text: 
  /* pngtest.c - a simple test program to test libpng
   *
   * Last changed in libpng 1.5.25 [December 3, 2015]
   * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
   * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   *
   * This code is released under the libpng license.
   * For conditions of distribution and use, see the disclaimer
   * and license in png.h
   *
   * 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 ..."
   */
  
  #define _POSIX_SOURCE 1
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  /* Defined so I can write to a file on gui/windowing platforms */
  /*  #define STDERR stderr  */
  #define STDERR stdout   /* For DOS */
  
  #include "png.h"
  
  /* 1.6.1 added support for the configure test harness, which uses 77 to indicate
   * a skipped test, in earlier versions we need to succeed on a skipped test, so:
   */
  #if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
  #  define SKIP 77
  #else
  #  define SKIP 0
  #endif
  
  /* Known chunks that exist in pngtest.png must be supported or pngtest will fail
   * simply as a result of re-ordering them.  This may be fixed in 1.7
   *
   * pngtest allocates a single row buffer for each row and overwrites it,
   * therefore if the write side doesn't support the writing of interlaced images
   * nothing can be done for an interlaced image (and the code below will fail
   * horribly trying to write extra data after writing garbage).
   */
  #if defined PNG_READ_SUPPORTED && /* else nothing can be done */\
     defined PNG_READ_bKGD_SUPPORTED &&\
     defined PNG_READ_cHRM_SUPPORTED &&\
     defined PNG_READ_gAMA_SUPPORTED &&\
     defined PNG_READ_oFFs_SUPPORTED &&\
     defined PNG_READ_pCAL_SUPPORTED &&\
     defined PNG_READ_pHYs_SUPPORTED &&\
     defined PNG_READ_sBIT_SUPPORTED &&\
     defined PNG_READ_sCAL_SUPPORTED &&\
     defined PNG_READ_sRGB_SUPPORTED &&\
     defined PNG_READ_sPLT_SUPPORTED &&\
     defined PNG_READ_tEXt_SUPPORTED &&\
     defined PNG_READ_tIME_SUPPORTED &&\
     defined PNG_READ_zTXt_SUPPORTED &&\
     (defined PNG_WRITE_INTERLACING_SUPPORTED || PNG_LIBPNG_VER >= 10700)
  
  #ifdef PNG_ZLIB_HEADER
  #  include PNG_ZLIB_HEADER /* defined by pnglibconf.h from 1.7 */
  #else
  #  include "zlib.h"
  #endif
  
  /* Copied from pngpriv.h but only used in error messages below. */
  #ifndef PNG_ZBUF_SIZE
  #  define PNG_ZBUF_SIZE 8192
  #endif
  #define FCLOSE(file) fclose(file)
  
  #ifndef PNG_STDIO_SUPPORTED
  typedef FILE                * png_FILE_p;
  #endif
  
  /* Makes pngtest verbose so we can find problems. */
  #ifndef PNG_DEBUG
  #  define PNG_DEBUG 0
  #endif
  
  #if PNG_DEBUG > 1
  #  define pngtest_debug(m)        ((void)fprintf(stderr, m "\n"))
  #  define pngtest_debug1(m,p1)    ((void)fprintf(stderr, m "\n", p1))
  #  define pngtest_debug2(m,p1,p2) ((void)fprintf(stderr, m "\n", p1, p2))
  #else
  #  define pngtest_debug(m)        ((void)0)
  #  define pngtest_debug1(m,p1)    ((void)0)
  #  define pngtest_debug2(m,p1,p2) ((void)0)
  #endif
  
  #if !PNG_DEBUG
  #  define SINGLE_ROWBUF_ALLOC  /* Makes buffer overruns easier to nail */
  #endif
  
  #ifndef PNG_UNUSED
  #  define PNG_UNUSED(param) (void)param;
  #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";
  
  #if PNG_LIBPNG_VER < 10619
  #define png_convert_to_rfc1123_buffer(ts, t) tIME_to_str(read_ptr, ts, t)
  
  static int
  tIME_to_str(png_structp png_ptr, png_charp ts, png_const_timep t)
  {
      png_const_charp str = png_convert_to_rfc1123(png_ptr, t);
  
      if (str == NULL)
          return 0;
  
      strcpy(ts, str);
      return 1;
  }
  #endif /* older libpng */
  #endif
  
  static int verbose = 0;
  static int strict = 0;
  static int relaxed = 0;
  static int unsupported_chunks = 0; /* chunk unsupported by libpng in input */
  static int error_count = 0; /* count calls to png_error */
  static int warning_count = 0; /* count calls to png_warning */
  
