/* makepng.c
 *
 * Copyright:
 */
#define COPYRIGHT "Copyright \302\251 2013,2015 John Cunningham Bowler"
/*
 * Last changed in libpng 1.7.0 [September 20, 2015]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 *
 * Make a test PNG image.  The arguments are as follows:
 *
 *  makepng [--sRGB|--linear|--1.8] [--color=<color>] color-type bit-depth \
 *      [file-name]
 *
 * The color-type may be numeric (and must match the numbers used by the PNG
 * specification) or one of the format names listed below.  The bit-depth is the
 * component bit depth, or the pixel bit-depth for a color-mapped image.
 *
 * Without any options no color-space information is written, with the options
 * an sRGB or the appropriate gAMA chunk is written.  "1.8" refers to the
 * display system used on older Apple computers to correct for high ambient
 * light levels in the viewing environment; it applies a transform of
 * approximately value^(1/1.45) to the color values and so a gAMA chunk of 65909
 * is written (1.45/2.2).
 *
 * The image data is generated internally.  Unless --color is given the images
 * used are as follows:
 *
 * 1 channel: a square image with a diamond, the least luminous colors are on
 *    the edge of the image, the most luminous in the center.
 *
 * 2 channels: the color channel increases in luminosity from top to bottom, the
 *    alpha channel increases in opacity from left to right.
 *
 * 3 channels: linear combinations of, from the top-left corner clockwise,
 *    black, green, white, red.
 *
 * 4 channels: linear combinations of, from the top-left corner clockwise,
 *    transparent, red, green, blue.
 *
 * For color-mapped images a four channel color-map is used and the PNG file has
 * a tRNS chunk, as follows:
 *
 * 1-bit: entry 0 is transparent-red, entry 1 is opaque-white
 * 2-bit: entry 0: transparent-green
 *        entry 1: 40%-red
 *        entry 2: 80%-blue
 *        entry 3: opaque-white
 * 4-bit: the 16 combinations of the 2-bit case
 * 8-bit: the 256 combinations of the 4-bit case
 *
 * The palette always has 2^bit-depth entries and the tRNS chunk one fewer.  The
 * image is the 1-channel diamond, but using palette index, not luminosity.
 *
 * Image size is determined by the final pixel depth in bits, i.e. channels x
 * bit-depth, as follows:
 *
 * 8 bits or less:    64x64
 * 16 bits:           256x256
 * More than 16 bits: 1024x1024
 *
 * Row filtering is turned off (the 'none' filter is used on every row) and the
 * images are not interlaced.
 *
 * If --color is given then the whole image has that color, color-mapped images
 * will have exactly one palette entry and all image files with be 16x16 in
 * size.  The color value is 1 to 4 decimal numbers as appropriate for the color
 * type.
 *
 * If file-name is given then the PNG is written to that file, else it is
 * written to stdout.  Notice that stdout is not supported on systems where, by
 * default, it assumes text output; this program makes no attempt to change the
 * text mode of stdout!
 */
#define _ISOC99_SOURCE /* for strtoull */

#include <stddef.h> /* for offsetof */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#include <errno.h>
#include <assert.h>
#include <stdint.h>

#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
#  include <config.h>
#endif

/* Define the following to use this test against your installed libpng, rather
 * than the one being built here:
 */
#ifdef PNG_FREESTANDING_TESTS
#  include <png.h>
#else
#  include "../../png.h"
#endif

#include <zlib.h>

/* Work round for GCC complaints about casting a (double) function result to
 * an unsigned:
 */
static unsigned int
flooru(double d)
{
   d = floor(d);
   return (unsigned int)d;
}

static png_byte
floorb(double d)
{
   d = floor(d);
   return (png_byte)d;
}

/* This structure is used for inserting extra chunks (the --insert argument, not
 * documented above.)
 */
typedef struct chunk_insert
{
   struct chunk_insert *next;
   void               (*insert)(png_structp, png_infop, int, png_charpp);
   int                  nparams;
   png_charp            parameters[1];
} chunk_insert;

static unsigned int
channels_of_type(int color_type)
{
   if (color_type & PNG_COLOR_MASK_PALETTE)
      return 1;

   else
   {
      int channels = 1;

      if (color_type & PNG_COLOR_MASK_COLOR)
         channels = 3;

      if (color_type & PNG_COLOR_MASK_ALPHA)
         return channels + 1;

      else
         return channels;
   }
}

static unsigned int
pixel_depth_of_type(int color_type, int bit_depth)
{
   return channels_of_type(color_type) * bit_depth;
}

static unsigned int
image_size_of_type(int color_type, int bit_depth, unsigned int *colors,
   int small)
{
   if (*colors)
      return 16;

   else
   {
      int pixel_depth = pixel_depth_of_type(color_type, bit_depth);

      if (small)
      {
         if (pixel_depth <= 8) /* there will be one row */
            return 1 << pixel_depth;

         else
            return 256;
      }

      else if (pixel_depth < 8)
         return 64;

      else if (pixel_depth > 16)
         return 1024;

      else
         return 256;
   }
}

static void
set_color(png_colorp color, png_bytep trans, unsigned int red,
   unsigned int green, unsigned int blue, unsigned int alpha,
   png_const_bytep gamma_table)
{
   color->red = gamma_table[red];
   color->green = gamma_table[green];
   color->blue = gamma_table[blue];
   *trans = (png_byte)alpha;
}

static int
generate_palette(png_colorp palette, png_bytep trans, int bit_depth,
   png_const_bytep gamma_table, unsigned int *colors)
{
   /*
    * 1-bit: entry 0 is transparent-red, entry 1 is opaque-white
    * 2-bit: entry 0: transparent-green
    *        entry 1: 40%-red
    *        entry 2: 80%-blue
    *        entry 3: opaque-white
    * 4-bit: the 16 combinations of the 2-bit case
    * 8-bit: the 256 combinations of the 4-bit case
    */
   switch (colors[0])
   {
      default:
         fprintf(stderr, "makepng: --colors=...: invalid count %u\n",
            colors[0]);
         exit(1);

      case 1:
         set_color(palette+0, trans+0, colors[1], colors[1], colors[1], 255,
            gamma_table);
         return 1;

      case 2:
         set_color(palette+0, trans+0, colors[1], colors[1], colors[1],
            colors[2], gamma_table);
         return 1;

      case 3:
         set_color(palette+0, trans+0, colors[1], colors[2], colors[3], 255,
            gamma_table);
         return 1;

      case 4:
         set_color(palette+0, trans+0, colors[1], colors[2], colors[3],
            colors[4], gamma_table);
         return 1;

      case 0:
         if (bit_depth == 1)
         {
            set_color(palette+0, trans+0, 255, 0, 0, 0, gamma_table);
            set_color(palette+1, trans+1, 255, 255, 255, 255, gamma_table);
            return 2;
         }

         else
         {
            unsigned int size = 1U << (bit_depth/2); /* 2, 4 or 16 */
            unsigned int x, y;
            volatile unsigned int ip = 0;

            for (x=0; x<size; ++x) for (y=0; y<size; ++y)
            {
               ip = x + (size * y);

