text: /* pngcp.c
   *
   * Copyright (c) 2016 John Cunningham Bowler
   *
   * Last changed in libpng 1.6.24 [August 4, 2016]
   *
   * This code is released under the libpng license.
   * For conditions of distribution and use, see the disclaimer
   * and license in png.h
   *
   * This is an example of copying a PNG without changes using the png_read_png
   * and png_write_png interfaces.  A considerable number of options are provided
   * to manipulate the compression of the PNG data and other compressed chunks.
   *
   * For a more extensive example that uses the transforms see
   * contrib/libtests/pngimage.c in the libpng distribution.
   */
  #include "pnglibconf.h" /* To find how libpng was configured. */
  
  #ifdef PNG_PNGCP_TIMING_SUPPORTED
     /* WARNING:
      *
      * This test is here to allow POSIX.1b extensions to be used if enabled in
      * the compile; specifically the code requires_POSIX_C_SOURCE support of
      * 199309L or later to enable clock_gettime use.
      *
      * IF this causes problems THEN compile with a strict ANSI C compiler and let
      * this code turn on the POSIX features that it minimally requires.
      *
      * IF this does not work there is probably a bug in your ANSI C compiler or
      * your POSIX implementation.
      */
  #  define _POSIX_C_SOURCE 199309L
  #else /* No timing support required */
  #  define _POSIX_SOURCE 1
  #endif
  
  #if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
  #  include <config.h>
  #endif
  
  #include <stdio.h>
  
  /* 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
  
  #if PNG_LIBPNG_VER < 10700
     /* READ_PNG and WRITE_PNG were not defined, so: */
  #  ifdef PNG_INFO_IMAGE_SUPPORTED
  #     ifdef PNG_SEQUENTIAL_READ_SUPPORTED
  #        define PNG_READ_PNG_SUPPORTED
  #     endif /* SEQUENTIAL_READ */
  #     ifdef PNG_WRITE_SUPPORTED
  #        define PNG_WRITE_PNG_SUPPORTED
  #     endif /* WRITE */
  #  endif /* INFO_IMAGE */
  #endif /* pre 1.7.0 */
  
  #if (defined(PNG_READ_PNG_SUPPORTED)) && (defined(PNG_WRITE_PNG_SUPPORTED))
  #include <stdarg.h>
  #include <stdlib.h>
  #include <string.h>
  #include <errno.h>
  #include <limits.h>
  #include <assert.h>
  
  #include <unistd.h>
  #include <sys/stat.h>
  
  #include <zlib.h>
  
  #ifndef PNG_SETJMP_SUPPORTED
  #  include <setjmp.h> /* because png.h did *not* include this */
  #endif
  
  #ifdef __cplusplus
  #  define voidcast(type, value) static_cast<type>(value)
  #else
  #  define voidcast(type, value) (value)
  #endif /* __cplusplus */
  
  #ifdef __GNUC__
     /* Many versions of GCC erroneously report that local variables unmodified
      * within the scope of a setjmp may be clobbered.  This hacks round the
      * problem (sometimes) without harming other compilers.
      */
  #  define gv volatile
  #else
  #  define gv
  #endif
  
  /* 'CLOCK_PROCESS_CPUTIME_ID' is one of the clock timers for clock_gettime.  It
   * need not be supported even when clock_gettime is available.  It returns the
   * 'CPU' time the process has consumed.  'CPU' time is assumed to include time
   * when the CPU is actually blocked by a pending cache fill but not time
   * waiting for page faults.  The attempt is to get a measure of the actual time
   * the implementation takes to read a PNG ignoring the potentially very large IO
   * overhead.
   */
  #ifdef PNG_PNGCP_TIMING_SUPPORTED
  #  include <time.h>   /* clock_gettime and associated definitions */
  #  ifndef CLOCK_PROCESS_CPUTIME_ID
        /* Prevent inclusion of the spurious code: */
  #     undef PNG_PNGCP_TIMING_SUPPORTED
  #  endif
  #endif /* PNGCP_TIMING */
  
  /* So if the timing feature has been activated: */
  
  /* This structure is used to control the test of a single file. */
  typedef enum
  {
     VERBOSE,        /* switches on all messages */
     INFORMATION,
     WARNINGS,       /* switches on warnings */
     LIBPNG_WARNING,
     APP_WARNING,
     ERRORS,         /* just errors */
     APP_FAIL,       /* continuable error - no need to longjmp */
     LIBPNG_ERROR,   /* this and higher cause a longjmp */
     LIBPNG_BUG,     /* erroneous behavior in libpng */
     APP_ERROR,      /* such as out-of-memory in a callback */
     QUIET,          /* no normal messages */
     USER_ERROR,     /* such as file-not-found */
     INTERNAL_ERROR
  } error_level;
  #define LEVEL_MASK      0xf   /* where the level is in 'options' */
  
  #define STRICT          0x010 /* Fail on warnings as well as errors */
  #define LOG             0x020 /* Log pass/fail to stdout */
  #define CONTINUE        0x040 /* Continue on APP_FAIL errors */
  #define SIZES           0x080 /* Report input and output sizes */
  #define SEARCH          0x100 /* Search IDAT compression options */
  #define NOWRITE         0x200 /* Do not write an output file */
  #ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
  #  define IGNORE_INDEX  0x400 /* Ignore out of range palette indices (BAD!) */
  #  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
  #     define FIX_INDEX  0x800 /* 'Fix' out of range palette indices (OK) */
  #  endif /* GET_PALETTE_MAX */
  #endif /* CHECK_FOR_INVALID_INDEX */
  #define OPTION     0x80000000 /* Used for handling options */
  #define LIST       0x80000001 /* Used for handling options */
  
  /* Result masks apply to the result bits in the 'results' field below; these
   * bits are simple 1U<<error_level.  A pass requires either nothing worse than
   * warnings (--relaxes) or nothing worse than information (--strict)
   */
  #define RESULT_STRICT(r)   (((r) & ~((1U<<WARNINGS)-1)) == 0)
  #define RESULT_RELAXED(r)  (((r) & ~((1U<<ERRORS)-1)) == 0)
  
