/* pngread.c - read a PNG file

 *

 * Last changed in libpng 1.2.30 [August 15, 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 an application calls directly to

 * read a PNG file or stream.

 */

#define PNG_INTERNAL

#include "png.h"

#if defined(PNG_READ_SUPPORTED)

/* 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,

      warn_fn, png_voidp_NULL, png_malloc_ptr_NULL, png_free_ptr_NULL));

}

/* 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\n");

#ifdef PNG_USER_MEM_SUPPORTED

   png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,

      (png_malloc_ptr)malloc_fn, (png_voidp)mem_ptr);

#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

   png_ptr->user_width_max=PNG_USER_WIDTH_MAX;

   png_ptr->user_height_max=PNG_USER_HEIGHT_MAX;

#endif

#ifdef PNG_SETJMP_SUPPORTED

#ifdef USE_FAR_KEYWORD

   if (setjmp(jmpbuf))

#else

   if (setjmp(png_ptr->jmpbuf))

#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);

   }

#ifdef USE_FAR_KEYWORD

   png_memcpy(png_ptr->jmpbuf, jmpbuf, png_sizeof(jmp_buf));

#endif

#endif

#ifdef PNG_USER_MEM_SUPPORTED

   png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);

#endif

   png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);

   if (user_png_ver)

   {

     i = 0;

     do

     {

       if (user_png_ver[i] != png_libpng_ver[i])

          png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;

     } while (png_libpng_ver[i++]);

   }

   else

        png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;

   if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)

   {

     /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so

      * we must recompile any applications that use any older library version.

      * For versions after libpng 1.0, we will be compatible, so we need

      * only check the first digit.

      */

     if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||

         (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||

         (user_png_ver[0] == '0' && user_png_ver[2] < '9'))

     {

#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)

        char msg[80];

        if (user_png_ver)

        {

          png_snprintf(msg, 80,

             "Application was compiled with png.h from libpng-%.20s",

             user_png_ver);

          png_warning(png_ptr, msg);

        }

        png_snprintf(msg, 80,

             "Application  is  running with png.c from libpng-%.20s",

           png_libpng_ver);

        png_warning(png_ptr, msg);

#endif

#ifdef PNG_ERROR_NUMBERS_SUPPORTED

        png_ptr->flags = 0;

#endif

        png_error(png_ptr,

           "Incompatible libpng version in application and library");

     }

   }

   /* initialize zbuf - compression buffer */

   png_ptr->zbuf_size = PNG_ZBUF_SIZE;

   png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,

     (png_uint_32)png_ptr->zbuf_size);

   png_ptr->zstream.zalloc = png_zalloc;

   png_ptr->zstream.zfree = png_zfree;

   png_ptr->zstream.opaque = (voidpf)png_ptr;

   switch (inflateInit(&png_ptr->zstream))

   {

     case Z_OK: /* Do nothing */ break;

     case Z_MEM_ERROR:

     case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory error"); break;

     case Z_VERSION_ERROR: png_error(png_ptr, "zlib version error"); break;

     default: png_error(png_ptr, "Unknown zlib error");

   }

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

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

   png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL);

#ifdef PNG_SETJMP_SUPPORTED

/* Applications that neglect to set up their own setjmp() and then encounter

   a png_error() will longjmp here.  Since the jmpbuf is then meaningless we

   abort instead of returning. */

#ifdef USE_FAR_KEYWORD

   if (setjmp(jmpbuf))

      PNG_ABORT();

   png_memcpy(png_ptr->jmpbuf, jmpbuf, png_sizeof(jmp_buf));

#else

   if (setjmp(png_ptr->jmpbuf))

      PNG_ABORT();

#endif

#endif

   return (png_ptr);

}

#if defined(PNG_1_0_X) || defined(PNG_1_2_X)

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

   This interface is deprecated in favour of the png_create_read_struct(),

   and it will disappear as of libpng-1.3.0. */

#undef png_read_init

void PNGAPI

png_read_init(png_structp png_ptr)

{

   /* We only come here via pre-1.0.7-compiled applications */

   png_read_init_2(png_ptr, "1.0.6 or earlier", 0, 0);

}

void PNGAPI

png_read_init_2(png_structp png_ptr, png_const_charp user_png_ver,

   png_size_t png_struct_size, png_size_t png_info_size)

{

   /* We only come here via pre-1.0.12-compiled applications */

   if (png_ptr == NULL) return;

#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)

   if (png_sizeof(png_struct) > png_struct_size ||

      png_sizeof(png_info) > png_info_size)

   {

      char msg[80];

      png_ptr->warning_fn = NULL;

      if (user_png_ver)

      {

        png_snprintf(msg, 80,

           "Application was compiled with png.h from libpng-%.20s",

           user_png_ver);

        png_warning(png_ptr, msg);

      }

      png_snprintf(msg, 80,

         "Application  is  running with png.c from libpng-%.20s",

         png_libpng_ver);

      png_warning(png_ptr, msg);

