pngset.c

/* pngset.c - storage of image information into info struct
 *
 * Last changed in libpng 1.6.18 [(PENDING RELEASE)]
 * Copyright (c) 1998-2015 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 code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 *
 * The functions here are used during reads to store data from the file
 * into the info struct, and during writes to store application data
 * into the info struct for writing into the file.  This abstracts the
 * info struct and allows us to change the structure in the future.
 */

#include "pngpriv.h"

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

#ifdef PNG_bKGD_SUPPORTED
void PNGAPI
png_set_bKGD(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_color_16p background)
{
   png_debug1(1, "in %s storage function", "bKGD");

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

   info_ptr->background = *background;
   info_ptr->valid |= PNG_INFO_bKGD;
}
#endif

#ifdef PNG_cHRM_SUPPORTED
void PNGFAPI
png_set_cHRM_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
    png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
    png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
    png_fixed_point blue_x, png_fixed_point blue_y)
{
   png_xy xy;

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

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

   xy.redx = red_x;
   xy.redy = red_y;
   xy.greenx = green_x;
   xy.greeny = green_y;
   xy.bluex = blue_x;
   xy.bluey = blue_y;
   xy.whitex = white_x;
   xy.whitey = white_y;

   if (png_colorspace_set_chromaticities(png_ptr, &info_ptr->colorspace, &xy,
       2/* override with app values*/) != 0)
      info_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;

   png_colorspace_sync_info(png_ptr, info_ptr);
}

void PNGFAPI
png_set_cHRM_XYZ_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
    png_fixed_point int_red_X, png_fixed_point int_red_Y,
    png_fixed_point int_red_Z, png_fixed_point int_green_X,
    png_fixed_point int_green_Y, png_fixed_point int_green_Z,
    png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
    png_fixed_point int_blue_Z)
{
   png_XYZ XYZ;

   png_debug1(1, "in %s storage function", "cHRM XYZ fixed");

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

   XYZ.red_X = int_red_X;
   XYZ.red_Y = int_red_Y;
   XYZ.red_Z = int_red_Z;
   XYZ.green_X = int_green_X;
   XYZ.green_Y = int_green_Y;
   XYZ.green_Z = int_green_Z;
   XYZ.blue_X = int_blue_X;
   XYZ.blue_Y = int_blue_Y;
   XYZ.blue_Z = int_blue_Z;

   if (png_colorspace_set_endpoints(png_ptr, &info_ptr->colorspace,
       &XYZ, 2) != 0)
      info_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;

   png_colorspace_sync_info(png_ptr, info_ptr);
}

#  ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_cHRM(png_const_structrp png_ptr, png_inforp info_ptr,
    double white_x, double white_y, double red_x, double red_y,
    double green_x, double green_y, double blue_x, double blue_y)
{
   png_set_cHRM_fixed(png_ptr, info_ptr,
      png_fixed(png_ptr, white_x, "cHRM White X"),
      png_fixed(png_ptr, white_y, "cHRM White Y"),
      png_fixed(png_ptr, red_x, "cHRM Red X"),
      png_fixed(png_ptr, red_y, "cHRM Red Y"),
      png_fixed(png_ptr, green_x, "cHRM Green X"),
      png_fixed(png_ptr, green_y, "cHRM Green Y"),
      png_fixed(png_ptr, blue_x, "cHRM Blue X"),
      png_fixed(png_ptr, blue_y, "cHRM Blue Y"));
}

void PNGAPI
png_set_cHRM_XYZ(png_const_structrp png_ptr, png_inforp info_ptr, double red_X,
    double red_Y, double red_Z, double green_X, double green_Y, double green_Z,
    double blue_X, double blue_Y, double blue_Z)
{
   png_set_cHRM_XYZ_fixed(png_ptr, info_ptr,
      png_fixed(png_ptr, red_X, "cHRM Red X"),
      png_fixed(png_ptr, red_Y, "cHRM Red Y"),
      png_fixed(png_ptr, red_Z, "cHRM Red Z"),
      png_fixed(png_ptr, green_X, "cHRM Red X"),
      png_fixed(png_ptr, green_Y, "cHRM Red Y"),
      png_fixed(png_ptr, green_Z, "cHRM Red Z"),
      png_fixed(png_ptr, blue_X, "cHRM Red X"),
      png_fixed(png_ptr, blue_Y, "cHRM Red Y"),
      png_fixed(png_ptr, blue_Z, "cHRM Red Z"));
}
#  endif /* FLOATING_POINT */

#endif /* cHRM */

#ifdef PNG_gAMA_SUPPORTED
void PNGFAPI
png_set_gAMA_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
    png_fixed_point file_gamma)
{
   png_debug1(1, "in %s storage function", "gAMA");

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

   png_colorspace_set_gamma(png_ptr, &info_ptr->colorspace, file_gamma);
   png_colorspace_sync_info(png_ptr, info_ptr);
}

#  ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_gAMA(png_const_structrp png_ptr, png_inforp info_ptr, double file_gamma)
{
   png_set_gAMA_fixed(png_ptr, info_ptr, png_fixed(png_ptr, file_gamma,
       "png_set_gAMA"));
}
#  endif
#endif

#ifdef PNG_hIST_SUPPORTED
void PNGAPI
png_set_hIST(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_uint_16p hist)
{
   int i;

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

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

   if (info_ptr->num_palette == 0 || info_ptr->num_palette
       > PNG_MAX_PALETTE_LENGTH)
   {
      png_warning(png_ptr,
          "Invalid palette size, hIST allocation skipped");

      return;
   }

   png_free_data(png_ptr, info_ptr, PNG_FREE_HIST, 0);