  /* OPTION DEFINITIONS */
  static const char range_lo[] = "low";
  static const char range_hi[] = "high";
  static const char all[] = "all";
  #define RANGE(lo,hi) { range_lo, lo }, { range_hi, hi }
  typedef struct value_list
  {
     const char *name;  /* the command line name of the value */
     int         value; /* the actual value to use */
  }  value_list;
  
  static const value_list
  #ifdef PNG_SW_COMPRESS_png_level
  vl_compression[] =
  {
     /* Overall compression control.  The order controls the search order for
      * 'all'.  Since the search is for the smallest the order used is low memory
      * then high speed.
      */
     { "low-memory",      PNG_COMPRESSION_LOW_MEMORY },
     { "high-speed",      PNG_COMPRESSION_HIGH_SPEED },
     { "high-read-speed", PNG_COMPRESSION_HIGH_READ_SPEED },
     { "low",             PNG_COMPRESSION_LOW },
     { "medium",          PNG_COMPRESSION_MEDIUM },
     { "old",             PNG_COMPRESSION_COMPAT },
     { "high",            PNG_COMPRESSION_HIGH },
     { all, 0 }
  },
  #endif /* SW_COMPRESS_png_level */
  
  #if defined(PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED) ||\
      defined(PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED)
  vl_strategy[] =
  {
     /* This controls the order of search. */
     { "huffman", Z_HUFFMAN_ONLY },
     { "RLE", Z_RLE },
     { "fixed", Z_FIXED }, /* the remainder do window searches */
     { "filtered", Z_FILTERED },
     { "default", Z_DEFAULT_STRATEGY },
     { all, 0 }
  },
  #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
  vl_windowBits_text[] =
  {
     { "default", MAX_WBITS/*from zlib*/ },
     { "minimum", 8 },
     RANGE(8, MAX_WBITS/*from zlib*/),
     { all, 0 }
  },
  #endif /* text compression */
  vl_level[] =
  {
     { "default", Z_DEFAULT_COMPRESSION /* this is -1 */ },
     { "none", Z_NO_COMPRESSION },
     { "speed", Z_BEST_SPEED },
     { "best", Z_BEST_COMPRESSION },
     { "0", Z_NO_COMPRESSION },
     RANGE(1, 9), /* this deliberately excludes '0' */
     { all, 0 }
  },
  vl_memLevel[] =
  {
     { "max", MAX_MEM_LEVEL }, /* zlib maximum */
     { "1", 1 }, /* zlib minimum */
     { "default", 8 }, /* zlib default */
     { "2", 2 },
     { "3", 3 },
     { "4", 4 },
     { "5", 5 }, /* for explicit testing */
     RANGE(6, MAX_MEM_LEVEL/*zlib*/), /* exclude 5 and below: zlib bugs */
     { all, 0 }
  },
  #endif /* WRITE_CUSTOMIZE_*COMPRESSION */
  #ifdef PNG_WRITE_FILTER_SUPPORTED
  vl_filter[] =
  {
     { all,      PNG_ALL_FILTERS   },
     { "off",    PNG_NO_FILTERS    },
     { "none",   PNG_FILTER_NONE   },
     { "sub",    PNG_FILTER_SUB    },
     { "up",     PNG_FILTER_UP     },
     { "avg",    PNG_FILTER_AVG    },
     { "paeth",  PNG_FILTER_PAETH  }
  },
  #endif /* WRITE_FILTER */
  #ifdef PNG_PNGCP_TIMING_SUPPORTED
  #  define PNGCP_TIME_READ  1
  #  define PNGCP_TIME_WRITE 2
  vl_time[] =
  {
     { "both",  PNGCP_TIME_READ+PNGCP_TIME_WRITE },
     { "off",   0 },
     { "read",  PNGCP_TIME_READ },
     { "write", PNGCP_TIME_WRITE }
  },
  #endif /* PNGCP_TIMING */
  vl_IDAT_size[] = /* for png_set_IDAT_size */
  {
     { "default", 0x7FFFFFFF },
     { "minimal", 1 },
     RANGE(1, 0x7FFFFFFF)
  },
  #ifndef PNG_SW_IDAT_size
     /* Pre 1.7 API: */
  #  define png_set_IDAT_size(p,v) png_set_compression_buffer_size(p, v)
  #endif /* !SW_IDAT_size */
  #define SL 8 /* stack limit in display, below */
  vl_log_depth[] = { { "on", 1 }, { "off", 0 }, RANGE(0, SL) },
  vl_on_off[] = { { "on", 1 }, { "off", 0 } };
  
  #ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
  static value_list
  vl_windowBits_IDAT[] =
  {
     { "default", MAX_WBITS },
     { "small", 9 },
     RANGE(8, MAX_WBITS), /* modified by set_windowBits_hi */
     { all, 0 }
  };
  #endif /* IDAT compression */
  
  typedef struct option
  {
     const char       *name;         /* name of the option */
     png_uint_32       opt;          /* an option, or OPTION or LIST */
     png_byte          search;       /* Search on --search */
     png_byte          value_count;  /* length of the list of values: */
     const value_list *values;       /* values for OPTION or LIST */
  }  option;
  
  static const option options[] =
  {
     /* struct display options, these are set when the command line is read */
  #  define S(n,v) { #n, v, 0, 2, vl_on_off },
     S(verbose,  VERBOSE)
     S(warnings, WARNINGS)
     S(errors,   ERRORS)
     S(quiet,    QUIET)
     S(strict,   STRICT)
     S(log,      LOG)
     S(continue, CONTINUE)
     S(sizes,    SIZES)
     S(search,   SEARCH)
     S(nowrite,  NOWRITE)
  #  ifdef IGNORE_INDEX
        S(ignore-palette-index, IGNORE_INDEX)
  #  endif /* IGNORE_INDEX */
  #  ifdef FIX_INDEX
        S(fix-palette-index, FIX_INDEX)
  #  endif /* FIX_INDEX */
  #  undef S
  