               /* size is at most 16, so the scaled value below fits in 16 bits
                */
#              define interp(pos, c1, c2) ((pos * c1) + ((size-pos) * c2))
#              define xyinterp(x, y, c1, c2, c3, c4) (((size * size / 2) +\
                  (interp(x, c1, c2) * y + (size-y) * interp(x, c3, c4))) /\
                  (size*size))

               set_color(palette+ip, trans+ip,
                  /* color:    green, red,blue,white */
                  xyinterp(x, y,   0, 255,   0, 255),
                  xyinterp(x, y, 255,   0,   0, 255),
                  xyinterp(x, y,   0,   0, 255, 255),
                  /* alpha:        0, 102, 204, 255) */
                  xyinterp(x, y,   0, 102, 204, 255),
                  gamma_table);
            }

            return ip+1;
         }
   }
}

static void
set_value(png_bytep row, size_t rowbytes, png_uint_32 x, unsigned int bit_depth,
   png_uint_32 value, png_const_bytep gamma_table, double conv)
{
   unsigned int mask = (1U << bit_depth)-1;

   x *= bit_depth;  /* Maximum x is 4*1024, maximum bit_depth is 16 */

   if (value <= mask)
   {
      png_uint_32 offset = x >> 3;

      if (offset < rowbytes && (bit_depth < 16 || offset+1 < rowbytes))
      {
         row += offset;

         switch (bit_depth)
         {
            case 1:
            case 2:
            case 4:
               /* Don't gamma correct - values get smashed */
               {
                  unsigned int shift = (8 - bit_depth) - (x & 0x7U);

                  mask <<= shift;
                  value = (value << shift) & mask;
                  *row = (png_byte)((*row & ~mask) | value);
               }
               return;

            default:
               fprintf(stderr, "makepng: bad bit depth (internal error)\n");
               exit(1);

            case 16:
               value = flooru(65535*pow(value/65535.,conv)+.5);
               *row++ = (png_byte)(value >> 8);
               *row = (png_byte)value;
               return;

            case 8:
               *row = gamma_table[value];
               return;
         }
      }

      else
      {
         fprintf(stderr, "makepng: row buffer overflow (internal error)\n");
         exit(1);
      }
   }

   else
   {
      fprintf(stderr, "makepng: component overflow (internal error)\n");
      exit(1);
   }
}

static int /* filter mask for row */
generate_row(png_bytep row, size_t rowbytes, unsigned int y, int color_type,
   int bit_depth, png_const_bytep gamma_table, double conv,
   unsigned int *colors, int small)
{
   int filters = 0; /* file *MASK*, 0 means the default, not NONE */
   png_uint_32 size_max = 
      image_size_of_type(color_type, bit_depth, colors, small)-1;
   png_uint_32 depth_max = (1U << bit_depth)-1; /* up to 65536 */

   if (colors[0] == 0) if (small)
   {
      unsigned int pixel_depth = pixel_depth_of_type(color_type, bit_depth);

      /* For pixel depths less than 16 generate a single row containing all the
       * possible pixel values.  For 16 generate all 65536 byte pair
       * combinations in a 256x256 pixel array.
       */
      switch (pixel_depth)
      {
         case 1:
            assert(y == 0 && rowbytes == 1 && size_max == 1);
            row[0] = 0x6CU; /* binary: 01101100, only top 2 bits used */
            filters = PNG_FILTER_NONE;
            break;

         case 2:
            assert(y == 0 && rowbytes == 1 && size_max == 3);
            row[0] = 0x1BU; /* binary 00011011, all bits used */
            filters = PNG_FILTER_NONE;
            break;

         case 4:
            assert(y == 0 && rowbytes == 8 && size_max == 15);
            row[0] = 0x01U;
            row[1] = 0x23U; /* SUB gives 0x22U for all following bytes */
            row[2] = 0x45U;
            row[3] = 0x67U;
            row[4] = 0x89U;
            row[5] = 0xABU;
            row[6] = 0xCDU;
            row[7] = 0xEFU;
            filters = PNG_FILTER_SUB;
            break;

         case 8:
            /* The row will have all the pixel values in order starting with
             * '1', the SUB filter will change every byte into '1' (including
             * the last, which generates pixel value '0').  Since the SUB filter
             * has value 1 this should result in maximum compression.
             */
            assert(y == 0 && rowbytes == 256 && size_max == 255);
            for (;;)
            {
               row[size_max] = 0xFFU & (size_max+1);
               if (size_max == 0)
                  break;
               --size_max;
            }
            filters = PNG_FILTER_SUB;
            break;

         case 16:
            /* Rows are generated such that each row has a constant difference
             * between the first and second byte of each pixel and so that the
             * difference increases by 1 at each row.  The rows start with the
             * first byte value of 0 and the value increases to 255 across the
             * row.
             *
             * The difference starts at 1, so the first row is:
             *
             *     0 1 1 2 2 3 3 4 ... 254 255 255 0
             *
             * This means that running the SUB filter on the first row produces:
             *
             *   [SUB==1] 0 1 0 1 0 1...
             *
             * Then the difference is 2 on the next row, giving:
             *
             *    0 2 1 3 2 4 3 5 ... 254 0 255 1
             *
             * When the UP filter is run on this libpng produces:
             *
             *   [UP ==2] 0 1 0 1 0 1...
             *
             * And so on for all the remain rows to the final two * rows:
             *
             *    row 254: 0 255 1 0 2 1 3 2 4 3 ... 254 253 255 254
             *    row 255: 0   0 1 1 2 2 3 3 4 4 ... 254 254 255 255
             */
            assert(rowbytes == 512 && size_max == 255);
            for (;;)
            {
               row[2*size_max  ] = 0xFFU & size_max;
               row[2*size_max+1] = 0xFFU & (size_max+y+1);
               if (size_max == 0)
                  break;
               --size_max;
            }
            filters = (y == 0 ? PNG_FILTER_SUB : PNG_FILTER_UP);
            break;

         case 24:
         case 32:
         case 48:
         case 64:
            /* The rows are filled by an alogorithm similar to the above, in the
             * first row pixel bytes are all equal, increasing from 0 by 1 for
             * each pixel.  In the second row the bytes within a pixel are
             * incremented 1,3,5,7,... from the previous row byte.  Using an odd
             * number ensures all the possible byte values are used.
             */
            assert(size_max == 255 && rowbytes == 256*(pixel_depth>>3));
            pixel_depth >>= 3; /* now in bytes */
            while (rowbytes > 0)
            {
               const size_t pixel_index = --rowbytes/pixel_depth;

               if (y == 0)
                  row[rowbytes] = 0xFFU & pixel_index;

               else
               {
                  const size_t byte_offset =
                     rowbytes - pixel_index * pixel_depth;

                  row[rowbytes] =
                     0xFFU & (pixel_index + (byte_offset * 2*y) + 1);
               }
            }
            filters = (y == 0 ? PNG_FILTER_SUB : PNG_FILTER_UP);
            break;

         default:
            assert(0/*NOT REACHED*/);
      }
   }
      
   else switch (channels_of_type(color_type))
   {
   /* 1 channel: a square image with a diamond, the least luminous colors are on
    *    the edge of the image, the most luminous in the center.
    */
      case 1:
         {
            png_uint_32 x;
            png_uint_32 base = 2*size_max - abs(2*y-size_max);

            for (x=0; x<=size_max; ++x)
            {
               png_uint_32 luma = base - abs(2*x-size_max);