  /* 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
  
  /* Defines for unknown chunk handling if required. */
  #ifndef PNG_HANDLE_CHUNK_ALWAYS
  #  define PNG_HANDLE_CHUNK_ALWAYS       3
  #endif
  #ifndef PNG_HANDLE_CHUNK_IF_SAFE
  #  define PNG_HANDLE_CHUNK_IF_SAFE      2
  #endif
  
  /* Utility to save typing/errors, the argument must be a name */
  #define MEMZERO(var) ((void)memset(&var, 0, sizeof var))
  
  /* 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;
  
  static void PNGCBAPI
  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");
  }
  
  #ifdef PNG_WRITE_SUPPORTED
  static void PNGCBAPI
  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");
  }
  #endif
  
  
  #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
  /* Example of using a user transform callback (doesn't do anything at present).
   */
  static void PNGCBAPI
  read_user_callback(png_structp png_ptr, png_row_infop row_info, png_bytep data)
  {
     PNG_UNUSED(png_ptr)
     PNG_UNUSED(row_info)
     PNG_UNUSED(data)
  }
  #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;
  
  static void PNGCBAPI
  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 /* WRITE_USER_TRANSFORM */
  
  #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 != 0)
        png_error(png_ptr, "Bad I/O state or buffer size");
  }
  #endif
  
  static void PNGCBAPI
  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
  }
  
  #ifdef PNG_WRITE_FLUSH_SUPPORTED
  static void PNGCBAPI
  pngtest_flush(png_structp png_ptr)
  {
     /* Do nothing; fflush() is said to be just a waste of energy. */
     PNG_UNUSED(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.
   */
  static void PNGCBAPI
  pngtest_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
  {
     png_size_t check;
  
     check = fwrite(data, 1, length, (png_FILE_p)png_get_io_ptr(png_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
  }
  #endif /* !STDIO */
  
  /* 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.
   */
  typedef struct
  {
     PNG_CONST char *file_name;
  }  pngtest_error_parameters;
  
  static void PNGCBAPI
  pngtest_warning(png_structp png_ptr, png_const_charp message)
  {
     PNG_CONST char *name = "UNKNOWN (ERROR!)";
     pngtest_error_parameters *test =
        (pngtest_error_parameters*)png_get_error_ptr(png_ptr);
  
     ++warning_count;
  
     if (test != NULL && test->file_name != NULL)
        name = test->file_name;
  
     fprintf(STDERR, "%s: libpng warning: %s\n", name, 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 PNGCBAPI
  pngtest_error(png_structp png_ptr, png_const_charp message)
  {
     ++error_count;
  
     pngtest_warning(png_ptr, message);
     /* We can return because png_error calls the default handler, which is
      * actually OK in this case.
      */
  }
  
  /* 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 than 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 *next;
  } memory_information;
  typedef memory_information *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 PNGCBAPI png_debug_malloc PNGARG((png_structp png_ptr,
      png_alloc_size_t size));
  void PNGCBAPI png_debug_free PNGARG((png_structp png_ptr, png_voidp ptr));
  
  png_voidp
  PNGCBAPI 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,
           (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. */
        memset(pinfo->pointer, 0xdd, pinfo->size);
  
        if (verbose != 0)
           printf("png_malloc %lu bytes at %p\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 PNGCBAPI
  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. */
     if (pinformation != NULL)
     {
        memory_infop *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. */
              memset(ptr, 0x55, pinfo->size);
              free(pinfo);
              pinfo = NULL;
              break;
           }
  
           if (pinfo->next == NULL)
           {
              fprintf(STDERR, "Pointer %p not found\n", ptr);
              break;
           }
  
           ppinfo = &pinfo->next;
        }
     }
  
     /* Finally free the data. */
     if (verbose != 0)
        printf("Freeing %p\n", ptr);
  
     if (ptr != NULL)
        free(ptr);
     ptr = NULL;
  }
  #endif /* USER_MEM && DEBUG */
  /* END of code to test memory allocation/deallocation */
  
  
  #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
  /* Demonstration of user chunk support of the sTER and vpAg chunks */
  
  /* (sTER is a public chunk not yet known by libpng.  vpAg is a private
  chunk used in ImageMagick to store "virtual page" size).  */
  
  static struct user_chunk_data
  {
     png_const_infop info_ptr;
     png_uint_32     vpAg_width, vpAg_height;
     png_byte        vpAg_units;
     png_byte        sTER_mode;
     int             location[2];
  }
  user_chunk_data;
  