   /* Changed from info->num_palette to PNG_MAX_PALETTE_LENGTH in
    * version 1.2.1
    */
   info_ptr->hist = png_voidcast(png_uint_16p, png_malloc_warn(png_ptr,
       PNG_MAX_PALETTE_LENGTH * (sizeof (png_uint_16))));

   if (info_ptr->hist == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for hIST chunk data");

      return;
   }

   info_ptr->free_me |= PNG_FREE_HIST;

   for (i = 0; i < info_ptr->num_palette; i++)
      info_ptr->hist[i] = hist[i];

   info_ptr->valid |= PNG_INFO_hIST;
}
#endif

void PNGAPI
png_set_IHDR(png_const_structrp png_ptr, png_inforp info_ptr,
    png_uint_32 width, png_uint_32 height, int bit_depth,
    int color_type, int interlace_type, int compression_type,
    int filter_type)
{
   png_debug1(1, "in %s storage function", "IHDR");

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

   info_ptr->width = width;
   info_ptr->height = height;
   info_ptr->bit_depth = (png_byte)bit_depth;
   info_ptr->color_type = (png_byte)color_type;
   info_ptr->compression_type = (png_byte)compression_type;
   info_ptr->filter_type = (png_byte)filter_type;
   info_ptr->interlace_type = (png_byte)interlace_type;

   png_check_IHDR (png_ptr, info_ptr->width, info_ptr->height,
       info_ptr->bit_depth, info_ptr->color_type, info_ptr->interlace_type,
       info_ptr->compression_type, info_ptr->filter_type);

   if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      info_ptr->channels = 1;

   else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
      info_ptr->channels = 3;

   else
      info_ptr->channels = 1;

   if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
      info_ptr->channels++;

   info_ptr->pixel_depth = (png_byte)(info_ptr->channels * info_ptr->bit_depth);

   info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, width);
}

#ifdef PNG_oFFs_SUPPORTED
void PNGAPI
png_set_oFFs(png_const_structrp png_ptr, png_inforp info_ptr,
    png_int_32 offset_x, png_int_32 offset_y, int unit_type)
{
   png_debug1(1, "in %s storage function", "oFFs");

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

   info_ptr->x_offset = offset_x;
   info_ptr->y_offset = offset_y;
   info_ptr->offset_unit_type = (png_byte)unit_type;
   info_ptr->valid |= PNG_INFO_oFFs;
}
#endif

#ifdef PNG_pCAL_SUPPORTED
void PNGAPI
png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_charp purpose, png_int_32 X0, png_int_32 X1, int type,
    int nparams, png_const_charp units, png_charpp params)
{
   png_size_t length;
   int i;

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

   if (png_ptr == NULL || info_ptr == NULL || purpose == NULL || units == NULL
       || (nparams > 0 && params == NULL))
      return;

   length = strlen(purpose) + 1;
   png_debug1(3, "allocating purpose for info (%lu bytes)",
       (unsigned long)length);

   /* TODO: validate format of calibration name and unit name */

   /* Check that the type matches the specification. */
   if (type < 0 || type > 3)
      png_error(png_ptr, "Invalid pCAL equation type");

   if (nparams < 0 || nparams > 255)
      png_error(png_ptr, "Invalid pCAL parameter count");

   /* Validate params[nparams] */
   for (i=0; i<nparams; ++i)
   {
      if (params[i] == NULL ||
          !png_check_fp_string(params[i], strlen(params[i])))
         png_error(png_ptr, "Invalid format for pCAL parameter");
   }

   info_ptr->pcal_purpose = png_voidcast(png_charp,
       png_malloc_warn(png_ptr, length));

   if (info_ptr->pcal_purpose == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for pCAL purpose");

      return;
   }

   memcpy(info_ptr->pcal_purpose, purpose, length);

   png_debug(3, "storing X0, X1, type, and nparams in info");
   info_ptr->pcal_X0 = X0;
   info_ptr->pcal_X1 = X1;
   info_ptr->pcal_type = (png_byte)type;
   info_ptr->pcal_nparams = (png_byte)nparams;

   length = strlen(units) + 1;
   png_debug1(3, "allocating units for info (%lu bytes)",
     (unsigned long)length);

   info_ptr->pcal_units = png_voidcast(png_charp,
      png_malloc_warn(png_ptr, length));

   if (info_ptr->pcal_units == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for pCAL units");

      return;
   }

   memcpy(info_ptr->pcal_units, units, length);

   info_ptr->pcal_params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
       (png_size_t)((nparams + 1) * (sizeof (png_charp)))));

   if (info_ptr->pcal_params == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for pCAL params");

      return;
   }

   memset(info_ptr->pcal_params, 0, (nparams + 1) * (sizeof (png_charp)));

   for (i = 0; i < nparams; i++)
   {
      length = strlen(params[i]) + 1;
      png_debug2(3, "allocating parameter %d for info (%lu bytes)", i,
          (unsigned long)length);

      info_ptr->pcal_params[i] = (png_charp)png_malloc_warn(png_ptr, length);

      if (info_ptr->pcal_params[i] == NULL)
      {
         png_warning(png_ptr, "Insufficient memory for pCAL parameter");

         return;
      }

      memcpy(info_ptr->pcal_params[i], params[i], length);
   }

   info_ptr->valid |= PNG_INFO_pCAL;
   info_ptr->free_me |= PNG_FREE_PCAL;
}
#endif

#ifdef PNG_sCAL_SUPPORTED
void PNGAPI
png_set_sCAL_s(png_const_structrp png_ptr, png_inforp info_ptr,
    int unit, png_const_charp swidth, png_const_charp sheight)
{
   png_size_t lengthw = 0, lengthh = 0;

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

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

   /* Double check the unit (should never get here with an invalid
    * unit unless this is an API call.)
    */
   if (unit != 1 && unit != 2)
      png_error(png_ptr, "Invalid sCAL unit");

   if (swidth == NULL || (lengthw = strlen(swidth)) == 0 ||
       swidth[0] == 45 /* '-' */ || !png_check_fp_string(swidth, lengthw))
      png_error(png_ptr, "Invalid sCAL width");

   if (sheight == NULL || (lengthh = strlen(sheight)) == 0 ||
       sheight[0] == 45 /* '-' */ || !png_check_fp_string(sheight, lengthh))
      png_error(png_ptr, "Invalid sCAL height");

   info_ptr->scal_unit = (png_byte)unit;

