-#endif
-   png_byte buf[4];
-
-   png_debug(1, "in png_handle_gAMA");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before gAMA");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid gAMA after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      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)
-      && !(info_ptr->valid & PNG_INFO_sRGB)
-#endif
-      )
-   {
-      png_warning(png_ptr, "Duplicate gAMA chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (length != 4)
-   {
-      png_warning(png_ptr, "Incorrect gAMA chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_crc_read(png_ptr, buf, 4);
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   igamma = (png_fixed_point)png_get_uint_32(buf);
-   /* check for zero gamma */
-   if (igamma == 0)
-      {
-         png_warning(png_ptr,
-           "Ignoring gAMA chunk with gamma=0");
-         return;
-      }
-
-#if defined(PNG_READ_sRGB_SUPPORTED)
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
-      if (PNG_OUT_OF_RANGE(igamma, 45500L, 500))
-      {
-         png_warning(png_ptr,
-           "Ignoring incorrect gAMA value when sRGB is also present");
-#ifndef PNG_NO_CONSOLE_IO
-         fprintf(stderr, "gamma = (%d/100000)", (int)igamma);
-#endif
-         return;
-      }
-#endif /* PNG_READ_sRGB_SUPPORTED */
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   file_gamma = (float)igamma / (float)100000.0;
-#  ifdef PNG_READ_GAMMA_SUPPORTED
-     png_ptr->gamma = file_gamma;
-#  endif
-     png_set_gAMA(png_ptr, info_ptr, file_gamma);
-#endif
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   png_set_gAMA_fixed(png_ptr, info_ptr, igamma);
-#endif
-}
-#endif
-
-#if defined(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");
-
-   buf[0] = buf[1] = buf[2] = buf[3] = 0;
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sBIT");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid sBIT after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-   {
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place sBIT chunk");
-   }
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
-   {
-      png_warning(png_ptr, "Duplicate sBIT chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-      truelen = 3;
-   else
-      truelen = (png_size_t)png_ptr->channels;
-
-   if (length != truelen || length > 4)
-   {
-      png_warning(png_ptr, "Incorrect sBIT chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_crc_read(png_ptr, buf, truelen);
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
-   {
-      png_ptr->sig_bit.red = buf[0];
-      png_ptr->sig_bit.green = buf[1];
-      png_ptr->sig_bit.blue = buf[2];
-      png_ptr->sig_bit.alpha = buf[3];
-   }
-   else
-   {
-      png_ptr->sig_bit.gray = buf[0];
-      png_ptr->sig_bit.red = buf[0];
-      png_ptr->sig_bit.green = buf[0];
-      png_ptr->sig_bit.blue = buf[0];
-      png_ptr->sig_bit.alpha = buf[1];
-   }
-   png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
-}
-#endif
-
-#if defined(PNG_READ_cHRM_SUPPORTED)
-void /* PRIVATE */
-png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   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
-   png_fixed_point int_x_white, int_y_white, int_x_red, int_y_red, int_x_green,
-      int_y_green, int_x_blue, int_y_blue;
-
-   png_uint_32 uint_x, uint_y;
-
-   png_debug(1, "in png_handle_cHRM");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before cHRM");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid cHRM after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Missing PLTE before cHRM");
-
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM)
-#if defined(PNG_READ_sRGB_SUPPORTED)
-      && !(info_ptr->valid & PNG_INFO_sRGB)
-#endif
-      )
-   {
-      png_warning(png_ptr, "Duplicate cHRM chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (length != 32)
-   {
-      png_warning(png_ptr, "Incorrect cHRM chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_crc_read(png_ptr, buf, 32);
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   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;
-
-   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;
-
-   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;
-
-   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;
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   white_x = (float)int_x_white / (float)100000.0;
-   white_y = (float)int_y_white / (float)100000.0;
-   red_x   = (float)int_x_red   / (float)100000.0;
-   red_y   = (float)int_y_red   / (float)100000.0;
-   green_x = (float)int_x_green / (float)100000.0;
-   green_y = (float)int_y_green / (float)100000.0;
-   blue_x  = (float)int_x_blue  / (float)100000.0;
-   blue_y  = (float)int_y_blue  / (float)100000.0;
-#endif
-
-#if defined(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) ||
-          PNG_OUT_OF_RANGE(int_x_red,   64000L, 1000) ||
-          PNG_OUT_OF_RANGE(int_y_red,   33000,  1000) ||
-          PNG_OUT_OF_RANGE(int_x_green, 30000,  1000) ||
-          PNG_OUT_OF_RANGE(int_y_green, 60000L, 1000) ||
-          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_FLOATING_POINT_SUPPORTED
-            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",
-               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 */
-         }
-         return;
-      }
-#endif /* PNG_READ_sRGB_SUPPORTED */
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   png_set_cHRM(png_ptr, info_ptr,
-      white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y);
-#endif
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   png_set_cHRM_fixed(png_ptr, info_ptr,
-      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
-}
-#endif
-
-#if defined(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");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sRGB");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid sRGB after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place sRGB chunk");
-
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB))
-   {
-      png_warning(png_ptr, "Duplicate sRGB chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (length != 1)
-   {
-      png_warning(png_ptr, "Incorrect sRGB chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_crc_read(png_ptr, buf, 1);
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   intent = buf[0];
-   /* check for bad intent */
-   if (intent >= PNG_sRGB_INTENT_LAST)
-   {
-      png_warning(png_ptr, "Unknown sRGB intent");
-      return;
-   }
-
-#if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA))
-   {
-   png_fixed_point igamma;
-#ifdef PNG_FIXED_POINT_SUPPORTED
-      igamma=info_ptr->int_gamma;
-#else
-#  ifdef PNG_FLOATING_POINT_SUPPORTED
-      igamma=(png_fixed_point)(info_ptr->gamma * 100000.);
-#  endif
-#endif
-      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
-#  ifdef PNG_FIXED_POINT_SUPPORTED
-         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);
-#    endif
-#  endif
-#endif
-      }
-   }
-#endif /* PNG_READ_gAMA_SUPPORTED */
-
-#ifdef PNG_READ_cHRM_SUPPORTED
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   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) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_y_red,   33000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_x_green, 30000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_y_green, 60000L, 1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_x_blue,  15000,  1000) ||
-          PNG_OUT_OF_RANGE(info_ptr->int_y_blue,   6000,  1000))
-         {
-            png_warning(png_ptr,
-              "Ignoring incorrect cHRM value when sRGB is also present");
