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

 *

 * libpng 1.2.5 - October 3, 2002

 * For conditions of distribution and use, see copyright notice in png.h

 * Copyright (c) 1998-2002 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.)

 */

#define PNG_INTERNAL

#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)

{

   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)

{

   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;

      }

#if defined(PNG_READ_tEXt_SUPPORTED)

      case PNG_READ_tEXt_MODE:

      {

         png_push_read_tEXt(png_ptr, info_ptr);

         break;

      }

#endif

#if defined(PNG_READ_zTXt_SUPPORTED)

      case PNG_READ_zTXt_MODE:

      {

         png_push_read_zTXt(png_ptr, info_ptr);

         break;

      }

#endif

#if defined(PNG_READ_iTXt_SUPPORTED)

      case PNG_READ_iTXt_MODE:

      {

         png_push_read_iTXt(png_ptr, info_ptr);

         break;

      }

#endif

      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_IHDR;

      PNG_IDAT;

      PNG_IEND;

      PNG_PLTE;

#if defined(PNG_READ_bKGD_SUPPORTED)

      PNG_bKGD;

#endif

#if defined(PNG_READ_cHRM_SUPPORTED)

      PNG_cHRM;

#endif

#if defined(PNG_READ_gAMA_SUPPORTED)

      PNG_gAMA;

#endif

#if defined(PNG_READ_hIST_SUPPORTED)

      PNG_hIST;

#endif

#if defined(PNG_READ_iCCP_SUPPORTED)

      PNG_iCCP;

#endif

#if defined(PNG_READ_iTXt_SUPPORTED)

      PNG_iTXt;

#endif

#if defined(PNG_READ_oFFs_SUPPORTED)

      PNG_oFFs;

#endif

#if defined(PNG_READ_pCAL_SUPPORTED)

      PNG_pCAL;

#endif

#if defined(PNG_READ_pHYs_SUPPORTED)

      PNG_pHYs;

#endif

#if defined(PNG_READ_sBIT_SUPPORTED)

      PNG_sBIT;

#endif

#if defined(PNG_READ_sCAL_SUPPORTED)

      PNG_sCAL;

#endif

#if defined(PNG_READ_sRGB_SUPPORTED)

      PNG_sRGB;

#endif

#if defined(PNG_READ_sPLT_SUPPORTED)

      PNG_sPLT;

#endif

#if defined(PNG_READ_tEXt_SUPPORTED)

      PNG_tEXt;

#endif

#if defined(PNG_READ_tIME_SUPPORTED)

      PNG_tIME;

#endif

#if defined(PNG_READ_tRNS_SUPPORTED)

      PNG_tRNS;

#endif

#if defined(PNG_READ_zTXt_SUPPORTED)

      PNG_zTXt;

#endif

#endif /* PNG_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_32(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_IHDR, 4))

   {

      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_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_bytep)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->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_ptr->irowbytes;

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

      return;

   }

   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);

   }

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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

#if defined(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_push_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#if defined(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_push_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);

   }

#endif

#if defined(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_push_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_push_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;

   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;

      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(png_ptr,

         (png_uint_32)new_max);

      png_memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);

      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_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_32(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_bytep)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);

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

         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);

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

        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)

{

   int ret;

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

      png_error(png_ptr, "Extra compression data");

   png_ptr->zstream.next_in = buffer;

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

   for(;;)

   {

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

      if (ret != Z_OK)

      {

         if (ret == Z_STREAM_END)

         {

            if (png_ptr->zstream.avail_in)

               png_error(png_ptr, "Extra compressed data");

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

            {

               png_push_process_row(png_ptr);

            }

            png_ptr->mode |= PNG_AFTER_IDAT;

            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;

            break;

         }

         else if (ret == Z_BUF_ERROR)

            break;

         else

            png_error(png_ptr, "Decompression Error");

      }

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

      {

         if ((

#if defined(PNG_READ_INTERLACING_SUPPORTED)

             png_ptr->interlaced && png_ptr->pass > 6) ||

             (!png_ptr->interlaced &&

#endif

             png_ptr->row_number == png_ptr->num_rows-1))