   ++lengthw;

   png_debug1(3, "allocating unit for info (%u bytes)", (unsigned int)lengthw);

   info_ptr->scal_s_width = png_voidcast(png_charp,
      png_malloc_warn(png_ptr, lengthw));

   if (info_ptr->scal_s_width == NULL)
   {
      png_warning(png_ptr, "Memory allocation failed while processing sCAL");

      return;
   }

   memcpy(info_ptr->scal_s_width, swidth, lengthw);

   ++lengthh;

   png_debug1(3, "allocating unit for info (%u bytes)", (unsigned int)lengthh);

   info_ptr->scal_s_height = png_voidcast(png_charp,
      png_malloc_warn(png_ptr, lengthh));

   if (info_ptr->scal_s_height == NULL)
   {
      png_free (png_ptr, info_ptr->scal_s_width);
      info_ptr->scal_s_width = NULL;

      png_warning(png_ptr, "Memory allocation failed while processing sCAL");

      return;
   }

   memcpy(info_ptr->scal_s_height, sheight, lengthh);

   info_ptr->valid |= PNG_INFO_sCAL;
   info_ptr->free_me |= PNG_FREE_SCAL;
}

#  ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_sCAL(png_const_structrp png_ptr, png_inforp info_ptr, int unit,
    double width, double height)
{
   png_debug1(1, "in %s storage function", "sCAL");

   /* Check the arguments. */
   if (width <= 0)
      png_warning(png_ptr, "Invalid sCAL width ignored");

   else if (height <= 0)
      png_warning(png_ptr, "Invalid sCAL height ignored");

   else
   {
      /* Convert 'width' and 'height' to ASCII. */
      char swidth[PNG_sCAL_MAX_DIGITS+1];
      char sheight[PNG_sCAL_MAX_DIGITS+1];

      png_ascii_from_fp(png_ptr, swidth, (sizeof swidth), width,
         PNG_sCAL_PRECISION);
      png_ascii_from_fp(png_ptr, sheight, (sizeof sheight), height,
         PNG_sCAL_PRECISION);

      png_set_sCAL_s(png_ptr, info_ptr, unit, swidth, sheight);
   }
}
#  endif

#  ifdef PNG_FIXED_POINT_SUPPORTED
void PNGAPI
png_set_sCAL_fixed(png_const_structrp png_ptr, png_inforp info_ptr, int unit,
    png_fixed_point width, png_fixed_point height)
{
   png_debug1(1, "in %s storage function", "sCAL");

   /* Check the arguments. */
   if (width <= 0)
      png_warning(png_ptr, "Invalid sCAL width ignored");

   else if (height <= 0)
      png_warning(png_ptr, "Invalid sCAL height ignored");

   else
   {
      /* Convert 'width' and 'height' to ASCII. */
      char swidth[PNG_sCAL_MAX_DIGITS+1];
      char sheight[PNG_sCAL_MAX_DIGITS+1];

      png_ascii_from_fixed(png_ptr, swidth, (sizeof swidth), width);
      png_ascii_from_fixed(png_ptr, sheight, (sizeof sheight), height);

      png_set_sCAL_s(png_ptr, info_ptr, unit, swidth, sheight);
   }
}
#  endif
#endif

#ifdef PNG_pHYs_SUPPORTED
void PNGAPI
png_set_pHYs(png_const_structrp png_ptr, png_inforp info_ptr,
    png_uint_32 res_x, png_uint_32 res_y, int unit_type)
{
   png_debug1(1, "in %s storage function", "pHYs");

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

   info_ptr->x_pixels_per_unit = res_x;
   info_ptr->y_pixels_per_unit = res_y;
   info_ptr->phys_unit_type = (png_byte)unit_type;
   info_ptr->valid |= PNG_INFO_pHYs;
}
#endif

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

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

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

   if (num_palette < 0 || num_palette > PNG_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 that has
    * 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;
}

#ifdef PNG_sBIT_SUPPORTED
void PNGAPI
png_set_sBIT(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_color_8p sig_bit)
{
   png_debug1(1, "in %s storage function", "sBIT");

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

   info_ptr->sig_bit = *sig_bit;
   info_ptr->valid |= PNG_INFO_sBIT;
}
#endif

#ifdef PNG_sRGB_SUPPORTED
void PNGAPI
png_set_sRGB(png_const_structrp png_ptr, png_inforp info_ptr, int srgb_intent)
{
   png_debug1(1, "in %s storage function", "sRGB");

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

   (void)png_colorspace_set_sRGB(png_ptr, &info_ptr->colorspace, srgb_intent);
   png_colorspace_sync_info(png_ptr, info_ptr);
}

void PNGAPI
png_set_sRGB_gAMA_and_cHRM(png_const_structrp png_ptr, png_inforp info_ptr,
    int srgb_intent)
{
   png_debug1(1, "in %s storage function", "sRGB_gAMA_and_cHRM");

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

   if (png_colorspace_set_sRGB(png_ptr, &info_ptr->colorspace,
       srgb_intent) != 0)
   {
      /* This causes the gAMA and cHRM to be written too */
      info_ptr->colorspace.flags |=
         PNG_COLORSPACE_FROM_gAMA|PNG_COLORSPACE_FROM_cHRM;
   }

   png_colorspace_sync_info(png_ptr, info_ptr);
}
#endif /* sRGB */


#ifdef PNG_iCCP_SUPPORTED
void PNGAPI
png_set_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_charp name, int compression_type,
    png_const_bytep profile, png_uint_32 proflen)
{
   png_charp new_iccp_name;
   png_bytep new_iccp_profile;
   png_size_t length;

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

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

   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
      png_app_error(png_ptr, "Invalid iCCP compression method");

   /* Set the colorspace first because this validates the profile; do not
    * override previously set app cHRM or gAMA here (because likely as not the
    * application knows better than libpng what the correct values are.)  Pass
    * the info_ptr color_type field to png_colorspace_set_ICC because in the
    * write case it has not yet been stored in png_ptr.
    */
   {
      int result = png_colorspace_set_ICC(png_ptr, &info_ptr->colorspace, name,
         proflen, profile, info_ptr->color_type);

      png_colorspace_sync_info(png_ptr, info_ptr);