-         }
-#endif /* PNG_FIXED_POINT_SUPPORTED */
-#endif /* PNG_READ_cHRM_SUPPORTED */
-
-   png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);
-}
-#endif /* PNG_READ_sRGB_SUPPORTED */
-
-#if defined(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_byte compression_type;
-   png_bytep pC;
-   png_charp profile;
-   png_uint_32 skip = 0;
-   png_uint_32 profile_size, profile_length;
-   png_size_t slength, prefix_length, data_length;
-
-   png_debug(1, "in png_handle_iCCP");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before iCCP");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid iCCP after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
-      /* Should be an error, but we can cope with it */
-      png_warning(png_ptr, "Out of place iCCP chunk");
-
-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP))
-   {
-      png_warning(png_ptr, "Duplicate iCCP chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-#ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
-   {
-      png_warning(png_ptr, "iCCP chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
-   }
-#endif
-
-   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)png_ptr->chunkdata, slength);
-
-   if (png_crc_finish(png_ptr, skip))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   png_ptr->chunkdata[slength] = 0x00;
-
-   for (profile = png_ptr->chunkdata; *profile; profile++)
-      /* empty loop to find end of name */ ;
-
-   ++profile;
-
-   /* there should be at least one zero (the compression type byte)
-      following the separator, and we should be on it  */
-   if ( profile >= png_ptr->chunkdata + slength - 1)
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "Malformed iCCP chunk");
-      return;
-   }
-
-   /* compression_type should always be zero */
-   compression_type = *profile++;
-   if (compression_type)
-   {
-      png_warning(png_ptr, "Ignoring nonzero compression type in iCCP chunk");
-      compression_type = 0x00;  /* Reset it to zero (libpng-1.0.6 through 1.0.8
-                                 wrote nonzero) */
-   }
-
-   prefix_length = profile - png_ptr->chunkdata;
-   png_decompress_chunk(png_ptr, compression_type,
-     slength, prefix_length, &data_length);
-
-   profile_length = data_length - prefix_length;
-
-   if ( prefix_length > data_length || profile_length < 4)
-   {
-      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)(png_ptr->chunkdata + prefix_length);
-   profile_size = ((*(pC    ))<<24) |
-                  ((*(pC + 1))<<16) |
-                  ((*(pC + 2))<< 8) |
-                  ((*(pC + 3))    );
-
-   if (profile_size < profile_length)
-      profile_length = profile_size;
-
-   if (profile_size > profile_length)
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "Ignoring truncated iCCP profile.");
-      return;
-   }
-
-   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)
-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 entry_start;
-   png_sPLT_t new_palette;
-#ifdef PNG_NO_POINTER_INDEXING
-   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");
-
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sPLT");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid sPLT after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-#ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
-   {
-      png_warning(png_ptr, "sPLT chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
-   }
-#endif
-
-   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)png_ptr->chunkdata, slength);
-
-   if (png_crc_finish(png_ptr, skip))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   png_ptr->chunkdata[slength] = 0x00;
-
-   for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start; entry_start++)
-      /* empty loop to find end of name */ ;
-   ++entry_start;
-
-   /* a sample depth should follow the separator, and we should be on it  */
-   if (entry_start > (png_bytep)png_ptr->chunkdata + slength - 2)
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "malformed sPLT chunk");
-      return;
-   }
-
-   new_palette.depth = *entry_start++;
-   entry_size = (new_palette.depth == 8 ? 6 : 10);
-   data_length = (slength - (entry_start - (png_bytep)png_ptr->chunkdata));
-
-   /* integrity-check the data length */
-   if (data_length % entry_size)
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      png_warning(png_ptr, "sPLT chunk has bad length");
-      return;
-   }
-
-   new_palette.nentries = (png_int_32) ( data_length / entry_size);
-   if ((png_uint_32) new_palette.nentries >
-       (png_uint_32) (PNG_SIZE_MAX / png_sizeof(png_sPLT_entry)))
-   {
-       png_warning(png_ptr, "sPLT chunk too long");
-       return;
-   }
-   new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
-       png_ptr, new_palette.nentries * png_sizeof(png_sPLT_entry));
-   if (new_palette.entries == NULL)
-   {
-       png_warning(png_ptr, "sPLT chunk requires too much memory");
-       return;
-   }
-
-#ifndef PNG_NO_POINTER_INDEXING
-   for (i = 0; i < new_palette.nentries; i++)
-   {
-      png_sPLT_entryp pp = new_palette.entries + i;
-
-      if (new_palette.depth == 8)
-      {
-          pp->red = *entry_start++;
-          pp->green = *entry_start++;
-          pp->blue = *entry_start++;
-          pp->alpha = *entry_start++;
-      }
-      else
-      {
-          pp->red   = png_get_uint_16(entry_start); entry_start += 2;
-          pp->green = png_get_uint_16(entry_start); entry_start += 2;
-          pp->blue  = png_get_uint_16(entry_start); entry_start += 2;
-          pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
-      }
-      pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
-   }
-#else
-   pp = new_palette.entries;
-   for (i = 0; i < new_palette.nentries; i++)
-   {
-
-      if (new_palette.depth == 8)
-      {
-          pp[i].red   = *entry_start++;
-          pp[i].green = *entry_start++;
-          pp[i].blue  = *entry_start++;
-          pp[i].alpha = *entry_start++;
-      }
-      else
-      {
-          pp[i].red   = png_get_uint_16(entry_start); entry_start += 2;
-          pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
-          pp[i].blue  = png_get_uint_16(entry_start); entry_start += 2;
-          pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
-      }
-      pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
-   }
-#endif
-
-   /* discard all chunk data except the name and stash that */
-   new_palette.name = png_ptr->chunkdata;
-
-   png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
-
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-   png_free(png_ptr, new_palette.entries);
-}
-#endif /* PNG_READ_sPLT_SUPPORTED */
-
-#if defined(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");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before tRNS");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid tRNS after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
-   {
-      png_warning(png_ptr, "Duplicate tRNS chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
-   {
-      png_byte buf[2];
-
-      if (length != 2)
-      {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
-         png_crc_finish(png_ptr, length);
-         return;
-      }
-
-      png_crc_read(png_ptr, buf, 2);
-      png_ptr->num_trans = 1;
-      png_ptr->trans_values.gray = png_get_uint_16(buf);
-   }
-   else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
-   {
-      png_byte buf[6];
-
-      if (length != 6)
-      {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
-         png_crc_finish(png_ptr, length);
-         return;
-      }
