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

 *

 * Last changed in libpng 1.2.32 [September 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.)

 */

#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)

{

   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;

      }

#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_CONST PNG_IHDR;

      PNG_CONST PNG_IDAT;

      PNG_CONST PNG_IEND;

      PNG_CONST PNG_PLTE;

#if defined(PNG_READ_bKGD_SUPPORTED)

      PNG_CONST PNG_bKGD;

#endif

#if defined(PNG_READ_cHRM_SUPPORTED)

      PNG_CONST PNG_cHRM;

#endif

#if defined(PNG_READ_gAMA_SUPPORTED)

      PNG_CONST PNG_gAMA;

#endif

#if defined(PNG_READ_hIST_SUPPORTED)

      PNG_CONST PNG_hIST;

#endif

#if defined(PNG_READ_iCCP_SUPPORTED)

      PNG_CONST PNG_iCCP;

#endif

#if defined(PNG_READ_iTXt_SUPPORTED)

      PNG_CONST PNG_iTXt;

#endif

#if defined(PNG_READ_oFFs_SUPPORTED)

      PNG_CONST PNG_oFFs;

#endif

#if defined(PNG_READ_pCAL_SUPPORTED)

      PNG_CONST PNG_pCAL;

#endif

#if defined(PNG_READ_pHYs_SUPPORTED)

      PNG_CONST PNG_pHYs;

#endif

#if defined(PNG_READ_sBIT_SUPPORTED)

      PNG_CONST PNG_sBIT;

#endif

#if defined(PNG_READ_sCAL_SUPPORTED)

      PNG_CONST PNG_sCAL;

#endif

#if defined(PNG_READ_sRGB_SUPPORTED)

      PNG_CONST PNG_sRGB;

#endif

#if defined(PNG_READ_sPLT_SUPPORTED)

      PNG_CONST PNG_sPLT;

#endif

#if defined(PNG_READ_tEXt_SUPPORTED)

      PNG_CONST PNG_tEXt;

#endif

#if defined(PNG_READ_tIME_SUPPORTED)

      PNG_CONST PNG_tIME;

#endif

#if defined(PNG_READ_tRNS_SUPPORTED)

      PNG_CONST PNG_tRNS;

#endif

#if defined(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_ptr->irowbytes;

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

      return;

   }

#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;