      /* Don't do any of the copying if the profile was bad, or inconsistent. */
      if (result == 0)
         return;

      /* But do write the gAMA and cHRM chunks from the profile. */
      info_ptr->colorspace.flags |=
         PNG_COLORSPACE_FROM_gAMA|PNG_COLORSPACE_FROM_cHRM;
   }

   length = strlen(name)+1;
   new_iccp_name = png_voidcast(png_charp, png_malloc_warn(png_ptr, length));

   if (new_iccp_name == NULL)
   {
      png_benign_error(png_ptr, "Insufficient memory to process iCCP chunk");

      return;
   }

   memcpy(new_iccp_name, name, length);
   new_iccp_profile = png_voidcast(png_bytep,
      png_malloc_warn(png_ptr, proflen));

   if (new_iccp_profile == NULL)
   {
      png_free(png_ptr, new_iccp_name);
      png_benign_error(png_ptr,
          "Insufficient memory to process iCCP profile");

      return;
   }

   memcpy(new_iccp_profile, profile, proflen);

   png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, 0);

   info_ptr->iccp_proflen = proflen;
   info_ptr->iccp_name = new_iccp_name;
   info_ptr->iccp_profile = new_iccp_profile;
   info_ptr->free_me |= PNG_FREE_ICCP;
   info_ptr->valid |= PNG_INFO_iCCP;
}
#endif

#ifdef PNG_TEXT_SUPPORTED
void PNGAPI
png_set_text(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_textp text_ptr, int num_text)
{
   int ret;
   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, num_text);

   if (ret != 0)
      png_error(png_ptr, "Insufficient memory to store text");
}

int /* PRIVATE */
png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_textp text_ptr, int num_text)
{
   int i;

   png_debug1(1, "in %lx storage function", png_ptr == NULL ? "unexpected" :
      (unsigned long)png_ptr->chunk_name);

   if (png_ptr == NULL || info_ptr == NULL || num_text <= 0 || text_ptr == NULL)
      return(0);

   /* Make sure we have enough space in the "text" array in info_struct
    * to hold all of the incoming text_ptr objects.  This compare can't overflow
    * because max_text >= num_text (anyway, subtract of two positive integers
    * can't overflow in any case.)
    */
   if (num_text > info_ptr->max_text - info_ptr->num_text)
   {
      int old_num_text = info_ptr->num_text;
      int max_text;
      png_textp new_text = NULL;

      /* Calculate an appropriate max_text, checking for overflow. */
      max_text = old_num_text;
      if (num_text <= INT_MAX - max_text)
      {
         max_text += num_text;

         /* Round up to a multiple of 8 */
         if (max_text < INT_MAX-8)
            max_text = (max_text + 8) & ~0x7;

         else
            max_text = INT_MAX;

         /* Now allocate a new array and copy the old members in; this does all
          * the overflow checks.
          */
         new_text = png_voidcast(png_textp,png_realloc_array(png_ptr,
            info_ptr->text, old_num_text, max_text-old_num_text,
            sizeof *new_text));
      }

      if (new_text == NULL)
      {
         png_chunk_report(png_ptr, "too many text chunks",
            PNG_CHUNK_WRITE_ERROR);

         return 1;
      }

      png_free(png_ptr, info_ptr->text);

      info_ptr->text = new_text;
      info_ptr->free_me |= PNG_FREE_TEXT;
      info_ptr->max_text = max_text;
      /* num_text is adjusted below as the entries are copied in */

      png_debug1(3, "allocated %d entries for info_ptr->text", max_text);
   }

   for (i = 0; i < num_text; i++)
   {
      size_t text_length, key_len;
      size_t lang_len, lang_key_len;
      png_textp textp = &(info_ptr->text[info_ptr->num_text]);

      if (text_ptr[i].key == NULL)
          continue;

      if (text_ptr[i].compression < PNG_TEXT_COMPRESSION_NONE ||
          text_ptr[i].compression >= PNG_TEXT_COMPRESSION_LAST)
      {
         png_chunk_report(png_ptr, "text compression mode is out of range",
            PNG_CHUNK_WRITE_ERROR);
         continue;
      }

      key_len = strlen(text_ptr[i].key);

      if (text_ptr[i].compression <= 0)
      {
         lang_len = 0;
         lang_key_len = 0;
      }

      else
#  ifdef PNG_iTXt_SUPPORTED
      {
         /* Set iTXt data */

         if (text_ptr[i].lang != NULL)
            lang_len = strlen(text_ptr[i].lang);

         else
            lang_len = 0;

         if (text_ptr[i].lang_key != NULL)
            lang_key_len = strlen(text_ptr[i].lang_key);

         else
            lang_key_len = 0;
      }
#  else /* iTXt */
      {
         png_chunk_report(png_ptr, "iTXt chunk not supported",
            PNG_CHUNK_WRITE_ERROR);
         continue;
      }
#  endif

      if (text_ptr[i].text == NULL || text_ptr[i].text[0] == '\0')
      {
         text_length = 0;
#  ifdef PNG_iTXt_SUPPORTED
         if (text_ptr[i].compression > 0)
            textp->compression = PNG_ITXT_COMPRESSION_NONE;

         else
#  endif
            textp->compression = PNG_TEXT_COMPRESSION_NONE;
      }

      else
      {
         text_length = strlen(text_ptr[i].text);
         textp->compression = text_ptr[i].compression;
      }

      textp->key = png_voidcast(png_charp,png_malloc_base(png_ptr,
          key_len + text_length + lang_len + lang_key_len + 4));

      if (textp->key == NULL)
      {
         png_chunk_report(png_ptr, "text chunk: out of memory",
               PNG_CHUNK_WRITE_ERROR);

         return 1;
      }

      png_debug2(2, "Allocated %lu bytes at %p in png_set_text",
          (unsigned long)(png_uint_32)
          (key_len + lang_len + lang_key_len + text_length + 4),
          textp->key);

      memcpy(textp->key, text_ptr[i].key, key_len);
      *(textp->key + key_len) = '\0';

      if (text_ptr[i].compression > 0)
      {
         textp->lang = textp->key + key_len + 1;
         memcpy(textp->lang, text_ptr[i].lang, lang_len);
         *(textp->lang + lang_len) = '\0';
         textp->lang_key = textp->lang + lang_len + 1;
         memcpy(textp->lang_key, text_ptr[i].lang_key, lang_key_len);
         *(textp->lang_key + lang_key_len) = '\0';
         textp->text = textp->lang_key + lang_key_len + 1;
      }

      else
      {
         textp->lang=NULL;
         textp->lang_key=NULL;
         textp->text = textp->key + key_len + 1;
      }

      if (text_length != 0)
         memcpy(textp->text, text_ptr[i].text, text_length);