-      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);
-   }
-   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-   {
-      if (!(png_ptr->mode & PNG_HAVE_PLTE))
-      {
-         /* Should be an error, but we can cope with it. */
-         png_warning(png_ptr, "Missing PLTE before tRNS");
-      }
-      if (length > (png_uint_32)png_ptr->num_palette ||
-          length > PNG_MAX_PALETTE_LENGTH)
-      {
-         png_warning(png_ptr, "Incorrect tRNS chunk length");
-         png_crc_finish(png_ptr, length);
-         return;
-      }
-      if (length == 0)
-      {
-         png_warning(png_ptr, "Zero length tRNS chunk");
-         png_crc_finish(png_ptr, length);
-         return;
-      }
-      png_crc_read(png_ptr, readbuf, (png_size_t)length);
-      png_ptr->num_trans = (png_uint_16)length;
-   }
-   else
-   {
-      png_warning(png_ptr, "tRNS chunk not allowed with alpha channel");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   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));
-}
-#endif
-
-#if defined(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");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before bKGD");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid bKGD after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-            !(png_ptr->mode & PNG_HAVE_PLTE))
-   {
-      png_warning(png_ptr, "Missing PLTE before bKGD");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
-   {
-      png_warning(png_ptr, "Duplicate bKGD chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-      truelen = 1;
-   else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
-      truelen = 6;
-   else
-      truelen = 2;
-
-   if (length != truelen)
-   {
-      png_warning(png_ptr, "Incorrect bKGD chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_crc_read(png_ptr, buf, truelen);
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   /* We convert the index value into RGB components so that we can allow
-    * arbitrary RGB values for background when we have transparency, and
-    * so it is easy to determine the RGB values of the background color
-    * from the info_ptr struct. */
-   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-   {
-      png_ptr->background.index = buf[0];
-      if (info_ptr && info_ptr->num_palette)
-      {
-          if (buf[0] >= info_ptr->num_palette)
-          {
-             png_warning(png_ptr, "Incorrect bKGD chunk index value");
-             return;
-          }
-          png_ptr->background.red =
-             (png_uint_16)png_ptr->palette[buf[0]].red;
-          png_ptr->background.green =
-             (png_uint_16)png_ptr->palette[buf[0]].green;
-          png_ptr->background.blue =
-             (png_uint_16)png_ptr->palette[buf[0]].blue;
-      }
-   }
-   else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
-   {
-      png_ptr->background.red =
-      png_ptr->background.green =
-      png_ptr->background.blue =
-      png_ptr->background.gray = png_get_uint_16(buf);
-   }
-   else
-   {
-      png_ptr->background.red = png_get_uint_16(buf);
-      png_ptr->background.green = png_get_uint_16(buf + 2);
-      png_ptr->background.blue = png_get_uint_16(buf + 4);
-   }
-
-   png_set_bKGD(png_ptr, info_ptr, &(png_ptr->background));
-}
-#endif
-
-#if defined(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");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before hIST");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid hIST after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (!(png_ptr->mode & PNG_HAVE_PLTE))
-   {
-      png_warning(png_ptr, "Missing PLTE before hIST");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
-   {
-      png_warning(png_ptr, "Duplicate hIST chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   num = length / 2 ;
-   if (num != (unsigned int) png_ptr->num_palette || num >
-      (unsigned int) PNG_MAX_PALETTE_LENGTH)
-   {
-      png_warning(png_ptr, "Incorrect hIST chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   for (i = 0; i < num; i++)
-   {
-      png_byte buf[2];
-
-      png_crc_read(png_ptr, buf, 2);
-      readbuf[i] = png_get_uint_16(buf);
-   }
-
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   png_set_hIST(png_ptr, info_ptr, readbuf);
-}
-#endif
-
-#if defined(PNG_READ_pHYs_SUPPORTED)
-void /* PRIVATE */
-png_handle_pHYs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_byte buf[9];
-   png_uint_32 res_x, res_y;
-   int unit_type;
-
-   png_debug(1, "in png_handle_pHYs");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before pHYs");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid pHYs after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
-   {
-      png_warning(png_ptr, "Duplicate pHYs chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (length != 9)
-   {
-      png_warning(png_ptr, "Incorrect pHYs chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_crc_read(png_ptr, buf, 9);
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   res_x = png_get_uint_32(buf);
-   res_y = png_get_uint_32(buf + 4);
-   unit_type = buf[8];
-   png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
-}
-#endif
-
-#if defined(PNG_READ_oFFs_SUPPORTED)
-void /* PRIVATE */
-png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_byte buf[9];
-   png_int_32 offset_x, offset_y;
-   int unit_type;
-
-   png_debug(1, "in png_handle_oFFs");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before oFFs");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid oFFs after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
-   {
-      png_warning(png_ptr, "Duplicate oFFs chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (length != 9)
-   {
-      png_warning(png_ptr, "Incorrect oFFs chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_crc_read(png_ptr, buf, 9);
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   offset_x = png_get_int_32(buf);
-   offset_y = png_get_int_32(buf + 4);
-   unit_type = buf[8];
-   png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
-}
-#endif
-
-#if defined(PNG_READ_pCAL_SUPPORTED)
-/* read the pCAL chunk (described in the PNG Extensions document) */
-void /* PRIVATE */
-png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_int_32 X0, X1;
-   png_byte type, nparams;
-   png_charp buf, units, endptr;
-   png_charpp params;
-   png_size_t slength;
-   int i;
-
-   png_debug(1, "in png_handle_pCAL");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before pCAL");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid pCAL after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
-   {
-      png_warning(png_ptr, "Duplicate pCAL chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_debug1(2, "Allocating and reading pCAL chunk data (%lu bytes)",
-      length + 1);
-   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.");
-       return;
-     }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
-
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   png_ptr->chunkdata[slength] = 0x00; /* null terminate the last string */
-
-   png_debug(3, "Finding end of pCAL purpose string");
-   for (buf = png_ptr->chunkdata; *buf; buf++)
-      /* empty loop */ ;
-
-   endptr = png_ptr->chunkdata + slength;
-
-   /* We need to have at least 12 bytes after the purpose string
-      in order to get the parameter information. */
-   if (endptr <= buf + 12)
-   {
-      png_warning(png_ptr, "Invalid pCAL data");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   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");
-   /* Check that we have the right number of parameters for known