  /* Used for location and order; zero means nothing. */
  #define have_sTER   0x01
  #define have_vpAg   0x02
  #define before_PLTE 0x10
  #define before_IDAT 0x20
  #define after_IDAT  0x40
  
  static void
  init_callback_info(png_const_infop info_ptr)
  {
     MEMZERO(user_chunk_data);
     user_chunk_data.info_ptr = info_ptr;
  }
  
  static int
  set_location(png_structp png_ptr, struct user_chunk_data *data, int what)
  {
     int location;
  
     if ((data->location[0] & what) != 0 || (data->location[1] & what) != 0)
        return 0; /* already have one of these */
  
     /* Find where we are (the code below zeroes info_ptr to indicate that the
      * chunks before the first IDAT have been read.)
      */
     if (data->info_ptr == NULL) /* after IDAT */
        location = what | after_IDAT;
  
     else if (png_get_valid(png_ptr, data->info_ptr, PNG_INFO_PLTE) != 0)
        location = what | before_IDAT;
  
     else
        location = what | before_PLTE;
  
     if (data->location[0] == 0)
        data->location[0] = location;
  
     else
        data->location[1] = location;
  
     return 1; /* handled */
  }
  
  static int PNGCBAPI
  read_user_chunk_callback(png_struct *png_ptr, png_unknown_chunkp chunk)
  {
     struct user_chunk_data *my_user_chunk_data =
        (struct user_chunk_data*)png_get_user_chunk_ptr(png_ptr);
  
     if (my_user_chunk_data == NULL)
        png_error(png_ptr, "lost user chunk pointer");
  
     /* 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 */
  
           if (set_location(png_ptr, my_user_chunk_data, have_sTER) != 0)
           {
              my_user_chunk_data->sTER_mode=chunk->data[0];
              return (1);
           }
  
           else
              return (0); /* duplicate sTER - give it to libpng */
        }
  
     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 */
  
     if (set_location(png_ptr, my_user_chunk_data, have_vpAg) == 0)
        return (0);  /* duplicate vpAg */
  
     my_user_chunk_data->vpAg_width = png_get_uint_31(png_ptr, chunk->data);
     my_user_chunk_data->vpAg_height = png_get_uint_31(png_ptr, chunk->data + 4);
     my_user_chunk_data->vpAg_units = chunk->data[8];
  
     return (1);
  }
  
  #ifdef PNG_WRITE_SUPPORTED
  static void
  write_sTER_chunk(png_structp write_ptr)
  {
     png_byte sTER[5] = {115,  84,  69,  82, '\0'};
  
     if (verbose != 0)
        fprintf(STDERR, "\n stereo mode = %d\n", user_chunk_data.sTER_mode);
  
     png_write_chunk(write_ptr, sTER, &user_chunk_data.sTER_mode, 1);
  }
  
  static void
  write_vpAg_chunk(png_structp write_ptr)
  {
     png_byte vpAg[5] = {118, 112,  65, 103, '\0'};
  
     png_byte vpag_chunk_data[9];
  
     if (verbose != 0)
        fprintf(STDERR, " vpAg = %lu x %lu, units = %d\n",
          (unsigned long)user_chunk_data.vpAg_width,
          (unsigned long)user_chunk_data.vpAg_height,
          user_chunk_data.vpAg_units);
  
     png_save_uint_32(vpag_chunk_data, user_chunk_data.vpAg_width);
     png_save_uint_32(vpag_chunk_data + 4, user_chunk_data.vpAg_height);
     vpag_chunk_data[8] = user_chunk_data.vpAg_units;
     png_write_chunk(write_ptr, vpAg, vpag_chunk_data, 9);
  }
  
  static void
  write_chunks(png_structp write_ptr, int location)
  {
     int i;
  
     /* Notice that this preserves the original chunk order, however chunks
      * intercepted by the callback will be written *after* chunks passed to
      * libpng.  This will actually reverse a pair of sTER chunks or a pair of
      * vpAg chunks, resulting in an error later.  This is not worth worrying
      * about - the chunks should not be duplicated!
      */
     for (i=0; i<2; ++i)
     {
        if (user_chunk_data.location[i] == (location | have_sTER))
           write_sTER_chunk(write_ptr);
  
        else if (user_chunk_data.location[i] == (location | have_vpAg))
           write_vpAg_chunk(write_ptr);
     }
  }
  #endif /* WRITE */
  #else /* !READ_USER_CHUNKS */
  #  define write_chunks(pp,loc) ((void)0)
  #endif
  /* END of code to demonstrate user chunk support */
  
