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

 *

 * (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

 */

#define PNG_NO_EXTERN

#include "png.h"

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

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

/* 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;

   if (num_bytes > 8)

   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)));

}

#endif /* PNG_READ_SUPPORTED */

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

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

voidpf /* PRIVATE */

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;

   if (png_ptr == NULL)

      return (NULL);

   if (items > PNG_UINT_32_MAX/size)

   {

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

     return (NULL);

   }

   p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;

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

   p->flags=save_flags;

   return ((voidpf)ptr);

}

/* Function to free memory for zlib */

void /* PRIVATE */

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");

   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;

   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.

 */

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;

   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));

}

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");

   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,

}

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");

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

      return;

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

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

   {

      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

   /* Free any tRNS entry */

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

   {

      info_ptr->valid &= ~PNG_INFO_tRNS;

   }

#endif

   /* Free any sCAL entry */

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

   {

#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

   /* Free any pCAL entry */

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

   {

      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]);

            }

            png_free(png_ptr, info_ptr->pcal_params);

            info_ptr->pcal_params = NULL;

         }

      info_ptr->valid &= ~PNG_INFO_pCAL;

   }

#endif

   /* Free any iCCP entry */

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

   {

      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

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

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

   {

      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 (png_ptr->unknown_chunk.data)

   {

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

      png_ptr->unknown_chunk.data = NULL;

   }

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

   {

      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

   /* Free any hIST entry */

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

   {

      png_free(png_ptr, info_ptr->hist);

      info_ptr->hist = NULL;

      info_ptr->valid &= ~PNG_INFO_hIST;

   }

#endif

   /* Free any PLTE entry that was internally allocated */

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

   {

      png_zfree(png_ptr, info_ptr->palette);

      info_ptr->palette = NULL;

      info_ptr->valid &= ~PNG_INFO_PLTE;

      info_ptr->num_palette = 0;

   }

   /* Free any image bits attached to the info structure */

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

   {

      if (info_ptr->row_pointers)

      {

         int row;

         for (row = 0; row < (int)info_ptr->height; row++)

         {

            png_free(png_ptr, info_ptr->row_pointers[row]);

         }

         png_free(png_ptr, info_ptr->row_pointers);

      }

      info_ptr->valid &= ~PNG_INFO_IDAT;

   }

#endif

   if (num == -1)

      info_ptr->free_me &= ~mask;

   else

      info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);

}

/* This is an internal routine to free any memory that the info struct is

 * pointing to before re-using it or freeing the struct itself.  Recall

 * that png_free() checks for NULL pointers for us.

 */

void /* PRIVATE */

png_info_destroy(png_structp png_ptr, png_infop info_ptr)

{

   png_debug(1, "in png_info_destroy");

   png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);

   if (png_ptr->num_chunk_list)

   {

      png_free(png_ptr, png_ptr->chunk_list);

      png_ptr->num_chunk_list = 0;

   }

#endif

   png_info_init_3(&info_ptr, png_sizeof(png_info));

}

#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */

/* This function returns a pointer to the io_ptr associated with the user

 * functions.  The application should free any memory associated with this

 * pointer before png_write_destroy() or png_read_destroy() are called.

 */

png_voidp PNGAPI

png_get_io_ptr(png_structp png_ptr)

{

   if (png_ptr == NULL)

      return (NULL);

   return (png_ptr->io_ptr);

}

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

/* Initialize the default input/output functions for the PNG file.  If you

 * use your own read or write routines, you can call either png_set_read_fn()

 * or png_set_write_fn() instead of png_init_io().  If you have defined

 * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't

 * necessarily available.

 */

void PNGAPI

png_init_io(png_structp png_ptr, png_FILE_p fp)

{

   png_debug(1, "in png_init_io");

   if (png_ptr == NULL)

      return;

   png_ptr->io_ptr = (png_voidp)fp;

}

#endif

/* Convert the supplied time into an RFC 1123 string suitable for use in

 * a "Creation Time" or other text-based time string.

 */

png_charp PNGAPI

png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)

{

   static PNG_CONST char short_months[12][4] =

        {"Jan", "Feb", "Mar", "Apr", "May", "Jun",

         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

   if (png_ptr == NULL)

      return (NULL);

   if (png_ptr->time_buffer == NULL)

   {

      png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*

         png_sizeof(char)));

   }