      *(textp->text + text_length) = '\0';

#  ifdef PNG_iTXt_SUPPORTED
      if (textp->compression > 0)
      {
         textp->text_length = 0;
         textp->itxt_length = text_length;
      }

      else
#  endif
      {
         textp->text_length = text_length;
         textp->itxt_length = 0;
      }

      info_ptr->num_text++;
      png_debug1(3, "transferred text chunk %d", info_ptr->num_text);
   }

   return(0);
}
#endif

#ifdef PNG_tIME_SUPPORTED
void PNGAPI
png_set_tIME(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_timep mod_time)
{
   png_debug1(1, "in %s storage function", "tIME");

   if (png_ptr == NULL || info_ptr == NULL || mod_time == NULL ||
       (png_ptr->mode & PNG_WROTE_tIME) != 0)
      return;

   if (mod_time->month == 0   || mod_time->month > 12  ||
       mod_time->day   == 0   || mod_time->day   > 31  ||
       mod_time->hour  > 23   || mod_time->minute > 59 ||
       mod_time->second > 60)
   {
      png_warning(png_ptr, "Ignoring invalid time value");

      return;
   }

   info_ptr->mod_time = *mod_time;
   info_ptr->valid |= PNG_INFO_tIME;
}
#endif

#ifdef PNG_tRNS_SUPPORTED
void PNGAPI
png_set_tRNS(png_structrp png_ptr, png_inforp info_ptr,
    png_const_bytep trans_alpha, int num_trans, png_const_color_16p trans_color)
{
   png_debug1(1, "in %s storage function", "tRNS");

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

      return;

   if (trans_alpha != NULL)
   {
       /* It may not actually be necessary to set png_ptr->trans_alpha 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 is incorrect; png_handle_tRNS effectively
        * relies on png_set_tRNS storing the information in png_struct
        * (otherwise it won't be there for the code in pngrtran.c).
        */

       png_free_data(png_ptr, info_ptr, PNG_FREE_TRNS, 0);

       /* Changed from num_trans to PNG_MAX_PALETTE_LENGTH in version 1.2.1 */
       png_ptr->trans_alpha = info_ptr->trans_alpha = png_voidcast(png_bytep,
         png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH));

       if (num_trans > 0 && num_trans <= PNG_MAX_PALETTE_LENGTH)
          memcpy(info_ptr->trans_alpha, trans_alpha, (png_size_t)num_trans);
   }

   if (trans_color != NULL)
   {
#ifdef PNG_WARNINGS_SUPPORTED
      if (info_ptr->bit_depth < 16)
      {
         int sample_max = (1 << info_ptr->bit_depth) - 1;

         if ((info_ptr->color_type == PNG_COLOR_TYPE_GRAY &&
             trans_color->gray > sample_max) ||
             (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
             (trans_color->red > sample_max ||
             trans_color->green > sample_max ||
             trans_color->blue > sample_max)))
            png_warning(png_ptr,
               "tRNS chunk has out-of-range samples for bit_depth");
      }
#endif

      info_ptr->trans_color = *trans_color;

      if (num_trans == 0)
         num_trans = 1;
   }

   info_ptr->num_trans = (png_uint_16)num_trans;

   if (num_trans != 0)
   {
      info_ptr->valid |= PNG_INFO_tRNS;
      info_ptr->free_me |= PNG_FREE_TRNS;
   }
}
#endif

#ifdef PNG_sPLT_SUPPORTED
void PNGAPI
png_set_sPLT(png_const_structrp png_ptr,
    png_inforp info_ptr, png_const_sPLT_tp entries, int nentries)
/*
 *  entries        - array of png_sPLT_t structures
 *                   to be added to the list of palettes
 *                   in the info structure.
 *
 *  nentries       - number of palette structures to be
 *                   added.
 */
{
   png_sPLT_tp np;

   if (png_ptr == NULL || info_ptr == NULL || nentries <= 0 || entries == NULL)
      return;

   /* Use the internal realloc function, which checks for all the possible
    * overflows.  Notice that the parameters are (int) and (size_t)
    */
   np = png_voidcast(png_sPLT_tp,png_realloc_array(png_ptr,
      info_ptr->splt_palettes, info_ptr->splt_palettes_num, nentries,
      sizeof *np));

   if (np == NULL)
   {
      /* Out of memory or too many chunks */
      png_chunk_report(png_ptr, "too many sPLT chunks", PNG_CHUNK_WRITE_ERROR);

      return;
   }

   png_free(png_ptr, info_ptr->splt_palettes);
   info_ptr->splt_palettes = np;
   info_ptr->free_me |= PNG_FREE_SPLT;

   np += info_ptr->splt_palettes_num;

   do
   {
      png_size_t length;

      /* Skip invalid input entries */
      if (entries->name == NULL || entries->entries == NULL)
      {
         /* png_handle_sPLT doesn't do this, so this is an app error */
         png_app_error(png_ptr, "png_set_sPLT: invalid sPLT");
         /* Just skip the invalid entry */
         continue;
      }

      np->depth = entries->depth;

      /* In the event of out-of-memory just return - there's no point keeping
       * on trying to add sPLT chunks.
       */
      length = strlen(entries->name) + 1;
      np->name = png_voidcast(png_charp, png_malloc_base(png_ptr, length));

      if (np->name == NULL)
         break;

      memcpy(np->name, entries->name, length);