  /* START of code to check that libpng has the required text support; this only
   * checks for the write support because if read support is missing the chunk
   * will simply not be reported back to pngtest.
   */
  #ifdef PNG_TEXT_SUPPORTED
  static void
  pngtest_check_text_support(png_structp png_ptr, png_textp text_ptr,
     int num_text)
  {
     while (num_text > 0)
     {
        switch (text_ptr[--num_text].compression)
        {
           case PNG_TEXT_COMPRESSION_NONE:
              break;
  
           case PNG_TEXT_COMPRESSION_zTXt:
  #           ifndef PNG_WRITE_zTXt_SUPPORTED
                 ++unsupported_chunks;
                 /* In libpng 1.7 this now does an app-error, so stop it: */
                 text_ptr[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
  #           endif
              break;
  
           case PNG_ITXT_COMPRESSION_NONE:
           case PNG_ITXT_COMPRESSION_zTXt:
  #           ifndef PNG_WRITE_iTXt_SUPPORTED
                 ++unsupported_chunks;
                 text_ptr[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
  #           endif
              break;
  
           default:
              /* This is an error */
              png_error(png_ptr, "invalid text chunk compression field");
              break;
        }
     }
  }
  #endif
  /* END of code to check that libpng has the required text support */
  
  /* Test one file */
  static 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 */
     pngtest_error_parameters error_parameters;
     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;
  #ifdef PNG_WRITE_FILTER_SUPPORTED
     int interlace_preserved = 1;
  #endif /* WRITE_FILTER */
  #else /* !WRITE */
     png_structp write_ptr = NULL;
     png_infop write_info_ptr = NULL;
     png_infop write_end_info_ptr = NULL;
  #endif /* !WRITE */
     png_bytep row_buf;
     png_uint_32 y;
     png_uint_32 width, height;
     volatile int num_passes;
     int pass;
     int bit_depth, color_type;
  
     row_buf = NULL;
     error_parameters.file_name = inname;
  
     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);
     }
  
     pngtest_debug("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_debug_malloc, png_debug_free);
  #else
     read_ptr =
        png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  #endif
     png_set_error_fn(read_ptr, &error_parameters, pngtest_error,
        pngtest_warning);
  
  #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
     png_set_error_fn(write_ptr, &error_parameters, pngtest_error,
        pngtest_warning);
  #endif
     pngtest_debug("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_READ_USER_CHUNKS_SUPPORTED
     init_callback_info(read_info_ptr);
     png_set_read_user_chunk_fn(read_ptr, &user_chunk_data,
       read_user_chunk_callback);
  #endif
  
  #ifdef PNG_SETJMP_SUPPORTED
     pngtest_debug("Setting jmpbuf for read struct");
     if (setjmp(png_jmpbuf(read_ptr)))
     {
        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 PNG_WRITE_SUPPORTED
     pngtest_debug("Setting jmpbuf for write struct");
  
     if (setjmp(png_jmpbuf(write_ptr)))
     {
        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);
     }
  #endif
  #endif
  
     if (strict != 0)
     {
        /* Treat png_benign_error() as errors on read */
        png_set_benign_errors(read_ptr, 0);
  
  #ifdef PNG_WRITE_SUPPORTED
        /* Treat them as errors on write */
        png_set_benign_errors(write_ptr, 0);
  #endif
  
        /* if strict is not set, then app warnings and errors are treated as
         * warnings in release builds, but not in unstable builds; this can be
         * changed with '--relaxed'.
         */
     }
  
     else if (relaxed != 0)
     {
        /* Allow application (pngtest) errors and warnings to pass */
        png_set_benign_errors(read_ptr, 1);
  
  #ifdef PNG_WRITE_SUPPORTED
        png_set_benign_errors(write_ptr, 1);
  #endif
     }
  
     pngtest_debug("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
     png_set_read_user_transform_fn(read_ptr, read_user_callback);
  #endif
  #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
     zero_samples = 0;
     png_set_write_user_transform_fn(write_ptr, count_zero_samples);
  #endif
  