               /* 'luma' is now in the range 0..2*size_max, we need
                * 0..depth_max
                */
               luma = (luma*depth_max + size_max) / (2*size_max);
               set_value(row, rowbytes, x, bit_depth, luma, gamma_table, conv);
            }
         }
         break;

   /* 2 channels: the color channel increases in luminosity from top to bottom,
    *    the alpha channel increases in opacity from left to right.
    */
      case 2:
         {
            png_uint_32 alpha = (depth_max * y * 2 + size_max) / (2 * size_max);
            png_uint_32 x;

            for (x=0; x<=size_max; ++x)
            {
               set_value(row, rowbytes, 2*x, bit_depth,
                  (depth_max * x * 2 + size_max) / (2 * size_max), gamma_table,
                  conv);
               set_value(row, rowbytes, 2*x+1, bit_depth, alpha, gamma_table,
                  conv);
            }
         }
         break;

   /* 3 channels: linear combinations of, from the top-left corner clockwise,
    *    black, green, white, red.
    */
      case 3:
         {
            /* x0: the black->red scale (the value of the red component) at the
             *     start of the row (blue and green are 0).
             * x1: the green->white scale (the value of the red and blue
             *     components at the end of the row; green is depth_max).
             */
            png_uint_32 Y = (depth_max * y * 2 + size_max) / (2 * size_max);
            png_uint_32 x;

            /* Interpolate x/depth_max from start to end:
             *
             *        start end         difference
             * red:     Y    Y            0
             * green:   0   depth_max   depth_max
             * blue:    0    Y            Y
             */
            for (x=0; x<=size_max; ++x)
            {
               set_value(row, rowbytes, 3*x+0, bit_depth, /* red */ Y,
                     gamma_table, conv);
               set_value(row, rowbytes, 3*x+1, bit_depth, /* green */
                  (depth_max * x * 2 + size_max) / (2 * size_max),
                  gamma_table, conv);
               set_value(row, rowbytes, 3*x+2, bit_depth, /* blue */
                  (Y * x * 2 + size_max) / (2 * size_max),
                  gamma_table, conv);
            }
         }
         break;

   /* 4 channels: linear combinations of, from the top-left corner clockwise,
    *    transparent, red, green, blue.
    */
      case 4:
         {
            /* x0: the transparent->blue scale (the value of the blue and alpha
             *     components) at the start of the row (red and green are 0).
             * x1: the red->green scale (the value of the red and green
             *     components at the end of the row; blue is 0 and alpha is
             *     depth_max).
             */
            png_uint_32 Y = (depth_max * y * 2 + size_max) / (2 * size_max);
            png_uint_32 x;

            /* Interpolate x/depth_max from start to end:
             *
             *        start    end       difference
             * red:     0   depth_max-Y depth_max-Y
             * green:   0       Y             Y
             * blue:    Y       0            -Y
             * alpha:   Y    depth_max  depth_max-Y
             */
            for (x=0; x<=size_max; ++x)
            {
               set_value(row, rowbytes, 4*x+0, bit_depth, /* red */
                  ((depth_max-Y) * x * 2 + size_max) / (2 * size_max),
                  gamma_table, conv);
               set_value(row, rowbytes, 4*x+1, bit_depth, /* green */
                  (Y * x * 2 + size_max) / (2 * size_max),
                  gamma_table, conv);
               set_value(row, rowbytes, 4*x+2, bit_depth, /* blue */
                  Y - (Y * x * 2 + size_max) / (2 * size_max),
                  gamma_table, conv);
               set_value(row, rowbytes, 4*x+3, bit_depth, /* alpha */
                  Y + ((depth_max-Y) * x * 2 + size_max) / (2 * size_max),
                  gamma_table, conv);
            }
         }
         break;

      default:
         fprintf(stderr, "makepng: internal bad channel count\n");
         exit(2);
   }

   else if (color_type & PNG_COLOR_MASK_PALETTE)
   {
      /* Palette with fixed color: the image rows are all 0 and the image width
       * is 16.
       */
      memset(row, 0, rowbytes);
   }

   else if (colors[0] == channels_of_type(color_type))
      switch (channels_of_type(color_type))
      {
         case 1:
            {
               const png_uint_32 luma = colors[1];
               png_uint_32 x;

               for (x=0; x<=size_max; ++x)
                  set_value(row, rowbytes, x, bit_depth, luma, gamma_table,
                     conv);
            }
            break;

         case 2:
            {
               const png_uint_32 luma = colors[1];
               const png_uint_32 alpha = colors[2];
               png_uint_32 x;

               for (x=0; x<size_max; ++x)
               {
                  set_value(row, rowbytes, 2*x, bit_depth, luma, gamma_table,
                     conv);
                  set_value(row, rowbytes, 2*x+1, bit_depth, alpha, gamma_table,
                     conv);
               }
            }
            break;

         case 3:
            {
               const png_uint_32 red = colors[1];
               const png_uint_32 green = colors[2];
               const png_uint_32 blue = colors[3];
               png_uint_32 x;

               for (x=0; x<=size_max; ++x)
               {
                  set_value(row, rowbytes, 3*x+0, bit_depth, red, gamma_table,
                     conv);
                  set_value(row, rowbytes, 3*x+1, bit_depth, green, gamma_table,
                     conv);
                  set_value(row, rowbytes, 3*x+2, bit_depth, blue, gamma_table,
                     conv);
               }
            }
            break;

         case 4:
            {
               const png_uint_32 red = colors[1];
               const png_uint_32 green = colors[2];
               const png_uint_32 blue = colors[3];
               const png_uint_32 alpha = colors[4];
               png_uint_32 x;

               for (x=0; x<=size_max; ++x)
               {
                  set_value(row, rowbytes, 4*x+0, bit_depth, red, gamma_table,
                     conv);
                  set_value(row, rowbytes, 4*x+1, bit_depth, green, gamma_table,
                     conv);
                  set_value(row, rowbytes, 4*x+2, bit_depth, blue, gamma_table,
                     conv);
                  set_value(row, rowbytes, 4*x+3, bit_depth, alpha, gamma_table,
                     conv);
               }
            }
         break;

         default:
            fprintf(stderr, "makepng: internal bad channel count\n");
            exit(2);
      }

