/* pngpread.c - read a png file in push mode

 *

 * Last changed in libpng 1.2.57 [(TO BE RELEASED)]

 * Copyright (c) 1998-2002,2004,2006-2010,2016 Glenn Randers-Pehrson

 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

 *

 * This code is released under the libpng license.

 * For conditions of distribution and use, see the disclaimer

 * and license in png.h

 */

#define PNG_INTERNAL

#define PNG_NO_PEDANTIC_WARNINGS

#include "png.h"

#ifdef PNG_PROGRESSIVE_READ_SUPPORTED

/* Push model modes */

#define PNG_READ_SIG_MODE   0

#define PNG_READ_CHUNK_MODE 1

#define PNG_READ_IDAT_MODE  2

#define PNG_SKIP_MODE       3

#define PNG_READ_tEXt_MODE  4

#define PNG_READ_zTXt_MODE  5

#define PNG_READ_DONE_MODE  6

#define PNG_READ_iTXt_MODE  7

#define PNG_ERROR_MODE      8

void PNGAPI

png_process_data(png_structp png_ptr, png_infop info_ptr,

   png_bytep buffer, png_size_t buffer_size)

{

   if (png_ptr == NULL || info_ptr == NULL)

      return;

   png_push_restore_buffer(png_ptr, buffer, buffer_size);

   while (png_ptr->buffer_size)

   {

      png_process_some_data(png_ptr, info_ptr);

   }

}

/* What we do with the incoming data depends on what we were previously

 * doing before we ran out of data...

 */

void /* PRIVATE */

png_process_some_data(png_structp png_ptr, png_infop info_ptr)

{

   if (png_ptr == NULL)

      return;

   switch (png_ptr->process_mode)

   {

      case PNG_READ_SIG_MODE:

      {

         png_push_read_sig(png_ptr, info_ptr);

         break;

      }

      case PNG_READ_CHUNK_MODE:

      {

         png_push_read_chunk(png_ptr, info_ptr);

         break;

      }

      case PNG_READ_IDAT_MODE:

      {

         png_push_read_IDAT(png_ptr);

         break;

      }

      case PNG_SKIP_MODE:

      {

         png_push_crc_finish(png_ptr);

         break;

      }

      default:

      {

         png_ptr->buffer_size = 0;

         break;

      }

   }

}

/* Read any remaining signature bytes from the stream and compare them with

 * the correct PNG signature.  It is possible that this routine is called

 * with bytes already read from the signature, either because they have been

 * checked by the calling application, or because of multiple calls to this

 * routine.

 */

void /* PRIVATE */

png_push_read_sig(png_structp png_ptr, png_infop info_ptr)

{

   png_size_t num_checked = png_ptr->sig_bytes,

             num_to_check = 8 - num_checked;

   if (png_ptr->buffer_size < num_to_check)

   {

      num_to_check = png_ptr->buffer_size;

   }

   png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),

      num_to_check);

   png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);

   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))

   {

      if (num_checked < 4 &&

          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))

         png_error(png_ptr, "Not a PNG file");

      else

         png_error(png_ptr, "PNG file corrupted by ASCII conversion");

   }

   else

   {

      if (png_ptr->sig_bytes >= 8)

      {

         png_ptr->process_mode = PNG_READ_CHUNK_MODE;

      }

   }

}

void /* PRIVATE */

png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)

{

#ifdef PNG_USE_LOCAL_ARRAYS

      PNG_CONST PNG_IHDR;

      PNG_CONST PNG_IDAT;

      PNG_CONST PNG_IEND;

      PNG_CONST PNG_PLTE;

#ifdef PNG_READ_bKGD_SUPPORTED

      PNG_CONST PNG_bKGD;

#endif

#ifdef PNG_READ_cHRM_SUPPORTED

      PNG_CONST PNG_cHRM;

#endif

#ifdef PNG_READ_gAMA_SUPPORTED

      PNG_CONST PNG_gAMA;

#endif

#ifdef PNG_READ_hIST_SUPPORTED

      PNG_CONST PNG_hIST;

#endif

#ifdef PNG_READ_iCCP_SUPPORTED

      PNG_CONST PNG_iCCP;

#endif

#ifdef PNG_READ_iTXt_SUPPORTED

      PNG_CONST PNG_iTXt;

#endif

#ifdef PNG_READ_oFFs_SUPPORTED

      PNG_CONST PNG_oFFs;

#endif

#ifdef PNG_READ_pCAL_SUPPORTED

      PNG_CONST PNG_pCAL;

#endif

#ifdef PNG_READ_pHYs_SUPPORTED

      PNG_CONST PNG_pHYs;