  #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
     /* Preserve all the unknown chunks, if possible.  If this is disabled then,
      * even if the png_{get,set}_unknown_chunks stuff is enabled, we can't use
      * libpng to *save* the unknown chunks on read (because we can't switch the
      * save option on!)
      *
      * Notice that if SET_UNKNOWN_CHUNKS is *not* supported read will discard all
      * unknown chunks and write will write them all.
      */
  #ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
     png_set_keep_unknown_chunks(read_ptr, PNG_HANDLE_CHUNK_ALWAYS,
        NULL, 0);
  #endif
  #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
     png_set_keep_unknown_chunks(write_ptr, PNG_HANDLE_CHUNK_ALWAYS,
        NULL, 0);
  #endif
  #endif
  
     pngtest_debug("Reading info struct");
     png_read_info(read_ptr, read_info_ptr);
  
  #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
     /* This is a bit of a hack; there is no obvious way in the callback function
      * to determine that the chunks before the first IDAT have been read, so
      * remove the info_ptr (which is only used to determine position relative to
      * PLTE) here to indicate that we are after the IDAT.
      */
     user_chunk_data.info_ptr = NULL;
  #endif
  
     pngtest_debug("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) != 0)
        {
           png_set_IHDR(write_ptr, write_info_ptr, width, height, bit_depth,
              color_type, interlace_type, compression_type, filter_type);
           /* num_passes may not be available below if interlace support is not
            * provided by libpng for both read and write.
            */
           switch (interlace_type)
           {
              case PNG_INTERLACE_NONE:
                 num_passes = 1;
                 break;
  
              case PNG_INTERLACE_ADAM7:
                 num_passes = 7;
                 break;
  
              default:
                 png_error(read_ptr, "invalid interlace type");
                 /*NOT REACHED*/
           }
        }
  
        else
           png_error(read_ptr, "png_get_IHDR failed");
     }
  #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) != 0)
        {
           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) != 0)
           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) != 0)
        {
           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) != 0)
           png_set_gAMA(write_ptr, write_info_ptr, gamma);
     }
  #endif
  #endif /* Floating point */
  #endif /* Fixed point */
  #ifdef PNG_iCCP_SUPPORTED
     {
        png_charp name;
        png_bytep profile;
        png_uint_32 proflen;
        int compression_type;
  
        if (png_get_iCCP(read_ptr, read_info_ptr, &name, &compression_type,
                        &profile, &proflen) != 0)
        {
           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) != 0)
           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) != 0)
           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) != 0)
        {
           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) != 0)
           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) != 0)
        {
           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) != 0)
        {
           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) != 0)
           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) != 0)
           png_set_sBIT(write_ptr, write_info_ptr, sig_bit);
     }
  #endif
  #ifdef PNG_sCAL_SUPPORTED
  #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
     defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
     {
        int unit;
        double scal_width, scal_height;
  
        if (png_get_sCAL(read_ptr, read_info_ptr, &unit, &scal_width,
           &scal_height) != 0)
        {
           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) != 0)
        {
           png_set_sCAL_s(write_ptr, write_info_ptr, unit, scal_width,
               scal_height);
        }
     }
  #endif
  #endif
  #endif
  
  #ifdef PNG_sPLT_SUPPORTED
     {
         png_sPLT_tp entries;
  
         int num_entries = (int) png_get_sPLT(read_ptr, read_info_ptr, &entries);
         if (num_entries)
         {
             png_set_sPLT(write_ptr, write_info_ptr, entries, num_entries);
         }
     }
  #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)
        {
           pngtest_debug1("Handling %d iTXt/tEXt/zTXt chunks", num_text);
  
           pngtest_check_text_support(read_ptr, text_ptr, num_text);
  
           if (verbose != 0)
           {
              int i;
  
              printf("\n");
              for (i=0; i<num_text; i++)
              {
                 printf("   Text compression[%d]=%d\n",
                       i, text_ptr[i].compression);
              }
           }
  
           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) != 0)
        {
           png_set_tIME(write_ptr, write_info_ptr, mod_time);
  #ifdef PNG_TIME_RFC1123_SUPPORTED
           if (png_convert_to_rfc1123_buffer(tIME_string, mod_time) != 0)
              tIME_string[(sizeof tIME_string) - 1] = '\0';
  
           else
           {
              strncpy(tIME_string, "*** invalid time ***", (sizeof tIME_string));
              tIME_string[(sizeof tIME_string) - 1] = '\0';
           }
  
           tIME_chunk_present++;
  #endif /* TIME_RFC1123 */
        }
     }
  #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) != 0)
        {
           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 = png_get_unknown_chunks(read_ptr, read_info_ptr,
           &unknowns);
  
        if (num_unknowns != 0)
        {
           png_set_unknown_chunks(write_ptr, write_info_ptr, unknowns,
             num_unknowns);
  #if PNG_LIBPNG_VER < 10600
           /* Copy the locations from the read_info_ptr.  The automatically
            * generated locations in write_end_info_ptr are wrong prior to 1.6.0
            * because they are reset from the write pointer (removed in 1.6.0).
            */
           {
              int i;
              for (i = 0; i < num_unknowns; i++)
                png_set_unknown_chunk_location(write_ptr, write_info_ptr, i,
                  unknowns[i].location);
           }
  #endif
        }
     }
  #endif
  