   else
   {
      fprintf(stderr,
         "makepng: --color: count(%u) does not match channels(%u)\n",
         colors[0], channels_of_type(color_type));
      exit(1);
   }

   return filters;
}


static void PNGCBAPI
makepng_warning(png_structp png_ptr, png_const_charp message)
{
   const char **ep = png_get_error_ptr(png_ptr);
   const char *name;

   if (ep != NULL && *ep != NULL)
      name = *ep;

   else
      name = "makepng";

  fprintf(stderr, "%s: warning: %s\n", name, message);
}

static void PNGCBAPI
makepng_error(png_structp png_ptr, png_const_charp message)
{
   makepng_warning(png_ptr, message);
   png_longjmp(png_ptr, 1);
}

static int /* 0 on success, else an error code */
write_png(const char **name, FILE *fp, int color_type, int bit_depth,
   volatile png_fixed_point gamma, chunk_insert * volatile insert,
   unsigned int filters, unsigned int *colors, int small)
{
   png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
      name, makepng_error, makepng_warning);
   volatile png_infop info_ptr = NULL;
   volatile png_bytep row = NULL;

   if (png_ptr == NULL)
   {
      fprintf(stderr, "makepng: OOM allocating write structure\n");
      return 1;
   }

   if (setjmp(png_jmpbuf(png_ptr)))
   {
      png_structp nv_ptr = png_ptr;
      png_infop nv_info = info_ptr;

      png_ptr = NULL;
      info_ptr = NULL;
      png_destroy_write_struct(&nv_ptr, &nv_info);
      if (row != NULL) free(row);
      return 1;
   }

   /* Allow benign errors so that we can write PNGs with errors */
   png_set_benign_errors(png_ptr, 1/*allowed*/);

   /* Max out the text compression level in an attempt to make the license
    * small.   If --small then do the same for the IDAT.
    */
   if (small)
      png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);

   png_set_text_compression_level(png_ptr, Z_BEST_COMPRESSION);

   png_init_io(png_ptr, fp);

   info_ptr = png_create_info_struct(png_ptr);
   if (info_ptr == NULL)
      png_error(png_ptr, "OOM allocating info structure");

   {
      const unsigned int size =
         image_size_of_type(color_type, bit_depth, colors, small);
      unsigned int ysize;
      png_fixed_point real_gamma = 45455; /* For sRGB */
      png_byte gamma_table[256];
      double conv;

      /* Normally images are square, but with 'small' we want to simply generate
       * all the pixel values, or all that we reasonably can:
       */
      if (small)
      {
         const unsigned int pixel_depth =
            pixel_depth_of_type(color_type, bit_depth);

         if (pixel_depth <= 8U)
         {
            assert(size == (1U<<pixel_depth));
            ysize = 1U;
         }

         else
         {
            assert(size == 256U);
            ysize = 256U;
         }
      }

      else
         ysize = size;

      /* This function uses the libpng values used on read to carry extra
       * information about the gamma:
       */
      if (gamma == PNG_GAMMA_MAC_18)
         gamma = 65909;

      else if (gamma > 0 && gamma < 1000)
         gamma = PNG_FP_1;

      if (gamma > 0)
         real_gamma = gamma;

      {
         unsigned int i;

         if (real_gamma == 45455) for (i=0; i<256; ++i)
         {
            gamma_table[i] = (png_byte)i;
            conv = 1.;
         }

         else
         {
            /* Convert 'i' from sRGB (45455) to real_gamma, this makes
             * the images look the same regardless of the gAMA chunk.
             */
            conv = real_gamma;
            conv /= 45455;

            gamma_table[0] = 0;

            for (i=1; i<255; ++i)
               gamma_table[i] = floorb(pow(i/255.,conv) * 255 + .5);

            gamma_table[255] = 255;
         }
      }

      png_set_IHDR(png_ptr, info_ptr, size, ysize, bit_depth, color_type,
         PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

      if (color_type & PNG_COLOR_MASK_PALETTE)
      {
         int npalette;
         png_color palette[256];
         png_byte trans[256];

         npalette = generate_palette(palette, trans, bit_depth, gamma_table,
            colors);
         png_set_PLTE(png_ptr, info_ptr, palette, npalette);
         png_set_tRNS(png_ptr, info_ptr, trans, npalette-1,
            NULL/*transparent color*/);

         /* Reset gamma_table to prevent the image rows being changed */
         for (npalette=0; npalette<256; ++npalette)
            gamma_table[npalette] = (png_byte)npalette;
      }

      if (gamma == PNG_DEFAULT_sRGB)
         png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_ABSOLUTE);

      else if (gamma > 0) /* Else don't set color space information */
      {
         png_set_gAMA_fixed(png_ptr, info_ptr, real_gamma);

         /* Just use the sRGB values here. */
         png_set_cHRM_fixed(png_ptr, info_ptr,
            /* color      x       y */
            /* white */ 31270, 32900,
            /* red   */ 64000, 33000,
            /* green */ 30000, 60000,
            /* blue  */ 15000,  6000
         );
      }

      /* Insert extra information. */
      while (insert != NULL)
      {
         insert->insert(png_ptr, info_ptr, insert->nparams, insert->parameters);
         insert = insert->next;
      }

      /* Write the file header. */
      png_write_info(png_ptr, info_ptr);

      /* Restrict the filters */
      png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, filters);

      {
#        ifdef PNG_WRITE_INTERLACING_SUPPORTED
            int passes = png_set_interlace_handling(png_ptr);
#        else /* !WRITE_INTERLACING */
            int passes = 1;
#        endif /* !WRITE_INTERLACING */
         int pass;
         png_size_t rowbytes = png_get_rowbytes(png_ptr, info_ptr);

         row = malloc(rowbytes);

         if (row == NULL)
            png_error(png_ptr, "OOM allocating row buffer");

         for (pass = 0; pass < passes; ++pass)
         {
            unsigned int y;

            for (y=0; y<ysize; ++y)
            {
               unsigned int row_filters =
                  generate_row(row, rowbytes, y, color_type, bit_depth,
                        gamma_table, conv, colors, small);

               if (row_filters != 0 && filters == PNG_ALL_FILTERS)
                  png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, row_filters);

               png_write_row(png_ptr, row);
            }
         }
      }
   }

   /* Finish writing the file. */
   png_write_end(png_ptr, info_ptr);