     /* OPTION settings, these and LIST settings are read on demand */
  #  define VLNAME(name) vl_ ## name
  #  define VLSIZE(name) voidcast(png_byte,\
                             (sizeof VLNAME(name))/(sizeof VLNAME(name)[0]))
  #  define VL(oname, name, type, search)\
     { oname, type, search, VLSIZE(name), VLNAME(name) },
  #  define VLO(oname, name, search) VL(oname, name, OPTION, search)
  
  #  ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
  #     define VLCIDAT(name) VLO(#name, name, 1/*search*/)
  #     ifdef PNG_SW_COMPRESS_level
  #        define VLCiCCP(name) VLO("ICC-profile-" #name, name, 0/*search*/)
  #     else
  #        define VLCiCCP(name)
  #     endif
  #  else
  #     define VLCIDAT(name)
  #     define VLCiCCP(name)
  #  endif /* WRITE_CUSTOMIZE_COMPRESSION */
  
  #  ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
  #     define VLCzTXt(name) VLO("text-" #name, name, 0/*search*/)
  #  else
  #     define VLCzTXt(name)
  #  endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
  
  #  define VLC(name) VLCIDAT(name) VLCiCCP(name) VLCzTXt(name)
  
  #  ifdef PNG_SW_COMPRESS_png_level
        /* The libpng compression level isn't searched because it justs sets the
         * other things that are searched!
         */
        VLO("compression", compression, 0)
        VLO("text-compression", compression, 0)
        VLO("ICC-profile-compression", compression, 0)
  #  endif /* SW_COMPRESS_png_level */
     VLC(strategy)
     VLO("windowBits", windowBits_IDAT, 1)
  #  ifdef PNG_SW_COMPRESS_windowBits
        VLO("ICC-profile-windowBits", windowBits_text/*sic*/, 0)
  #  endif
     VLO("text-windowBits", windowBits_text, 0)
     VLC(level)
     VLC(memLevel)
     VLO("IDAT-size", IDAT_size, 0)
     VLO("log-depth", log_depth, 0)
  
  #  undef VLO
  
     /* LIST settings */
  #  define VLL(name, search) VL(#name, name, LIST, search)
  #ifdef PNG_WRITE_FILTER_SUPPORTED
     VLL(filter, 0)
  #endif /* WRITE_FILTER */
  #ifdef PNG_PNGCP_TIMING_SUPPORTED
     VLL(time, 0)
  #endif /* PNGCP_TIMING */
  #  undef VLL
  #  undef VL
  };
  
  #ifdef __cplusplus
     static const size_t option_count((sizeof options)/(sizeof options[0]));
  #else /* !__cplusplus */
  #  define option_count ((sizeof options)/(sizeof options[0]))
  #endif /* !__cplusplus */
  
  static const char *
  cts(int ct)
  {
     switch (ct)
     {
        case PNG_COLOR_TYPE_PALETTE:     return "P";
        case PNG_COLOR_TYPE_GRAY:        return "G";
        case PNG_COLOR_TYPE_GRAY_ALPHA:  return "GA";
        case PNG_COLOR_TYPE_RGB:         return "RGB";
        case PNG_COLOR_TYPE_RGB_ALPHA:   return "RGBA";
        default:                         return "INVALID";
     }
  }
  
  struct display
  {
     jmp_buf          error_return;      /* Where to go to on error */
     unsigned int     errset;            /* error_return is set */
  
     const char      *operation;         /* What is happening */
     const char      *filename;          /* The name of the original file */
     const char      *output_file;       /* The name of the output file */
  
     /* Used on both read and write: */
     FILE            *fp;
  
     /* Used on a read, both the original read and when validating a written
      * image.
      */
     png_alloc_size_t read_size;
     png_structp      read_pp;
     png_infop        ip;
  #  if PNG_LIBPNG_VER < 10700 && defined PNG_TEXT_SUPPORTED
        png_textp     text_ptr; /* stash of text chunks */
        int           num_text;
        int           text_stashed;
  #  endif /* pre 1.7 */
  
  #  ifdef PNG_PNGCP_TIMING_SUPPORTED
        struct timespec   read_time;
        struct timespec   read_time_total;
        struct timespec   write_time;
        struct timespec   write_time_total;
  #  endif /* PNGCP_TIMING */
  
     /* Used to write a new image (the original info_ptr is used) */
  #  define MAX_SIZE ((png_alloc_size_t)(-1))
     png_alloc_size_t write_size;
     png_alloc_size_t best_size;
     png_structp      write_pp;
  
     /* Base file information */
     png_alloc_size_t size;
     png_uint_32      w;
     png_uint_32      h;
     int              bpp;
     png_byte         ct;
     int              no_warnings;       /* Do not output libpng warnings */
     int              min_windowBits;    /* The windowBits range is 8..8 */
  
     /* Options handling */
     png_uint_32      results;             /* A mask of errors seen */
     png_uint_32      options;             /* See display_log below */
     png_byte         entry[option_count]; /* The selected entry+1 of an option
                                            * that appears on the command line, or
                                            * 0 if it was not given. */
     int              value[option_count]; /* Corresponding value */
  
     /* Compression exhaustive testing */
     /* Temporary variables used only while testing a single collection of
      * settings:
      */
     unsigned int     csp;               /* next stack entry to use */
     unsigned int     nsp;               /* highest active entry+1 found so far */
  