  #ifdef PNG_WRITE_SUPPORTED
     pngtest_debug("Writing info struct");
  
     /* Write the info in two steps so that if we write the 'unknown' chunks here
      * they go to the correct place.
      */
     png_write_info_before_PLTE(write_ptr, write_info_ptr);
  
     write_chunks(write_ptr, before_PLTE); /* before PLTE */
  
     png_write_info(write_ptr, write_info_ptr);
  
     write_chunks(write_ptr, before_IDAT); /* after PLTE */
  #endif
  
  #ifdef SINGLE_ROWBUF_ALLOC
     pngtest_debug("Allocating row buffer...");
     row_buf = (png_bytep)png_malloc(read_ptr,
        png_get_rowbytes(read_ptr, read_info_ptr));
  
     pngtest_debug1("\t0x%08lx", (unsigned long)row_buf);
  #endif /* SINGLE_ROWBUF_ALLOC */
     pngtest_debug("Writing row data");
  
  #if defined(PNG_READ_INTERLACING_SUPPORTED) &&\
     defined(PNG_WRITE_INTERLACING_SUPPORTED)
     /* Both must be defined for libpng to be able to handle the interlace,
      * otherwise it gets handled below by simply reading and writing the passes
      * directly.
      */
     if (png_set_interlace_handling(read_ptr) != num_passes)
        png_error(write_ptr,
              "png_set_interlace_handling(read): wrong pass count ");
     if (png_set_interlace_handling(write_ptr) != num_passes)
        png_error(write_ptr,
              "png_set_interlace_handling(write): wrong pass count ");
  #else /* png_set_interlace_handling not called on either read or write */
  #  define calc_pass_height
  #endif /* not using libpng interlace handling */
  
  #ifdef PNGTEST_TIMING
     t_stop = (float)clock();
     t_misc += (t_stop - t_start);
     t_start = t_stop;
  #endif
     for (pass = 0; pass < num_passes; pass++)
     {
  #     ifdef calc_pass_height
           png_uint_32 pass_height;
  
           if (num_passes == 7) /* interlaced */
           {
              if (PNG_PASS_COLS(width, pass) > 0)
                 pass_height = PNG_PASS_ROWS(height, pass);
  
              else
                 pass_height = 0;
           }
  
           else /* not interlaced */
              pass_height = height;
  #     else
  #        define pass_height height
  #     endif
  
        pngtest_debug1("Writing row data for pass %d", pass);
        for (y = 0; y < pass_height; y++)
        {
  #ifndef SINGLE_ROWBUF_ALLOC
           pngtest_debug2("Allocating row buffer (pass %d, y = %u)...", pass, y);
  
           row_buf = (png_bytep)png_malloc(read_ptr,
              png_get_rowbytes(read_ptr, read_info_ptr));
  
           pngtest_debug2("\t0x%08lx (%lu bytes)", (unsigned long)row_buf,
              (unsigned long)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 /* WRITE */
  
  #ifndef SINGLE_ROWBUF_ALLOC
           pngtest_debug2("Freeing row buffer (pass %d, y = %u)", pass, y);
           png_free(read_ptr, row_buf);
           row_buf = NULL;
  #endif /* !SINGLE_ROWBUF_ALLOC */
        }
     }
  
  #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
  #  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
  #endif
  
     pngtest_debug("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)
        {
           pngtest_debug1("Handling %d iTXt/tEXt/zTXt chunks", num_text);
  
           pngtest_check_text_support(read_ptr, text_ptr, num_text);
  
           if (verbose != 0)
           {
              int i;
  
              printf("\n");
              for (i=0; i<num_text; i++)
              {
                 printf("   Text compression[%d]=%d\n",
                       i, text_ptr[i].compression);
              }
           }
  