#endif

#ifdef PNG_READ_sBIT_SUPPORTED

      PNG_CONST PNG_sBIT;

#endif

#ifdef PNG_READ_sCAL_SUPPORTED

      PNG_CONST PNG_sCAL;

#endif

#ifdef PNG_READ_sRGB_SUPPORTED

      PNG_CONST PNG_sRGB;

#endif

#ifdef PNG_READ_sPLT_SUPPORTED

      PNG_CONST PNG_sPLT;

#endif

#ifdef PNG_READ_tEXt_SUPPORTED

      PNG_CONST PNG_tEXt;

#endif

#ifdef PNG_READ_tIME_SUPPORTED

      PNG_CONST PNG_tIME;

#endif

#ifdef PNG_READ_tRNS_SUPPORTED

      PNG_CONST PNG_tRNS;

#endif

#ifdef PNG_READ_zTXt_SUPPORTED

      PNG_CONST PNG_zTXt;

#endif

#endif /* PNG_USE_LOCAL_ARRAYS */

   /* First we make sure we have enough data for the 4 byte chunk name

    * and the 4 byte chunk length before proceeding with decoding the

    * chunk data.  To fully decode each of these chunks, we also make

    * sure we have enough data in the buffer for the 4 byte CRC at the

    * end of every chunk (except IDAT, which is handled separately).

    */

   if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))

   {

      png_byte chunk_length[4];

      if (png_ptr->buffer_size < 8)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_push_fill_buffer(png_ptr, chunk_length, 4);

      png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);

      png_reset_crc(png_ptr);

      png_crc_read(png_ptr, png_ptr->chunk_name, 4);

      png_check_chunk_name(png_ptr, png_ptr->chunk_name);

      png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;

   }

   if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))

     if (png_ptr->mode & PNG_AFTER_IDAT)

        png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;

   if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))

   {

      if (png_ptr->push_length != 13)

         png_error(png_ptr, "Invalid IHDR length");

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);

   }

   else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);

      png_ptr->process_mode = PNG_READ_DONE_MODE;

      png_push_have_end(png_ptr, info_ptr);

   }

#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED

   else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))

         png_ptr->mode |= PNG_HAVE_IDAT;

      png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);

      if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))

         png_ptr->mode |= PNG_HAVE_PLTE;

      else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))

      {

         if (!(png_ptr->mode & PNG_HAVE_IHDR))

            png_error(png_ptr, "Missing IHDR before IDAT");

         else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&

                  !(png_ptr->mode & PNG_HAVE_PLTE))

            png_error(png_ptr, "Missing PLTE before IDAT");

      }

   }

#endif

   else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);

   }

   else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))

   {

      /* If we reach an IDAT chunk, this means we have read all of the

       * header chunks, and we can start reading the image (or if this

       * is called after the image has been read - we have an error).

       */

      if (!(png_ptr->mode & PNG_HAVE_IHDR))

         png_error(png_ptr, "Missing IHDR before IDAT");

      else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&

          !(png_ptr->mode & PNG_HAVE_PLTE))

         png_error(png_ptr, "Missing PLTE before IDAT");

      if (png_ptr->mode & PNG_HAVE_IDAT)

      {

         if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))

            if (png_ptr->push_length == 0)

               return;

         if (png_ptr->mode & PNG_AFTER_IDAT)

            png_error(png_ptr, "Too many IDAT's found");

      }

      png_ptr->idat_size = png_ptr->push_length;

      png_ptr->mode |= PNG_HAVE_IDAT;

      png_ptr->process_mode = PNG_READ_IDAT_MODE;

      png_push_have_info(png_ptr, info_ptr);

      png_ptr->zstream.avail_out =

          (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,

          png_ptr->iwidth) + 1;

      png_ptr->zstream.next_out = png_ptr->row_buf;

      return;

   }

#ifdef PNG_READ_gAMA_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_sBIT_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_cHRM_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_sRGB_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_iCCP_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_sPLT_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_tRNS_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_bKGD_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_hIST_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_pHYs_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_oFFs_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_pCAL_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_sCAL_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_tIME_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_tEXt_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_zTXt_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#ifdef PNG_READ_iTXt_SUPPORTED

   else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

   else

   {

      if (png_ptr->push_length + 4 > png_ptr->buffer_size)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);

   }

   png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;

}

void /* PRIVATE */

png_push_crc_skip(png_structp png_ptr, png_uint_32 skip)

{

   png_ptr->process_mode = PNG_SKIP_MODE;

   png_ptr->skip_length = skip;

}

void /* PRIVATE */

png_push_crc_finish(png_structp png_ptr)

