/* pngread.c - read a PNG file

 *

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

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

 *

 * This code is released under the libpng license.

 * For conditions of distribution and use, see the disclaimer

 * and license in png.h

 *

 * This file contains routines that an application calls directly to

 * read a PNG file or stream.

 */

#include "png.h"

/* Create a PNG structure for reading, and allocate any memory needed. */

png_structp PNGAPI

png_create_read_struct(png_const_charp user_png_ver, png_voidp error_ptr,

   png_error_ptr error_fn, png_error_ptr warn_fn)

{

#ifdef PNG_USER_MEM_SUPPORTED

   return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn,

}

/* Alternate create PNG structure for reading, and allocate any memory needed. */

png_structp PNGAPI

png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,

   png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,

   png_malloc_ptr malloc_fn, png_free_ptr free_fn)

{

#endif /* PNG_USER_MEM_SUPPORTED */

#ifdef PNG_SETJMP_SUPPORTED

   volatile

#endif

   png_structp png_ptr;

#ifdef PNG_SETJMP_SUPPORTED

#ifdef USE_FAR_KEYWORD

   jmp_buf jmpbuf;

#endif

#endif

   int i;

   png_debug(1, "in png_create_read_struct");

#ifdef PNG_USER_MEM_SUPPORTED

   png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,

#else

   png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);

#endif

   if (png_ptr == NULL)

      return (NULL);

   /* Added at libpng-1.2.6 */

#ifdef PNG_SET_USER_LIMITS_SUPPORTED

#endif

#ifdef PNG_SETJMP_SUPPORTED

#ifdef USE_FAR_KEYWORD

   if (setjmp(jmpbuf))

#else

#endif

   {

      png_free(png_ptr, png_ptr->zbuf);

      png_ptr->zbuf = NULL;

#ifdef PNG_USER_MEM_SUPPORTED

      png_destroy_struct_2((png_voidp)png_ptr,

         (png_free_ptr)free_fn, (png_voidp)mem_ptr);

#else

      png_destroy_struct((png_voidp)png_ptr);

#endif

      return (NULL);

   }

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

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

   return (png_ptr);

}

/* Read the information before the actual image data.  This has been

 * changed in v0.90 to allow reading a file that already has the magic

 * bytes read from the stream.  You can tell libpng how many bytes have

 * been read from the beginning of the stream (up to the maximum of 8)

 * via png_set_sig_bytes(), and we will only check the remaining bytes

 * here.  The application can then have access to the signature bytes we

 * read if it is determined that this isn't a valid PNG file.

 */

void PNGAPI

png_read_info(png_structp png_ptr, png_infop info_ptr)

{

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

      return;

   /* If we haven't checked all of the PNG signature bytes, do so now. */

   if (png_ptr->sig_bytes < 8)

   {

      png_size_t num_checked = png_ptr->sig_bytes,

                 num_to_check = 8 - num_checked;

      png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);

      png_ptr->sig_bytes = 8;

      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");

      }

      if (num_checked < 3)

         png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;

   }

   for (;;)

   {

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

#endif

      png_uint_32 length = png_read_chunk_header(png_ptr);

      PNG_CONST png_bytep chunk_name = png_ptr->chunk_name;

      /* This should be a binary subdivision search or a hash for

       * matching the chunk name rather than a linear search.

       */

      if (!png_memcmp(chunk_name, png_IDAT, 4))

        if (png_ptr->mode & PNG_AFTER_IDAT)

          png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;

      if (!png_memcmp(chunk_name, png_IHDR, 4))

         png_handle_IHDR(png_ptr, info_ptr, length);

      else if (!png_memcmp(chunk_name, png_IEND, 4))

         png_handle_IEND(png_ptr, info_ptr, length);

#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED

      else if (png_handle_as_unknown(png_ptr, chunk_name))