-      equation types. */
-   if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
-       (type == PNG_EQUATION_BASE_E && nparams != 3) ||
-       (type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
-       (type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
-   {
-      png_warning(png_ptr, "Invalid pCAL parameters for equation type");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-   else if (type >= PNG_EQUATION_LAST)
-   {
-      png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
-   }
-
-   for (buf = units; *buf; buf++)
-      /* Empty loop to move past the units string. */ ;
-
-   png_debug(3, "Allocating pCAL parameters array");
-   params = (png_charpp)png_malloc_warn(png_ptr,
-      (png_uint_32)(nparams * png_sizeof(png_charp))) ;
-   if (params == NULL)
-     {
-       png_free(png_ptr, png_ptr->chunkdata);
-       png_ptr->chunkdata = NULL;
-       png_warning(png_ptr, "No memory for pCAL params.");
-       return;
-     }
-
-   /* Get pointers to the start of each parameter string. */
-   for (i = 0; i < (int)nparams; i++)
-   {
-      buf++; /* Skip the null string terminator from previous parameter. */
-
-      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, png_ptr->chunkdata);
-         png_ptr->chunkdata = NULL;
-         png_free(png_ptr, params);
-         return;
-      }
-   }
-
-   png_set_pCAL(png_ptr, info_ptr, png_ptr->chunkdata, X0, X1, type, nparams,
-      units, params);
-
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-   png_free(png_ptr, params);
-}
-#endif
-
-#if defined(PNG_READ_sCAL_SUPPORTED)
-/* read the sCAL chunk */
-void /* PRIVATE */
-png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_charp ep;
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   double width, height;
-   png_charp vp;
-#else
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   png_charp swidth, sheight;
-#endif
-#endif
-   png_size_t slength;
-
-   png_debug(1, "in png_handle_sCAL");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before sCAL");
-   else if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-      png_warning(png_ptr, "Invalid sCAL after IDAT");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
-   {
-      png_warning(png_ptr, "Duplicate sCAL chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_debug1(2, "Allocating and reading sCAL chunk data (%lu bytes)",
-      length + 1);
-   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");
-      return;
-   }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
-
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   png_ptr->chunkdata[slength] = 0x00; /* null terminate the last string */
-
-   ep = png_ptr->chunkdata + 1;        /* skip unit byte */
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   width = png_strtod(png_ptr, ep, &vp);
-   if (*vp)
-   {
-      png_warning(png_ptr, "malformed width string in sCAL chunk");
-      return;
-   }
-#else
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   swidth = (png_charp)png_malloc_warn(png_ptr, png_strlen(ep) + 1);
-   if (swidth == NULL)
-   {
-      png_warning(png_ptr, "Out of memory while processing sCAL chunk width");
-      return;
-   }
-   png_memcpy(swidth, ep, (png_size_t)png_strlen(ep));
-#endif
-#endif
-
-   for (ep = png_ptr->chunkdata; *ep; ep++)
-      /* empty loop */ ;
-   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 = png_strtod(png_ptr, ep, &vp);
-   if (*vp)
-   {
-      png_warning(png_ptr, "malformed height string in sCAL chunk");
-      return;
-   }
-#else
-#ifdef PNG_FIXED_POINT_SUPPORTED
-   sheight = (png_charp)png_malloc_warn(png_ptr, png_strlen(ep) + 1);
-   if (sheight == NULL)
-   {
-      png_warning(png_ptr, "Out of memory while processing sCAL chunk height");
-      return;
-   }
-   png_memcpy(sheight, ep, (png_size_t)png_strlen(ep));
-#endif
-#endif
-
-   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, 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);
-#endif
-      return;
-   }
-
-
-#ifdef PNG_FLOATING_POINT_SUPPORTED
-   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, png_ptr->chunkdata[0], swidth, sheight);
-#endif
-#endif
-
-   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);
-#endif
-}
-#endif
-
-#if defined(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");
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Out of place tIME chunk");
-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
-   {
-      png_warning(png_ptr, "Duplicate tIME chunk");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   if (png_ptr->mode & PNG_HAVE_IDAT)
-      png_ptr->mode |= PNG_AFTER_IDAT;
-
-   if (length != 7)
-   {
-      png_warning(png_ptr, "Incorrect tIME chunk length");
-      png_crc_finish(png_ptr, length);
-      return;
-   }
-
-   png_crc_read(png_ptr, buf, 7);
-   if (png_crc_finish(png_ptr, 0))
-      return;
-
-   mod_time.second = buf[6];
-   mod_time.minute = buf[5];
-   mod_time.hour = buf[4];
-   mod_time.day = buf[3];
-   mod_time.month = buf[2];
-   mod_time.year = png_get_uint_16(buf);
-
-   png_set_tIME(png_ptr, info_ptr, &mod_time);
-}
-#endif
-
-#if defined(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)
-{
-   png_textp text_ptr;
-   png_charp key;
-   png_charp text;
-   png_uint_32 skip = 0;
-   png_size_t slength;
-   int ret;
-
-   png_debug(1, "in png_handle_tEXt");
-
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before tEXt");
-
-   if (png_ptr->mode & PNG_HAVE_IDAT)
-      png_ptr->mode |= PNG_AFTER_IDAT;
-
-#ifdef PNG_MAX_MALLOC_64K
-   if (length > (png_uint_32)65535L)
-   {
-      png_warning(png_ptr, "tEXt chunk too large to fit in memory");
-      skip = length - (png_uint_32)65535L;
-      length = (png_uint_32)65535L;
-   }
-#endif
-
-   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.");
-     return;
-   }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
-
-   if (png_crc_finish(png_ptr, skip))
-   {
-      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 */ ;
-
-   if (text != key + slength)
-      text++;
-
-   text_ptr = (png_textp)png_malloc_warn(png_ptr,
-      (png_uint_32)png_sizeof(png_text));
-   if (text_ptr == NULL)
-   {
-     png_warning(png_ptr, "Not enough memory to process text chunk.");
-     png_free(png_ptr, png_ptr->chunkdata);
-     png_ptr->chunkdata = NULL;
-     return;
-   }
-   text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
-   text_ptr->key = key;
-#ifdef PNG_iTXt_SUPPORTED
-   text_ptr->lang = NULL;
-   text_ptr->lang_key = NULL;
-   text_ptr->itxt_length = 0;
-#endif
-   text_ptr->text = text;
-   text_ptr->text_length = png_strlen(text);
-
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
-
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-   png_free(png_ptr, text_ptr);
-   if (ret)
-     png_warning(png_ptr, "Insufficient memory to process text chunk.");
-}
-#endif
-
-#if defined(PNG_READ_zTXt_SUPPORTED)
-/* note: this does not correctly handle chunks that are > 64K under DOS */
-void /* PRIVATE */
-png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_textp text_ptr;
-   png_charp text;
-   int comp_type;
-   int ret;
-   png_size_t slength, prefix_len, data_len;
-
-   png_debug(1, "in png_handle_zTXt");
-
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before zTXt");
-
-   if (png_ptr->mode & PNG_HAVE_IDAT)
-      png_ptr->mode |= PNG_AFTER_IDAT;
-
-#ifdef PNG_MAX_MALLOC_64K
-   /* We will no doubt have problems with chunks even half this size, but
-      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_crc_finish(png_ptr, length);
-     return;
-   }
-#endif
-
-   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.");