{

   if (png_ptr->skip_length && png_ptr->save_buffer_size)

   {

      png_size_t save_size;

      if (png_ptr->skip_length < (png_uint_32)png_ptr->save_buffer_size)

         save_size = (png_size_t)png_ptr->skip_length;

      else

         save_size = png_ptr->save_buffer_size;

      png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);

      png_ptr->skip_length -= save_size;

      png_ptr->buffer_size -= save_size;

      png_ptr->save_buffer_size -= save_size;

      png_ptr->save_buffer_ptr += save_size;

   }

   if (png_ptr->skip_length && png_ptr->current_buffer_size)

   {

      png_size_t save_size;

      if (png_ptr->skip_length < (png_uint_32)png_ptr->current_buffer_size)

         save_size = (png_size_t)png_ptr->skip_length;

      else

         save_size = png_ptr->current_buffer_size;

      png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);

      png_ptr->skip_length -= save_size;

      png_ptr->buffer_size -= save_size;

      png_ptr->current_buffer_size -= save_size;

      png_ptr->current_buffer_ptr += save_size;

   }

   if (!png_ptr->skip_length)

   {

      if (png_ptr->buffer_size < 4)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_crc_finish(png_ptr, 0);

      png_ptr->process_mode = PNG_READ_CHUNK_MODE;

   }

}

void PNGAPI

png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)

{

   png_bytep ptr;

   if (png_ptr == NULL)

      return;

   ptr = buffer;

   if (png_ptr->save_buffer_size)

   {

      png_size_t save_size;

      if (length < png_ptr->save_buffer_size)

         save_size = length;

      else

         save_size = png_ptr->save_buffer_size;

      png_memcpy(ptr, png_ptr->save_buffer_ptr, save_size);

      length -= save_size;

      ptr += save_size;

      png_ptr->buffer_size -= save_size;

      png_ptr->save_buffer_size -= save_size;

      png_ptr->save_buffer_ptr += save_size;

   }

   if (length && png_ptr->current_buffer_size)

   {

      png_size_t save_size;

      if (length < png_ptr->current_buffer_size)

         save_size = length;

      else

         save_size = png_ptr->current_buffer_size;

      png_memcpy(ptr, png_ptr->current_buffer_ptr, save_size);

      png_ptr->buffer_size -= save_size;

      png_ptr->current_buffer_size -= save_size;

      png_ptr->current_buffer_ptr += save_size;

   }

}

void /* PRIVATE */

png_push_save_buffer(png_structp png_ptr)

{

   if (png_ptr->save_buffer_size)

   {

      if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)

      {

         png_size_t i, istop;

         png_bytep sp;

         png_bytep dp;

         istop = png_ptr->save_buffer_size;

         for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;

            i < istop; i++, sp++, dp++)

         {

            *dp = *sp;

         }

      }

   }

   if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >

      png_ptr->save_buffer_max)

   {

      png_size_t new_max;

      png_bytep old_buffer;

      if (png_ptr->save_buffer_size > PNG_SIZE_MAX -

         (png_ptr->current_buffer_size + 256))

      {

        png_error(png_ptr, "Potential overflow of save_buffer");

      }

      new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;

      old_buffer = png_ptr->save_buffer;

      png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,

         (png_uint_32)new_max);

      if (png_ptr->save_buffer == NULL)

      {

        png_free(png_ptr, old_buffer);

        png_error(png_ptr, "Insufficient memory for save_buffer");

      }

      else

      {

        if (old_buffer)

          png_memcpy(png_ptr->save_buffer, old_buffer,

             png_ptr->save_buffer_size);

        else if (png_ptr->save_buffer_size)

          png_error(png_ptr, "save_buffer error");

        png_free(png_ptr, old_buffer);

        png_ptr->save_buffer_max = new_max;

      }

   }

   if (png_ptr->current_buffer_size)

   {

      png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,

         png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);

      png_ptr->save_buffer_size += png_ptr->current_buffer_size;

      png_ptr->current_buffer_size = 0;

   }

   png_ptr->save_buffer_ptr = png_ptr->save_buffer;

   png_ptr->buffer_size = 0;

}

void /* PRIVATE */

png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,

   png_size_t buffer_length)

{

   png_ptr->current_buffer = buffer;

   png_ptr->current_buffer_size = buffer_length;

   png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;

   png_ptr->current_buffer_ptr = png_ptr->current_buffer;

}

void /* PRIVATE */

png_push_read_IDAT(png_structp png_ptr)

{

#ifdef PNG_USE_LOCAL_ARRAYS

   PNG_CONST PNG_IDAT;

#endif

   if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))

