/* png.c - location for general purpose libpng functions

 *

 * 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.)

 */

#define PNG_INTERNAL

#define PNG_NO_EXTERN

#include "png.h"

/* Generate a compiler error if there is an old png.h in the search path. */

typedef version_1_2_32 Your_png_h_is_not_version_1_2_32;

/* Version information for C files.  This had better match the version

 * string defined in png.h.  */

#ifdef PNG_USE_GLOBAL_ARRAYS

/* png_libpng_ver was changed to a function in version 1.0.5c */

PNG_CONST char png_libpng_ver[18] = PNG_LIBPNG_VER_STRING;

#ifdef PNG_READ_SUPPORTED

/* png_sig was changed to a function in version 1.0.5c */

/* Place to hold the signature string for a PNG file. */

PNG_CONST png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};

#endif /* PNG_READ_SUPPORTED */

/* Invoke global declarations for constant strings for known chunk types */

PNG_IHDR;

PNG_IDAT;

PNG_IEND;

PNG_PLTE;

PNG_bKGD;

PNG_cHRM;

PNG_gAMA;

PNG_hIST;

PNG_iCCP;

PNG_iTXt;

PNG_oFFs;

PNG_pCAL;

PNG_sCAL;

PNG_pHYs;

PNG_sBIT;

PNG_sPLT;

PNG_sRGB;

PNG_tEXt;

PNG_tIME;

PNG_tRNS;

PNG_zTXt;

#ifdef PNG_READ_SUPPORTED

/* arrays to facilitate easy interlacing - use pass (0 - 6) as index */

/* start of interlace block */

PNG_CONST int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};

/* offset to next interlace block */

PNG_CONST int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};

/* start of interlace block in the y direction */

PNG_CONST int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};

/* offset to next interlace block in the y direction */

PNG_CONST int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};

/* Height of interlace block.  This is not currently used - if you need

 * it, uncomment it here and in png.h

PNG_CONST int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};

*/

/* Mask to determine which pixels are valid in a pass */

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

/* Mask to determine which pixels to overwrite while displaying */

PNG_CONST int FARDATA png_pass_dsp_mask[]

   = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};

#endif /* PNG_READ_SUPPORTED */

#endif /* PNG_USE_GLOBAL_ARRAYS */

/* Tells libpng that we have already handled the first "num_bytes" bytes

 * of the PNG file signature.  If the PNG data is embedded into another

 * stream we can set num_bytes = 8 so that libpng will not attempt to read

 * or write any of the magic bytes before it starts on the IHDR.

 */

#ifdef PNG_READ_SUPPORTED

void PNGAPI

png_set_sig_bytes(png_structp png_ptr, int num_bytes)

{

   if (png_ptr == NULL) return;

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

   if (num_bytes > 8)

      png_error(png_ptr, "Too many bytes for PNG signature.");

   png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);

}

/* Checks whether the supplied bytes match the PNG signature.  We allow

 * checking less than the full 8-byte signature so that those apps that

 * already read the first few bytes of a file to determine the file type

 * can simply check the remaining bytes for extra assurance.  Returns

 * an integer less than, equal to, or greater than zero if sig is found,

 * respectively, to be less than, to match, or be greater than the correct

 * PNG signature (this is the same behaviour as strcmp, memcmp, etc).

 */

int PNGAPI

png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)

{

   png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};

   if (num_to_check > 8)

      num_to_check = 8;

   else if (num_to_check < 1)

      return (-1);

   if (start > 7)

      return (-1);

   if (start + num_to_check > 8)

      num_to_check = 8 - start;

   return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));

}

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

/* (Obsolete) function to check signature bytes.  It does not allow one

 * to check a partial signature.  This function might be removed in the

 * future - use png_sig_cmp().  Returns true (nonzero) if the file is PNG.

 */

int PNGAPI

png_check_sig(png_bytep sig, int num)

{

  return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));

}

#endif

#endif /* PNG_READ_SUPPORTED */

#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)

/* Function to allocate memory for zlib and clear it to 0. */

#ifdef PNG_1_0_X

voidpf PNGAPI

#else

voidpf /* private */

#endif

png_zalloc(voidpf png_ptr, uInt items, uInt size)

{

   png_voidp ptr;

   png_structp p=(png_structp)png_ptr;

   png_uint_32 save_flags=p->flags;

   png_uint_32 num_bytes;

   if (png_ptr == NULL) return (NULL);

   if (items > PNG_UINT_32_MAX/size)

   {

     png_warning (p, "Potential overflow in png_zalloc()");

     return (NULL);

   }

   num_bytes = (png_uint_32)items * size;

   p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;

   ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);

   p->flags=save_flags;