   {
      png_structp nv_ptr = png_ptr;
      png_infop nv_info = info_ptr;

      png_ptr = NULL;
      info_ptr = NULL;
      png_destroy_write_struct(&nv_ptr, &nv_info);
   }
   free(row);
   return 0;
}


static size_t
load_file(png_const_charp name, png_bytepp result)
{
   FILE *fp = tmpfile();

   if (fp != NULL)
   {
      FILE *ip = fopen(name, "rb");

      if (ip != NULL)
      {
         size_t total = 0;
         int ch;

         for (;;)
         {
            ch = getc(ip);
            if (ch == EOF) break;
            putc(ch, fp);
            ++total;
         }

         if (ferror(ip))
         {
            perror(name);
            fprintf(stderr, "%s: read error\n", name);
            (void)fclose(ip);
         }

         else
         {
            (void)fclose(ip);

            if (ferror(fp))
            {
               perror("temporary file");
               fprintf(stderr, "temporary file write error\n");
            }

            else
            {
               rewind(fp);

               if (total > 0)
               {
                  /* Round up to a multiple of 4 here to allow an iCCP profile
                   * to be padded to a 4x boundary.
                   */
                  png_bytep data = malloc((total+3)&~3);

                  if (data != NULL)
                  {
                     size_t new_size = 0;

                     for (;;)
                     {
                        ch = getc(fp);
                        if (ch == EOF) break;
                        data[new_size++] = (png_byte)ch;
                     }

                     if (ferror(fp) || new_size != total)
                     {
                        perror("temporary file");
                        fprintf(stderr, "temporary file read error\n");
                        free(data);
                     }

                     else
                     {
                        (void)fclose(fp);
                        *result = data;
                        return total;
                     }
                  }

                  else
                     fprintf(stderr, "%s: out of memory loading file\n", name);
               }

               else
                  fprintf(stderr, "%s: empty file\n", name);
            }
         }
      }

      else
      {
         perror(name);
         fprintf(stderr, "%s: open failed\n", name);
      }

      fclose(fp);
   }

   else
      fprintf(stderr, "makepng: %s: could not open temporary file\n", name);

   exit(1);
   return 0;
}

static png_size_t
load_fake(png_charp param, png_bytepp profile)
{
   char *endptr = NULL;
   uint64_t size = strtoull(param, &endptr, 0/*base*/);

   /* The 'fake' format is <number>*[string] */
   if (endptr != NULL && *endptr == '*')
   {
      size_t len = strlen(++endptr);
      size_t result = (size_t)size;

      if (len == 0) len = 1; /* capture the terminating '\0' */

      /* Now repeat that string to fill 'size' bytes. */
      if (result == size && (*profile = malloc(result)) != NULL)
      {
         png_bytep out = *profile;

         if (len == 1)
            memset(out, *endptr, result);

         else
         {
            while (size >= len)
            {
               memcpy(out, endptr, len);
               out += len;
               size -= len;
            }
            memcpy(out, endptr, size);
         }

         return result;
      }

      else
      {
         fprintf(stderr, "%s: size exceeds system limits\n", param);
         exit(1);
      }
   }

   return 0;
}

static void
check_param_count(int nparams, int expect)
{
   if (nparams != expect)
   {
      fprintf(stderr, "bad parameter count (internal error)\n");
      exit(1);
   }
}

static void
insert_iCCP(png_structp png_ptr, png_infop info_ptr, int nparams,
   png_charpp params)
{
   png_bytep profile = NULL;
   png_uint_32 proflen = 0;
   int result;

   check_param_count(nparams, 2);

   switch (params[1][0])
   {
      case '<':
         {
            png_size_t filelen = load_file(params[1]+1, &profile);
            if (filelen > 0xfffffffc) /* Maximum profile length */
            {
               fprintf(stderr, "%s: file too long (%lu) for an ICC profile\n",
                  params[1]+1, (unsigned long)filelen);
               exit(1);
            }

            proflen = (png_uint_32)filelen;
         }
         break;

      case '0': case '1': case '2': case '3': case '4':
      case '5': case '6': case '7': case '8': case '9':
         {
            png_size_t fake_len = load_fake(params[1], &profile);

            if (fake_len > 0) /* else a simple parameter */
            {
               if (fake_len > 0xffffffff) /* Maximum profile length */
               {
                  fprintf(stderr,
                     "%s: fake data too long (%lu) for an ICC profile\n",
                     params[1], (unsigned long)fake_len);
                  exit(1);
               }
               proflen = (png_uint_32)(fake_len & ~3U);
               /* Always fix up the profile length. */
               png_save_uint_32(profile, proflen);
               break;
            }
         }

      default:
         fprintf(stderr, "--insert iCCP \"%s\": unrecognized\n", params[1]);
         fprintf(stderr, "  use '<' to read a file: \"<filename\"\n");
         exit(1);
   }

   result = 1;

   if (proflen & 3)
   {
      fprintf(stderr,
         "makepng: --insert iCCP %s: profile length made a multiple of 4\n",
         params[1]);

      /* load_file allocates extra space for this padding, the ICC spec requires
       * padding with zero bytes.
       */
      while (proflen & 3)
         profile[proflen++] = 0;
   }

   if (profile != NULL && proflen > 3)
   {
      png_uint_32 prof_header = png_get_uint_32(profile);

      if (prof_header != proflen)
      {
         fprintf(stderr, "--insert iCCP %s: profile length field wrong:\n",
            params[1]);
         fprintf(stderr, "  actual %lu, recorded value %lu (corrected)\n",
            (unsigned long)proflen, (unsigned long)prof_header);
         png_save_uint_32(profile, proflen);
      }
   }

   if (result && profile != NULL && proflen >=4)
      png_set_iCCP(png_ptr, info_ptr, params[0], PNG_COMPRESSION_TYPE_BASE,
         profile, proflen);

   if (profile)
      free(profile);

   if (!result)
      exit(1);
}

static void
clear_text(png_text *text, png_charp keyword)
{
   text->compression = -1; /* none */
   text->key = keyword;
   text->text = NULL;
   text->text_length = 0; /* libpng calculates this */
   text->itxt_length = 0; /* libpng calculates this */
   text->lang = NULL;
   text->lang_key = NULL;
}

static void
set_text(png_structp png_ptr, png_infop info_ptr, png_textp text,
   png_charp param)
{
   switch (param[0])
   {
      case '<':
         {
            png_bytep file = NULL;

            text->text_length = load_file(param+1, &file);
            text->text = (png_charp)file;
         }
         break;

      case '0': case '1': case '2': case '3': case '4':
      case '5': case '6': case '7': case '8': case '9':
         {
            png_bytep data = NULL;
            png_size_t fake_len = load_fake(param, &data);

            if (fake_len > 0) /* else a simple parameter */
            {
               text->text_length = fake_len;
               text->text = (png_charp)data;
               break;
            }
         }

      default:
         text->text = param;
         break;
   }

   png_set_text(png_ptr, info_ptr, text, 1);

   if (text->text != param)
      free(text->text);
}

static void
insert_tEXt(png_structp png_ptr, png_infop info_ptr, int nparams,
   png_charpp params)
{
   png_text text;

   check_param_count(nparams, 2);
   clear_text(&text, params[0]);
   set_text(png_ptr, info_ptr, &text, params[1]);
}

static void
insert_zTXt(png_structp png_ptr, png_infop info_ptr, int nparams,
   png_charpp params)
{
   png_text text;

   check_param_count(nparams, 2);
   clear_text(&text, params[0]);
   text.compression = 0; /* deflate */
   set_text(png_ptr, info_ptr, &text, params[1]);
}

static void
insert_iTXt(png_structp png_ptr, png_infop info_ptr, int nparams,
   png_charpp params)
{
   png_text text;

   check_param_count(nparams, 4);
   clear_text(&text, params[0]);
   text.compression = 2; /* iTXt + deflate */
   text.lang = params[1];/* language tag */
   text.lang_key = params[2]; /* translated keyword */
   set_text(png_ptr, info_ptr, &text, params[3]);
}

static void
insert_hIST(png_structp png_ptr, png_infop info_ptr, int nparams,
      png_charpp params)
{
   int i;
   png_uint_16 freq[256];