      {

         if (!png_memcmp(chunk_name, png_IDAT, 4))

            png_ptr->mode |= PNG_HAVE_IDAT;

         png_handle_unknown(png_ptr, info_ptr, length);

         if (!png_memcmp(chunk_name, png_PLTE, 4))

            png_ptr->mode |= PNG_HAVE_PLTE;

         else if (!png_memcmp(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");

            break;

         }

      }

#endif

      else if (!png_memcmp(chunk_name, png_PLTE, 4))

         png_handle_PLTE(png_ptr, info_ptr, length);

      else if (!png_memcmp(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");

         png_ptr->idat_size = length;

         png_ptr->mode |= PNG_HAVE_IDAT;

         break;

      }

      else if (!png_memcmp(chunk_name, png_bKGD, 4))

         png_handle_bKGD(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_cHRM, 4))

         png_handle_cHRM(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_gAMA, 4))

         png_handle_gAMA(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_hIST, 4))

         png_handle_hIST(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_oFFs, 4))

         png_handle_oFFs(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_pCAL, 4))

         png_handle_pCAL(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_sCAL, 4))

         png_handle_sCAL(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_pHYs, 4))

         png_handle_pHYs(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_sBIT, 4))

         png_handle_sBIT(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_sRGB, 4))

         png_handle_sRGB(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_iCCP, 4))

         png_handle_iCCP(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_sPLT, 4))

         png_handle_sPLT(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_tEXt, 4))

         png_handle_tEXt(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_tIME, 4))

         png_handle_tIME(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_tRNS, 4))

         png_handle_tRNS(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_zTXt, 4))

         png_handle_zTXt(png_ptr, info_ptr, length);

#endif

      else if (!png_memcmp(chunk_name, png_iTXt, 4))

         png_handle_iTXt(png_ptr, info_ptr, length);

#endif

      else

         png_handle_unknown(png_ptr, info_ptr, length);

   }

}

/* Optional call to update the users info_ptr structure */

void PNGAPI

png_read_update_info(png_structp png_ptr, png_infop info_ptr)

{

   png_debug(1, "in png_read_update_info");

   if (png_ptr == NULL)

      return;

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

      png_read_start_row(png_ptr);

   else

      png_warning(png_ptr,

      "Ignoring extra png_read_update_info() call; row buffer not reallocated");

   png_read_transform_info(png_ptr, info_ptr);

}

/* Initialize palette, background, etc, after transformations

 * are set, but before any reading takes place.  This allows

 * the user to obtain a gamma-corrected palette, for example.

 * If the user doesn't call this, we will do it ourselves.

 */

void PNGAPI

png_start_read_image(png_structp png_ptr)

{

   png_debug(1, "in png_start_read_image");

   if (png_ptr == NULL)

      return;

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

      png_read_start_row(png_ptr);

}

void PNGAPI

png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)

{

   PNG_CONST int png_pass_dsp_mask[7] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,

      0xff};

   PNG_CONST int png_pass_mask[7] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};

   int ret;

   if (png_ptr == NULL)

      return;

   png_debug2(1, "in png_read_row (row %lu, pass %d)",

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

      png_read_start_row(png_ptr);

   if (png_ptr->row_number == 0 && png_ptr->pass == 0)

   {

   /* Check for transforms that have been set but were defined out */

#if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)

   if (png_ptr->transformations & PNG_INVERT_MONO)

#endif

#if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)

   if (png_ptr->transformations & PNG_FILLER)

#endif

#if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && !defined(PNG_READ_PACKSWAP_SUPPORTED)

   if (png_ptr->transformations & PNG_PACKSWAP)

#endif

#if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)

   if (png_ptr->transformations & PNG_PACK)

#endif

#if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)

   if (png_ptr->transformations & PNG_SHIFT)

#endif

#if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)

   if (png_ptr->transformations & PNG_BGR)

#endif

#if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)

   if (png_ptr->transformations & PNG_SWAP_BYTES)

#endif

   }

   /* If interlaced and we do not need a new row, combine row and return */

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

   {

      switch (png_ptr->pass)