           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) != 0)
        {
           png_set_tIME(write_ptr, write_end_info_ptr, mod_time);
  #ifdef PNG_TIME_RFC1123_SUPPORTED
           if (png_convert_to_rfc1123_buffer(tIME_string, mod_time) != 0)
              tIME_string[(sizeof tIME_string) - 1] = '\0';
  
           else
           {
              strncpy(tIME_string, "*** invalid time ***", sizeof tIME_string);
              tIME_string[(sizeof tIME_string)-1] = '\0';
           }
  
           tIME_chunk_present++;
  #endif /* TIME_RFC1123 */
        }
     }
  #endif
  #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
     {
        png_unknown_chunkp unknowns;
        int num_unknowns = png_get_unknown_chunks(read_ptr, end_info_ptr,
           &unknowns);
  
        if (num_unknowns != 0)
        {
           png_set_unknown_chunks(write_ptr, write_end_info_ptr, unknowns,
             num_unknowns);
  #if PNG_LIBPNG_VER < 10600
           /* Copy the locations from the read_info_ptr.  The automatically
            * generated locations in write_end_info_ptr are wrong prior to 1.6.0
            * because they are reset from the write pointer (removed in 1.6.0).
            */
           {
              int i;
              for (i = 0; i < num_unknowns; i++)
                png_set_unknown_chunk_location(write_ptr, write_end_info_ptr, i,
                  unknowns[i].location);
           }
  #endif
        }
     }
  #endif
  
  #ifdef PNG_WRITE_SUPPORTED
  #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
     /* Normally one would use Z_DEFAULT_STRATEGY for text compression.
      * This is here just to make pngtest replicate the results from libpng
      * versions prior to 1.5.4, and to test this new API.
      */
     png_set_text_compression_strategy(write_ptr, Z_FILTERED);
  #endif
  
     /* When the unknown vpAg/sTER chunks are written by pngtest the only way to
      * do it is to write them *before* calling png_write_end.  When unknown
      * chunks are written by libpng, however, they are written just before IEND.
      * There seems to be no way round this, however vpAg/sTER are not expected
      * after IDAT.
      */
     write_chunks(write_ptr, after_IDAT);
  
     png_write_end(write_ptr, write_end_info_ptr);
  #endif
  
  #ifdef PNG_EASY_ACCESS_SUPPORTED
     if (verbose != 0)
     {
        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
  
     pngtest_debug("Destroying data structs");
  #ifdef SINGLE_ROWBUF_ALLOC
     pngtest_debug("destroying row_buf for read_ptr");
     png_free(read_ptr, row_buf);
     row_buf = NULL;
  #endif /* SINGLE_ROWBUF_ALLOC */
     pngtest_debug("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
     pngtest_debug("destroying write_end_info_ptr");
     png_destroy_info_struct(write_ptr, &write_end_info_ptr);
     pngtest_debug("destroying write_ptr, write_info_ptr");
     png_destroy_write_struct(&write_ptr, &write_info_ptr);
  #endif
     pngtest_debug("Destruction complete.");
  
     FCLOSE(fpin);
     FCLOSE(fpout);
  
     /* Summarize any warnings or errors and in 'strict' mode fail the test.
      * Unsupported chunks can result in warnings, in that case ignore the strict
      * setting, otherwise fail the test on warnings as well as errors.
      */
     if (error_count > 0)
     {
        /* We don't really expect to get here because of the setjmp handling
         * above, but this is safe.
         */
        fprintf(STDERR, "\n  %s: %d libpng errors found (%d warnings)",
           inname, error_count, warning_count);
  
        if (strict != 0)
           return (1);
     }
  
  #  ifdef PNG_WRITE_SUPPORTED
        /* If there is no write support nothing was written! */
        else if (unsupported_chunks > 0)
        {
           fprintf(STDERR, "\n  %s: unsupported chunks (%d)%s",
              inname, unsupported_chunks, strict ? ": IGNORED --strict!" : "");
        }
  #  endif
  
     else if (warning_count > 0)
     {
        fprintf(STDERR, "\n  %s: %d libpng warnings found",
           inname, warning_count);
  
        if (strict != 0)
           return (1);
     }
  
     pngtest_debug("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);
     }
  
  #if defined (PNG_WRITE_SUPPORTED) /* else nothing was written */ &&\
      defined (PNG_WRITE_FILTER_SUPPORTED)
     if (interlace_preserved != 0) /* else the files will be changed */
     {
        for (;;)
        {
           static int wrote_question = 0;
           png_size_t num_in, num_out;
           char inbuf[256], outbuf[256];
  
           num_in = fread(inbuf, 1, sizeof inbuf, fpin);
           num_out = fread(outbuf, 1, sizeof outbuf, fpout);
  
           if (num_in != num_out)
           {
              fprintf(STDERR, "\nFiles %s and %s are of a different size\n",
                      inname, outname);
  
              if (wrote_question == 0 && unsupported_chunks == 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);
  
              if (strict != 0 && unsupported_chunks == 0)
                return (1);
  
              else
                return (0);
           }
  
           if (num_in == 0)
              break;
  
           if (memcmp(inbuf, outbuf, num_in))
           {
              fprintf(STDERR, "\nFiles %s and %s are different\n", inname,
                 outname);
  
              if (wrote_question == 0 && unsupported_chunks == 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);
  