     /* Values used while iterating through all the combinations of settings for a
      * single file:
      */
     unsigned int     tsp;               /* nsp from the last run; this is the
                                          * index+1 of the highest active entry on
                                          * this run; this entry will be advanced.
                                          */
     int              opt_string_start;  /* Position in buffer for the first
                                          * searched option; non-zero if earlier
                                          * options were set on the command line.
                                          */
     struct stack
     {
        png_alloc_size_t best_size;      /* Best so far for this option */
        png_alloc_size_t lo_size;
        png_alloc_size_t hi_size;
        int              lo, hi;         /* For binary chop of a range */
        int              best_val;       /* Best value found so far */
        int              opt_string_end; /* End of the option string in 'curr' */
        png_byte         opt;            /* The option being tested */
        png_byte         entry;          /* The next value entry to be tested */
        png_byte         end;            /* This is the last entry */
     }                stack[SL];         /* Stack of entries being tested */
     char             curr[32*SL];       /* current options being tested */
     char             best[32*SL];       /* best options */
  
     char             namebuf[FILENAME_MAX]; /* output file name */
  };
  
  static void
  display_init(struct display *dp)
     /* Call this only once right at the start to initialize the control
      * structure, the (struct buffer) lists are maintained across calls - the
      * memory is not freed.
      */
  {
     memset(dp, 0, sizeof *dp);
     dp->operation = "internal error";
     dp->filename = "command line";
     dp->output_file = "no output file";
     dp->options = WARNINGS; /* default to !verbose, !quiet */
     dp->fp = NULL;
     dp->read_pp = NULL;
     dp->ip = NULL;
     dp->write_pp = NULL;
     dp->min_windowBits = -1; /* this is an OPTIND, so -1 won't match anything */
  #  if PNG_LIBPNG_VER < 10700 && defined PNG_TEXT_SUPPORTED
        dp->text_ptr = NULL;
        dp->num_text = 0;
        dp->text_stashed = 0;
  #  endif /* pre 1.7 */
  }
  
  static void
  display_clean_read(struct display *dp)
  {
     if (dp->read_pp != NULL)
        png_destroy_read_struct(&dp->read_pp, NULL, NULL);
  
     if (dp->fp != NULL)
     {
        FILE *fp = dp->fp;
        dp->fp = NULL;
        (void)fclose(fp);
     }
  }
  
  static void
  display_clean_write(struct display *dp)
  {
     if (dp->fp != NULL)
     {
        FILE *fp = dp->fp;
        dp->fp = NULL;
        (void)fclose(fp);
     }
  
     if (dp->write_pp != NULL)
        png_destroy_write_struct(&dp->write_pp, dp->tsp > 0 ? NULL : &dp->ip);
  }
  
  static void
  display_clean(struct display *dp)
  {
     display_clean_read(dp);
     display_clean_write(dp);
     dp->output_file = NULL;
  
  #  if PNG_LIBPNG_VER < 10700 && defined PNG_TEXT_SUPPORTED
        /* This is actually created and used by the write code, but only
         * once; it has to be retained for subsequent writes of the same file.
         */
        if (dp->text_stashed)
        {
           dp->text_stashed = 0;
           dp->num_text = 0;
           free(dp->text_ptr);
           dp->text_ptr = NULL;
        }
  #  endif /* pre 1.7 */
  
     /* leave the filename for error detection */
     dp->results = 0; /* reset for next time */
  }
  
  static void
  display_destroy(struct display *dp)
  {
     /* Release any memory held in the display. */
     display_clean(dp);
  }
  
  static struct display *
  get_dp(png_structp pp)
     /* The display pointer is always stored in the png_struct error pointer */
  {
     struct display *dp = (struct display*)png_get_error_ptr(pp);
  
     if (dp == NULL)
     {
        fprintf(stderr, "pngcp: internal error (no display)\n");
        exit(99); /* prevents a crash */
     }
  
     return dp;
  }
  
  /* error handling */
  #ifdef __GNUC__
  #  define VGATTR __attribute__((__format__ (__printf__,3,4)))
     /* Required to quiet GNUC warnings when the compiler sees a stdarg function
      * that calls one of the stdio v APIs.
      */
  #else
  #  define VGATTR
  #endif
  static void VGATTR
  display_log(struct display *dp, error_level level, const char *fmt, ...)
     /* 'level' is as above, fmt is a stdio style format string.  This routine
      * does not return if level is above LIBPNG_WARNING
      */
  {
     dp->results |= 1U << level;
  
     if (level > (error_level)(dp->options & LEVEL_MASK))
     {
        const char *lp;
        va_list ap;
  
        switch (level)
        {
           case INFORMATION:    lp = "information"; break;
           case LIBPNG_WARNING: lp = "warning(libpng)"; break;
           case APP_WARNING:    lp = "warning(pngcp)"; break;
           case APP_FAIL:       lp = "error(continuable)"; break;
           case LIBPNG_ERROR:   lp = "error(libpng)"; break;
           case LIBPNG_BUG:     lp = "bug(libpng)"; break;
           case APP_ERROR:      lp = "error(pngcp)"; break;
           case USER_ERROR:     lp = "error(user)"; break;
  
           case INTERNAL_ERROR: /* anything unexpected is an internal error: */
           case VERBOSE: case WARNINGS: case ERRORS: case QUIET:
           default:             lp = "bug(pngcp)"; break;
        }
  
        fprintf(stderr, "%s: %s: %s",
           dp->filename != NULL ? dp->filename : "<stdin>", lp, dp->operation);
  
        fprintf(stderr, ": ");
  
        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        va_end(ap);
  
        fputc('\n', stderr);
     }
     /* else do not output any message */
  
     /* Errors cause this routine to exit to the fail code */
     if (level > APP_FAIL || (level > ERRORS && !(dp->options & CONTINUE)))
     {
        if (dp->errset)
           longjmp(dp->error_return, level);
  
        else
           exit(99);
     }
  }
  
  #if PNG_LIBPNG_VER < 10700 && defined PNG_TEXT_SUPPORTED
  static void
  text_stash(struct display *dp)
  {
     /* libpng 1.6 and earlier fixed a bug whereby text chunks were written
      * multiple times by png_write_png; the issue was that png_write_png passed
      * the same png_info to both png_write_info and png_write_end.  Rather than
      * fixing it by recording the information in the png_struct, or by recording
      * where to write the chunks, the fix made was to change the 'compression'
      * field of the chunk to invalid values, rendering the png_info somewhat
      * useless.
      *
      * The only fix for this given that we use the png_info more than once is to
      * make a copy of the text chunks and png_set_text it each time.  This adds a
      * text chunks, so they get replicated, but only the new set gets written
      * each time.  This uses memory like crazy but there is no way to delete the
      * useless chunks from the png_info.
      *
      * To make this slightly more efficient only the top level structure is
      * copied; since the old strings are actually preserved (in 1.6 and earlier)
      * this happens to work.
      */
     png_textp chunks = NULL;
  