      /* IMPORTANT: we have memory now that won't get freed if something else
       * goes wrong; this code must free it.  png_malloc_array produces no
       * warnings; use a png_chunk_report (below) if there is an error.
       */
      np->entries = png_voidcast(png_sPLT_entryp, png_malloc_array(png_ptr,
          entries->nentries, sizeof (png_sPLT_entry)));

      if (np->entries == NULL)
      {
         png_free(png_ptr, np->name);
         np->name = NULL;
         break;
      }

      np->nentries = entries->nentries;
      /* This multiply can't overflow because png_malloc_array has already
       * checked it when doing the allocation.
       */
      memcpy(np->entries, entries->entries,
         entries->nentries * sizeof (png_sPLT_entry));

      /* Note that 'continue' skips the advance of the out pointer and out
       * count, so an invalid entry is not added.
       */
      info_ptr->valid |= PNG_INFO_sPLT;
      ++(info_ptr->splt_palettes_num);
      ++np;
   }
   while (++entries, --nentries);

   if (nentries > 0)
      png_chunk_report(png_ptr, "sPLT out of memory", PNG_CHUNK_WRITE_ERROR);
}
#endif /* sPLT */

#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
static png_byte
check_location(png_const_structrp png_ptr, int location)
{
   location &= (PNG_HAVE_IHDR|PNG_HAVE_PLTE|PNG_AFTER_IDAT);

   /* New in 1.6.0; copy the location and check it.  This is an API
    * change; previously the app had to use the
    * png_set_unknown_chunk_location API below for each chunk.
    */
   if (location == 0 && (png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
   {
      /* Write struct, so unknown chunks come from the app */
      png_app_warning(png_ptr,
         "png_set_unknown_chunks now expects a valid location");
      /* Use the old behavior */
      location = (png_byte)(png_ptr->mode &
         (PNG_HAVE_IHDR|PNG_HAVE_PLTE|PNG_AFTER_IDAT));
   }

   /* This need not be an internal error - if the app calls
    * png_set_unknown_chunks on a read pointer it must get the location right.
    */
   if (location == 0)
      png_error(png_ptr, "invalid location in png_set_unknown_chunks");

   /* Now reduce the location to the top-most set bit by removing each least
    * significant bit in turn.
    */
   while (location != (location & -location))
      location &= ~(location & -location);

   /* The cast is safe because 'location' is a bit mask and only the low four
    * bits are significant.
    */
   return (png_byte)location;
}

void PNGAPI
png_set_unknown_chunks(png_const_structrp png_ptr,
   png_inforp info_ptr, png_const_unknown_chunkp unknowns, int num_unknowns)
{
   png_unknown_chunkp np;

   if (png_ptr == NULL || info_ptr == NULL || num_unknowns <= 0 ||
       unknowns == NULL)
      return;

   /* Check for the failure cases where support has been disabled at compile
    * time.  This code is hardly ever compiled - it's here because
    * STORE_UNKNOWN_CHUNKS is set by both read and write code (compiling in this
    * code) but may be meaningless if the read or write handling of unknown
    * chunks is not compiled in.
    */
#  if !defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) && \
      defined(PNG_READ_SUPPORTED)
      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
      {
         png_app_error(png_ptr, "no unknown chunk support on read");

         return;
      }
#  endif
#  if !defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED) && \
      defined(PNG_WRITE_SUPPORTED)
      if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
      {
         png_app_error(png_ptr, "no unknown chunk support on write");

         return;
      }
#  endif

   /* Prior to 1.6.0 this code used png_malloc_warn; however, this meant that
    * unknown critical chunks could be lost with just a warning resulting in
    * undefined behavior.  Now png_chunk_report is used to provide behavior
    * appropriate to read or write.
    */
   np = png_voidcast(png_unknown_chunkp, png_realloc_array(png_ptr,
         info_ptr->unknown_chunks, info_ptr->unknown_chunks_num, num_unknowns,
         sizeof *np));

   if (np == NULL)
   {
      png_chunk_report(png_ptr, "too many unknown chunks",
         PNG_CHUNK_WRITE_ERROR);

      return;
   }

   png_free(png_ptr, info_ptr->unknown_chunks);
   info_ptr->unknown_chunks = np; /* safe because it is initialized */
   info_ptr->free_me |= PNG_FREE_UNKN;

   np += info_ptr->unknown_chunks_num;

   /* Increment unknown_chunks_num each time round the loop to protect the
    * just-allocated chunk data.
    */
   for (; num_unknowns > 0; --num_unknowns, ++unknowns)
   {
      memcpy(np->name, unknowns->name, (sizeof np->name));
      np->name[(sizeof np->name)-1] = '\0';
      np->location = check_location(png_ptr, unknowns->location);

      if (unknowns->size == 0)
      {
         np->data = NULL;
         np->size = 0;
      }

      else
      {
         np->data = png_voidcast(png_bytep,
            png_malloc_base(png_ptr, unknowns->size));

         if (np->data == NULL)
         {
            png_chunk_report(png_ptr, "unknown chunk: out of memory",
               PNG_CHUNK_WRITE_ERROR);
            /* But just skip storing the unknown chunk */
            continue;
         }

         memcpy(np->data, unknowns->data, unknowns->size);
         np->size = unknowns->size;
      }

      /* These increments are skipped on out-of-memory for the data - the
       * unknown chunk entry gets overwritten if the png_chunk_report returns.
       * This is correct in the read case (the chunk is just dropped.)
       */
      ++np;
      ++(info_ptr->unknown_chunks_num);
   }
}

void PNGAPI
png_set_unknown_chunk_location(png_const_structrp png_ptr, png_inforp info_ptr,
    int chunk, int location)
{
   /* This API is pretty pointless in 1.6.0 because the location can be set
    * before the call to png_set_unknown_chunks.
    *
    * TODO: add a png_app_warning in 1.7
    */
   if (png_ptr != NULL && info_ptr != NULL && chunk >= 0 &&
      chunk < info_ptr->unknown_chunks_num)
   {
      if ((location & (PNG_HAVE_IHDR|PNG_HAVE_PLTE|PNG_AFTER_IDAT)) == 0)
      {
         png_app_error(png_ptr, "invalid unknown chunk location");
         /* Fake out the pre 1.6.0 behavior: */
         if ((location & PNG_HAVE_IDAT) != 0) /* undocumented! */
            location = PNG_AFTER_IDAT;

         else
            location = PNG_HAVE_IHDR; /* also undocumented */
      }

      info_ptr->unknown_chunks[chunk].location =
         check_location(png_ptr, location);
   }
}
#endif /* STORE_UNKNOWN_CHUNKS */