   }

#endif

   if (png_sizeof(png_struct) > png_struct_size)

     {

       png_ptr->error_fn = NULL;

#ifdef PNG_ERROR_NUMBERS_SUPPORTED

       png_ptr->flags = 0;

#endif

       png_error(png_ptr,

       "The png struct allocated by the application for reading is too small.");

     }

   if (png_sizeof(png_info) > png_info_size)

     {

       png_ptr->error_fn = NULL;

#ifdef PNG_ERROR_NUMBERS_SUPPORTED

       png_ptr->flags = 0;

#endif

       png_error(png_ptr,

         "The info struct allocated by application for reading is too small.");

     }

   png_read_init_3(&png_ptr, user_png_ver, png_struct_size);

}

#endif /* PNG_1_0_X || PNG_1_2_X */

void PNGAPI

png_read_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,

   png_size_t png_struct_size)

{

#ifdef PNG_SETJMP_SUPPORTED

   jmp_buf tmp_jmp;  /* to save current jump buffer */

#endif

   int i = 0;

   png_structp png_ptr=*ptr_ptr;

   if (png_ptr == NULL) return;

   do

   {

     if (user_png_ver[i] != png_libpng_ver[i])

     {

#ifdef PNG_LEGACY_SUPPORTED

       png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;

#else

       png_ptr->warning_fn = NULL;

       png_warning(png_ptr,

        "Application uses deprecated png_read_init() and should be recompiled.");

       break;

#endif

     }

   } while (png_libpng_ver[i++]);

   png_debug(1, "in png_read_init_3\n");

#ifdef PNG_SETJMP_SUPPORTED

   /* save jump buffer and error functions */

   png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));

#endif

   if (png_sizeof(png_struct) > png_struct_size)

   {

      png_destroy_struct(png_ptr);

      *ptr_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);

      png_ptr = *ptr_ptr;

   }

   /* reset all variables to 0 */

   png_memset(png_ptr, 0, png_sizeof(png_struct));

#ifdef PNG_SETJMP_SUPPORTED

   /* restore jump buffer */

   png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof(jmp_buf));

#endif

   /* added at libpng-1.2.6 */

#ifdef PNG_SET_USER_LIMITS_SUPPORTED

   png_ptr->user_width_max=PNG_USER_WIDTH_MAX;

   png_ptr->user_height_max=PNG_USER_HEIGHT_MAX;

#endif

   /* initialize zbuf - compression buffer */

   png_ptr->zbuf_size = PNG_ZBUF_SIZE;

   png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,

     (png_uint_32)png_ptr->zbuf_size);

   png_ptr->zstream.zalloc = png_zalloc;

   png_ptr->zstream.zfree = png_zfree;

   png_ptr->zstream.opaque = (voidpf)png_ptr;

   switch (inflateInit(&png_ptr->zstream))

   {

     case Z_OK: /* Do nothing */ break;

     case Z_MEM_ERROR:

     case Z_STREAM_ERROR: png_error(png_ptr, "zlib memory"); break;

     case Z_VERSION_ERROR: png_error(png_ptr, "zlib version"); break;

     default: png_error(png_ptr, "Unknown zlib error");

   }

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

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

   png_set_read_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL);

}

#ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED

/* 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;

   png_debug(1, "in png_read_info\n");

   /* 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 (;;)

   {

#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_sPLT_SUPPORTED)

      PNG_CONST PNG_sPLT;

#endif

#if defined(PNG_READ_sRGB_SUPPORTED)

      PNG_CONST PNG_sRGB;

#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 */

      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;

      }

#if defined(PNG_READ_bKGD_SUPPORTED)

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

         png_handle_bKGD(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_cHRM_SUPPORTED)

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

         png_handle_cHRM(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_gAMA_SUPPORTED)

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

         png_handle_gAMA(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_hIST_SUPPORTED)

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

         png_handle_hIST(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_oFFs_SUPPORTED)

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

         png_handle_oFFs(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_pCAL_SUPPORTED)

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

         png_handle_pCAL(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_sCAL_SUPPORTED)

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

         png_handle_sCAL(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_pHYs_SUPPORTED)

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

         png_handle_pHYs(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_sBIT_SUPPORTED)

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

         png_handle_sBIT(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_sRGB_SUPPORTED)

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

         png_handle_sRGB(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_iCCP_SUPPORTED)

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

         png_handle_iCCP(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_sPLT_SUPPORTED)

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

         png_handle_sPLT(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_tEXt_SUPPORTED)

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

         png_handle_tEXt(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_tIME_SUPPORTED)

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

         png_handle_tIME(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_tRNS_SUPPORTED)

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

         png_handle_tRNS(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_zTXt_SUPPORTED)

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

         png_handle_zTXt(png_ptr, info_ptr, length);

#endif

#if defined(PNG_READ_iTXt_SUPPORTED)

      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);

   }