     dp->num_text = png_get_text(dp->write_pp, dp->ip, &chunks, NULL);
  
     if (dp->num_text > 0)
     {
        dp->text_ptr = voidcast(png_textp, malloc(dp->num_text * sizeof *chunks));
  
        if (dp->text_ptr == NULL)
           display_log(dp, APP_ERROR, "text chunks: stash malloc failed");
  
        else
           memcpy(dp->text_ptr, chunks, dp->num_text * sizeof *chunks);
     }
  
     dp->text_stashed = 1; /* regardless of whether there are chunks or not */
  }
  
  #define text_stash(dp) if (!dp->text_stashed) text_stash(dp)
  
  static void
  text_restore(struct display *dp)
  {
     /* libpng makes a copy, so this is fine: */
     if (dp->text_ptr != NULL)
        png_set_text(dp->write_pp, dp->ip, dp->text_ptr, dp->num_text);
  }
  
  #define text_restore(dp) if (dp->text_stashed) text_restore(dp)
  
  #else
  #define text_stash(dp) ((void)0)
  #define text_restore(dp) ((void)0)
  #endif /* pre 1.7 */
  
  /* OPTIONS:
   *
   * The command handles options of the forms:
   *
   *    --option
   *       Turn an option on (Option)
   *    --no-option
   *       Turn an option off (Option)
   *    --option=value
   *       Set an option to a value (Value)
   *    --option=val1,val2,val3
   *       Set an option to a bitmask constructed from the values (List)
   */
  static png_byte
  option_index(struct display *dp, const char *opt, size_t len)
     /* Return the index (in options[]) of the given option, outputs an error if
      * it does not exist.  Takes the name of the option and a length (number of
      * characters in the name).
      */
  {
     png_byte j;
  
     for (j=0; j<option_count; ++j)
        if (strncmp(options[j].name, opt, len) == 0 && options[j].name[len] == 0)
           return j;
  
     /* If the setjmp buffer is set the code is asking for an option index; this
      * is bad.  Otherwise this is the command line option parsing.
      */
     display_log(dp, dp->errset ? INTERNAL_ERROR : USER_ERROR,
           "%.*s: unknown option", (int)/*SAFE*/len, opt);
     abort(); /* NOT REACHED */
  }
  
  /* This works for an option name (no quotes): */
  #define OPTIND(dp, name) option_index(dp, #name, (sizeof #name)-1)
  
  static int
  get_option(struct display *dp, const char *opt, int *value)
  {
     png_byte i = option_index(dp, opt, strlen(opt));
  
     if (dp->entry[i]) /* option was set on command line */
     {
        *value = dp->value[i];
        return 1;
     }
  
     else
        return 0;
  }
  
  static int
  set_opt_string_(struct display *dp, unsigned int sp, png_byte opt,
        const char *entry_name)
     /* Add the appropriate option string to dp->curr. */
  {
     int offset, add;
  
     if (sp > 0)
        offset = dp->stack[sp-1].opt_string_end;
  
     else
        offset = dp->opt_string_start;
  
     if (entry_name == range_lo)
        add = sprintf(dp->curr+offset, " --%s=%d", options[opt].name,
              dp->value[opt]);
  
     else
        add = sprintf(dp->curr+offset, " --%s=%s", options[opt].name, entry_name);
  
     if (add < 0)
        display_log(dp, INTERNAL_ERROR, "sprintf failed");
  
     assert(offset+add < (int)/*SAFE*/sizeof dp->curr);
     return offset+add;
  }
  
  static void
  set_opt_string(struct display *dp, unsigned int sp)
     /* Add the appropriate option string to dp->curr. */
  {
     dp->stack[sp].opt_string_end = set_opt_string_(dp, sp, dp->stack[sp].opt, 
        options[dp->stack[sp].opt].values[dp->stack[sp].entry].name);
  }
  
  static void
  record_opt(struct display *dp, png_byte opt, const char *entry_name)
     /* Record this option in dp->curr; called for an option not being searched,
      * the caller passes in the name of the value, or range_lo to use the
      * numerical value.
      */
  {
     unsigned int sp = dp->csp; /* stack entry of next searched option */
  
     if (sp >= dp->tsp)
     {
        /* At top of stack; add the opt string for this entry to the previous
         * searched entry or the start of the dp->curr buffer if there is nothing
         * on the stack yet (sp == 0).
         */
        int offset = set_opt_string_(dp, sp, opt, entry_name);
  
        if (sp > 0)
           dp->stack[sp-1].opt_string_end = offset;
  
        else
           dp->opt_string_start = offset;
     }
  
     /* else do nothing: option already recorded */
  }
  
  static int
  opt_list_end(struct display *dp, png_byte opt, png_byte entry)
  {
     if (options[opt].values[entry].name == range_lo)
        return entry+1U >= options[opt].value_count /* missing range_hi */ ||
           options[opt].values[entry+1U].name != range_hi /* likewise */ ||
           options[opt].values[entry+1U].value <= dp->value[opt] /* range end */;
  
     else
        return entry+1U >= options[opt].value_count /* missing 'all' */ ||
           options[opt].values[entry+1U].name == all /* last entry */;
  }
  
  static void
  push_opt(struct display *dp, unsigned int sp, png_byte opt, int search)
     /* Push a new option onto the stack, initializing the new stack entry
      * appropriately; this does all the work of next_opt (setting end/nsp) for
      * the first entry in the list.
      */
  {
     png_byte entry;
     const char *entry_name;
  
     assert(sp == dp->tsp && sp < SL);
  