   /* libpng takes the count from the PLTE count; we don't check it here but we
    * do set the array to 0 for unspecified entries.
    */
   memset(freq, 0, sizeof freq);
   for (i=0; i<nparams; ++i)
   {
      char *endptr = NULL;
      unsigned long int l = strtoul(params[i], &endptr, 0/*base*/);

      if (params[i][0] && *endptr == 0 && l <= 65535)
         freq[i] = (png_uint_16)l;

      else
      {
         fprintf(stderr, "hIST[%d]: %s: invalid frequency\n", i, params[i]);
         exit(1);
      }
   }

   png_set_hIST(png_ptr, info_ptr, freq);
}

#if 0
static void
insert_sPLT(png_structp png_ptr, png_infop info_ptr, int nparams, png_charpp params)
{
   fprintf(stderr, "insert sPLT: NYI\n");
}
#endif

static int
find_parameters(png_const_charp what, png_charp param, png_charp *list,
   int nparams)
{
   /* Parameters are separated by '\n' or ':' characters, up to nparams are
    * accepted (more is an error) and the number found is returned.
    */
   int i;
   for (i=0; *param && i<nparams; ++i)
   {
      list[i] = param;
      while (*++param) if (*param == '\n' || *param == ':')
      {
         *param++ = 0; /* Terminate last parameter */
         break;        /* And start a new one. */
      }
   }

   if (*param)
   {
      fprintf(stderr, "--insert %s: too many parameters (%s)\n", what, param);
      exit(1);
   }

   list[i] = NULL; /* terminates list */
   return i; /* number of parameters filled in */
}

static void
bad_parameter_count(png_const_charp what, int nparams)
{
   fprintf(stderr, "--insert %s: bad parameter count %d\n", what, nparams);
   exit(1);
}

static chunk_insert *
make_insert(png_const_charp what,
   void (*insert)(png_structp, png_infop, int, png_charpp),
   int nparams, png_charpp list)
{
   int i;
   chunk_insert *cip;

   cip = malloc(offsetof(chunk_insert,parameters) +
      nparams * sizeof (png_charp));

   if (cip == NULL)
   {
      fprintf(stderr, "--insert %s: out of memory allocating %d parameters\n",
         what, nparams);
      exit(1);
   }

   cip->next = NULL;
   cip->insert = insert;
   cip->nparams = nparams;
   for (i=0; i<nparams; ++i)
      cip->parameters[i] = list[i];

   return cip;
}

static chunk_insert *
find_insert(png_const_charp what, png_charp param)
{
   png_uint_32 chunk = 0;
   png_charp parameter_list[1024];
   int i, nparams;

   /* Assemble the chunk name */
   for (i=0; i<4; ++i)
   {
      char ch = what[i];

      if ((ch >= 65 && ch <= 90) || (ch >= 97 && ch <= 122))
         chunk = (chunk << 8) + what[i];

      else
         break;
   }

   if (i < 4 || what[4] != 0)
   {
      fprintf(stderr, "makepng --insert \"%s\": invalid chunk name\n", what);
      exit(1);
   }

   /* Assemble the parameter list. */
   nparams = find_parameters(what, param, parameter_list, 1024);

#  define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d))

   switch (chunk)
   {
      case CHUNK(105,67,67,80):  /* iCCP */
         if (nparams == 2)
            return make_insert(what, insert_iCCP, nparams, parameter_list);
         break;

      case CHUNK(116,69,88,116): /* tEXt */
         if (nparams == 2)
            return make_insert(what, insert_tEXt, nparams, parameter_list);
         break;

      case CHUNK(122,84,88,116): /* zTXt */
         if (nparams == 2)
            return make_insert(what, insert_zTXt, nparams, parameter_list);
         break;

      case CHUNK(105,84,88,116): /* iTXt */
         if (nparams == 4)
            return make_insert(what, insert_iTXt, nparams, parameter_list);
         break;

      case CHUNK(104,73,83,84):  /* hIST */
         if (nparams <= 256)
            return make_insert(what, insert_hIST, nparams, parameter_list);
         break;

#if 0
      case CHUNK(115,80,76,84):  /* sPLT */
         return make_insert(what, insert_sPLT, nparams, parameter_list);
#endif

      default:
         fprintf(stderr, "makepng --insert \"%s\": unrecognized chunk name\n",
            what);
         exit(1);
   }

   bad_parameter_count(what, nparams);
   return NULL;
}

/* This is necessary because libpng expects writeable strings for things like
 * text chunks (maybe this should be fixed...)
 */
static png_charp
strstash(png_const_charp foo)
{
   /* The program indicates a memory allocation error by crashing, this is by
    * design.
    */
   png_charp bar = malloc(strlen(foo)+1);
   return strcpy(bar, foo);
}

/* These are used to insert Copyright and Licence fields, they allow the text to
 * have \n unlike the --insert option.
 */
static chunk_insert *
add_iTXt(const char *key, const char *language, const char *language_key,
      const png_const_charp *text)
{
   static char what[5] = { 105, 84, 88, 116, 0 };
   png_charp parameter_list[5];

   parameter_list[0] = strstash(key);
   parameter_list[1] = strstash(language);
   parameter_list[2] = strstash(language_key);

   {
      size_t foo = 0;
      png_charp bar;
      const png_const_charp *line = text;

      while (*line != NULL)
         foo += strlen(*line++);

      parameter_list[3] = bar = malloc(foo+1);

      line = text;
      while (*line != NULL)
      {
         foo = strlen(*line);
         memcpy(bar, *line++, foo);
         bar += foo;
      }

      *bar = 0;
   }

   parameter_list[4] = NULL;

   return make_insert(what, insert_iTXt, 4, parameter_list);
}

/* This is a not-very-good parser for a sequence of numbers (including 0).  It
 * doesn't accept some apparently valid things, but it accepts all the sensible
 * combinations.
 */
static void
parse_color(char *arg, unsigned int *colors)
{
   unsigned int ncolors = 0;

   while (*arg && ncolors < 4)
   {
      char *ep = arg;

      unsigned long ul = strtoul(arg, &ep, 0);

      if (ul > 65535)
      {
         fprintf(stderr, "makepng --color=...'%s': too big\n", arg);
         exit(1);
      }

      if (ep == arg)
      {
         fprintf(stderr, "makepng --color=...'%s': not a valid color\n", arg);
         exit(1);
      }

      if (*ep) ++ep; /* skip a separator */
      arg = ep;

      colors[++ncolors] = (unsigned int)ul; /* checked above */
   }

   if (*arg)
   {
      fprintf(stderr, "makepng --color=...'%s': too many values\n", arg);
      exit(1);
   }