-     return;
-   }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   png_ptr->chunkdata[slength] = 0x00;
-
-   for (text = png_ptr->chunkdata; *text; text++)
-      /* empty loop */ ;
-
-   /* zTXt must have some text after the chunkdataword */
-   if (text >= png_ptr->chunkdata + slength - 2)
-   {
-      png_warning(png_ptr, "Truncated zTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-   else
-   {
-       comp_type = *(++text);
-       if (comp_type != PNG_TEXT_COMPRESSION_zTXt)
-       {
-          png_warning(png_ptr, "Unknown compression type in zTXt chunk");
-          comp_type = PNG_TEXT_COMPRESSION_zTXt;
-       }
-       text++;        /* skip the compression_method byte */
-   }
-   prefix_len = text - png_ptr->chunkdata;
-
-   png_decompress_chunk(png_ptr, comp_type,
-     (png_size_t)length, prefix_len, &data_len);
-
-   text_ptr = (png_textp)png_malloc_warn(png_ptr,
-      (png_uint_32)png_sizeof(png_text));
-   if (text_ptr == NULL)
-   {
-     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 = 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 = png_ptr->chunkdata + prefix_len;
-   text_ptr->text_length = data_len;
-
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
-
-   png_free(png_ptr, text_ptr);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-   if (ret)
-     png_error(png_ptr, "Insufficient memory to store zTXt chunk.");
-}
-#endif
-
-#if defined(PNG_READ_iTXt_SUPPORTED)
-/* note: this does not correctly handle chunks that are > 64K under DOS */
-void /* PRIVATE */
-png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
-{
-   png_textp text_ptr;
-   png_charp key, lang, text, lang_key;
-   int comp_flag;
-   int comp_type = 0;
-   int ret;
-   png_size_t slength, prefix_len, data_len;
-
-   png_debug(1, "in png_handle_iTXt");
-
-
-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
-      png_error(png_ptr, "Missing IHDR before iTXt");
-
-   if (png_ptr->mode & PNG_HAVE_IDAT)
-      png_ptr->mode |= PNG_AFTER_IDAT;
-
-#ifdef PNG_MAX_MALLOC_64K
-   /* We will no doubt have problems with chunks even half this size, but
-      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_crc_finish(png_ptr, length);
-     return;
-   }
-#endif
-
-   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.");
-     return;
-   }
-   slength = (png_size_t)length;
-   png_crc_read(png_ptr, (png_bytep)png_ptr->chunkdata, slength);
-   if (png_crc_finish(png_ptr, 0))
-   {
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   png_ptr->chunkdata[slength] = 0x00;
-
-   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 */
-
-   if (lang >= png_ptr->chunkdata + slength - 3)
-   {
-      png_warning(png_ptr, "Truncated iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-   else
-   {
-       comp_flag = *lang++;
-       comp_type = *lang++;
-   }
-
-   for (lang_key = lang; *lang_key; lang_key++)
-      /* empty loop */ ;
-   lang_key++;        /* skip NUL separator */
-
-   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 */
-   if (text >= png_ptr->chunkdata + slength)
-   {
-      png_warning(png_ptr, "Malformed iTXt chunk");
-      png_free(png_ptr, png_ptr->chunkdata);
-      png_ptr->chunkdata = NULL;
-      return;
-   }
-
-   prefix_len = text - png_ptr->chunkdata;
-
-   key=png_ptr->chunkdata;
-   if (comp_flag)
-       png_decompress_chunk(png_ptr, comp_type,
-         (size_t)length, prefix_len, &data_len);
-   else
-       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));
-   if (text_ptr == NULL)
-   {
-     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 = 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 = png_ptr->chunkdata;
-   text_ptr->text = png_ptr->chunkdata + prefix_len;
-
-   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);
-
-   png_free(png_ptr, text_ptr);
-   png_free(png_ptr, png_ptr->chunkdata);
-   png_ptr->chunkdata = NULL;
-   if (ret)
-     png_error(png_ptr, "Insufficient memory to store iTXt chunk.");
-}
-#endif
-
-/* This function is called when we haven't found a handler for a
-   chunk.  If there isn't a problem with the chunk itself (ie bad
-   chunk name, CRC, or a critical chunk), the chunk is silently ignored
-   -- unless the PNG_FLAG_UNKNOWN_CHUNKS_SUPPORTED flag is on in which
-   case it will be saved away to be written out later. */
-void /* PRIVATE */
-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");
-
-
-   if (png_ptr->mode & PNG_HAVE_IDAT)
-   {
-#ifdef PNG_USE_LOCAL_ARRAYS
-      PNG_CONST PNG_IDAT;
-#endif
-      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))  /* not an IDAT */
-         png_ptr->mode |= PNG_AFTER_IDAT;
-   }
-
-   if (!(png_ptr->chunk_name[0] & 0x20))
-   {
-#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
-      if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
-           PNG_HANDLE_CHUNK_ALWAYS
-#if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
-           && png_ptr->read_user_chunk_fn == NULL
-#endif
-        )
-#endif
-          png_chunk_error(png_ptr, "unknown critical chunk");
-   }
-
-#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
-   if ((png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS) ||
-       (png_ptr->read_user_chunk_fn != NULL))
-   {
-#ifdef PNG_MAX_MALLOC_64K
-       if (length > (png_uint_32)65535L)
-       {
-           png_warning(png_ptr, "unknown chunk too large to fit in memory");
-           skip = length - (png_uint_32)65535L;
-           length = (png_uint_32)65535L;
-       }
-#endif
-       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);
-       }
-#if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
-       if (png_ptr->read_user_chunk_fn != NULL)
-       {
-          /* callback to user unknown chunk handler */
-          int ret;
-          ret = (*(png_ptr->read_user_chunk_fn))
-            (png_ptr, &png_ptr->unknown_chunk);
-          if (ret < 0)
-             png_chunk_error(png_ptr, "error in user chunk");
-          if (ret == 0)
-          {
-             if (!(png_ptr->chunk_name[0] & 0x20))
-                if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
-                     PNG_HANDLE_CHUNK_ALWAYS)
-                   png_chunk_error(png_ptr, "unknown critical chunk");
-             png_set_unknown_chunks(png_ptr, info_ptr,
-               &png_ptr->unknown_chunk, 1);
-          }
-       }
-       else
-#endif
-       png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
-       png_free(png_ptr, png_ptr->unknown_chunk.data);
-       png_ptr->unknown_chunk.data = NULL;
-   }
-   else
-#endif
-      skip = length;
-
-   png_crc_finish(png_ptr, skip);
-
-#if !defined(PNG_READ_USER_CHUNKS_SUPPORTED)
-   info_ptr = info_ptr; /* quiet compiler warnings about unused info_ptr */
-#endif
-}
-
-/* This function is called to verify that a chunk name is valid.
-   This function can't have the "critical chunk check" incorporated
-   into it, since in the future we will need to be able to call user
-   functions to handle unknown critical chunks after we check that
-   the chunk name itself is valid. */
-
-#define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
-
-void /* PRIVATE */
-png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
-{
-   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]))
-   {
-      png_chunk_error(png_ptr, "invalid chunk type");
-   }
-}
-
-/* Combines the row recently read in with the existing pixels in the
-   row.  This routine takes care of alpha and transparency if requested.
-   This routine also handles the two methods of progressive display
-   of interlaced images, depending on the mask value.