              /* NOTE: the unsupported_chunks escape is permitted here because
               * unsupported text chunk compression will result in the compression
               * mode being changed (to NONE) yet, in the test case, the result
               * can be exactly the same size!
               */
              if (strict != 0 && unsupported_chunks == 0)
                return (1);
  
              else
                return (0);
           }
        }
     }
  #endif /* WRITE && WRITE_FILTER */
  
     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;
  
     png_structp dummy_ptr;
  
     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);
  
     /* 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 if (strcmp(argv[1], "--strict") == 0)
        {
           status_dots_requested = 0;
           verbose = 1;
           inname = argv[2];
           strict++;
           relaxed = 0;
        }
  
        else if (strcmp(argv[1], "--relaxed") == 0)
        {
           status_dots_requested = 0;
           verbose = 1;
           inname = argv[2];
           strict = 0;
           relaxed++;
        }
  
        else
        {
           inname = argv[1];
           status_dots_requested = 0;
        }
     }
  
     if (multiple == 0 && argc == 3 + verbose)
       outname = argv[2 + verbose];
  
     if ((multiple == 0 && argc > 3 + verbose) ||
         (multiple != 0 && 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 != 0)
     {
        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]);
  #if PNG_DEBUG > 0
           fprintf(STDERR, "\n");
  #endif
           kerror = test_one_file(argv[i], outname);
           if (kerror == 0)
           {
  #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_TIME_RFC1123_SUPPORTED
              if (tIME_chunk_present != 0)
                 fprintf(STDERR, " tIME = %s\n", tIME_string);
  
              tIME_chunk_present = 0;
  #endif /* TIME_RFC1123 */
           }
  
           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 %p\n",
                   (unsigned long)pinfo->size,
                   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);
  #if PNG_DEBUG > 0
              fprintf(STDERR, "\n");
  #endif
           }
  
           kerror = test_one_file(inname, outname);
  
           if (kerror == 0)
           {
              if (verbose == 1 || i == 2)
              {
  #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_TIME_RFC1123_SUPPORTED
               if (tIME_chunk_present != 0)
                  fprintf(STDERR, " tIME = %s\n", tIME_string);
  #endif /* TIME_RFC1123 */
              }
           }
  
           else
           {
              if (verbose == 0 && i != 2)
              {
                 fprintf(STDERR, "\n Testing %s:", inname);
  #if PNG_DEBUG > 0
                 fprintf(STDERR, "\n");
  #endif
              }
  
              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 %p\n",
                     (unsigned long)pinfo->size, 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");
  
     dummy_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
     fprintf(STDERR, " Default limits:\n");
     fprintf(STDERR, "  width_max  = %lu\n",
        (unsigned long) png_get_user_width_max(dummy_ptr));
     fprintf(STDERR, "  height_max = %lu\n",
        (unsigned long) png_get_user_height_max(dummy_ptr));
     if (png_get_chunk_cache_max(dummy_ptr) == 0)
        fprintf(STDERR, "  cache_max  = unlimited\n");
     else
        fprintf(STDERR, "  cache_max  = %lu\n",
           (unsigned long) png_get_chunk_cache_max(dummy_ptr));
     if (png_get_chunk_malloc_max(dummy_ptr) == 0)
        fprintf(STDERR, "  malloc_max = unlimited\n");
     else
        fprintf(STDERR, "  malloc_max = %lu\n",
           (unsigned long) png_get_chunk_malloc_max(dummy_ptr));
     png_destroy_read_struct(&dummy_ptr, NULL, NULL);
  
     return (int)(ierror != 0);
  }
  #else
  int
  main(void)
  {
     fprintf(STDERR,
        " test ignored because libpng was not built with read support\n");
     /* And skip this test */
     return SKIP;
  }
  #endif
  
  /* Generate a compiler error if there is an old png.h in the search path. */
  typedef png_libpng_version_1_6_22 Your_png_h_is_not_version_1_6_22;
  