     /* The starting entry is entry 0 unless there is a range in which case it is
      * the entry corresponding to range_lo:
      */
     entry = options[opt].value_count;
     assert(entry > 0U);
  
     do
     {
        entry_name = options[opt].values[--entry].name;
        if (entry_name == range_lo)
           break;
     }
     while (entry > 0U);
  
     dp->tsp = sp+1U;
     dp->stack[sp].best_size =
        dp->stack[sp].lo_size =
        dp->stack[sp].hi_size = MAX_SIZE;
  
     if (search && entry_name == range_lo) /* search this range */
     {
        dp->stack[sp].lo = options[opt].values[entry].value;
        /* check for a mal-formed RANGE above: */
        assert(entry+1 < options[opt].value_count &&
               options[opt].values[entry+1].name == range_hi);
        dp->stack[sp].hi = options[opt].values[entry+1].value;
     }
  
     else
     {
        /* next_opt will just iterate over the range. */
        dp->stack[sp].lo = INT_MAX;
        dp->stack[sp].hi = INT_MIN; /* Prevent range chop */
     }
  
     dp->stack[sp].opt = opt;
     dp->stack[sp].entry = entry;
     dp->stack[sp].best_val = dp->value[opt] = options[opt].values[entry].value;
  
     set_opt_string(dp, sp);
  
     /* This works for the search case too; if the range has only one entry 'end'
      * will be marked here.
      */
     if (opt_list_end(dp, opt, entry))
     {
        dp->stack[sp].end = 1;
        /* Skip the warning if pngcp did this itself.  See the code in
         * set_windowBits_hi.
         */
        if (opt != dp->min_windowBits)
           display_log(dp, APP_WARNING, "%s: only testing one value",
                 options[opt].name);
     }
  
     else
     {
        dp->stack[sp].end = 0;
        dp->nsp = dp->tsp;
     }
  
     /* Do a lazy cache of the text chunks for libpng 1.6 and earlier; this is
      * because they can only be written once(!) so if we are going to re-use the
      * png_info we need a copy.
      */
     text_stash(dp);
  }
  
  static void
  next_opt(struct display *dp, unsigned int sp)
     /* Return the next value for this option.  When called 'sp' is expected to be
      * the topmost stack entry - only the topmost entry changes each time round -
      * and there must be a valid entry to return.  next_opt will set dp->nsp to
      * sp+1 if more entries are available, otherwise it will not change it and
      * set dp->stack[s].end to true.
      */
  {
     int search = 0;
     png_byte entry, opt;
     const char *entry_name;
  
     /* dp->stack[sp] must be the top stack entry and it must be active: */
     assert(sp+1U == dp->tsp && !dp->stack[sp].end);
  
     opt = dp->stack[sp].opt;
     entry = dp->stack[sp].entry;
     assert(entry+1U < options[opt].value_count);
     entry_name = options[opt].values[entry].name;
     assert(entry_name != NULL);
  
     /* For ranges increment the value but don't change the entry, for all other
      * cases move to the next entry and load its value:
      */
     if (entry_name == range_lo) /* a range */
     {
        /* A range can be iterated over or searched.  The default iteration option
         * is indicated by hi < lo on the stack, otherwise the range being search
         * is [lo..hi] (inclusive).
         */
        if (dp->stack[sp].lo > dp->stack[sp].hi)
           dp->value[opt]++;
  
        else
        {
           /* This is the best size found for this option value: */
           png_alloc_size_t best_size = dp->stack[sp].best_size;
           int lo = dp->stack[sp].lo;
           int hi = dp->stack[sp].hi;
           int val = dp->value[opt];
  
           search = 1; /* end is determined here */
           assert(best_size < MAX_SIZE);
  
           if (val == lo)
           {
              /* Finding the best for the low end of the range: */
              dp->stack[sp].lo_size = best_size;
              assert(hi > val);
  
              if (hi == val+1) /* only 2 entries */
                 dp->stack[sp].end = 1;
  
              val = hi;
           }
  
           else if (val == hi)
           {
              dp->stack[sp].hi_size = best_size;
              assert(val > lo+1); /* else 'end' set above */
  
              if (val == lo+2) /* only three entries to test */
                 dp->stack[sp].end = 1;
  
              val = (lo + val)/2;
           }
  
           else
           {
              png_alloc_size_t lo_size = dp->stack[sp].lo_size;
              png_alloc_size_t hi_size = dp->stack[sp].hi_size;
  
              /* lo and hi should have been tested. */
              assert(lo_size < MAX_SIZE && hi_size < MAX_SIZE);
  
              /* These cases arise with the 'probe' handling below when there is a
               * dip or peak in the size curve.
               */
              if (val < lo) /* probing a new lo */
              {
                 /* Swap lo and val: */
                 dp->stack[sp].lo = val;
                 dp->stack[sp].lo_size = best_size;
                 val = lo;
                 best_size = lo_size;
                 lo = dp->stack[sp].lo;
                 lo_size = dp->stack[sp].lo_size;
              }
  
              else if (val > hi) /* probing a new hi */
              {
                 /* Swap hi and val: */
                 dp->stack[sp].hi = val;
                 dp->stack[sp].hi_size = best_size;
                 val = hi;
                 best_size = hi_size;
                 hi = dp->stack[sp].hi;
                 hi_size = dp->stack[sp].hi_size;
              }
  
              /* The following should be true or something got messed up above. */
              assert(lo < val && val < hi);
  