#ifdef PNG_MNG_FEATURES_SUPPORTED
png_uint_32 PNGAPI
png_permit_mng_features (png_structrp png_ptr, png_uint_32 mng_features)
{
   png_debug(1, "in png_permit_mng_features");

   if (png_ptr == NULL)
      return 0;

   png_ptr->mng_features_permitted = mng_features & PNG_ALL_MNG_FEATURES;

   return png_ptr->mng_features_permitted;
}
#endif

#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
static unsigned int
add_one_chunk(png_bytep list, unsigned int count, png_const_bytep add, int keep)
{
   unsigned int i;

   /* Utility function: update the 'keep' state of a chunk if it is already in
    * the list, otherwise add it to the list.
    */
   for (i=0; i<count; ++i, list += 5)
   {
      if (memcmp(list, add, 4) == 0)
      {
         list[4] = (png_byte)keep;

         return count;
      }
   }

   if (keep != PNG_HANDLE_CHUNK_AS_DEFAULT)
   {
      ++count;
      memcpy(list, add, 4);
      list[4] = (png_byte)keep;
   }

   return count;
}

void PNGAPI
png_set_keep_unknown_chunks(png_structrp png_ptr, int keep,
    png_const_bytep chunk_list, int num_chunks_in)
{
   png_bytep new_list;
   unsigned int num_chunks, old_num_chunks;

   if (png_ptr == NULL)
      return;

   if (keep < 0 || keep >= PNG_HANDLE_CHUNK_LAST)
   {
      png_app_error(png_ptr, "png_set_keep_unknown_chunks: invalid keep");

      return;
   }

   if (num_chunks_in <= 0)
   {
      png_ptr->unknown_default = keep;

      /* '0' means just set the flags, so stop here */
      if (num_chunks_in == 0)
        return;
   }

   if (num_chunks_in < 0)
   {
      /* Ignore all unknown chunks and all chunks recognized by
       * libpng except for IHDR, PLTE, tRNS, IDAT, and IEND
       */
      static PNG_CONST png_byte chunks_to_ignore[] = {
         98,  75,  71,  68, '\0',  /* bKGD */
         99,  72,  82,  77, '\0',  /* cHRM */
        103,  65,  77,  65, '\0',  /* gAMA */
        104,  73,  83,  84, '\0',  /* hIST */
        105,  67,  67,  80, '\0',  /* iCCP */
        105,  84,  88, 116, '\0',  /* iTXt */
        111,  70,  70, 115, '\0',  /* oFFs */
        112,  67,  65,  76, '\0',  /* pCAL */
        112,  72,  89, 115, '\0',  /* pHYs */
        115,  66,  73,  84, '\0',  /* sBIT */
        115,  67,  65,  76, '\0',  /* sCAL */
        115,  80,  76,  84, '\0',  /* sPLT */
        115,  84,  69,  82, '\0',  /* sTER */
        115,  82,  71,  66, '\0',  /* sRGB */
        116,  69,  88, 116, '\0',  /* tEXt */
        116,  73,  77,  69, '\0',  /* tIME */
        122,  84,  88, 116, '\0'   /* zTXt */
      };

      chunk_list = chunks_to_ignore;
      num_chunks = (unsigned int)/*SAFE*/(sizeof chunks_to_ignore)/5U;
   }

   else /* num_chunks_in > 0 */
   {
      if (chunk_list == NULL)
      {
         /* Prior to 1.6.0 this was silently ignored, now it is an app_error
          * which can be switched off.
          */
         png_app_error(png_ptr, "png_set_keep_unknown_chunks: no chunk list");

         return;
      }

      num_chunks = num_chunks_in;
   }

   old_num_chunks = png_ptr->num_chunk_list;
   if (png_ptr->chunk_list == NULL)
      old_num_chunks = 0;

   /* Since num_chunks is always restricted to UINT_MAX/5 this can't overflow.
    */
   if (num_chunks + old_num_chunks > UINT_MAX/5)
   {
      png_app_error(png_ptr, "png_set_keep_unknown_chunks: too many chunks");

      return;
   }

   /* If these chunks are being reset to the default then no more memory is
    * required because add_one_chunk above doesn't extend the list if the 'keep'
    * parameter is the default.
    */
   if (keep != 0)
   {
      new_list = png_voidcast(png_bytep, png_malloc(png_ptr,
          5 * (num_chunks + old_num_chunks)));

      if (old_num_chunks > 0)
         memcpy(new_list, png_ptr->chunk_list, 5*old_num_chunks);
   }

   else if (old_num_chunks > 0)
      new_list = png_ptr->chunk_list;

   else
      new_list = NULL;

   /* Add the new chunks together with each one's handling code.  If the chunk
    * already exists the code is updated, otherwise the chunk is added to the
    * end.  (In libpng 1.6.0 order no longer matters because this code enforces
    * the earlier convention that the last setting is the one that is used.)
    */
   if (new_list != NULL)
   {
      png_const_bytep inlist;
      png_bytep outlist;
      unsigned int i;

      for (i=0; i<num_chunks; ++i)
      {
         old_num_chunks = add_one_chunk(new_list, old_num_chunks,
            chunk_list+5*i, keep);
      }

      /* Now remove any spurious 'default' entries. */
      num_chunks = 0;
      for (i=0, inlist=outlist=new_list; i<old_num_chunks; ++i, inlist += 5)
      {
         if (inlist[4])
         {
            if (outlist != inlist)
               memcpy(outlist, inlist, 5);
            outlist += 5;
            ++num_chunks;
         }
      }