-   The mask value describes which pixels are to be combined with
-   the row.  The pattern always repeats every 8 pixels, so just 8
-   bits are needed.  A one indicates the pixel is to be combined,
-   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.  */
-
-void /* PRIVATE */
-png_combine_row(png_structp png_ptr, png_bytep row, int mask)
-{
-   png_debug(1, "in png_combine_row");
-   if (mask == 0xff)
-   {
-      png_memcpy(row, png_ptr->row_buf + 1,
-         PNG_ROWBYTES(png_ptr->row_info.pixel_depth, png_ptr->width));
-   }
-   else
-   {
-      switch (png_ptr->row_info.pixel_depth)
-      {
-         case 1:
-         {
-            png_bytep sp = png_ptr->row_buf + 1;
-            png_bytep dp = row;
-            int s_inc, s_start, s_end;
-            int m = 0x80;
-            int shift;
-            png_uint_32 i;
-            png_uint_32 row_width = png_ptr->width;
-
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
-            if (png_ptr->transformations & PNG_PACKSWAP)
-            {
-                s_start = 0;
-                s_end = 7;
-                s_inc = 1;
-            }
-            else
-#endif
-            {
-                s_start = 7;
-                s_end = 0;
-                s_inc = -1;
-            }
-
-            shift = s_start;
-
-            for (i = 0; i < row_width; i++)
-            {
-               if (m & mask)
-               {
-                  int value;
-
-                  value = (*sp >> shift) & 0x01;
-                  *dp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
-                  *dp |= (png_byte)(value << shift);
-               }
-
-               if (shift == s_end)
-               {
-                  shift = s_start;
-                  sp++;
-                  dp++;
-               }
-               else
-                  shift += s_inc;
-
-               if (m == 1)
-                  m = 0x80;
-               else
-                  m >>= 1;
-            }
-            break;
-         }
-         case 2:
-         {
-            png_bytep sp = png_ptr->row_buf + 1;
-            png_bytep dp = row;
-            int s_start, s_end, s_inc;
-            int m = 0x80;
-            int shift;
-            png_uint_32 i;
-            png_uint_32 row_width = png_ptr->width;
-            int value;
-
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
-            if (png_ptr->transformations & PNG_PACKSWAP)
-            {
-               s_start = 0;
-               s_end = 6;
-               s_inc = 2;
-            }
-            else
-#endif
-            {
-               s_start = 6;
-               s_end = 0;
-               s_inc = -2;
-            }
-
-            shift = s_start;
-
-            for (i = 0; i < row_width; i++)
-            {
-               if (m & mask)
-               {
-                  value = (*sp >> shift) & 0x03;
-                  *dp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
-                  *dp |= (png_byte)(value << shift);
-               }
-
-               if (shift == s_end)
-               {
-                  shift = s_start;
-                  sp++;
-                  dp++;
-               }
-               else
-                  shift += s_inc;
-               if (m == 1)
-                  m = 0x80;
-               else
-                  m >>= 1;
-            }
-            break;
-         }
-         case 4:
-         {
-            png_bytep sp = png_ptr->row_buf + 1;
-            png_bytep dp = row;
-            int s_start, s_end, s_inc;
-            int m = 0x80;
-            int shift;
-            png_uint_32 i;
-            png_uint_32 row_width = png_ptr->width;
-            int value;
-
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
-            if (png_ptr->transformations & PNG_PACKSWAP)
-            {
-               s_start = 0;
-               s_end = 4;
-               s_inc = 4;
-            }
-            else
-#endif
-            {
-               s_start = 4;
-               s_end = 0;
-               s_inc = -4;
-            }
-            shift = s_start;
-
-            for (i = 0; i < row_width; i++)
-            {
-               if (m & mask)
-               {
-                  value = (*sp >> shift) & 0xf;
-                  *dp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
-                  *dp |= (png_byte)(value << shift);
-               }
-
-               if (shift == s_end)
-               {
-                  shift = s_start;
-                  sp++;
-                  dp++;
-               }
-               else
-                  shift += s_inc;
-               if (m == 1)
-                  m = 0x80;
-               else
-                  m >>= 1;
-            }
-            break;
-         }
-         default:
-         {
-            png_bytep sp = png_ptr->row_buf + 1;
-            png_bytep dp = row;
-            png_size_t pixel_bytes = (png_ptr->row_info.pixel_depth >> 3);
-            png_uint_32 i;
-            png_uint_32 row_width = png_ptr->width;
-            png_byte m = 0x80;
-
-
-            for (i = 0; i < row_width; i++)
-            {
-               if (m & mask)
-               {
-                  png_memcpy(dp, sp, pixel_bytes);
-               }
-
-               sp += pixel_bytes;
-               dp += pixel_bytes;
-
-               if (m == 1)
-                  m = 0x80;
-               else
-                  m >>= 1;
-            }
-            break;
-         }
-      }
-   }
-}
-
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-/* 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)
- */
-void /* PRIVATE */
-png_do_read_interlace(png_structp png_ptr)
-{
-   png_row_infop row_info = &(png_ptr->row_info);
-   png_bytep row = png_ptr->row_buf + 1;
-   int pass = png_ptr->pass;
-   png_uint_32 transformations = png_ptr->transformations;
-#ifdef PNG_USE_LOCAL_ARRAYS
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
-   /* offset to next interlace block */
-   PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
-#endif
-
-   png_debug(1, "in png_do_read_interlace");
-   if (row != NULL && row_info != NULL)
-   {
-      png_uint_32 final_width;
-
-      final_width = row_info->width * png_pass_inc[pass];
-
-      switch (row_info->pixel_depth)
-      {
-         case 1:
-         {
-            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
-            png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
-            int sshift, dshift;
-            int s_start, s_end, s_inc;
-            int jstop = png_pass_inc[pass];
-            png_byte v;
-            png_uint_32 i;
-            int j;
-
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
-            if (transformations & PNG_PACKSWAP)
-            {
-                sshift = (int)((row_info->width + 7) & 0x07);
-                dshift = (int)((final_width + 7) & 0x07);
-                s_start = 7;
-                s_end = 0;
-                s_inc = -1;
-            }
-            else
-#endif
-            {
-                sshift = 7 - (int)((row_info->width + 7) & 0x07);
-                dshift = 7 - (int)((final_width + 7) & 0x07);
-                s_start = 0;
-                s_end = 7;
-                s_inc = 1;
-            }
-
-            for (i = 0; i < row_info->width; i++)
-            {
-               v = (png_byte)((*sp >> sshift) & 0x01);
-               for (j = 0; j < jstop; j++)
-               {
-                  *dp &= (png_byte)((0x7f7f >> (7 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
-                  if (dshift == s_end)
-                  {
-                     dshift = s_start;
-                     dp--;
-                  }
-                  else
-                     dshift += s_inc;
-               }
-               if (sshift == s_end)
-               {
-                  sshift = s_start;
-                  sp--;
-               }
-               else
-                  sshift += s_inc;
-            }
-            break;
-         }
-         case 2:
-         {
-            png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
-            png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
-            int sshift, dshift;
-            int s_start, s_end, s_inc;