   *colors = ncolors;
}

int
main(int argc, char **argv)
{
   FILE *fp = stdout;
   const char *file_name = NULL;
   int color_type = 8; /* invalid */
   int bit_depth = 32; /* invalid */
   int small = 0; /* make full size images */
   unsigned int colors[5];
   unsigned int filters = PNG_ALL_FILTERS;
   png_fixed_point gamma = 0; /* not set */
   chunk_insert *head_insert = NULL;
   chunk_insert **insert_ptr = &head_insert;

   memset(colors, 0, sizeof colors);

   while (--argc > 0)
   {
      char *arg = *++argv;

      if (strcmp(arg, "--small") == 0)
      {
         small = 1;
         continue;
      }

      if (strcmp(arg, "--sRGB") == 0)
      {
         gamma = PNG_DEFAULT_sRGB;
         continue;
      }

      if (strcmp(arg, "--linear") == 0)
      {
         gamma = PNG_FP_1;
         continue;
      }

      if (strcmp(arg, "--1.8") == 0)
      {
         gamma = PNG_GAMMA_MAC_18;
         continue;
      }

      if (strcmp(arg, "--nofilters") == 0)
      {
         filters = PNG_FILTER_NONE;
         continue;
      }

      if (strncmp(arg, "--color=", 8) == 0)
      {
          parse_color(arg+8, colors);
          continue;
      }

      if (argc >= 3 && strcmp(arg, "--insert") == 0)
      {
         png_const_charp what = *++argv;
         png_charp param = *++argv;
         chunk_insert *new_insert;

         argc -= 2;

         new_insert = find_insert(what, param);

         if (new_insert != NULL)
         {
            *insert_ptr = new_insert;
            insert_ptr = &new_insert->next;
         }

         continue;
      }

      if (arg[0] == '-')
      {
         fprintf(stderr, "makepng: %s: invalid option\n", arg);
         exit(1);
      }

      if (strcmp(arg, "palette") == 0)
      {
         color_type = PNG_COLOR_TYPE_PALETTE;
         continue;
      }

      if (strncmp(arg, "gray", 4) == 0)
      {
         if (arg[4] == 0)
         {
            color_type = PNG_COLOR_TYPE_GRAY;
            continue;
         }

         else if (strcmp(arg+4, "a") == 0 ||
            strcmp(arg+4, "alpha") == 0 ||
            strcmp(arg+4, "-alpha") == 0)
         {
            color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
            continue;
         }
      }

      if (strncmp(arg, "rgb", 3) == 0)
      {
         if (arg[3] == 0)
         {
            color_type = PNG_COLOR_TYPE_RGB;
            continue;
         }

         else if (strcmp(arg+3, "a") == 0 ||
            strcmp(arg+3, "alpha") == 0 ||
            strcmp(arg+3, "-alpha") == 0)
         {
            color_type = PNG_COLOR_TYPE_RGB_ALPHA;
            continue;
         }
      }

      if (color_type == 8 && isdigit(arg[0]))
      {
         color_type = atoi(arg);
         if (color_type < 0 || color_type > 6 || color_type == 1 ||
            color_type == 5)
         {
            fprintf(stderr, "makepng: %s: not a valid color type\n", arg);
            exit(1);
         }

         continue;
      }

      if (bit_depth == 32 && isdigit(arg[0]))
      {
         bit_depth = atoi(arg);
         if (bit_depth <= 0 || bit_depth > 16 ||
            (bit_depth & -bit_depth) != bit_depth)
         {
            fprintf(stderr, "makepng: %s: not a valid bit depth\n", arg);
            exit(1);
         }

         continue;
      }

      if (argc == 1) /* It's the file name */
      {
         fp = fopen(arg, "wb");
         if (fp == NULL)
         {
            fprintf(stderr, "%s: %s: could not open\n", arg, strerror(errno));
            exit(1);
         }

         file_name = arg;
         continue;
      }

      fprintf(stderr, "makepng: %s: unknown argument\n", arg);
      exit(1);
   } /* argument while loop */

   if (color_type == 8 || bit_depth == 32)
   {
      fprintf(stderr, "usage: makepng [--small] [--sRGB|--linear|--1.8] "
         "[--color=...] color-type bit-depth [file-name]\n"
         "  Make a test PNG file, by default writes to stdout.\n"
         "  Other options are available, UTSL.\n");
      exit(1);
   }

   /* Check the colors */
   {
      const unsigned int lim = (color_type == PNG_COLOR_TYPE_PALETTE ? 255U :
         (1U<<bit_depth)-1);
      unsigned int i;

      for (i=1; i<=colors[0]; ++i)
         if (colors[i] > lim)
         {
            fprintf(stderr, "makepng: --color=...: %u out of range [0..%u]\n",
               colors[i], lim);
            exit(1);
         }
   }

   /* small and colors are incomparible (will probably crash if both are used at
    * the same time!)
    */
   if (small && colors[0] != 0)
   {
      fprintf(stderr, "makepng: --color --small: only one at a time!\n");
      exit(1);
   }

   /* Restrict the filters for more speed to those we know are used for the
    * generated images.
    */
   if (filters == PNG_ALL_FILTERS && !small/*small provides defaults*/)
   {
      if ((color_type & PNG_COLOR_MASK_PALETTE) != 0 || bit_depth < 8)
         filters = PNG_FILTER_NONE;

      else if (color_type & PNG_COLOR_MASK_COLOR) /* rgb */
      {
         if (bit_depth == 8)
            filters &= ~(PNG_FILTER_NONE | PNG_FILTER_AVG);

         else
            filters = PNG_FILTER_SUB | PNG_FILTER_PAETH;
      }

      else /* gray 8 or 16-bit */
         filters &= ~PNG_FILTER_NONE;
   }

   /* Insert standard copyright and licence text. */
   {
      static png_const_charp copyright[] =
      {
         COPYRIGHT,
         NULL
      };
      chunk_insert *new_insert = add_iTXt("Copyright", "en", "Copyright",
            copyright);

      if (new_insert != NULL)
      {
         *insert_ptr = new_insert;
         insert_ptr = &new_insert->next;
      }