      /* This means the application has removed all the specialized handling. */
      if (num_chunks == 0)
      {
         if (png_ptr->chunk_list != new_list)
            png_free(png_ptr, new_list);

         new_list = NULL;
      }
   }

   else
      num_chunks = 0;

   png_ptr->num_chunk_list = num_chunks;

   if (png_ptr->chunk_list != new_list)
   {
      if (png_ptr->chunk_list != NULL)
         png_free(png_ptr, png_ptr->chunk_list);

      png_ptr->chunk_list = new_list;
   }
}
#endif

#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
void PNGAPI
png_set_read_user_chunk_fn(png_structrp png_ptr, png_voidp user_chunk_ptr,
    png_user_chunk_ptr read_user_chunk_fn)
{
   png_debug(1, "in png_set_read_user_chunk_fn");

   if (png_ptr == NULL)
      return;

   png_ptr->read_user_chunk_fn = read_user_chunk_fn;
   png_ptr->user_chunk_ptr = user_chunk_ptr;
}
#endif

#ifdef PNG_INFO_IMAGE_SUPPORTED
void PNGAPI
png_set_rows(png_const_structrp png_ptr, png_inforp info_ptr,
    png_bytepp row_pointers)
{
   png_debug1(1, "in %s storage function", "rows");

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

   if (info_ptr->row_pointers != NULL &&
       (info_ptr->row_pointers != row_pointers))
      png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);

   info_ptr->row_pointers = row_pointers;

   if (row_pointers != NULL)
      info_ptr->valid |= PNG_INFO_IDAT;
}
#endif

void PNGAPI
png_set_compression_buffer_size(png_structrp png_ptr, png_size_t size)
{
    if (png_ptr == NULL)
       return;

    if (size == 0 || size > PNG_UINT_31_MAX)
       png_error(png_ptr, "invalid compression buffer size");

#  ifdef PNG_SEQUENTIAL_READ_SUPPORTED
      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
      {
         png_ptr->IDAT_read_size = (png_uint_32)size; /* checked above */
         return;
      }
#  endif

#  ifdef PNG_WRITE_SUPPORTED
      if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
      {
         if (png_ptr->zowner != 0)
         {
            png_warning(png_ptr,
              "Compression buffer size cannot be changed because it is in use");

            return;
         }

#ifndef __COVERITY__
         /* Some compilers complain that this is always false.  However, it
          * can be true when integer overflow happens.
          */
         if (size > ZLIB_IO_MAX)
         {
            png_warning(png_ptr,
               "Compression buffer size limited to system maximum");
            size = ZLIB_IO_MAX; /* must fit */
         }
#endif

         if (size < 6)
         {
            /* Deflate will potentially go into an infinite loop on a SYNC_FLUSH
             * if this is permitted.
             */
            png_warning(png_ptr,
               "Compression buffer size cannot be reduced below 6");

            return;
         }

         if (png_ptr->zbuffer_size != size)
         {
            png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
            png_ptr->zbuffer_size = (uInt)size;
         }
      }
#  endif
}

void PNGAPI
png_set_invalid(png_const_structrp png_ptr, png_inforp info_ptr, int mask)
{
   if (png_ptr != NULL && info_ptr != NULL)
      info_ptr->valid &= ~mask;
}


#ifdef PNG_SET_USER_LIMITS_SUPPORTED
/* This function was added to libpng 1.2.6 */
void PNGAPI
png_set_user_limits (png_structrp png_ptr, png_uint_32 user_width_max,
    png_uint_32 user_height_max)
{
   /* Images with dimensions larger than these limits will be
    * rejected by png_set_IHDR().  To accept any PNG datastream
    * regardless of dimensions, set both limits to 0x7ffffffL.
    */
   if (png_ptr == NULL)
      return;

   png_ptr->user_width_max = user_width_max;
   png_ptr->user_height_max = user_height_max;
}

/* This function was added to libpng 1.4.0 */
void PNGAPI
png_set_chunk_cache_max (png_structrp png_ptr, png_uint_32 user_chunk_cache_max)
{
   if (png_ptr != NULL)
      png_ptr->user_chunk_cache_max = user_chunk_cache_max;
}

/* This function was added to libpng 1.4.1 */
void PNGAPI
png_set_chunk_malloc_max (png_structrp png_ptr,
    png_alloc_size_t user_chunk_malloc_max)
{
   if (png_ptr != NULL)
      png_ptr->user_chunk_malloc_max = user_chunk_malloc_max;
}
#endif /* ?SET_USER_LIMITS */


#ifdef PNG_BENIGN_ERRORS_SUPPORTED
void PNGAPI
png_set_benign_errors(png_structrp png_ptr, int allowed)
{
   png_debug(1, "in png_set_benign_errors");

   /* If allowed is 1, png_benign_error() is treated as a warning.
    *
    * If allowed is 0, png_benign_error() is treated as an error (which
    * is the default behavior if png_set_benign_errors() is not called).
    */

   if (allowed != 0)
      png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN |
         PNG_FLAG_APP_WARNINGS_WARN | PNG_FLAG_APP_ERRORS_WARN;

   else
      png_ptr->flags &= ~(PNG_FLAG_BENIGN_ERRORS_WARN |
         PNG_FLAG_APP_WARNINGS_WARN | PNG_FLAG_APP_ERRORS_WARN);
}
#endif /* BENIGN_ERRORS */

#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
   /* Whether to report invalid palette index; added at libng-1.5.10.
    * It is possible for an indexed (color-type==3) PNG file to contain
    * pixels with invalid (out-of-range) indexes if the PLTE chunk has
    * fewer entries than the image's bit-depth would allow. We recover
    * from this gracefully by filling any incomplete palette with zeros
    * (opaque black).  By default, when this occurs libpng will issue
    * a benign error.  This API can be used to override that behavior.
    */
void PNGAPI
png_set_check_for_invalid_index(png_structrp png_ptr, int allowed)
{
   png_debug(1, "in png_set_check_for_invalid_index");

   if (allowed > 0)
      png_ptr->num_palette_max = 0;

   else
      png_ptr->num_palette_max = -1;
}
#endif
#endif /* READ || WRITE */