#if defined(PNG_1_0_X) && !defined(PNG_NO_ZALLOC_ZERO)

   if (ptr == NULL)

       return ((voidpf)ptr);

   if (num_bytes > (png_uint_32)0x8000L)

   {

      png_memset(ptr, 0, (png_size_t)0x8000L);

      png_memset((png_bytep)ptr + (png_size_t)0x8000L, 0,

         (png_size_t)(num_bytes - (png_uint_32)0x8000L));

   }

   else

   {

      png_memset(ptr, 0, (png_size_t)num_bytes);

   }

#endif

   return ((voidpf)ptr);

}

/* function to free memory for zlib */

#ifdef PNG_1_0_X

void PNGAPI

#else

void /* private */

#endif

png_zfree(voidpf png_ptr, voidpf ptr)

{

   png_free((png_structp)png_ptr, (png_voidp)ptr);

}

/* Reset the CRC variable to 32 bits of 1's.  Care must be taken

 * in case CRC is > 32 bits to leave the top bits 0.

 */

void /* PRIVATE */

png_reset_crc(png_structp png_ptr)

{

   png_ptr->crc = crc32(0, Z_NULL, 0);

}

/* Calculate the CRC over a section of data.  We can only pass as

 * much data to this routine as the largest single buffer size.  We

 * also check that this data will actually be used before going to the

 * trouble of calculating it.

 */

void /* PRIVATE */

png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)

{

   int need_crc = 1;

   if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */

   {

      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==

          (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))

         need_crc = 0;

   }

   else                                                    /* critical */

   {

      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)

         need_crc = 0;

   }

   if (need_crc)

      png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length);

}

/* Allocate the memory for an info_struct for the application.  We don't

 * really need the png_ptr, but it could potentially be useful in the

 * future.  This should be used in favour of malloc(png_sizeof(png_info))

 * and png_info_init() so that applications that want to use a shared

 * libpng don't have to be recompiled if png_info changes size.

 */

png_infop PNGAPI

png_create_info_struct(png_structp png_ptr)

{

   png_infop info_ptr;

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

   if (png_ptr == NULL) return (NULL);

#ifdef PNG_USER_MEM_SUPPORTED

   info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,

      png_ptr->malloc_fn, png_ptr->mem_ptr);

#else

   info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);

#endif

   if (info_ptr != NULL)

      png_info_init_3(&info_ptr, png_sizeof(png_info));

   return (info_ptr);

}

/* This function frees the memory associated with a single info struct.

 * Normally, one would use either png_destroy_read_struct() or

 * png_destroy_write_struct() to free an info struct, but this may be

 * useful for some applications.

 */

void PNGAPI

png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)

{

   png_infop info_ptr = NULL;

   if (png_ptr == NULL) return;

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

   if (info_ptr_ptr != NULL)

      info_ptr = *info_ptr_ptr;

   if (info_ptr != NULL)

   {

      png_info_destroy(png_ptr, info_ptr);

#ifdef PNG_USER_MEM_SUPPORTED

      png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,

          png_ptr->mem_ptr);

#else

      png_destroy_struct((png_voidp)info_ptr);

#endif

      *info_ptr_ptr = NULL;

   }

}

/* Initialize the info structure.  This is now an internal function (0.89)

 * and applications using it are urged to use png_create_info_struct()

 * instead.

 */

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

#undef png_info_init

void PNGAPI

png_info_init(png_infop info_ptr)

{

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

   png_info_init_3(&info_ptr, 0);

}

#endif

void PNGAPI

png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)

{

   png_infop info_ptr = *ptr_ptr;

   if (info_ptr == NULL) return;

   png_debug(1, "in png_info_init_3\n");

   if (png_sizeof(png_info) > png_info_struct_size)

     {

       png_destroy_struct(info_ptr);

       info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);

       *ptr_ptr = info_ptr;

     }

   /* set everything to 0 */

   png_memset(info_ptr, 0, png_sizeof(png_info));

}

#ifdef PNG_FREE_ME_SUPPORTED

void PNGAPI

png_data_freer(png_structp png_ptr, png_infop info_ptr,

   int freer, png_uint_32 mask)

{

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

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

      return;

   if (freer == PNG_DESTROY_WILL_FREE_DATA)

      info_ptr->free_me |= mask;

   else if (freer == PNG_USER_WILL_FREE_DATA)

      info_ptr->free_me &= ~mask;

   else

      png_warning(png_ptr,

         "Unknown freer parameter in png_data_freer.");

}

#endif

void PNGAPI

png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,

   int num)

{

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

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

      return;

#if defined(PNG_TEXT_SUPPORTED)

/* free text item num or (if num == -1) all text items */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)