              /* If there are only four entries (lo, val, hi plus one more) just
               * test the remaining entry.
               */
              if (hi == lo+3)
              {
                 /* Because of the 'probe' code val can either be lo+1 or hi-1; we
                  * need to test the other.
                  */
                 val = lo + ((val == lo+1) ? 2 : 1);
                 assert(lo < val && val < hi);
                 dp->stack[sp].end = 1;
              }
  
              else
              {
                 /* There are at least 2 entries still untested between lo and hi,
                  * i.e. hi >= lo+4.  'val' is the midpoint +/- 0.5
                  *
                  * Separate out the four easy cases when lo..val..hi are
                  * monotonically decreased or (more weird) increasing:
                  */
                 assert(hi > lo+3);
  
                 if (lo_size <= best_size && best_size <= hi_size)
                 {
                    /* Select the low range; testing this first favours the low
                     * range over the high range when everything comes out equal.
                     * Because of the probing 'val' may be lo+1.  In that case end
                     * the search and set 'val' to lo+2.
                     */
                    if (val == lo+1)
                    {
                       ++val;
                       dp->stack[sp].end = 1;
                    }
  
                    else
                    {
                       dp->stack[sp].hi = hi = val;
                       dp->stack[sp].hi_size = best_size;
                       val = (lo + val) / 2;
                    }
                 }
  
                 else if (lo_size >= best_size && best_size >= hi_size)
                 {
                    /* Monotonically decreasing size; this is the expected case.
                     * Select the high end of the range.  As above, val may be
                     * hi-1.
                     */
                    if (val == hi-1)
                    {
                       --val;
                       dp->stack[sp].end = 1;
                    }
  
                    else
                    {
                       dp->stack[sp].lo = lo = val;
                       dp->stack[sp].lo_size = best_size;
                       val = (val + hi) / 2;
                    }
                 }
  
                 /* If both those tests failed 'best_size' is either greater than
                  * or less than both lo_size and hi_size.  There is a peak or dip
                  * in the curve of sizes from lo to hi and val is on the peak or
                  * dip.
                  *
                  * Because the ranges being searched as so small (level is 1..9,
                  * windowBits 8..15, memLevel 1..9) there will only be at most
                  * three untested values between lo..val and val..hi, so solve
                  * the problem by probing down from hi or up from lo, whichever
                  * is the higher.
                  *
                  * This is the place where 'val' is set to outside the range
                  * lo..hi, described as 'probing', though maybe 'narrowing' would
                  * be more accurate.
                  */
                 else if (lo_size <= hi_size) /* down from hi */
                 {
                    dp->stack[sp].hi = val;
                    dp->stack[sp].hi_size = best_size;
                    val = --hi;
                 }
  
                 else /* up from low */
                 {
                    dp->stack[sp].lo = val;
                    dp->stack[sp].lo_size = best_size;
                    val = ++lo;
                 }
  
                 /* lo and hi are still the true range limits, check for the end
                  * condition.
                  */
                 assert(hi > lo+1);
                 if (hi <= lo+2)
                    dp->stack[sp].end = 1;
              }
           }
  
           assert(val != dp->stack[sp].best_val); /* should be a new value */
           dp->value[opt] = val;
           dp->stack[sp].best_size = MAX_SIZE;
        }
     }
  
     else
     {
        /* Increment 'entry' */
        dp->value[opt] = options[opt].values[++entry].value;
        dp->stack[sp].entry = entry;
     }
  
     set_opt_string(dp, sp);
  
     if (!search && opt_list_end(dp, opt, entry)) /* end of list */
        dp->stack[sp].end = 1;
  
     else if (!dp->stack[sp].end) /* still active after all these tests */
        dp->nsp = dp->tsp;
  }
  
  static int
  compare_option(const struct display *dp, unsigned int sp)
  {
     int opt = dp->stack[sp].opt;
  
     /* If the best so far is numerically less than the current value the
      * current set of options is invariably worse.
      */
     if (dp->stack[sp].best_val < dp->value[opt])
        return -1;
  
     /* Lists of options are searched out of numerical order (currently only
      * strategy), so only return +1 here when a range is being searched.
      */
     else if (dp->stack[sp].best_val > dp->value[opt])
     {
        if (dp->stack[sp].lo <= dp->stack[sp].hi /*searching*/)
           return 1;
  
        else
           return -1;
     }
  
     else
        return 0; /* match; current value is the best one */
  }
  
  static int
  advance_opt(struct display *dp, png_byte opt, int search)
  {
     unsigned int sp = dp->csp++; /* my stack entry */
  
     assert(sp >= dp->nsp); /* nsp starts off zero */
  
     /* If the entry was active in the previous run dp->stack[sp] is already
      * set up and dp->tsp will be greater than sp, otherwise a new entry
      * needs to be created.
      *
      * dp->nsp is handled this way:
      *
      * 1) When an option is pushed onto the stack dp->nsp and dp->tsp are
      *    both set (by push_opt) to the next stack entry *unless* there is
      *    only one entry in the new list, in which case dp->stack[sp].end
      *    is set.
      *
      * 2) For the top stack entry next_opt is called.  The entry must be
      *    active (dp->stack[sp].end is not set) and either 'nsp' or 'end'
      *    will be updated as appropriate.
      *
      * 3) For lower stack entries nsp is set unless the stack entry is
      *    already at the end.  This means that when all the higher entries
      *    are popped this entry will be too.
      */
     if (sp >= dp->tsp)
     {
        push_opt(dp, sp, opt, search); /* This sets tsp to sp+1 */
        return 1; /* initialized */
     }
  
     else
     {
        int ret = 0; /* unchanged */
  
        /* An option that is already on the stack; update best_size and best_val
         * if appropriate.  On the first run there are no previous values and
         * dp->write_size will be MAX_SIZE, however on the first run dp->tsp
         * starts off as 0.
         */
        assert(dp->write_size > 0U && dp->write_size < MAX_SIZE);
  
        if (dp->stack[sp].best_size > dp->write_size ||
            (dp->stack[sp].best_size == dp->write_size &&
             compare_option(dp, sp) > 0))
        {
           dp->stack[sp].best_size = dp->write_size;
           dp->stack[sp].best_val = dp->value[opt];
        }
  
        if (sp+1U >= dp->tsp)
        {
           next_opt(dp, sp);
           ret = 1; /* advanced */
        }
  
        else if (!dp->stack[sp].end) /* Active, not at top of stack */
           dp->nsp = sp+1U;
  
        return ret; /* advanced || unchanged */
     }
  }
  
  static int
  getallopts_(struct display *dp, png_byte opt, int *value, int record)
     /* Like getop but iterate over all the values if the option was set to "all".
      */
  {
     if (dp->entry[opt]) /* option was set on command line */
     {
        /* Simple, single value, entries don't have a stack frame and have a fixed
         * value (it doesn't change once set on the command line).  Otherwise the
         * value (entry) selected from the command line is 'all':
         */
        const char *entry_name = options[opt].values[dp->entry[opt]-1].name;
  
        if (entry_name == all)
           (void)advance_opt(dp, opt, 0/*do not search; iterate*/);
  
        else if (record)
           record_opt(dp, opt, entry_name);
  