      {
         static png_const_charp text[] =
         {
            "Statement of Purpose\n",
            "\n",
            "The laws of most jurisdictions throughout the world\n",
            "automatically confer exclusive Copyright and Related Rights\n",
            "(defined below) upon the creator and subsequent owner(s)\n",
            "(each and all, an \"owner\") of an original work of\n",
            "authorship and/or a database (each, a \"Work\").\n",
            "\n",
            "Certain owners wish to permanently relinquish those rights\n",
            "to a Work for the purpose of contributing to a commons of\n",
            "creative, cultural and scientific works (\"Commons\") that\n",
            "the public can reliably and without fear of later claims\n",
            "of infringement build upon, modify, incorporate in other\n",
            "works, reuse and redistribute as freely as possible in any\n",
            "form whatsoever and for any purposes, including without\n",
            "limitation commercial purposes. These owners may contribute\n",
            "to the Commons to promote the ideal of a free culture and\n",
            "the further production of creative, cultural and scientific\n",
            "works, or to gain reputation or greater distribution for\n",
            "their Work in part through the use and efforts of others.\n",
            "\n",
            "For these and/or other purposes and motivations, and\n",
            "without any expectation of additional consideration or\n",
            "compensation, the person associating CC0 with a Work (the\n",
            "\"Affirmer\"), to the extent that he or she is an owner\n",
            "of Copyright and Related Rights in the Work, voluntarily\n",
            "elects to apply CC0 to the Work and publicly distribute\n",
            "the Work under its terms, with knowledge of his or her\n",
            "Copyright and Related Rights in the Work and the meaning\n",
            "and intended legal effect of CC0 on those rights.\n",
            "\n",
            "1. Copyright and Related Rights. A Work made available\n",
            "under CC0 may be protected by copyright and related\n",
            "or neighboring rights (\"Copyright and Related\n",
            "Rights\"). Copyright and Related Rights include, but are\n",
            "not limited to, the following:\n",
            "\n",
            "the right to reproduce, adapt, distribute, perform,\n",
            "display, communicate, and translate a Work; moral rights\n",
            "retained by the original author(s) and/or performer(s);\n",
            "publicity and privacy rights pertaining to a person's image\n",
            "or likeness depicted in a Work; rights protecting against\n",
            "unfair competition in regards to a Work, subject to the\n",
            "limitations in paragraph 4(a), below; rights protecting the\n",
            "extraction, dissemination, use and reuse of data in a Work;\n",
            "database rights (such as those arising under Directive\n",
            "96/9/EC of the European Parliament and of the Council of\n",
            "11 March 1996 on the legal protection of databases, and\n",
            "under any national implementation thereof, including any\n",
            "amended or successor version of such directive); and other\n",
            "similar, equivalent or corresponding rights throughout the\n",
            "world based on applicable law or treaty, and any national\n",
            "implementations thereof.  2. Waiver. To the greatest extent\n",
            "permitted by, but not in contravention of, applicable law,\n",
            "Affirmer hereby overtly, fully, permanently, irrevocably\n",
            "and unconditionally waives, abandons, and surrenders all\n",
            "of Affirmer's Copyright and Related Rights and associated\n",
            "claims and causes of action, whether now known or unknown\n",
            "(including existing as well as future claims and causes\n",
            "of action), in the Work (i) in all territories worldwide,\n",
            "(ii) for the maximum duration provided by applicable law\n",
            "or treaty (including future time extensions), (iii) in any\n",
            "current or future medium and for any number of copies,\n",
            "and (iv) for any purpose whatsoever, including without\n",
            "limitation commercial, advertising or promotional purposes\n",
            "(the \"Waiver\"). Affirmer makes the Waiver for the benefit\n",
            "of each member of the public at large and to the detriment\n",
            "of Affirmer's heirs and successors, fully intending that\n",
            "such Waiver shall not be subject to revocation, rescission,\n",
            "cancellation, termination, or any other legal or equitable\n",
            "action to disrupt the quiet enjoyment of the Work by the\n",
            "public as contemplated by Affirmer's express Statement\n",
            "of Purpose.\n",
            "\n",
            "3. Public License Fallback. Should any part of the Waiver\n",
            "for any reason be judged legally invalid or ineffective\n",
            "under applicable law, then the Waiver shall be preserved to\n",
            "the maximum extent permitted taking into account Affirmer's\n",
            "express Statement of Purpose. In addition, to the extent\n",
            "the Waiver is so judged Affirmer hereby grants to each\n",
            "affected person a royalty-free, non transferable, non\n",
            "sublicensable, non exclusive, irrevocable and unconditional\n",
            "license to exercise Affirmer's Copyright and Related\n",
            "Rights in the Work (i) in all territories worldwide, (ii)\n",
            "for the maximum duration provided by applicable law or\n",
            "treaty (including future time extensions), (iii) in any\n",
            "current or future medium and for any number of copies,\n",
            "and (iv) for any purpose whatsoever, including without\n",
            "limitation commercial, advertising or promotional purposes\n",
            "(the \"License\"). The License shall be deemed effective as\n",
            "of the date CC0 was applied by Affirmer to the Work. Should\n",
            "any part of the License for any reason be judged legally\n",
            "invalid or ineffective under applicable law, such partial\n",
            "invalidity or ineffectiveness shall not invalidate the\n",
            "remainder of the License, and in such case Affirmer hereby\n",
            "affirms that he or she will not (i) exercise any of his or\n",
            "her remaining Copyright and Related Rights in the Work or\n",
            "(ii) assert any associated claims and causes of action with\n",
            "respect to the Work, in either case contrary to Affirmer's\n",
            "express Statement of Purpose.\n",
            "\n",
            "4. Limitations and Disclaimers.\n",
            "\n",
            "No trademark or patent rights held by Affirmer are waived,\n",
            "abandoned, surrendered, licensed or otherwise affected by\n",
            "this document.  Affirmer offers the Work as-is and makes no\n",
            "representations or warranties of any kind concerning the\n",
            "Work, express, implied, statutory or otherwise, including\n",
            "without limitation warranties of title, merchantability,\n",
            "fitness for a particular purpose, non infringement, or\n",
            "the absence of latent or other defects, accuracy, or the\n",
            "present or absence of errors, whether or not discoverable,\n",
            "all to the greatest extent permissible under applicable\n",
            "law.  Affirmer disclaims responsibility for clearing\n",
            "rights of other persons that may apply to the Work or any\n",
            "use thereof, including without limitation any person's\n",
            "Copyright and Related Rights in the Work. Further, Affirmer\n",
            "disclaims responsibility for obtaining any necessary\n",
            "consents, permissions or other rights required for any use\n",
            "of the Work.  Affirmer understands and acknowledges that\n",
            "Creative Commons is not a party to this document and has\n",
            "no duty or obligation with respect to this CC0 or use of\n",
            "the Work.\n",
            NULL
         };

         new_insert = add_iTXt("Licence", "en-us", "License", text);
      }

      if (new_insert != NULL)
      {
         *insert_ptr = new_insert;
         insert_ptr = &new_insert->next;
      }
   }

   {
      int ret = write_png(&file_name, fp, color_type, bit_depth, gamma,
         head_insert, filters, colors, small);

      if (ret != 0 && file_name != NULL)
         remove(file_name);

      return ret;
   }
}