-            int jstop = png_pass_inc[pass];
-            png_uint_32 i;
-
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
-            if (transformations & PNG_PACKSWAP)
-            {
-               sshift = (int)(((row_info->width + 3) & 0x03) << 1);
-               dshift = (int)(((final_width + 3) & 0x03) << 1);
-               s_start = 6;
-               s_end = 0;
-               s_inc = -2;
-            }
-            else
-#endif
-            {
-               sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
-               dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
-               s_start = 0;
-               s_end = 6;
-               s_inc = 2;
-            }
-
-            for (i = 0; i < row_info->width; i++)
-            {
-               png_byte v;
-               int j;
-
-               v = (png_byte)((*sp >> sshift) & 0x03);
-               for (j = 0; j < jstop; j++)
-               {
-                  *dp &= (png_byte)((0x3f3f >> (6 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
-                  if (dshift == s_end)
-                  {
-                     dshift = s_start;
-                     dp--;
-                  }
-                  else
-                     dshift += s_inc;
-               }
-               if (sshift == s_end)
-               {
-                  sshift = s_start;
-                  sp--;
-               }
-               else
-                  sshift += s_inc;
-            }
-            break;
-         }
-         case 4:
-         {
-            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
-            png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
-            int sshift, dshift;
-            int s_start, s_end, s_inc;
-            png_uint_32 i;
-            int jstop = png_pass_inc[pass];
-
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
-            if (transformations & PNG_PACKSWAP)
-            {
-               sshift = (int)(((row_info->width + 1) & 0x01) << 2);
-               dshift = (int)(((final_width + 1) & 0x01) << 2);
-               s_start = 4;
-               s_end = 0;
-               s_inc = -4;
-            }
-            else
-#endif
-            {
-               sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
-               dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
-               s_start = 0;
-               s_end = 4;
-               s_inc = 4;
-            }
-
-            for (i = 0; i < row_info->width; i++)
-            {
-               png_byte v = (png_byte)((*sp >> sshift) & 0xf);
-               int j;
-
-               for (j = 0; j < jstop; j++)
-               {
-                  *dp &= (png_byte)((0xf0f >> (4 - dshift)) & 0xff);
-                  *dp |= (png_byte)(v << dshift);
-                  if (dshift == s_end)
-                  {
-                     dshift = s_start;
-                     dp--;
-                  }
-                  else
-                     dshift += s_inc;
-               }
-               if (sshift == s_end)
-               {
-                  sshift = s_start;
-                  sp--;
-               }
-               else
-                  sshift += s_inc;
-            }
-            break;
-         }
-         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 dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
-
-            int jstop = png_pass_inc[pass];
-            png_uint_32 i;
-
-            for (i = 0; i < row_info->width; i++)
-            {
-               png_byte v[8];
-               int j;
-
-               png_memcpy(v, sp, pixel_bytes);
-               for (j = 0; j < jstop; j++)
-               {
-                  png_memcpy(dp, v, pixel_bytes);
-                  dp -= pixel_bytes;
-               }
-               sp -= pixel_bytes;
-            }
-            break;
-         }
-      }
-      row_info->width = final_width;
-      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
-   }
-#if !defined(PNG_READ_PACKSWAP_SUPPORTED)
-   transformations = transformations; /* silence compiler warning */
-#endif
-}
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
-
-void /* PRIVATE */
-png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
-   png_bytep prev_row, int filter)
-{
-   png_debug(1, "in png_read_filter_row");
-   png_debug2(2, "row = %lu, filter = %d", png_ptr->row_number, filter);
-   switch (filter)
-   {
-      case PNG_FILTER_VALUE_NONE:
-         break;
-      case PNG_FILTER_VALUE_SUB:
-      {
-         png_uint_32 i;
-         png_uint_32 istop = row_info->rowbytes;
-         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
-         png_bytep rp = row + bpp;
-         png_bytep lp = row;
-
-         for (i = bpp; i < istop; i++)
-         {
-            *rp = (png_byte)(((int)(*rp) + (int)(*lp++)) & 0xff);
-            rp++;
-         }
-         break;
-      }
-      case PNG_FILTER_VALUE_UP:
-      {
-         png_uint_32 i;
-         png_uint_32 istop = row_info->rowbytes;
-         png_bytep rp = row;
-         png_bytep pp = prev_row;
-
-         for (i = 0; i < istop; i++)
-         {
-            *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
-            rp++;
-         }
-         break;
-      }
-      case PNG_FILTER_VALUE_AVG:
-      {
-         png_uint_32 i;
-         png_bytep rp = row;
-         png_bytep pp = prev_row;
-         png_bytep lp = row;
-         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
-         png_uint_32 istop = row_info->rowbytes - bpp;
-
-         for (i = 0; i < bpp; i++)
-         {
-            *rp = (png_byte)(((int)(*rp) +
-               ((int)(*pp++) / 2 )) & 0xff);
-            rp++;
-         }
-
-         for (i = 0; i < istop; i++)
-         {
-            *rp = (png_byte)(((int)(*rp) +
-               (int)(*pp++ + *lp++) / 2 ) & 0xff);
-            rp++;
-         }
-         break;
-      }
-      case PNG_FILTER_VALUE_PAETH:
-      {
-         png_uint_32 i;
-         png_bytep rp = row;
-         png_bytep pp = prev_row;
-         png_bytep lp = row;
-         png_bytep cp = prev_row;
-         png_uint_32 bpp = (row_info->pixel_depth + 7) >> 3;
-         png_uint_32 istop=row_info->rowbytes - bpp;
-
-         for (i = 0; i < bpp; i++)
-         {
-            *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
-            rp++;
-         }
-
-         for (i = 0; i < istop; i++)   /* use leftover rp,pp */
-         {
-            int a, b, c, pa, pb, pc, p;
-
-            a = *lp++;
-            b = *pp++;
-            c = *cp++;
-
-            p = b - c;
-            pc = a - c;
-
-#ifdef PNG_USE_ABS
-            pa = abs(p);
-            pb = abs(pc);
-            pc = abs(p + pc);
-#else
-            pa = p < 0 ? -p : p;
-            pb = pc < 0 ? -pc : pc;
-            pc = (p + pc) < 0 ? -(p + pc) : p + pc;
-#endif
-
-            /*
-               if (pa <= pb && pa <= pc)
-                  p = a;
-               else if (pb <= pc)
-                  p = b;
-               else
-                  p = c;
-             */
-
-            p = (pa <= pb && pa <= pc) ? a : (pb <= pc) ? b : c;
-
-            *rp = (png_byte)(((int)(*rp) + p) & 0xff);
-            rp++;
-         }
-         break;
-      }
-      default:
-         png_warning(png_ptr, "Ignoring bad adaptive filter type");
-         *row = 0;
-         break;
-   }
-}
-
-void /* PRIVATE */
-png_read_finish_row(png_structp png_ptr)
-{
-#ifdef PNG_USE_LOCAL_ARRAYS
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
-
-   /* start of interlace block */
-   PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
-
-   /* 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 */
-   PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
-
-   /* offset to next interlace block in the y direction */
-   PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
-#endif
-
-   png_debug(1, "in png_read_finish_row");
-   png_ptr->row_number++;
-   if (png_ptr->row_number < png_ptr->num_rows)
-      return;
-
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (png_ptr->interlaced)
-   {
-      png_ptr->row_number = 0;
-      png_memset_check(png_ptr, png_ptr->prev_row, 0,