   {

      png_byte chunk_length[4];

      if (png_ptr->buffer_size < 8)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_push_fill_buffer(png_ptr, chunk_length, 4);

      png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);

      png_reset_crc(png_ptr);

      png_crc_read(png_ptr, png_ptr->chunk_name, 4);

      png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;

      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))

      {

         png_ptr->process_mode = PNG_READ_CHUNK_MODE;

         if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))

            png_error(png_ptr, "Not enough compressed data");

         return;

      }

      png_ptr->idat_size = png_ptr->push_length;

   }

   if (png_ptr->idat_size && png_ptr->save_buffer_size)

   {

      png_size_t save_size;

      if (png_ptr->idat_size < (png_uint_32)png_ptr->save_buffer_size)

      {

         save_size = (png_size_t)png_ptr->idat_size;

         /* Check for overflow */

         if ((png_uint_32)save_size != png_ptr->idat_size)

            png_error(png_ptr, "save_size overflowed in pngpread");

      }

      else

         save_size = png_ptr->save_buffer_size;

      png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);

      png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);

      png_ptr->idat_size -= save_size;

      png_ptr->buffer_size -= save_size;

      png_ptr->save_buffer_size -= save_size;

      png_ptr->save_buffer_ptr += save_size;

   }

   if (png_ptr->idat_size && png_ptr->current_buffer_size)

   {

      png_size_t save_size;

      if (png_ptr->idat_size < (png_uint_32)png_ptr->current_buffer_size)

      {

         save_size = (png_size_t)png_ptr->idat_size;

         /* Check for overflow */

         if ((png_uint_32)save_size != png_ptr->idat_size)

            png_error(png_ptr, "save_size overflowed in pngpread");

      }

      else

         save_size = png_ptr->current_buffer_size;

      png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);

      png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);

      png_ptr->idat_size -= save_size;

      png_ptr->buffer_size -= save_size;

      png_ptr->current_buffer_size -= save_size;

      png_ptr->current_buffer_ptr += save_size;

   }

   if (!png_ptr->idat_size)

   {

      if (png_ptr->buffer_size < 4)

      {

         png_push_save_buffer(png_ptr);

         return;

      }

      png_crc_finish(png_ptr, 0);

      png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;

      png_ptr->mode |= PNG_AFTER_IDAT;

   }

}

void /* PRIVATE */

png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,

   png_size_t buffer_length)

{

   /* The caller checks for a non-zero buffer length. */

   if (!(buffer_length > 0) || buffer == NULL)

      png_error(png_ptr, "No IDAT data (internal error)");

   /* This routine must process all the data it has been given

    * before returning, calling the row callback as required to

    * handle the uncompressed results.

    */

   png_ptr->zstream.next_in = buffer;

   png_ptr->zstream.avail_in = (uInt)buffer_length;

   /* Keep going until the decompressed data is all processed

    * or the stream marked as finished.

    */

   while (png_ptr->zstream.avail_in > 0 &&

	  !(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))

   {

      int ret;

      /* We have data for zlib, but we must check that zlib

       * has somewhere to put the results.  It doesn't matter

       * if we don't expect any results -- it may be the input

       * data is just the LZ end code.

       */

      if (!(png_ptr->zstream.avail_out > 0))

      {

         png_ptr->zstream.avail_out =

             (uInt) PNG_ROWBYTES(png_ptr->pixel_depth,

             png_ptr->iwidth) + 1;

         png_ptr->zstream.next_out = png_ptr->row_buf;

      }

      /* Using Z_SYNC_FLUSH here means that an unterminated

       * LZ stream can still be handled (a stream with a missing

       * end code), otherwise (Z_NO_FLUSH) a future zlib

       * implementation might defer output and, therefore,

       * change the current behavior.  (See comments in inflate.c

       * for why this doesn't happen at present with zlib 1.2.5.)

       */

      ret = inflate(&png_ptr->zstream, Z_SYNC_FLUSH);

      /* Check for any failure before proceeding. */

      if (ret != Z_OK && ret != Z_STREAM_END)

      {

	 /* Terminate the decompression. */

	 png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;

         /* This may be a truncated stream (missing or

	  * damaged end code).  Treat that as a warning.

	  */

         if (png_ptr->row_number >= png_ptr->num_rows ||

	     png_ptr->pass > 6)

	    png_warning(png_ptr, "Truncated compressed data in IDAT");

	 else

	    png_error(png_ptr, "Decompression error in IDAT");

	 /* Skip the check on unprocessed input */

         return;

      }

      /* Did inflate output any data? */

      if (png_ptr->zstream.next_out != png_ptr->row_buf)

      {