png_set_PLTE(png_structrp png_ptr, png_inforp info_ptr,
    png_const_colorp palette, int num_palette)
{

   png_uint_32 max_palette_length;

   png_debug1(1, "in %s storage function", "PLTE");

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

   max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
      (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;

   if (num_palette < 0 || num_palette > (int) max_palette_length)
   {
      if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
         png_error(png_ptr, "Invalid palette length");

      else
      {
         png_warning(png_ptr, "Invalid palette length");

         return;
      }
   }

   if ((num_palette > 0 && palette == NULL) ||
      (num_palette == 0
#        ifdef PNG_MNG_FEATURES_SUPPORTED
            && (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0
#        endif
      ))
   {
      png_error(png_ptr, "Invalid palette");
   }

   /* It may not actually be necessary to set png_ptr->palette here;
    * we do it for backward compatibility with the way the png_handle_tRNS
    * function used to do the allocation.
    *
    * 1.6.0: the above statement appears to be incorrect; something has to set
    * the palette inside png_struct on read.
    */
   png_free_data(png_ptr, info_ptr, PNG_FREE_PLTE, 0);

   /* Changed in libpng-1.2.1 to allocate PNG_MAX_PALETTE_LENGTH instead
    * of num_palette entries, in case of an invalid PNG file or incorrect
    * call to png_set_PLTE() with too-large sample values.
    */
   png_ptr->palette = png_voidcast(png_colorp, png_calloc(png_ptr,
       PNG_MAX_PALETTE_LENGTH * (sizeof (png_color))));

   if (num_palette > 0)
      memcpy(png_ptr->palette, palette, num_palette * (sizeof (png_color)));
   info_ptr->palette = png_ptr->palette;
   info_ptr->num_palette = png_ptr->num_palette = (png_uint_16)num_palette;

   info_ptr->free_me |= PNG_FREE_PLTE;

   info_ptr->valid |= PNG_INFO_PLTE;
}
Unknown