-         png_ptr->rowbytes + 1);
-      do
-      {
-         png_ptr->pass++;
-         if (png_ptr->pass >= 7)
-            break;
-         png_ptr->iwidth = (png_ptr->width +
-            png_pass_inc[png_ptr->pass] - 1 -
-            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 +
-               png_pass_yinc[png_ptr->pass] - 1 -
-               png_pass_ystart[png_ptr->pass]) /
-               png_pass_yinc[png_ptr->pass];
-            if (!(png_ptr->num_rows))
-               continue;
-         }
-         else  /* if (png_ptr->transformations & PNG_INTERLACE) */
-            break;
-      } while (png_ptr->iwidth == 0);
-
-      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_CONST PNG_IDAT;
-#endif
-      char extra;
-      int ret;
-
-      png_ptr->zstream.next_out = (Byte *)&extra;
-      png_ptr->zstream.avail_out = (uInt)1;
-      for (;;)
-      {
-         if (!(png_ptr->zstream.avail_in))
-         {
-            while (!png_ptr->idat_size)
-            {
-               png_byte chunk_length[4];
-
-               png_crc_finish(png_ptr, 0);
-
-               png_read_data(png_ptr, chunk_length, 4);
-               png_ptr->idat_size = png_get_uint_31(png_ptr, chunk_length);
-               png_reset_crc(png_ptr);
-               png_crc_read(png_ptr, png_ptr->chunk_name, 4);
-               if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
-                  png_error(png_ptr, "Not enough image data");
-
-            }
-            png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
-            png_ptr->zstream.next_in = png_ptr->zbuf;
-            if (png_ptr->zbuf_size > png_ptr->idat_size)
-               png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
-            png_crc_read(png_ptr, png_ptr->zbuf, png_ptr->zstream.avail_in);
-            png_ptr->idat_size -= png_ptr->zstream.avail_in;
-         }
-         ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
-         if (ret == Z_STREAM_END)
-         {
-            if (!(png_ptr->zstream.avail_out) || png_ptr->zstream.avail_in ||
-               png_ptr->idat_size)
-               png_warning(png_ptr, "Extra compressed data");
-            png_ptr->mode |= PNG_AFTER_IDAT;
-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-            break;
-         }
-         if (ret != Z_OK)
-            png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
-                      "Decompression Error");
-
-         if (!(png_ptr->zstream.avail_out))
-         {
-            png_warning(png_ptr, "Extra compressed data.");
-            png_ptr->mode |= PNG_AFTER_IDAT;
-            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
-            break;
-         }
-
-      }
-      png_ptr->zstream.avail_out = 0;
-   }
-
-   if (png_ptr->idat_size || png_ptr->zstream.avail_in)
-      png_warning(png_ptr, "Extra compression data");
-
-   inflateReset(&png_ptr->zstream);
-
-   png_ptr->mode |= PNG_AFTER_IDAT;
-}
-
-void /* PRIVATE */
-png_read_start_row(png_structp png_ptr)
-{
-#ifdef PNG_USE_LOCAL_ARRAYS
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
-
-   /* start of interlace block */
-   PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
-
-   /* 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 */
-   PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
-
-   /* offset to next interlace block in the y direction */
-   PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
-#endif
-#endif
-
-   int max_pixel_depth;
-   png_size_t row_bytes;
-
-   png_debug(1, "in png_read_start_row");
-   png_ptr->zstream.avail_in = 0;
-   png_init_read_transformations(png_ptr);
-#ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (png_ptr->interlaced)
-   {
-      if (!(png_ptr->transformations & PNG_INTERLACE))
-         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
-            png_pass_ystart[0]) / png_pass_yinc[0];
-      else
-         png_ptr->num_rows = png_ptr->height;
-
-      png_ptr->iwidth = (png_ptr->width +
-         png_pass_inc[png_ptr->pass] - 1 -
-         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;
-   }
-   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)
-   if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
-      max_pixel_depth = 8;
-#endif
-
-#if defined(PNG_READ_EXPAND_SUPPORTED)
-   if (png_ptr->transformations & PNG_EXPAND)
-   {
-      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-      {
-         if (png_ptr->num_trans)
-            max_pixel_depth = 32;
-         else
-            max_pixel_depth = 24;
-      }
-      else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
-      {
-         if (max_pixel_depth < 8)
-            max_pixel_depth = 8;
-         if (png_ptr->num_trans)
-            max_pixel_depth *= 2;
-      }
-      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
-      {
-         if (png_ptr->num_trans)
-         {
-            max_pixel_depth *= 4;
-            max_pixel_depth /= 3;
-         }
-      }
-   }
-#endif
-
-#if defined(PNG_READ_FILLER_SUPPORTED)
-   if (png_ptr->transformations & (PNG_FILLER))
-   {
-      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-         max_pixel_depth = 32;
-      else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
-      {
-         if (max_pixel_depth <= 8)
-            max_pixel_depth = 16;
-         else
-            max_pixel_depth = 32;
-      }
-      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
-      {
-         if (max_pixel_depth <= 32)
-            max_pixel_depth = 32;
-         else
-            max_pixel_depth = 64;
-      }
-   }
-#endif
-
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
-   if (png_ptr->transformations & PNG_GRAY_TO_RGB)
-   {
-      if (
-#if defined(PNG_READ_EXPAND_SUPPORTED)
-        (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
-#endif
-#if defined(PNG_READ_FILLER_SUPPORTED)
-        (png_ptr->transformations & (PNG_FILLER)) ||
-#endif
-        png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
-      {
-         if (max_pixel_depth <= 16)
-            max_pixel_depth = 32;
-         else
-            max_pixel_depth = 64;
-      }
-      else
-      {
-         if (max_pixel_depth <= 8)
-           {
-             if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
-               max_pixel_depth = 32;
-             else
-               max_pixel_depth = 24;
-           }
-         else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
-            max_pixel_depth = 64;
-         else
-            max_pixel_depth = 48;
-      }
-   }
-#endif
-
-#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
-defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
-     {
-       int user_pixel_depth = png_ptr->user_transform_depth*
-         png_ptr->user_transform_channels;
-       if (user_pixel_depth > max_pixel_depth)
-         max_pixel_depth=user_pixel_depth;
-     }
-#endif
-
-   /* align the width on the next larger 8 pixels.  Mainly used
-      for interlacing */
-   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) +
-      1 + ((max_pixel_depth + 7) >> 3);
-#ifdef PNG_MAX_MALLOC_64K
-   if (row_bytes > (png_uint_32)65536L)
-      png_error(png_ptr, "This image requires a row greater than 64KB");
-#endif
-
-   if (row_bytes + 64 > png_ptr->old_big_row_buf_size)
-   {
-     png_free(png_ptr, png_ptr->big_row_buf);
-     png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes+64);
-     png_ptr->row_buf = png_ptr->big_row_buf+32;
-     png_ptr->old_big_row_buf_size = row_bytes+64;
-   }
-
-#ifdef PNG_MAX_MALLOC_64K
-   if ((png_uint_32)png_ptr->rowbytes + 1 > (png_uint_32)65536L)
-      png_error(png_ptr, "This image requires a row greater than 64KB");
-#endif
-   if ((png_uint_32)png_ptr->rowbytes > (png_uint_32)(PNG_SIZE_MAX - 1))
-      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_debug1(3, "width = %lu,", png_ptr->width);
-   png_debug1(3, "height = %lu,", png_ptr->height);
-   png_debug1(3, "iwidth = %lu,", png_ptr->iwidth);
-   png_debug1(3, "num_rows = %lu,", png_ptr->num_rows);
-   png_debug1(3, "rowbytes = %lu,", png_ptr->rowbytes);
-   png_debug1(3, "irowbytes = %lu", png_ptr->irowbytes);
-
-   png_ptr->flags |= PNG_FLAG_ROW_INIT;
-}
-#endif /* PNG_READ_SUPPORTED */