#else

if (mask & PNG_FREE_TEXT)

#endif

{

   if (num != -1)

   {

     if (info_ptr->text && info_ptr->text[num].key)

     {

         png_free(png_ptr, info_ptr->text[num].key);

         info_ptr->text[num].key = NULL;

     }

   }

   else

   {

       int i;

       for (i = 0; i < info_ptr->num_text; i++)

           png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);

       png_free(png_ptr, info_ptr->text);

       info_ptr->text = NULL;

       info_ptr->num_text=0;

   }

}

#endif

#if defined(PNG_tRNS_SUPPORTED)

/* free any tRNS entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)

#else

if ((mask & PNG_FREE_TRNS) && (png_ptr->flags & PNG_FLAG_FREE_TRNS))

#endif

{

    png_free(png_ptr, info_ptr->trans);

    info_ptr->trans = NULL;

    info_ptr->valid &= ~PNG_INFO_tRNS;

#ifndef PNG_FREE_ME_SUPPORTED

    png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;

#endif

}

#endif

#if defined(PNG_sCAL_SUPPORTED)

/* free any sCAL entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)

#else

if (mask & PNG_FREE_SCAL)

#endif

{

#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)

    png_free(png_ptr, info_ptr->scal_s_width);

    png_free(png_ptr, info_ptr->scal_s_height);

    info_ptr->scal_s_width = NULL;

    info_ptr->scal_s_height = NULL;

#endif

    info_ptr->valid &= ~PNG_INFO_sCAL;

}

#endif

#if defined(PNG_pCAL_SUPPORTED)

/* free any pCAL entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)

#else

if (mask & PNG_FREE_PCAL)

#endif

{

    png_free(png_ptr, info_ptr->pcal_purpose);

    png_free(png_ptr, info_ptr->pcal_units);

    info_ptr->pcal_purpose = NULL;

    info_ptr->pcal_units = NULL;

    if (info_ptr->pcal_params != NULL)

    {

        int i;

        for (i = 0; i < (int)info_ptr->pcal_nparams; i++)

        {

          png_free(png_ptr, info_ptr->pcal_params[i]);

          info_ptr->pcal_params[i]=NULL;

        }

        png_free(png_ptr, info_ptr->pcal_params);

        info_ptr->pcal_params = NULL;

    }

    info_ptr->valid &= ~PNG_INFO_pCAL;

}

#endif

#if defined(PNG_iCCP_SUPPORTED)

/* free any iCCP entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)

#else

if (mask & PNG_FREE_ICCP)

#endif

{

    png_free(png_ptr, info_ptr->iccp_name);

    png_free(png_ptr, info_ptr->iccp_profile);

    info_ptr->iccp_name = NULL;

    info_ptr->iccp_profile = NULL;

    info_ptr->valid &= ~PNG_INFO_iCCP;

}

#endif

#if defined(PNG_sPLT_SUPPORTED)

/* free a given sPLT entry, or (if num == -1) all sPLT entries */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)

#else

if (mask & PNG_FREE_SPLT)

#endif

{

   if (num != -1)

   {

      if (info_ptr->splt_palettes)

      {

          png_free(png_ptr, info_ptr->splt_palettes[num].name);

          png_free(png_ptr, info_ptr->splt_palettes[num].entries);

          info_ptr->splt_palettes[num].name = NULL;

          info_ptr->splt_palettes[num].entries = NULL;

      }

   }

   else

   {

       if (info_ptr->splt_palettes_num)

       {

         int i;

         for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)

            png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);

         png_free(png_ptr, info_ptr->splt_palettes);

         info_ptr->splt_palettes = NULL;

         info_ptr->splt_palettes_num = 0;

       }

       info_ptr->valid &= ~PNG_INFO_sPLT;

   }

}

#endif

#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)

  if (png_ptr->unknown_chunk.data)

  {

    png_free(png_ptr, png_ptr->unknown_chunk.data);

    png_ptr->unknown_chunk.data = NULL;

  }

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)

#else

if (mask & PNG_FREE_UNKN)

#endif

{

   if (num != -1)

   {

       if (info_ptr->unknown_chunks)

       {

          png_free(png_ptr, info_ptr->unknown_chunks[num].data);

          info_ptr->unknown_chunks[num].data = NULL;

       }

   }

   else

   {

       int i;

       if (info_ptr->unknown_chunks_num)

       {

         for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)

            png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);

         png_free(png_ptr, info_ptr->unknown_chunks);

         info_ptr->unknown_chunks = NULL;

         info_ptr->unknown_chunks_num = 0;

       }

   }

}

#endif

#if defined(PNG_hIST_SUPPORTED)

/* free any hIST entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)

#else