         {

           if (png_ptr->zstream.avail_in)

             png_warning(png_ptr, "Too much data in IDAT chunks");

           png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;

           break;

         }

         png_push_process_row(png_ptr);

         png_ptr->zstream.avail_out = (uInt)png_ptr->irowbytes;

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

      }

      else

         break;

   }

}

void /* PRIVATE */

png_push_process_row(png_structp png_ptr)

{

   png_ptr->row_info.color_type = png_ptr->color_type;

   png_ptr->row_info.width = png_ptr->iwidth;

   png_ptr->row_info.channels = png_ptr->channels;

   png_ptr->row_info.bit_depth = png_ptr->bit_depth;

   png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;

   png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *

      (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);

   png_read_filter_row(png_ptr, &(png_ptr->row_info),

      png_ptr->row_buf + 1, png_ptr->prev_row + 1,

      (int)(png_ptr->row_buf[0]));

   png_memcpy_check(png_ptr, png_ptr->prev_row, png_ptr->row_buf,

      png_ptr->rowbytes + 1);

   if (png_ptr->transformations)

      png_do_read_transformations(png_ptr);

#if defined(PNG_READ_INTERLACING_SUPPORTED)

   /* blow up interlaced rows to full size */

   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))

   {

      if (png_ptr->pass < 6)

/*       old interface (pre-1.0.9):

         png_do_read_interlace(&(png_ptr->row_info),

            png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);

 */

         png_do_read_interlace(png_ptr);

    switch (png_ptr->pass)

    {

         case 0:

         {

            int i;

            for (i = 0; i < 8 && png_ptr->pass == 0; i++)

            {

               png_push_have_row(png_ptr, png_ptr->row_buf + 1);

               png_read_push_finish_row(png_ptr); /* updates png_ptr->pass */

            }

            if (png_ptr->pass == 2) /* pass 1 might be empty */

            {

               for (i = 0; i < 4 && png_ptr->pass == 2; i++)

               {

                  png_push_have_row(png_ptr, png_bytep_NULL);

                  png_read_push_finish_row(png_ptr);

               }

            }

            if (png_ptr->pass == 4 && png_ptr->height <= 4)

            {

               for (i = 0; i < 2 && png_ptr->pass == 4; i++)

               {

                  png_push_have_row(png_ptr, png_bytep_NULL);

                  png_read_push_finish_row(png_ptr);

               }

            }

            if (png_ptr->pass == 6 && png_ptr->height <= 4)

            {

                png_push_have_row(png_ptr, png_bytep_NULL);

                png_read_push_finish_row(png_ptr);

            }

            break;

         }

         case 1:

         {

            int i;

            for (i = 0; i < 8 && png_ptr->pass == 1; i++)

            {

               png_push_have_row(png_ptr, png_ptr->row_buf + 1);

               png_read_push_finish_row(png_ptr);

            }

            if (png_ptr->pass == 2) /* skip top 4 generated rows */

            {

               for (i = 0; i < 4 && png_ptr->pass == 2; i++)

               {

                  png_push_have_row(png_ptr, png_bytep_NULL);

                  png_read_push_finish_row(png_ptr);

               }

            }

            break;

         }

         case 2:

         {

            int i;

            for (i = 0; i < 4 && png_ptr->pass == 2; i++)

            {

               png_push_have_row(png_ptr, png_ptr->row_buf + 1);

               png_read_push_finish_row(png_ptr);

            }

            for (i = 0; i < 4 && png_ptr->pass == 2; i++)

            {

               png_push_have_row(png_ptr, png_bytep_NULL);

               png_read_push_finish_row(png_ptr);

            }

            if (png_ptr->pass == 4) /* pass 3 might be empty */

            {

               for (i = 0; i < 2 && png_ptr->pass == 4; i++)

               {

                  png_push_have_row(png_ptr, png_bytep_NULL);

                  png_read_push_finish_row(png_ptr);

               }

            }

            break;

         }

         case 3: