code:
/* pngset.c - storage of image information into info struct
 *
 * Last changed in libpng 1.4.5 [December 9, 2010]
 * Copyright (c) 1998-2010 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.
 */

#define PNG_NO_PEDANTIC_WARNINGS
#include "png.h"
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
#include "pngpriv.h"

#ifdef PNG_bKGD_SUPPORTED
void PNGAPI
png_set_bKGD(png_structp png_ptr, png_infop info_ptr, png_color_16p background)
{
   png_debug1(1, "in %s storage function", "bKGD");

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

   png_memcpy(&(info_ptr->background), background, png_sizeof(png_color_16));
   info_ptr->valid |= PNG_INFO_bKGD;
}
#endif

#ifdef PNG_cHRM_SUPPORTED
#ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_cHRM(png_structp png_ptr, png_infop 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_debug1(1, "in %s storage function", "cHRM");

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

   info_ptr->x_white = (float)white_x;
   info_ptr->y_white = (float)white_y;
   info_ptr->x_red   = (float)red_x;
   info_ptr->y_red   = (float)red_y;
   info_ptr->x_green = (float)green_x;
   info_ptr->y_green = (float)green_y;
   info_ptr->x_blue  = (float)blue_x;
   info_ptr->y_blue  = (float)blue_y;
#ifdef PNG_FIXED_POINT_SUPPORTED
   info_ptr->int_x_white = (png_fixed_point)(white_x*100000.+0.5);
   info_ptr->int_y_white = (png_fixed_point)(white_y*100000.+0.5);
   info_ptr->int_x_red   = (png_fixed_point)(  red_x*100000.+0.5);
   info_ptr->int_y_red   = (png_fixed_point)(  red_y*100000.+0.5);
   info_ptr->int_x_green = (png_fixed_point)(green_x*100000.+0.5);
   info_ptr->int_y_green = (png_fixed_point)(green_y*100000.+0.5);
   info_ptr->int_x_blue  = (png_fixed_point)( blue_x*100000.+0.5);
   info_ptr->int_y_blue  = (png_fixed_point)( blue_y*100000.+0.5);
#endif
   info_ptr->valid |= PNG_INFO_cHRM;
}
#endif /* PNG_FLOATING_POINT_SUPPORTED */

#ifdef PNG_FIXED_POINT_SUPPORTED
void PNGAPI
png_set_cHRM_fixed(png_structp png_ptr, png_infop 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_debug1(1, "in %s storage function", "cHRM fixed");

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

#ifdef PNG_CHECK_cHRM_SUPPORTED
   if (png_check_cHRM_fixed(png_ptr,
      white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y))
#endif
   {
      info_ptr->int_x_white = white_x;
      info_ptr->int_y_white = white_y;
      info_ptr->int_x_red   = red_x;
      info_ptr->int_y_red   = red_y;
      info_ptr->int_x_green = green_x;
      info_ptr->int_y_green = green_y;
      info_ptr->int_x_blue  = blue_x;
      info_ptr->int_y_blue  = blue_y;
#ifdef  PNG_FLOATING_POINT_SUPPORTED
      info_ptr->x_white = (float)(white_x/100000.);
      info_ptr->y_white = (float)(white_y/100000.);
      info_ptr->x_red   = (float)(  red_x/100000.);
      info_ptr->y_red   = (float)(  red_y/100000.);
      info_ptr->x_green = (float)(green_x/100000.);
      info_ptr->y_green = (float)(green_y/100000.);
      info_ptr->x_blue  = (float)( blue_x/100000.);
      info_ptr->y_blue  = (float)( blue_y/100000.);
#endif
      info_ptr->valid |= PNG_INFO_cHRM;
   }
}
#endif /* PNG_FIXED_POINT_SUPPORTED */
#endif /* PNG_cHRM_SUPPORTED */

#ifdef PNG_gAMA_SUPPORTED
#ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_gAMA(png_structp png_ptr, png_infop info_ptr, double file_gamma)
{
   double png_gamma;

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

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

   /* Check for overflow */
   if (file_gamma > 21474.83)
   {
      png_warning(png_ptr, "Limiting gamma to 21474.83");
      png_gamma=21474.83;
   }
   else
      png_gamma = file_gamma;
   info_ptr->gamma = (float)png_gamma;
#ifdef PNG_FIXED_POINT_SUPPORTED
   info_ptr->int_gamma = (int)(png_gamma*100000.+.5);
#endif
   info_ptr->valid |= PNG_INFO_gAMA;
   if (png_gamma == 0.0)
      png_warning(png_ptr, "Setting gamma=0");
}
#endif
void PNGAPI
png_set_gAMA_fixed(png_structp png_ptr, png_infop info_ptr, png_fixed_point
   int_gamma)
{
   png_fixed_point png_gamma;

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

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

   if (int_gamma > (png_fixed_point)PNG_UINT_31_MAX)
   {
      png_warning(png_ptr, "Limiting gamma to 21474.83");
      png_gamma=PNG_UINT_31_MAX;
   }
   else
   {
      if (int_gamma < 0)
      {
         png_warning(png_ptr, "Setting negative gamma to zero");
         png_gamma = 0;
      }
      else
         png_gamma = int_gamma;
   }
#ifdef PNG_FLOATING_POINT_SUPPORTED
   info_ptr->gamma = (float)(png_gamma/100000.);
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
   info_ptr->int_gamma = png_gamma;
#endif
   info_ptr->valid |= PNG_INFO_gAMA;
   if (png_gamma == 0)
      png_warning(png_ptr, "Setting gamma=0");
}
#endif

#ifdef PNG_hIST_SUPPORTED
void PNGAPI
png_set_hIST(png_structp png_ptr, png_infop info_ptr, png_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
    */
   png_ptr->hist = (png_uint_16p)png_malloc_warn(png_ptr,
      PNG_MAX_PALETTE_LENGTH * png_sizeof(png_uint_16));
   if (png_ptr->hist == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for hIST chunk data");
      return;
   }

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

   info_ptr->free_me |= PNG_FREE_HIST;
}
#endif

void PNGAPI
png_set_IHDR(png_structp png_ptr, png_infop 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)
      info_ptr->channels = 3;
   else
      info_ptr->channels = 1;
   if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
      info_ptr->channels++;
   info_ptr->pixel_depth = (png_byte)(info_ptr->channels * info_ptr->bit_depth);

   /* Check for potential overflow */
   if (width > (PNG_UINT_32_MAX
                 >> 3)      /* 8-byte RGBA pixels */
                 - 64       /* bigrowbuf hack */
                 - 1        /* filter byte */
                 - 7*8      /* rounding of width to multiple of 8 pixels */
                 - 8)       /* extra max_pixel_depth pad */
      info_ptr->rowbytes = 0;
   else
      info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, width);
}

#ifdef PNG_oFFs_SUPPORTED
void PNGAPI
png_set_oFFs(png_structp png_ptr, png_infop 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_structp png_ptr, png_infop info_ptr,
   png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams,
   png_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)
      return;

   length = png_strlen(purpose) + 1;
   png_debug1(3, "allocating purpose for info (%lu bytes)",
     (unsigned long)length);
   info_ptr->pcal_purpose = (png_charp)png_malloc_warn(png_ptr, length);
   if (info_ptr->pcal_purpose == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for pCAL purpose");
      return;
   }
   png_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 = png_strlen(units) + 1;
   png_debug1(3, "allocating units for info (%lu bytes)",
     (unsigned long)length);
   info_ptr->pcal_units = (png_charp)png_malloc_warn(png_ptr, length);
   if (info_ptr->pcal_units == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for pCAL units");
      return;
   }
   png_memcpy(info_ptr->pcal_units, units, length);

   info_ptr->pcal_params = (png_charpp)png_malloc_warn(png_ptr,
      (png_size_t)((nparams + 1) * png_sizeof(png_charp)));
   if (info_ptr->pcal_params == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for pCAL params");
      return;
   }

   png_memset(info_ptr->pcal_params, 0, (nparams + 1) * png_sizeof(png_charp));

   for (i = 0; i < nparams; i++)
   {
      length = png_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;
      }
      png_memcpy(info_ptr->pcal_params[i], params[i], length);
   }

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

#if defined(PNG_READ_sCAL_SUPPORTED) || defined(PNG_WRITE_sCAL_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_sCAL(png_structp png_ptr, png_infop info_ptr,
             int unit, double width, double height)
{
   png_debug1(1, "in %s storage function", "sCAL");

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

   info_ptr->scal_unit = (png_byte)unit;
   info_ptr->scal_pixel_width = width;
   info_ptr->scal_pixel_height = height;

   info_ptr->valid |= PNG_INFO_sCAL;
}
#else
#ifdef PNG_FIXED_POINT_SUPPORTED
void PNGAPI
png_set_sCAL_s(png_structp png_ptr, png_infop info_ptr,
             int unit, png_charp swidth, png_charp sheight)
{
   png_size_t length;

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

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

   info_ptr->scal_unit = (png_byte)unit;

   length = png_strlen(swidth) + 1;
   png_debug1(3, "allocating unit for info (%u bytes)",
      (unsigned int)length);
   info_ptr->scal_s_width = (png_charp)png_malloc_warn(png_ptr, length);
   if (info_ptr->scal_s_width == NULL)
   {
      png_warning(png_ptr,
         "Memory allocation failed while processing sCAL");
      return;
   }
   png_memcpy(info_ptr->scal_s_width, swidth, length);

   length = png_strlen(sheight) + 1;
   png_debug1(3, "allocating unit for info (%u bytes)",
      (unsigned int)length);
   info_ptr->scal_s_height = (png_charp)png_malloc_warn(png_ptr, length);
   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;
   }
   png_memcpy(info_ptr->scal_s_height, sheight, length);
   info_ptr->valid |= PNG_INFO_sCAL;
   info_ptr->free_me |= PNG_FREE_SCAL;
}
#endif
#endif
#endif

#ifdef PNG_pHYs_SUPPORTED
void PNGAPI
png_set_pHYs(png_structp png_ptr, png_infop 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_structp png_ptr, png_infop info_ptr,
   png_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;
      }
   }

   /* 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.
    */
   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_colorp)png_calloc(png_ptr,
      PNG_MAX_PALETTE_LENGTH * png_sizeof(png_color));
   png_memcpy(png_ptr->palette, palette, num_palette * png_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_structp png_ptr, png_infop info_ptr,
   png_color_8p sig_bit)
{
   png_debug1(1, "in %s storage function", "sBIT");

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

   png_memcpy(&(info_ptr->sig_bit), sig_bit, png_sizeof(png_color_8));
   info_ptr->valid |= PNG_INFO_sBIT;
}
#endif

#ifdef PNG_sRGB_SUPPORTED
void PNGAPI
png_set_sRGB(png_structp png_ptr, png_infop info_ptr, int intent)
{
   png_debug1(1, "in %s storage function", "sRGB");

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

   info_ptr->srgb_intent = (png_byte)intent;
   info_ptr->valid |= PNG_INFO_sRGB;
}

void PNGAPI
png_set_sRGB_gAMA_and_cHRM(png_structp png_ptr, png_infop info_ptr,
   int intent)
{
#ifdef PNG_gAMA_SUPPORTED
#ifdef PNG_FLOATING_POINT_SUPPORTED
   float file_gamma;
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
   png_fixed_point int_file_gamma;
#endif
#endif
#ifdef PNG_cHRM_SUPPORTED
#ifdef PNG_FLOATING_POINT_SUPPORTED
   float white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y;
#endif
   png_fixed_point int_white_x, int_white_y, int_red_x, int_red_y, int_green_x,
      int_green_y, int_blue_x, int_blue_y;
#endif
   png_debug1(1, "in %s storage function", "sRGB_gAMA_and_cHRM");

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

   png_set_sRGB(png_ptr, info_ptr, intent);

#ifdef PNG_gAMA_SUPPORTED
#ifdef PNG_FLOATING_POINT_SUPPORTED
   file_gamma = (float).45455;
   png_set_gAMA(png_ptr, info_ptr, file_gamma);
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
   int_file_gamma = 45455L;
   png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
#endif
#endif

#ifdef PNG_cHRM_SUPPORTED
   int_white_x = 31270L;
   int_white_y = 32900L;
   int_red_x   = 64000L;
   int_red_y   = 33000L;
   int_green_x = 30000L;
   int_green_y = 60000L;
   int_blue_x  = 15000L;
   int_blue_y  =  6000L;

#ifdef PNG_FLOATING_POINT_SUPPORTED
   white_x = (float).3127;
   white_y = (float).3290;
   red_x   = (float).64;
   red_y   = (float).33;
   green_x = (float).30;
   green_y = (float).60;
   blue_x  = (float).15;
   blue_y  = (float).06;
#endif

#ifdef PNG_FIXED_POINT_SUPPORTED
   png_set_cHRM_fixed(png_ptr, info_ptr,
       int_white_x, int_white_y, int_red_x, int_red_y, int_green_x,
       int_green_y, int_blue_x, int_blue_y);
#endif
#ifdef PNG_FLOATING_POINT_SUPPORTED
   png_set_cHRM(png_ptr, info_ptr,
       white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y);
#endif
#endif /* cHRM */
}
#endif /* sRGB */

#ifdef PNG_iCCP_SUPPORTED
void PNGAPI
png_set_iCCP(png_structp png_ptr, png_infop info_ptr,
             png_charp name, int compression_type,
             png_charp profile, png_uint_32 proflen)
{
   png_charp new_iccp_name;
   png_charp new_iccp_profile;
   png_uint_32 length;

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

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

   length = png_strlen(name)+1;
   new_iccp_name = (png_charp)png_malloc_warn(png_ptr, length);
   if (new_iccp_name == NULL)
   {
        png_warning(png_ptr, "Insufficient memory to process iCCP chunk");
      return;
   }
   png_memcpy(new_iccp_name, name, length);
   new_iccp_profile = (png_charp)png_malloc_warn(png_ptr, proflen);
   if (new_iccp_profile == NULL)
   {
      png_free (png_ptr, new_iccp_name);
      png_warning(png_ptr,
          "Insufficient memory to process iCCP profile");
      return;
   }
   png_memcpy(new_iccp_profile, profile, (png_size_t)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;
   /* Compression is always zero but is here so the API and info structure
    * does not have to change if we introduce multiple compression types
    */
   info_ptr->iccp_compression = (png_byte)compression_type;
   info_ptr->free_me |= PNG_FREE_ICCP;
   info_ptr->valid |= PNG_INFO_iCCP;
}
#endif

#ifdef PNG_TEXT_SUPPORTED
void PNGAPI
png_set_text(png_structp png_ptr, png_infop info_ptr, png_textp text_ptr,
             int num_text)
{
   int ret;
   ret = png_set_text_2(png_ptr, info_ptr, text_ptr, num_text);
   if (ret)
      png_error(png_ptr, "Insufficient memory to store text");
}

int /* PRIVATE */
png_set_text_2(png_structp png_ptr, png_infop info_ptr, png_textp text_ptr,
               int num_text)
{
   int i;

   png_debug1(1, "in %s storage function", ((png_ptr == NULL ||
      png_ptr->chunk_name[0] == '\0') ?
      "text" : (png_const_charp)png_ptr->chunk_name));

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

   /* Make sure we have enough space in the "text" array in info_struct
    * to hold all of the incoming text_ptr objects.
    */
   if (info_ptr->num_text + num_text > info_ptr->max_text)
   {
      if (info_ptr->text != NULL)
      {
         png_textp old_text;
         int old_max;

         old_max = info_ptr->max_text;
         info_ptr->max_text = info_ptr->num_text + num_text + 8;
         old_text = info_ptr->text;
         info_ptr->text = (png_textp)png_malloc_warn(png_ptr,
            (png_size_t)(info_ptr->max_text * png_sizeof(png_text)));
         if (info_ptr->text == NULL)
         {
            png_free(png_ptr, old_text);
            return(1);
         }
         png_memcpy(info_ptr->text, old_text, (png_size_t)(old_max *
            png_sizeof(png_text)));
         png_free(png_ptr, old_text);
      }
      else
      {
         info_ptr->max_text = num_text + 8;
         info_ptr->num_text = 0;
         info_ptr->text = (png_textp)png_malloc_warn(png_ptr,
            (png_size_t)(info_ptr->max_text * png_sizeof(png_text)));
         if (info_ptr->text == NULL)
            return(1);
         info_ptr->free_me |= PNG_FREE_TEXT;
      }
      png_debug1(3, "allocated %d entries for info_ptr->text",
         info_ptr->max_text);
   }
   for (i = 0; i < num_text; i++)
   {
      png_size_t text_length, key_len;
      png_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_warning(png_ptr, "text compression mode is out of range");
         continue;
      }

      key_len = png_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 = png_strlen(text_ptr[i].lang);
         else
            lang_len = 0;
         if (text_ptr[i].lang_key != NULL)
            lang_key_len = png_strlen(text_ptr[i].lang_key);
         else
            lang_key_len = 0;
      }
#else /* PNG_iTXt_SUPPORTED */
      {
         png_warning(png_ptr, "iTXt chunk not supported");
         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 = png_strlen(text_ptr[i].text);
         textp->compression = text_ptr[i].compression;
      }

      textp->key = (png_charp)png_malloc_warn(png_ptr,
         (png_size_t)
         (key_len + text_length + lang_len + lang_key_len + 4));
      if (textp->key == NULL)
         return(1);
      png_debug2(2, "Allocated %lu bytes at %x in png_set_text",
                 (unsigned long)(png_uint_32)
                 (key_len + lang_len + lang_key_len + text_length + 4),
                 (int)textp->key);

      png_memcpy(textp->key, text_ptr[i].key,(png_size_t)(key_len));
      *(textp->key + key_len) = '\0';
#ifdef PNG_iTXt_SUPPORTED
      if (text_ptr[i].compression > 0)
      {
         textp->lang = textp->key + key_len + 1;
         png_memcpy(textp->lang, text_ptr[i].lang, lang_len);
         *(textp->lang + lang_len) = '\0';
         textp->lang_key = textp->lang + lang_len + 1;
         png_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
#endif
      {
#ifdef PNG_iTXt_SUPPORTED
         textp->lang=NULL;
         textp->lang_key=NULL;
#endif
         textp->text = textp->key + key_len + 1;
      }
      if (text_length)
         png_memcpy(textp->text, text_ptr[i].text,
            (png_size_t)(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;
#ifdef PNG_iTXt_SUPPORTED
         textp->itxt_length = 0;
#endif
      }
      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_structp png_ptr, png_infop info_ptr, png_timep mod_time)
{
   png_debug1(1, "in %s storage function", "tIME");

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

   png_memcpy(&(info_ptr->mod_time), mod_time, png_sizeof(png_time));
   info_ptr->valid |= PNG_INFO_tIME;
}
#endif

#ifdef PNG_tRNS_SUPPORTED
void PNGAPI
png_set_tRNS(png_structp png_ptr, png_infop info_ptr,
   png_bytep trans_alpha, int num_trans, png_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.
        */

       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_bytep)png_malloc(png_ptr,
           (png_size_t)PNG_MAX_PALETTE_LENGTH);
       if (num_trans > 0 && num_trans <= PNG_MAX_PALETTE_LENGTH)
          png_memcpy(info_ptr->trans_alpha, trans_alpha, (png_size_t)num_trans);
   }

   if (trans_color != NULL)
   {
      int sample_max = (1 << info_ptr->bit_depth);
      if ((info_ptr->color_type == PNG_COLOR_TYPE_GRAY &&
          (int)trans_color->gray > sample_max) ||
          (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
          ((int)trans_color->red > sample_max ||
          (int)trans_color->green > sample_max ||
          (int)trans_color->blue > sample_max)))
         png_warning(png_ptr,
            "tRNS chunk has out-of-range samples for bit_depth");
      png_memcpy(&(info_ptr->trans_color), trans_color,
         png_sizeof(png_color_16));
      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_structp png_ptr,
             png_infop info_ptr, png_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;
   int i;

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

   np = (png_sPLT_tp)png_malloc_warn(png_ptr,
       (info_ptr->splt_palettes_num + nentries) *
        (png_size_t)png_sizeof(png_sPLT_t));
   if (np == NULL)
   {
      png_warning(png_ptr, "No memory for sPLT palettes");
      return;
   }

   png_memcpy(np, info_ptr->splt_palettes,
       info_ptr->splt_palettes_num * png_sizeof(png_sPLT_t));
   png_free(png_ptr, info_ptr->splt_palettes);
   info_ptr->splt_palettes=NULL;

   for (i = 0; i < nentries; i++)
   {
      png_sPLT_tp to = np + info_ptr->splt_palettes_num + i;
      png_sPLT_tp from = entries + i;
      png_uint_32 length;

      length = png_strlen(from->name) + 1;
      to->name = (png_charp)png_malloc_warn(png_ptr, (png_size_t)length);
      if (to->name == NULL)
      {
         png_warning(png_ptr,
           "Out of memory while processing sPLT chunk");
         continue;
      }
      png_memcpy(to->name, from->name, length);
      to->entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
          (png_size_t)(from->nentries * png_sizeof(png_sPLT_entry)));
      if (to->entries == NULL)
      {
         png_warning(png_ptr,
           "Out of memory while processing sPLT chunk");
         png_free(png_ptr, to->name);
         to->name = NULL;
         continue;
      }
      png_memcpy(to->entries, from->entries,
          from->nentries * png_sizeof(png_sPLT_entry));
      to->nentries = from->nentries;
      to->depth = from->depth;
   }

   info_ptr->splt_palettes = np;
   info_ptr->splt_palettes_num += nentries;
   info_ptr->valid |= PNG_INFO_sPLT;
   info_ptr->free_me |= PNG_FREE_SPLT;
}
#endif /* PNG_sPLT_SUPPORTED */

#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
void PNGAPI
png_set_unknown_chunks(png_structp png_ptr,
   png_infop info_ptr, png_unknown_chunkp unknowns, int num_unknowns)
{
   png_unknown_chunkp np;
   int i;

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

   np = (png_unknown_chunkp)png_malloc_warn(png_ptr,
       (png_size_t)((info_ptr->unknown_chunks_num + num_unknowns) *
       png_sizeof(png_unknown_chunk)));
   if (np == NULL)
   {
      png_warning(png_ptr,
          "Out of memory while processing unknown chunk");
      return;
   }

   png_memcpy(np, info_ptr->unknown_chunks,
       info_ptr->unknown_chunks_num * png_sizeof(png_unknown_chunk));
   png_free(png_ptr, info_ptr->unknown_chunks);
   info_ptr->unknown_chunks = NULL;

   for (i = 0; i < num_unknowns; i++)
   {
      png_unknown_chunkp to = np + info_ptr->unknown_chunks_num + i;
      png_unknown_chunkp from = unknowns + i;

      png_memcpy((png_charp)to->name, (png_charp)from->name,
          png_sizeof(from->name));
      to->name[png_sizeof(to->name)-1] = '\0';
      to->size = from->size;
      /* Note our location in the read or write sequence */
      to->location = (png_byte)(png_ptr->mode & 0xff);

      if (from->size == 0)
         to->data=NULL;
      else
      {
         to->data = (png_bytep)png_malloc_warn(png_ptr,
           (png_size_t)from->size);
         if (to->data == NULL)
         {
            png_warning(png_ptr,
             "Out of memory while processing unknown chunk");
            to->size = 0;
         }
         else
            png_memcpy(to->data, from->data, from->size);
      }
   }

   info_ptr->unknown_chunks = np;
   info_ptr->unknown_chunks_num += num_unknowns;
   info_ptr->free_me |= PNG_FREE_UNKN;
}
void PNGAPI
png_set_unknown_chunk_location(png_structp png_ptr, png_infop info_ptr,
   int chunk, int location)
{
   if (png_ptr != NULL && info_ptr != NULL && chunk >= 0 && chunk <
       (int)info_ptr->unknown_chunks_num)
      info_ptr->unknown_chunks[chunk].location = (png_byte)location;
}
#endif

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

   if (png_ptr == NULL)
      return (png_uint_32)0;
   png_ptr->mng_features_permitted =
     (png_byte)(mng_features & PNG_ALL_MNG_FEATURES);
   return (png_uint_32)png_ptr->mng_features_permitted;
}
#endif

#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
void PNGAPI
png_set_keep_unknown_chunks(png_structp png_ptr, int keep, png_bytep
   chunk_list, int num_chunks)
{
   png_bytep new_list, p;
   int i, old_num_chunks;
   if (png_ptr == NULL)
      return;
   if (num_chunks == 0)
   {
      if (keep == PNG_HANDLE_CHUNK_ALWAYS || keep == PNG_HANDLE_CHUNK_IF_SAFE)
         png_ptr->flags |= PNG_FLAG_KEEP_UNKNOWN_CHUNKS;
      else
         png_ptr->flags &= ~PNG_FLAG_KEEP_UNKNOWN_CHUNKS;

      if (keep == PNG_HANDLE_CHUNK_ALWAYS)
         png_ptr->flags |= PNG_FLAG_KEEP_UNSAFE_CHUNKS;
      else
         png_ptr->flags &= ~PNG_FLAG_KEEP_UNSAFE_CHUNKS;
      return;
   }
   if (chunk_list == NULL)
      return;
   old_num_chunks = png_ptr->num_chunk_list;
   new_list=(png_bytep)png_malloc(png_ptr,
      (png_size_t)
       (5*(num_chunks + old_num_chunks)));
   if (png_ptr->chunk_list != NULL)
   {
      png_memcpy(new_list, png_ptr->chunk_list,
          (png_size_t)(5*old_num_chunks));
      png_free(png_ptr, png_ptr->chunk_list);
      png_ptr->chunk_list=NULL;
   }
   png_memcpy(new_list + 5*old_num_chunks, chunk_list,
       (png_size_t)(5*num_chunks));
   for (p = new_list + 5*old_num_chunks + 4, i = 0; i<num_chunks; i++, p += 5)
      *p=(png_byte)keep;
   png_ptr->num_chunk_list = old_num_chunks + num_chunks;
   png_ptr->chunk_list = new_list;
   png_ptr->free_me |= PNG_FREE_LIST;
}
#endif

#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
void PNGAPI
png_set_read_user_chunk_fn(png_structp 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_structp png_ptr, png_infop 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 && (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)
      info_ptr->valid |= PNG_INFO_IDAT;
}
#endif

void PNGAPI
png_set_compression_buffer_size(png_structp png_ptr,
    png_size_t size)
{
    if (png_ptr == NULL)
       return;
    png_free(png_ptr, png_ptr->zbuf);
    png_ptr->zbuf_size = size;
    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr, size);
    png_ptr->zstream.next_out = png_ptr->zbuf;
    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
}

void PNGAPI
png_set_invalid(png_structp png_ptr, png_infop info_ptr, int mask)
{
   if (png_ptr && info_ptr)
      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_structp 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_structp png_ptr,
   png_uint_32 user_chunk_cache_max)
{
    if (png_ptr)
       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_structp png_ptr,
   png_alloc_size_t user_chunk_malloc_max)
{
    if (png_ptr)
       png_ptr->user_chunk_malloc_max =
          (png_size_t)user_chunk_malloc_max;
}
#endif /* ?PNG_SET_USER_LIMITS_SUPPORTED */

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

   if (allowed)
      png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
   else
      png_ptr->flags &= ~PNG_FLAG_BENIGN_ERRORS_WARN;
}
#endif /* PNG_BENIGN_ERRORS_SUPPORTED */
#endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */


code:
/* pngtest.c - a simple test program to test libpng
 *
 * Last changed in libpng 1.4.5 [December 9, 2010]
 * Copyright (c) 1998-2010 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
 *
 * This program reads in a PNG image, writes it out again, and then
 * compares the two files.  If the files are identical, this shows that
 * the basic chunk handling, filtering, and (de)compression code is working
 * properly.  It does not currently test all of the transforms, although
 * it probably should.
 *
 * The program will report "FAIL" in certain legitimate cases:
 * 1) when the compression level or filter selection method is changed.
 * 2) when the maximum IDAT size (PNG_ZBUF_SIZE in pngconf.h) is not 8192.
 * 3) unknown unsafe-to-copy ancillary chunks or unknown critical chunks
 *    exist in the input file.
 * 4) others not listed here...
 * In these cases, it is best to check with another tool such as "pngcheck"
 * to see what the differences between the two files are.
 *
 * If a filename is given on the command-line, then this file is used
 * for the input, rather than the default "pngtest.png".  This allows
 * testing a wide variety of files easily.  You can also test a number
 * of files at once by typing "pngtest -m file1.png file2.png ..."
 */

#include "png.h"
#include "pngpriv.h"

#  include <stdio.h>
#  include <stdlib.h>
#  define FCLOSE(file) fclose(file)

#ifndef PNG_STDIO_SUPPORTED
     typedef FILE                * png_FILE_p;
#endif

/* Makes pngtest verbose so we can find problems (needs to be before png.h) */
#ifndef PNG_DEBUG
#  define PNG_DEBUG 0
#endif

#if !PNG_DEBUG
#  define SINGLE_ROWBUF_ALLOC  /* Makes buffer overruns easier to nail */
#endif

/* Turn on CPU timing
#define PNGTEST_TIMING
*/

#ifndef PNG_FLOATING_POINT_SUPPORTED
#undef PNGTEST_TIMING
#endif

#ifdef PNGTEST_TIMING
static float t_start, t_stop, t_decode, t_encode, t_misc;
#include <time.h>
#endif

#ifdef PNG_TIME_RFC1123_SUPPORTED
#define PNG_tIME_STRING_LENGTH 29
static int tIME_chunk_present = 0;
static char tIME_string[PNG_tIME_STRING_LENGTH] = "tIME chunk is not present";
#endif

static int verbose = 0;

int test_one_file PNGARG((PNG_CONST char *inname, PNG_CONST char *outname));

#ifdef __TURBOC__
#include <mem.h>
#endif

/* Defined so I can write to a file on gui/windowing platforms */
/*  #define STDERR stderr  */
#define STDERR stdout   /* For DOS */

/* In case a system header (e.g., on AIX) defined jmpbuf */
#ifdef jmpbuf
#  undef jmpbuf
#endif

/* Define png_jmpbuf() in case we are using a pre-1.0.6 version of libpng */
#ifndef png_jmpbuf
#  define png_jmpbuf(png_ptr) png_ptr->jmpbuf
#endif

/* Example of using row callbacks to make a simple progress meter */
static int status_pass = 1;
static int status_dots_requested = 0;
static int status_dots = 1;

void
read_row_callback(png_structp png_ptr, png_uint_32 row_number, int pass);
void
read_row_callback(png_structp png_ptr, png_uint_32 row_number, int pass)
{
   if (png_ptr == NULL || row_number > PNG_UINT_31_MAX)
      return;
   if (status_pass != pass)
   {
      fprintf(stdout, "\n Pass %d: ", pass);
      status_pass = pass;
      status_dots = 31;
   }
   status_dots--;
   if (status_dots == 0)
   {
      fprintf(stdout, "\n         ");
      status_dots=30;
   }
   fprintf(stdout, "r");
}

void
write_row_callback(png_structp png_ptr, png_uint_32 row_number, int pass);
void
write_row_callback(png_structp png_ptr, png_uint_32 row_number, int pass)
{
   if (png_ptr == NULL || row_number > PNG_UINT_31_MAX || pass > 7)
      return;
   fprintf(stdout, "w");
}

#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
/* Example of using user transform callback (we don't transform anything,
 * but merely examine the row filters.  We set this to 256 rather than
 * 5 in case illegal filter values are present.)
 */
static png_uint_32 filters_used[256];
void
count_filters(png_structp png_ptr, png_row_infop row_info, png_bytep data);
void
count_filters(png_structp png_ptr, png_row_infop row_info, png_bytep data)
{
   if (png_ptr != NULL && row_info != NULL)
      ++filters_used[*(data - 1)];
}
#endif

#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
/* Example of using user transform callback (we don't transform anything,
 * but merely count the zero samples)
 */

static png_uint_32 zero_samples;

void
count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data);
void
count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data)
{
   png_bytep dp = data;
   if (png_ptr == NULL)return;

   /* Contents of row_info:
    *  png_uint_32 width      width of row
    *  png_uint_32 rowbytes   number of bytes in row
    *  png_byte color_type    color type of pixels
    *  png_byte bit_depth     bit depth of samples
    *  png_byte channels      number of channels (1-4)
    *  png_byte pixel_depth   bits per pixel (depth*channels)
    */

    /* Counts the number of zero samples (or zero pixels if color_type is 3 */

    if (row_info->color_type == 0 || row_info->color_type == 3)
    {
       int pos = 0;
       png_uint_32 n, nstop;
       for (n = 0, nstop=row_info->width; n<nstop; n++)
       {
          if (row_info->bit_depth == 1)
          {
             if (((*dp << pos++ ) & 0x80) == 0)
                zero_samples++;
             if (pos == 8)
             {
                pos = 0;
                dp++;
             }
          }
          if (row_info->bit_depth == 2)
          {
             if (((*dp << (pos+=2)) & 0xc0) == 0)
                zero_samples++;
             if (pos == 8)
             {
                pos = 0;
                dp++;
             }
          }
          if (row_info->bit_depth == 4)
          {
             if (((*dp << (pos+=4)) & 0xf0) == 0)
                zero_samples++;
             if (pos == 8)
             {
                pos = 0;
                dp++;
             }
          }
          if (row_info->bit_depth == 8)
             if (*dp++ == 0)
                zero_samples++;
          if (row_info->bit_depth == 16)
          {
             if ((*dp | *(dp+1)) == 0)
                zero_samples++;
             dp+=2;
          }
       }
    }
    else /* Other color types */
    {
       png_uint_32 n, nstop;
       int channel;
       int color_channels = row_info->channels;
       if (row_info->color_type > 3)color_channels--;

       for (n = 0, nstop=row_info->width; n<nstop; n++)
       {
          for (channel = 0; channel < color_channels; channel++)
          {
             if (row_info->bit_depth == 8)
                if (*dp++ == 0)
                   zero_samples++;
             if (row_info->bit_depth == 16)
             {
                if ((*dp | *(dp+1)) == 0)
                   zero_samples++;
                dp+=2;
             }
          }
          if (row_info->color_type > 3)
          {
             dp++;
             if (row_info->bit_depth == 16)
                dp++;
          }
       }
    }
}
#endif /* PNG_WRITE_USER_TRANSFORM_SUPPORTED */

static int wrote_question = 0;

#ifndef PNG_STDIO_SUPPORTED
/* START of code to validate stdio-free compilation */
/* These copies of the default read/write functions come from pngrio.c and
 * pngwio.c.  They allow "don't include stdio" testing of the library.
 * This is the function that does the actual reading of data.  If you are
 * not reading from a standard C stream, you should create a replacement
 * read_data function and use it at run time with png_set_read_fn(), rather
 * than changing the library.
 */

#ifdef PNG_IO_STATE_SUPPORTED
void
pngtest_check_io_state(png_structp png_ptr, png_size_t data_length,
   png_uint_32 io_op);
void
pngtest_check_io_state(png_structp png_ptr, png_size_t data_length,
   png_uint_32 io_op)
{
   png_uint_32 io_state = png_get_io_state(png_ptr);
   int err = 0;

   /* Check if the current operation (reading / writing) is as expected. */
   if ((io_state & PNG_IO_MASK_OP) != io_op)
      png_error(png_ptr, "Incorrect operation in I/O state");

   /* Check if the buffer size specific to the current location
    * (file signature / header / data / crc) is as expected.
    */
   switch (io_state & PNG_IO_MASK_LOC)
   {
   case PNG_IO_SIGNATURE:
      if (data_length > 8)
         err = 1;
      break;
   case PNG_IO_CHUNK_HDR:
      if (data_length != 8)
         err = 1;
      break;
   case PNG_IO_CHUNK_DATA:
      break;  /* no restrictions here */
   case PNG_IO_CHUNK_CRC:
      if (data_length != 4)
         err = 1;
      break;
   default:
      err = 1;  /* uninitialized */
   }
   if (err)
      png_error(png_ptr, "Bad I/O state or buffer size");
}
#endif

#ifndef USE_FAR_KEYWORD
static void
pngtest_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_size_t check = 0;
   png_voidp io_ptr;

   /* fread() returns 0 on error, so it is OK to store this in a png_size_t
    * instead of an int, which is what fread() actually returns.
    */
   io_ptr = png_get_io_ptr(png_ptr);
   if (io_ptr != NULL)
   {
      check = fread(data, 1, length, (png_FILE_p)io_ptr);
   }

   if (check != length)
   {
      png_error(png_ptr, "Read Error");
   }

#ifdef PNG_IO_STATE_SUPPORTED
   pngtest_check_io_state(png_ptr, length, PNG_IO_READING);
#endif
}
#else
/* This is the model-independent version. Since the standard I/O library
   can't handle far buffers in the medium and small models, we have to copy
   the data.
*/

#define NEAR_BUF_SIZE 1024
#define MIN(a,b) (a <= b ? a : b)

static void
pngtest_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_size_t check;
   png_byte *n_data;
   png_FILE_p io_ptr;

   /* Check if data really is near. If so, use usual code. */
   n_data = (png_byte *)CVT_PTR_NOCHECK(data);
   io_ptr = (png_FILE_p)CVT_PTR(png_get_io_ptr(png_ptr));
   if ((png_bytep)n_data == data)
   {
      check = fread(n_data, 1, length, io_ptr);
   }
   else
   {
      png_byte buf[NEAR_BUF_SIZE];
      png_size_t read, remaining, err;
      check = 0;
      remaining = length;
      do
      {
         read = MIN(NEAR_BUF_SIZE, remaining);
         err = fread(buf, 1, 1, io_ptr);
         png_memcpy(data, buf, read); /* Copy far buffer to near buffer */
         if (err != read)
            break;
         else
            check += err;
         data += read;
         remaining -= read;
      }
      while (remaining != 0);
   }
   if (check != length)
      png_error(png_ptr, "Read Error");

#ifdef PNG_IO_STATE_SUPPORTED
   pngtest_check_io_state(png_ptr, length, PNG_IO_READING);
#endif
}
#endif /* USE_FAR_KEYWORD */

#ifdef PNG_WRITE_FLUSH_SUPPORTED
static void
pngtest_flush(png_structp png_ptr)
{
   /* Do nothing; fflush() is said to be just a waste of energy. */
   png_ptr = png_ptr;  /* Stifle compiler warning */
}
#endif

/* This is the function that does the actual writing of data.  If you are
 * not writing to a standard C stream, you should create a replacement
 * write_data function and use it at run time with png_set_write_fn(), rather
 * than changing the library.
 */
#ifndef USE_FAR_KEYWORD
static void
pngtest_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_size_t check;
   png_FILE_p io_ptr;
   io_ptr = (png_FILE_p)CVT_PTR(png_get_io_ptr(png_ptr));

   check = fwrite(data, 1, length, io_ptr);
   if (check != length)
   {
      png_error(png_ptr, "Write Error");
   }

#ifdef PNG_IO_STATE_SUPPORTED
   pngtest_check_io_state(png_ptr, length, PNG_IO_WRITING);
#endif
}
#else
/* This is the model-independent version. Since the standard I/O library
   can't handle far buffers in the medium and small models, we have to copy
   the data.
*/

#define NEAR_BUF_SIZE 1024
#define MIN(a,b) (a <= b ? a : b)

static void
pngtest_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
   png_size_t check;
   png_byte *near_data;  /* Needs to be "png_byte *" instead of "png_bytep" */
   png_FILE_p io_ptr;

   /* Check if data really is near. If so, use usual code. */
   near_data = (png_byte *)CVT_PTR_NOCHECK(data);
   io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
   if ((png_bytep)near_data == data)
   {
      check = fwrite(near_data, 1, length, io_ptr);
   }
   else
   {
      png_byte buf[NEAR_BUF_SIZE];
      png_size_t written, remaining, err;
      check = 0;
      remaining = length;
      do
      {
         written = MIN(NEAR_BUF_SIZE, remaining);
         png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
         err = fwrite(buf, 1, written, io_ptr);
         if (err != written)
            break;
         else
            check += err;
         data += written;
         remaining -= written;
      }
      while (remaining != 0);
   }
   if (check != length)
   {
      png_error(png_ptr, "Write Error");
   }

#ifdef PNG_IO_STATE_SUPPORTED
   pngtest_check_io_state(png_ptr, length, PNG_IO_WRITING);
#endif
}
#endif /* USE_FAR_KEYWORD */

/* This function is called when there is a warning, but the library thinks
 * it can continue anyway.  Replacement functions don't have to do anything
 * here if you don't want to.  In the default configuration, png_ptr is
 * not used, but it is passed in case it may be useful.
 */
static void
pngtest_warning(png_structp png_ptr, png_const_charp message)
{
   PNG_CONST char *name = "UNKNOWN (ERROR!)";
   char *test;
   test = png_get_error_ptr(png_ptr);
   if (test == NULL)
     fprintf(STDERR, "%s: libpng warning: %s\n", name, message);
   else
     fprintf(STDERR, "%s: libpng warning: %s\n", test, message);
}

/* This is the default error handling function.  Note that replacements for
 * this function MUST NOT RETURN, or the program will likely crash.  This
 * function is used by default, or if the program supplies NULL for the
 * error function pointer in png_set_error_fn().
 */
static void
pngtest_error(png_structp png_ptr, png_const_charp message)
{
   pngtest_warning(png_ptr, message);
   /* We can return because png_error calls the default handler, which is
    * actually OK in this case.
    */
}
#endif /* !PNG_STDIO_SUPPORTED */
/* END of code to validate stdio-free compilation */

/* START of code to validate memory allocation and deallocation */
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG

/* Allocate memory.  For reasonable files, size should never exceed
 * 64K.  However, zlib may allocate more then 64K if you don't tell
 * it not to.  See zconf.h and png.h for more information.  zlib does
 * need to allocate exactly 64K, so whatever you call here must
 * have the ability to do that.
 *
 * This piece of code can be compiled to validate max 64K allocations
 * by setting MAXSEG_64K in zlib zconf.h *or* PNG_MAX_MALLOC_64K.
 */
typedef struct memory_information
{
   png_alloc_size_t          size;
   png_voidp                 pointer;
   struct memory_information FAR *next;
} memory_information;
typedef memory_information FAR *memory_infop;

static memory_infop pinformation = NULL;
static int current_allocation = 0;
static int maximum_allocation = 0;
static int total_allocation = 0;
static int num_allocations = 0;

png_voidp png_debug_malloc
   PNGARG((png_structp png_ptr, png_alloc_size_t size));
void png_debug_free PNGARG((png_structp png_ptr, png_voidp ptr));

png_voidp
png_debug_malloc(png_structp png_ptr, png_alloc_size_t size)
{

   /* png_malloc has already tested for NULL; png_create_struct calls
    * png_debug_malloc directly, with png_ptr == NULL which is OK
    */

   if (size == 0)
      return (NULL);

   /* This calls the library allocator twice, once to get the requested
      buffer and once to get a new free list entry. */
   {
      /* Disable malloc_fn and free_fn */
      memory_infop pinfo;
      png_set_mem_fn(png_ptr, NULL, NULL, NULL);
      pinfo = (memory_infop)png_malloc(png_ptr,
         png_sizeof(*pinfo));
      pinfo->size = size;
      current_allocation += size;
      total_allocation += size;
      num_allocations ++;
      if (current_allocation > maximum_allocation)
         maximum_allocation = current_allocation;
      pinfo->pointer = png_malloc(png_ptr, size);
      /* Restore malloc_fn and free_fn */
      png_set_mem_fn(png_ptr,
          NULL, png_debug_malloc, png_debug_free);
      if (size != 0 && pinfo->pointer == NULL)
      {
         current_allocation -= size;
         total_allocation -= size;
         png_error(png_ptr,
           "out of memory in pngtest->png_debug_malloc");
      }
      pinfo->next = pinformation;
      pinformation = pinfo;
      /* Make sure the caller isn't assuming zeroed memory. */
      png_memset(pinfo->pointer, 0xdd, pinfo->size);
      if (verbose)
         printf("png_malloc %lu bytes at %x\n", (unsigned long)size,
            pinfo->pointer);
      return (png_voidp)(pinfo->pointer);
   }
}

/* Free a pointer.  It is removed from the list at the same time. */
void
png_debug_free(png_structp png_ptr, png_voidp ptr)
{
   if (png_ptr == NULL)
      fprintf(STDERR, "NULL pointer to png_debug_free.\n");
   if (ptr == 0)
   {
#if 0 /* This happens all the time. */
      fprintf(STDERR, "WARNING: freeing NULL pointer\n");
#endif
      return;
   }

   /* Unlink the element from the list. */
   {
      memory_infop FAR *ppinfo = &pinformation;
      for (;;)
      {
         memory_infop pinfo = *ppinfo;
         if (pinfo->pointer == ptr)
         {
            *ppinfo = pinfo->next;
            current_allocation -= pinfo->size;
            if (current_allocation < 0)
               fprintf(STDERR, "Duplicate free of memory\n");
            /* We must free the list element too, but first kill
               the memory that is to be freed. */
            png_memset(ptr, 0x55, pinfo->size);
            png_free_default(png_ptr, pinfo);
            pinfo = NULL;
            break;
         }
         if (pinfo->next == NULL)
         {
            fprintf(STDERR, "Pointer %x not found\n", (unsigned int)ptr);
            break;
         }
         ppinfo = &pinfo->next;
      }
   }

   /* Finally free the data. */
   if (verbose)
      printf("Freeing %x\n", ptr);
   png_free_default(png_ptr, ptr);
   ptr = NULL;
}
#endif /* PNG_USER_MEM_SUPPORTED && PNG_DEBUG */
/* END of code to test memory allocation/deallocation */

/* Demonstration of user chunk support of the sTER and vpAg chunks */
#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED

/* (sTER is a public chunk not yet known by libpng.  vpAg is a private
chunk used in ImageMagick to store "virtual page" size).  */

static png_uint_32 user_chunk_data[4];

    /* 0: sTER mode + 1
     * 1: vpAg width
     * 2: vpAg height
     * 3: vpAg units
     */

static int read_user_chunk_callback(png_struct *png_ptr,
   png_unknown_chunkp chunk)
{
   png_uint_32
     *my_user_chunk_data;

   /* Return one of the following:
    *    return (-n);  chunk had an error
    *    return (0);  did not recognize
    *    return (n);  success
    *
    * The unknown chunk structure contains the chunk data:
    * png_byte name[5];
    * png_byte *data;
    * png_size_t size;
    *
    * Note that libpng has already taken care of the CRC handling.
    */

   if (chunk->name[0] == 115 && chunk->name[1] ==  84 &&     /* s  T */
       chunk->name[2] ==  69 && chunk->name[3] ==  82)       /* E  R */
      {
         /* Found sTER chunk */
         if (chunk->size != 1)
            return (-1); /* Error return */
         if (chunk->data[0] != 0 && chunk->data[0] != 1)
            return (-1);  /* Invalid mode */
         my_user_chunk_data=(png_uint_32 *) png_get_user_chunk_ptr(png_ptr);
         my_user_chunk_data[0]=chunk->data[0]+1;
         return (1);
      }

   if (chunk->name[0] != 118 || chunk->name[1] != 112 ||    /* v  p */
       chunk->name[2] !=  65 || chunk->name[3] != 103)      /* A  g */
      return (0); /* Did not recognize */

   /* Found ImageMagick vpAg chunk */

   if (chunk->size != 9)
      return (-1); /* Error return */

   my_user_chunk_data=(png_uint_32 *) png_get_user_chunk_ptr(png_ptr);

   my_user_chunk_data[1]=png_get_uint_31(png_ptr, chunk->data);
   my_user_chunk_data[2]=png_get_uint_31(png_ptr, chunk->data + 4);
   my_user_chunk_data[3]=(png_uint_32)chunk->data[8];

   return (1);

}
#endif
/* END of code to demonstrate user chunk support */

/* Test one file */
int
test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
{
   static png_FILE_p fpin;
   static png_FILE_p fpout;  /* "static" prevents setjmp corruption */
   png_structp read_ptr;
   png_infop read_info_ptr, end_info_ptr;
#ifdef PNG_WRITE_SUPPORTED
   png_structp write_ptr;
   png_infop write_info_ptr;
   png_infop write_end_info_ptr;
#else
   png_structp write_ptr = NULL;
   png_infop write_info_ptr = NULL;
   png_infop write_end_info_ptr = NULL;
#endif
   png_bytep row_buf;
   png_uint_32 y;
   png_uint_32 width, height;
   int num_pass, pass;
   int bit_depth, color_type;
#ifdef PNG_SETJMP_SUPPORTED
#ifdef USE_FAR_KEYWORD
   jmp_buf jmpbuf;
#endif
#endif

   char inbuf[256], outbuf[256];

   row_buf = NULL;

   if ((fpin = fopen(inname, "rb")) == NULL)
   {
      fprintf(STDERR, "Could not find input file %s\n", inname);
      return (1);
   }

   if ((fpout = fopen(outname, "wb")) == NULL)
   {
      fprintf(STDERR, "Could not open output file %s\n", outname);
      FCLOSE(fpin);
      return (1);
   }

   png_debug(0, "Allocating read and write structures");
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
   read_ptr =
      png_create_read_struct_2(PNG_LIBPNG_VER_STRING, NULL,
      NULL, NULL, NULL,
      (png_malloc_ptr)png_debug_malloc, (png_free_ptr)png_debug_free);
#else
   read_ptr =
      png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
#endif
#ifndef PNG_STDIO_SUPPORTED
   png_set_error_fn(read_ptr, (png_voidp)inname, pngtest_error,
       pngtest_warning);
#endif

#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
   user_chunk_data[0] = 0;
   user_chunk_data[1] = 0;
   user_chunk_data[2] = 0;
   user_chunk_data[3] = 0;
   png_set_read_user_chunk_fn(read_ptr, user_chunk_data,
     read_user_chunk_callback);

#endif
#ifdef PNG_WRITE_SUPPORTED
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
   write_ptr =
      png_create_write_struct_2(PNG_LIBPNG_VER_STRING, NULL,
      NULL, NULL, NULL, png_debug_malloc, png_debug_free);
#else
   write_ptr =
      png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
#endif
#ifndef PNG_STDIO_SUPPORTED
   png_set_error_fn(write_ptr, (png_voidp)inname, pngtest_error,
       pngtest_warning);
#endif
#endif
   png_debug(0, "Allocating read_info, write_info and end_info structures");
   read_info_ptr = png_create_info_struct(read_ptr);
   end_info_ptr = png_create_info_struct(read_ptr);
#ifdef PNG_WRITE_SUPPORTED
   write_info_ptr = png_create_info_struct(write_ptr);
   write_end_info_ptr = png_create_info_struct(write_ptr);
#endif

#ifdef PNG_SETJMP_SUPPORTED
   png_debug(0, "Setting jmpbuf for read struct");
#ifdef USE_FAR_KEYWORD
   if (setjmp(jmpbuf))
#else
   if (setjmp(png_jmpbuf(read_ptr)))
#endif
   {
      fprintf(STDERR, "%s -> %s: libpng read error\n", inname, outname);
      png_free(read_ptr, row_buf);
      row_buf = NULL;
      png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
#ifdef PNG_WRITE_SUPPORTED
      png_destroy_info_struct(write_ptr, &write_end_info_ptr);
      png_destroy_write_struct(&write_ptr, &write_info_ptr);
#endif
      FCLOSE(fpin);
      FCLOSE(fpout);
      return (1);
   }
#ifdef USE_FAR_KEYWORD
   png_memcpy(png_jmpbuf(read_ptr), jmpbuf, png_sizeof(jmp_buf));
#endif

#ifdef PNG_WRITE_SUPPORTED
   png_debug(0, "Setting jmpbuf for write struct");
#ifdef USE_FAR_KEYWORD
   if (setjmp(jmpbuf))
#else
   if (setjmp(png_jmpbuf(write_ptr)))
#endif
   {
      fprintf(STDERR, "%s -> %s: libpng write error\n", inname, outname);
      png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
      png_destroy_info_struct(write_ptr, &write_end_info_ptr);
#ifdef PNG_WRITE_SUPPORTED
      png_destroy_write_struct(&write_ptr, &write_info_ptr);
#endif
      FCLOSE(fpin);
      FCLOSE(fpout);
      return (1);
   }
#ifdef USE_FAR_KEYWORD
   png_memcpy(png_jmpbuf(write_ptr), jmpbuf, png_sizeof(jmp_buf));
#endif
#endif
#endif

   png_debug(0, "Initializing input and output streams");
#ifdef PNG_STDIO_SUPPORTED
   png_init_io(read_ptr, fpin);
#  ifdef PNG_WRITE_SUPPORTED
   png_init_io(write_ptr, fpout);
#  endif
#else
   png_set_read_fn(read_ptr, (png_voidp)fpin, pngtest_read_data);
#  ifdef PNG_WRITE_SUPPORTED
   png_set_write_fn(write_ptr, (png_voidp)fpout,  pngtest_write_data,
#    ifdef PNG_WRITE_FLUSH_SUPPORTED
      pngtest_flush);
#    else
      NULL);
#    endif
#  endif
#endif
   if (status_dots_requested == 1)
   {
#ifdef PNG_WRITE_SUPPORTED
      png_set_write_status_fn(write_ptr, write_row_callback);
#endif
      png_set_read_status_fn(read_ptr, read_row_callback);
   }
   else
   {
#ifdef PNG_WRITE_SUPPORTED
      png_set_write_status_fn(write_ptr, NULL);
#endif
      png_set_read_status_fn(read_ptr, NULL);
   }

#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
   {
      int i;
      for (i = 0; i<256; i++)
         filters_used[i] = 0;
      png_set_read_user_transform_fn(read_ptr, count_filters);
   }
#endif
#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
   zero_samples = 0;
   png_set_write_user_transform_fn(write_ptr, count_zero_samples);
#endif

#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
#  ifndef PNG_HANDLE_CHUNK_ALWAYS
#    define PNG_HANDLE_CHUNK_ALWAYS       3
#  endif
   png_set_keep_unknown_chunks(read_ptr, PNG_HANDLE_CHUNK_ALWAYS,
      NULL, 0);
#endif
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
#  ifndef PNG_HANDLE_CHUNK_IF_SAFE
#    define PNG_HANDLE_CHUNK_IF_SAFE      2
#  endif
   png_set_keep_unknown_chunks(write_ptr, PNG_HANDLE_CHUNK_IF_SAFE,
      NULL, 0);
#endif

   png_debug(0, "Reading info struct");
   png_read_info(read_ptr, read_info_ptr);

   png_debug(0, "Transferring info struct");
   {
      int interlace_type, compression_type, filter_type;

      if (png_get_IHDR(read_ptr, read_info_ptr, &width, &height, &bit_depth,
          &color_type, &interlace_type, &compression_type, &filter_type))
      {
         png_set_IHDR(write_ptr, write_info_ptr, width, height, bit_depth,
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
            color_type, interlace_type, compression_type, filter_type);
#else
            color_type, PNG_INTERLACE_NONE, compression_type, filter_type);
#endif
      }
   }
#ifdef PNG_FIXED_POINT_SUPPORTED
#ifdef PNG_cHRM_SUPPORTED
   {
      png_fixed_point white_x, white_y, red_x, red_y, green_x, green_y, blue_x,
         blue_y;
      if (png_get_cHRM_fixed(read_ptr, read_info_ptr, &white_x, &white_y,
         &red_x, &red_y, &green_x, &green_y, &blue_x, &blue_y))
      {
         png_set_cHRM_fixed(write_ptr, write_info_ptr, white_x, white_y, red_x,
            red_y, green_x, green_y, blue_x, blue_y);
      }
   }
#endif
#ifdef PNG_gAMA_SUPPORTED
   {
      png_fixed_point gamma;

      if (png_get_gAMA_fixed(read_ptr, read_info_ptr, &gamma))
         png_set_gAMA_fixed(write_ptr, write_info_ptr, gamma);
   }
#endif
#else /* Use floating point versions */
#ifdef PNG_FLOATING_POINT_SUPPORTED
#ifdef PNG_cHRM_SUPPORTED
   {
      double white_x, white_y, red_x, red_y, green_x, green_y, blue_x,
         blue_y;
      if (png_get_cHRM(read_ptr, read_info_ptr, &white_x, &white_y, &red_x,
         &red_y, &green_x, &green_y, &blue_x, &blue_y))
      {
         png_set_cHRM(write_ptr, write_info_ptr, white_x, white_y, red_x,
            red_y, green_x, green_y, blue_x, blue_y);
      }
   }
#endif
#ifdef PNG_gAMA_SUPPORTED
   {
      double gamma;

      if (png_get_gAMA(read_ptr, read_info_ptr, &gamma))
         png_set_gAMA(write_ptr, write_info_ptr, gamma);
   }
#endif
#endif /* Floating point */
#endif /* Fixed point */
#ifdef PNG_iCCP_SUPPORTED
   {
      png_charp name;
      png_charp profile;
      png_uint_32 proflen;
      int compression_type;

      if (png_get_iCCP(read_ptr, read_info_ptr, &name, &compression_type,
                      &profile, &proflen))
      {
         png_set_iCCP(write_ptr, write_info_ptr, name, compression_type,
                      profile, proflen);
      }
   }
#endif
#ifdef PNG_sRGB_SUPPORTED
   {
      int intent;

      if (png_get_sRGB(read_ptr, read_info_ptr, &intent))
         png_set_sRGB(write_ptr, write_info_ptr, intent);
   }
#endif
   {
      png_colorp palette;
      int num_palette;

      if (png_get_PLTE(read_ptr, read_info_ptr, &palette, &num_palette))
         png_set_PLTE(write_ptr, write_info_ptr, palette, num_palette);
   }
#ifdef PNG_bKGD_SUPPORTED
   {
      png_color_16p background;

      if (png_get_bKGD(read_ptr, read_info_ptr, &background))
      {
         png_set_bKGD(write_ptr, write_info_ptr, background);
      }
   }
#endif
#ifdef PNG_hIST_SUPPORTED
   {
      png_uint_16p hist;

      if (png_get_hIST(read_ptr, read_info_ptr, &hist))
         png_set_hIST(write_ptr, write_info_ptr, hist);
   }
#endif
#ifdef PNG_oFFs_SUPPORTED
   {
      png_int_32 offset_x, offset_y;
      int unit_type;

      if (png_get_oFFs(read_ptr, read_info_ptr, &offset_x, &offset_y,
          &unit_type))
      {
         png_set_oFFs(write_ptr, write_info_ptr, offset_x, offset_y, unit_type);
      }
   }
#endif
#ifdef PNG_pCAL_SUPPORTED
   {
      png_charp purpose, units;
      png_charpp params;
      png_int_32 X0, X1;
      int type, nparams;

      if (png_get_pCAL(read_ptr, read_info_ptr, &purpose, &X0, &X1, &type,
         &nparams, &units, &params))
      {
         png_set_pCAL(write_ptr, write_info_ptr, purpose, X0, X1, type,
            nparams, units, params);
      }
   }
#endif
#ifdef PNG_pHYs_SUPPORTED
   {
      png_uint_32 res_x, res_y;
      int unit_type;

      if (png_get_pHYs(read_ptr, read_info_ptr, &res_x, &res_y, &unit_type))
         png_set_pHYs(write_ptr, write_info_ptr, res_x, res_y, unit_type);
   }
#endif
#ifdef PNG_sBIT_SUPPORTED
   {
      png_color_8p sig_bit;

      if (png_get_sBIT(read_ptr, read_info_ptr, &sig_bit))
         png_set_sBIT(write_ptr, write_info_ptr, sig_bit);
   }
#endif
#ifdef PNG_sCAL_SUPPORTED
#ifdef PNG_FLOATING_POINT_SUPPORTED
   {
      int unit;
      double scal_width, scal_height;

      if (png_get_sCAL(read_ptr, read_info_ptr, &unit, &scal_width,
         &scal_height))
      {
         png_set_sCAL(write_ptr, write_info_ptr, unit, scal_width, scal_height);
      }
   }
#else
#ifdef PNG_FIXED_POINT_SUPPORTED
   {
      int unit;
      png_charp scal_width, scal_height;

      if (png_get_sCAL_s(read_ptr, read_info_ptr, &unit, &scal_width,
          &scal_height))
      {
         png_set_sCAL_s(write_ptr, write_info_ptr, unit, scal_width,
             scal_height);
      }
   }
#endif
#endif
#endif
#ifdef PNG_TEXT_SUPPORTED
   {
      png_textp text_ptr;
      int num_text;

      if (png_get_text(read_ptr, read_info_ptr, &text_ptr, &num_text) > 0)
      {
         png_debug1(0, "Handling %d iTXt/tEXt/zTXt chunks", num_text);
         png_set_text(write_ptr, write_info_ptr, text_ptr, num_text);
      }
   }
#endif
#ifdef PNG_tIME_SUPPORTED
   {
      png_timep mod_time;

      if (png_get_tIME(read_ptr, read_info_ptr, &mod_time))
      {
         png_set_tIME(write_ptr, write_info_ptr, mod_time);
#ifdef PNG_TIME_RFC1123_SUPPORTED
         /* We have to use png_memcpy instead of "=" because the string
          * pointed to by png_convert_to_rfc1123() gets free'ed before
          * we use it.
          */
         png_memcpy(tIME_string,
                    png_convert_to_rfc1123(read_ptr, mod_time),
                    png_sizeof(tIME_string));
         tIME_string[png_sizeof(tIME_string) - 1] = '\0';
         tIME_chunk_present++;
#endif /* PNG_TIME_RFC1123_SUPPORTED */
      }
   }
#endif
#ifdef PNG_tRNS_SUPPORTED
   {
      png_bytep trans_alpha;
      int num_trans;
      png_color_16p trans_color;

      if (png_get_tRNS(read_ptr, read_info_ptr, &trans_alpha, &num_trans,
         &trans_color))
      {
         int sample_max = (1 << bit_depth);
         /* libpng doesn't reject a tRNS chunk with out-of-range samples */
         if (!((color_type == PNG_COLOR_TYPE_GRAY &&
             (int)trans_color->gray > sample_max) ||
             (color_type == PNG_COLOR_TYPE_RGB &&
             ((int)trans_color->red > sample_max ||
             (int)trans_color->green > sample_max ||
             (int)trans_color->blue > sample_max))))
            png_set_tRNS(write_ptr, write_info_ptr, trans_alpha, num_trans,
               trans_color);
      }
   }
#endif
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
   {
      png_unknown_chunkp unknowns;
      int num_unknowns = (int)png_get_unknown_chunks(read_ptr, read_info_ptr,
         &unknowns);
      if (num_unknowns)
      {
         png_size_t i;
         png_set_unknown_chunks(write_ptr, write_info_ptr, unknowns,
           num_unknowns);
         /* Copy the locations from the read_info_ptr.  The automatically
          * generated locations in write_info_ptr are wrong because we
          * haven't written anything yet.
          */
         for (i = 0; i < (png_size_t)num_unknowns; i++)
           png_set_unknown_chunk_location(write_ptr, write_info_ptr, i,
             unknowns[i].location);
      }
   }
#endif

#ifdef PNG_WRITE_SUPPORTED
   png_debug(0, "Writing info struct");

/* If we wanted, we could write info in two steps:
 * png_write_info_before_PLTE(write_ptr, write_info_ptr);
 */
   png_write_info(write_ptr, write_info_ptr);

#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
   if (user_chunk_data[0] != 0)
   {
      png_byte png_sTER[5] = {115,  84,  69,  82, '\0'};

      unsigned char
        ster_chunk_data[1];

      if (verbose)
         fprintf(STDERR, "\n stereo mode = %lu\n",
           (unsigned long)(user_chunk_data[0] - 1));
      ster_chunk_data[0]=(unsigned char)(user_chunk_data[0] - 1);
      png_write_chunk(write_ptr, png_sTER, ster_chunk_data, 1);
   }
   if (user_chunk_data[1] != 0 || user_chunk_data[2] != 0)
   {
      png_byte png_vpAg[5] = {118, 112,  65, 103, '\0'};

      unsigned char
        vpag_chunk_data[9];

      if (verbose)
         fprintf(STDERR, " vpAg = %lu x %lu, units = %lu\n",
           (unsigned long)user_chunk_data[1],
           (unsigned long)user_chunk_data[2],
           (unsigned long)user_chunk_data[3]);
      png_save_uint_32(vpag_chunk_data, user_chunk_data[1]);
      png_save_uint_32(vpag_chunk_data + 4, user_chunk_data[2]);
      vpag_chunk_data[8] = (unsigned char)(user_chunk_data[3] & 0xff);
      png_write_chunk(write_ptr, png_vpAg, vpag_chunk_data, 9);
   }

#endif
#endif

#ifdef SINGLE_ROWBUF_ALLOC
   png_debug(0, "Allocating row buffer...");
   row_buf = (png_bytep)png_malloc(read_ptr,
      png_get_rowbytes(read_ptr, read_info_ptr));
   png_debug1(0, "0x%08lx", (unsigned long)row_buf);
#endif /* SINGLE_ROWBUF_ALLOC */
   png_debug(0, "Writing row data");

#if defined(PNG_READ_INTERLACING_SUPPORTED) || \
  defined(PNG_WRITE_INTERLACING_SUPPORTED)
   num_pass = png_set_interlace_handling(read_ptr);
#  ifdef PNG_WRITE_SUPPORTED
   png_set_interlace_handling(write_ptr);
#  endif
#else
   num_pass = 1;
#endif

#ifdef PNGTEST_TIMING
   t_stop = (float)clock();
   t_misc += (t_stop - t_start);
   t_start = t_stop;
#endif
   for (pass = 0; pass < num_pass; pass++)
   {
      png_debug1(0, "Writing row data for pass %d", pass);
      for (y = 0; y < height; y++)
      {
#ifndef SINGLE_ROWBUF_ALLOC
         png_debug2(0, "Allocating row buffer (pass %d, y = %ld)...", pass, y);
         row_buf = (png_bytep)png_malloc(read_ptr,
            png_get_rowbytes(read_ptr, read_info_ptr));
         png_debug2(0, "0x%08lx (%ld bytes)", (unsigned long)row_buf,
            png_get_rowbytes(read_ptr, read_info_ptr));
#endif /* !SINGLE_ROWBUF_ALLOC */
         png_read_rows(read_ptr, (png_bytepp)&row_buf, NULL, 1);

#ifdef PNG_WRITE_SUPPORTED
#ifdef PNGTEST_TIMING
         t_stop = (float)clock();
         t_decode += (t_stop - t_start);
         t_start = t_stop;
#endif
         png_write_rows(write_ptr, (png_bytepp)&row_buf, 1);
#ifdef PNGTEST_TIMING
         t_stop = (float)clock();
         t_encode += (t_stop - t_start);
         t_start = t_stop;
#endif
#endif /* PNG_WRITE_SUPPORTED */

#ifndef SINGLE_ROWBUF_ALLOC
         png_debug2(0, "Freeing row buffer (pass %d, y = %ld)", pass, y);
         png_free(read_ptr, row_buf);
         row_buf = NULL;
#endif /* !SINGLE_ROWBUF_ALLOC */
      }
   }

#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
   png_free_data(read_ptr, read_info_ptr, PNG_FREE_UNKN, -1);
#endif
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
   png_free_data(write_ptr, write_info_ptr, PNG_FREE_UNKN, -1);
#endif

   png_debug(0, "Reading and writing end_info data");

   png_read_end(read_ptr, end_info_ptr);
#ifdef PNG_TEXT_SUPPORTED
   {
      png_textp text_ptr;
      int num_text;

      if (png_get_text(read_ptr, end_info_ptr, &text_ptr, &num_text) > 0)
      {
         png_debug1(0, "Handling %d iTXt/tEXt/zTXt chunks", num_text);
         png_set_text(write_ptr, write_end_info_ptr, text_ptr, num_text);
      }
   }
#endif
#ifdef PNG_tIME_SUPPORTED
   {
      png_timep mod_time;

      if (png_get_tIME(read_ptr, end_info_ptr, &mod_time))
      {
         png_set_tIME(write_ptr, write_end_info_ptr, mod_time);
#ifdef PNG_TIME_RFC1123_SUPPORTED
         /* We have to use png_memcpy instead of "=" because the string
            pointed to by png_convert_to_rfc1123() gets free'ed before
            we use it */
         png_memcpy(tIME_string,
                    png_convert_to_rfc1123(read_ptr, mod_time),
                    png_sizeof(tIME_string));
         tIME_string[png_sizeof(tIME_string) - 1] = '\0';
         tIME_chunk_present++;
#endif /* PNG_TIME_RFC1123_SUPPORTED */
      }
   }
#endif
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
   {
      png_unknown_chunkp unknowns;
      int num_unknowns;
      num_unknowns = (int)png_get_unknown_chunks(read_ptr, end_info_ptr,
         &unknowns);
      if (num_unknowns)
      {
         png_size_t i;
         png_set_unknown_chunks(write_ptr, write_end_info_ptr, unknowns,
           num_unknowns);
         /* Copy the locations from the read_info_ptr.  The automatically
          * generated locations in write_end_info_ptr are wrong because we
          * haven't written the end_info yet.
          */
         for (i = 0; i < (png_size_t)num_unknowns; i++)
           png_set_unknown_chunk_location(write_ptr, write_end_info_ptr, i,
             unknowns[i].location);
      }
   }
#endif
#ifdef PNG_WRITE_SUPPORTED
   png_write_end(write_ptr, write_end_info_ptr);
#endif

#ifdef PNG_EASY_ACCESS_SUPPORTED
   if (verbose)
   {
      png_uint_32 iwidth, iheight;
      iwidth = png_get_image_width(write_ptr, write_info_ptr);
      iheight = png_get_image_height(write_ptr, write_info_ptr);
      fprintf(STDERR, "\n Image width = %lu, height = %lu\n",
         (unsigned long)iwidth, (unsigned long)iheight);
   }
#endif

   png_debug(0, "Destroying data structs");
#ifdef SINGLE_ROWBUF_ALLOC
   png_debug(1, "destroying row_buf for read_ptr");
   png_free(read_ptr, row_buf);
   row_buf = NULL;
#endif /* SINGLE_ROWBUF_ALLOC */
   png_debug(1, "destroying read_ptr, read_info_ptr, end_info_ptr");
   png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
#ifdef PNG_WRITE_SUPPORTED
   png_debug(1, "destroying write_end_info_ptr");
   png_destroy_info_struct(write_ptr, &write_end_info_ptr);
   png_debug(1, "destroying write_ptr, write_info_ptr");
   png_destroy_write_struct(&write_ptr, &write_info_ptr);
#endif
   png_debug(0, "Destruction complete.");

   FCLOSE(fpin);
   FCLOSE(fpout);

   png_debug(0, "Opening files for comparison");
   if ((fpin = fopen(inname, "rb")) == NULL)
   {
      fprintf(STDERR, "Could not find file %s\n", inname);
      return (1);
   }

   if ((fpout = fopen(outname, "rb")) == NULL)
   {
      fprintf(STDERR, "Could not find file %s\n", outname);
      FCLOSE(fpin);
      return (1);
   }

   for (;;)
   {
      png_size_t num_in, num_out;

         num_in = fread(inbuf, 1, 1, fpin);
         num_out = fread(outbuf, 1, 1, fpout);

      if (num_in != num_out)
      {
         fprintf(STDERR, "\nFiles %s and %s are of a different size\n",
                 inname, outname);
         if (wrote_question == 0)
         {
            fprintf(STDERR,
         "   Was %s written with the same maximum IDAT chunk size (%d bytes),",
              inname, PNG_ZBUF_SIZE);
            fprintf(STDERR,
              "\n   filtering heuristic (libpng default), compression");
            fprintf(STDERR,
              " level (zlib default),\n   and zlib version (%s)?\n\n",
              ZLIB_VERSION);
            wrote_question = 1;
         }
         FCLOSE(fpin);
         FCLOSE(fpout);
         return (0);
      }

      if (!num_in)
         break;

      if (png_memcmp(inbuf, outbuf, num_in))
      {
         fprintf(STDERR, "\nFiles %s and %s are different\n", inname, outname);
         if (wrote_question == 0)
         {
            fprintf(STDERR,
         "   Was %s written with the same maximum IDAT chunk size (%d bytes),",
                 inname, PNG_ZBUF_SIZE);
            fprintf(STDERR,
              "\n   filtering heuristic (libpng default), compression");
            fprintf(STDERR,
              " level (zlib default),\n   and zlib version (%s)?\n\n",
              ZLIB_VERSION);
            wrote_question = 1;
         }
         FCLOSE(fpin);
         FCLOSE(fpout);
         return (0);
      }
   }

   FCLOSE(fpin);
   FCLOSE(fpout);

   return (0);
}

/* Input and output filenames */
#ifdef RISCOS
static PNG_CONST char *inname = "pngtest/png";
static PNG_CONST char *outname = "pngout/png";
#else
static PNG_CONST char *inname = "pngtest.png";
static PNG_CONST char *outname = "pngout.png";
#endif

int
main(int argc, char *argv[])
{
   int multiple = 0;
   int ierror = 0;

   fprintf(STDERR, "\n Testing libpng version %s\n", PNG_LIBPNG_VER_STRING);
   fprintf(STDERR, "   with zlib   version %s\n", ZLIB_VERSION);
   fprintf(STDERR, "%s", png_get_copyright(NULL));
   /* Show the version of libpng used in building the library */
   fprintf(STDERR, " library (%lu):%s",
      (unsigned long)png_access_version_number(),
      png_get_header_version(NULL));
   /* Show the version of libpng used in building the application */
   fprintf(STDERR, " pngtest (%lu):%s", (unsigned long)PNG_LIBPNG_VER,
      PNG_HEADER_VERSION_STRING);
   fprintf(STDERR, " sizeof(png_struct)=%ld, sizeof(png_info)=%ld\n",
                    (long)png_sizeof(png_struct), (long)png_sizeof(png_info));

   /* Do some consistency checking on the memory allocation settings, I'm
    * not sure this matters, but it is nice to know, the first of these
    * tests should be impossible because of the way the macros are set
    * in pngconf.h
    */
#if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
      fprintf(STDERR, " NOTE: Zlib compiled for max 64k, libpng not\n");
#endif
   /* I think the following can happen. */
#if !defined(MAXSEG_64K) && defined(PNG_MAX_MALLOC_64K)
      fprintf(STDERR, " NOTE: libpng compiled for max 64k, zlib not\n");
#endif

   if (strcmp(png_libpng_ver, PNG_LIBPNG_VER_STRING))
   {
      fprintf(STDERR,
         "Warning: versions are different between png.h and png.c\n");
      fprintf(STDERR, "  png.h version: %s\n", PNG_LIBPNG_VER_STRING);
      fprintf(STDERR, "  png.c version: %s\n\n", png_libpng_ver);
      ++ierror;
   }

   if (argc > 1)
   {
      if (strcmp(argv[1], "-m") == 0)
      {
         multiple = 1;
         status_dots_requested = 0;
      }
      else if (strcmp(argv[1], "-mv") == 0 ||
               strcmp(argv[1], "-vm") == 0 )
      {
         multiple = 1;
         verbose = 1;
         status_dots_requested = 1;
      }
      else if (strcmp(argv[1], "-v") == 0)
      {
         verbose = 1;
         status_dots_requested = 1;
         inname = argv[2];
      }
      else
      {
         inname = argv[1];
         status_dots_requested = 0;
      }
   }

   if (!multiple && argc == 3 + verbose)
     outname = argv[2 + verbose];

   if ((!multiple && argc > 3 + verbose) || (multiple && argc < 2))
   {
     fprintf(STDERR,
       "usage: %s [infile.png] [outfile.png]\n\t%s -m {infile.png}\n",
        argv[0], argv[0]);
     fprintf(STDERR,
       "  reads/writes one PNG file (without -m) or multiple files (-m)\n");
     fprintf(STDERR,
       "  with -m %s is used as a temporary file\n", outname);
     exit(1);
   }

   if (multiple)
   {
      int i;
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
      int allocation_now = current_allocation;
#endif
      for (i=2; i<argc; ++i)
      {
         int kerror;
         fprintf(STDERR, "\n Testing %s:", argv[i]);
         kerror = test_one_file(argv[i], outname);
         if (kerror == 0)
         {
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
            int k;
#endif
#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
            fprintf(STDERR, "\n PASS (%lu zero samples)\n",
               (unsigned long)zero_samples);
#else
            fprintf(STDERR, " PASS\n");
#endif
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
            for (k = 0; k<256; k++)
               if (filters_used[k])
                  fprintf(STDERR, " Filter %d was used %lu times\n",
                     k, (unsigned long)filters_used[k]);
#endif
#ifdef PNG_TIME_RFC1123_SUPPORTED
         if (tIME_chunk_present != 0)
            fprintf(STDERR, " tIME = %s\n", tIME_string);
         tIME_chunk_present = 0;
#endif /* PNG_TIME_RFC1123_SUPPORTED */
         }
         else
         {
            fprintf(STDERR, " FAIL\n");
            ierror += kerror;
         }
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
         if (allocation_now != current_allocation)
            fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
               current_allocation - allocation_now);
         if (current_allocation != 0)
         {
            memory_infop pinfo = pinformation;

            fprintf(STDERR, "MEMORY ERROR: %d bytes still allocated\n",
               current_allocation);
            while (pinfo != NULL)
            {
               fprintf(STDERR, " %lu bytes at %x\n",
                 (unsigned long)pinfo->size,
                 (unsigned int) pinfo->pointer);
               pinfo = pinfo->next;
            }
         }
#endif
      }
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
         fprintf(STDERR, " Current memory allocation: %10d bytes\n",
            current_allocation);
         fprintf(STDERR, " Maximum memory allocation: %10d bytes\n",
            maximum_allocation);
         fprintf(STDERR, " Total   memory allocation: %10d bytes\n",
            total_allocation);
         fprintf(STDERR, "     Number of allocations: %10d\n",
            num_allocations);
#endif
   }
   else
   {
      int i;
      for (i = 0; i<3; ++i)
      {
         int kerror;
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
         int allocation_now = current_allocation;
#endif
         if (i == 1) status_dots_requested = 1;
         else if (verbose == 0)status_dots_requested = 0;
         if (i == 0 || verbose == 1 || ierror != 0)
            fprintf(STDERR, "\n Testing %s:", inname);
         kerror = test_one_file(inname, outname);
         if (kerror == 0)
         {
            if (verbose == 1 || i == 2)
            {
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
                int k;
#endif
#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
                fprintf(STDERR, "\n PASS (%lu zero samples)\n",
                   (unsigned long)zero_samples);
#else
                fprintf(STDERR, " PASS\n");
#endif
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
                for (k = 0; k<256; k++)
                   if (filters_used[k])
                      fprintf(STDERR, " Filter %d was used %lu times\n",
                         k, (unsigned long)filters_used[k]);
#endif
#ifdef PNG_TIME_RFC1123_SUPPORTED
             if (tIME_chunk_present != 0)
                fprintf(STDERR, " tIME = %s\n", tIME_string);
#endif /* PNG_TIME_RFC1123_SUPPORTED */
            }
         }
         else
         {
            if (verbose == 0 && i != 2)
               fprintf(STDERR, "\n Testing %s:", inname);
            fprintf(STDERR, " FAIL\n");
            ierror += kerror;
         }
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
         if (allocation_now != current_allocation)
             fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
               current_allocation - allocation_now);
         if (current_allocation != 0)
         {
             memory_infop pinfo = pinformation;

             fprintf(STDERR, "MEMORY ERROR: %d bytes still allocated\n",
                current_allocation);
             while (pinfo != NULL)
             {
                fprintf(STDERR, " %lu bytes at %x\n",
                   (unsigned long)pinfo->size, (unsigned int)pinfo->pointer);
                pinfo = pinfo->next;
             }
          }
#endif
       }
#if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
       fprintf(STDERR, " Current memory allocation: %10d bytes\n",
          current_allocation);
       fprintf(STDERR, " Maximum memory allocation: %10d bytes\n",
          maximum_allocation);
       fprintf(STDERR, " Total   memory allocation: %10d bytes\n",
          total_allocation);
       fprintf(STDERR, "     Number of allocations: %10d\n",
            num_allocations);
#endif
   }

#ifdef PNGTEST_TIMING
   t_stop = (float)clock();
   t_misc += (t_stop - t_start);
   t_start = t_stop;
   fprintf(STDERR, " CPU time used = %.3f seconds",
      (t_misc+t_decode+t_encode)/(float)CLOCKS_PER_SEC);
   fprintf(STDERR, " (decoding %.3f,\n",
      t_decode/(float)CLOCKS_PER_SEC);
   fprintf(STDERR, "        encoding %.3f ,",
      t_encode/(float)CLOCKS_PER_SEC);
   fprintf(STDERR, " other %.3f seconds)\n\n",
      t_misc/(float)CLOCKS_PER_SEC);
#endif

   if (ierror == 0)
      fprintf(STDERR, " libpng passes test\n");
   else
      fprintf(STDERR, " libpng FAILS test\n");
   return (int)(ierror != 0);
}

/* Generate a compiler error if there is an old png.h in the search path. */
typedef version_1_4_5 your_png_h_is_not_version_1_4_5;

license: mit