        *value = dp->value[opt];
        return 1; /* set */
     }
  
     else
        return 0; /* not set */
  }
  
  static int
  getallopts(struct display *dp, const char *opt_str, int *value)
  {
     return getallopts_(dp, option_index(dp, opt_str, strlen(opt_str)), value, 0);
  }
  
  static int
  getsearchopts(struct display *dp, const char *opt_str, int *value)
     /* As above except that if the option was not set try a search */
  {
     png_byte istrat;
     png_byte opt = option_index(dp, opt_str, strlen(opt_str));
     int record = options[opt].search;
     const char *entry_name;
  
     /* If it was set on the command line honour the setting, including 'all'
      * which will override the built in search:
      */
     if (getallopts_(dp, opt, value, record))
        return 1;
  
     else if (!record) /* not a search option */
        return 0; /* unset and not searched */
  
     /* Otherwise decide what to do here. */
     istrat = OPTIND(dp, strategy);
     entry_name = range_lo; /* record the value, not the name */
  
     if (opt == istrat) /* search all strategies */
        (void)advance_opt(dp, opt, 0/*iterate*/), record=0;
  
     else if (opt == OPTIND(dp, level))
     {
        /* Both RLE and HUFFMAN don't benefit from level increases */
        if (dp->value[istrat] == Z_RLE || dp->value[istrat] == Z_HUFFMAN_ONLY)
           dp->value[opt] = 1;
  
        else /* fixed, filtered or default */
           (void)advance_opt(dp, opt, 1/*search*/), record=0;
     }
  
     else if (opt == OPTIND(dp, windowBits))
     {
        /* Changing windowBits for strategies that do not search the window is
         * pointless.  Huffman-only does not search, RLE only searches backwards
         * one byte, so given that the maximum string length is 258, a windowBits
         * of 9 is always sufficient.
         */
        if (dp->value[istrat] == Z_HUFFMAN_ONLY)
           dp->value[opt] = 8;
  
        else if (dp->value[istrat] == Z_RLE)
           dp->value[opt] = 9;
  
        else /* fixed, filtered or default */
           (void)advance_opt(dp, opt, 1/*search*/), record=0;
     }
  
     else if (opt == OPTIND(dp, memLevel))
     {
  #     if 0
           (void)advance_opt(dp, opt, 0/*all*/), record=0;
  #     else
           dp->value[opt] = MAX_MEM_LEVEL;
  #     endif
     }
  
     else /* something else */
        assert(0=="reached");
  
     if (record)
        record_opt(dp, opt, entry_name);
  
     /* One of the above searched options: */
     *value = dp->value[opt];
     return 1;
  }
  
  static int
  find_val(struct display *dp, png_byte opt, const char *str, size_t len)
     /* Like option_index but sets (index+i) of the entry in options[opt] that
      * matches str[0..len-1] into dp->entry[opt] as well as returning the actual
      * value.
      */
  {
     int rlo = INT_MAX, rhi = INT_MIN;
     png_byte j, irange = 0;
  
     for (j=1U; j<=options[opt].value_count; ++j)
     {
        if (strncmp(options[opt].values[j-1U].name, str, len) == 0 &&
            options[opt].values[j-1U].name[len] == 0)
        {
           dp->entry[opt] = j;
           return options[opt].values[j-1U].value;
        }
        else if (options[opt].values[j-1U].name == range_lo)
           rlo = options[opt].values[j-1U].value, irange = j;
        else if (options[opt].values[j-1U].name == range_hi)
           rhi = options[opt].values[j-1U].value;
     }
  
     /* No match on the name, but there may be a range. */
     if (irange > 0)
     {
        char *ep = NULL;
        long l = strtol(str, &ep, 0);
  
        if (ep == str+len && l >= rlo && l <= rhi)
        {
           dp->entry[opt] = irange; /* range_lo */
           return (int)/*SAFE*/l;
        }
     }
  
     display_log(dp, dp->errset ? INTERNAL_ERROR : USER_ERROR,
           "%s: unknown value setting '%.*s'", options[opt].name,
           (int)/*SAFE*/len, str);
     abort(); /* NOT REACHED */
  }
  
  static int
  opt_check(struct display *dp, const char *arg)
  {
     assert(dp->errset == 0);
  
     if (arg != NULL && arg[0] == '-' && arg[1] == '-')
     {
        int i = 0, negate = (strncmp(arg+2, "no-", 3) == 0), val;
        png_byte j;
  
        if (negate)
           arg += 5; /* --no- */
  
        else
           arg += 2; /* -- */
  
        /* Find the length (expect arg\0 or arg=) */
        while (arg[i] != 0 && arg[i] != '=') ++i;
  
        /* So arg[0..i-1] is the argument name, this does not return if this isn't
         * a valid option name.
         */
        j = option_index(dp, arg, i);
  
        /* It matcheth an option; check the remainder. */
        if (arg[i] == 0) /* no specified value, use the default */
        {
           val = options[j].values[negate].value;
           dp->entry[j] = (png_byte)/*SAFE*/(negate + 1U);
        }
  
        else
        {
           const char *list = arg + (i+1);
  
           /* Expect a single value here unless this is a list, in which case
            * multiple values are combined.
            */
           if (options[j].opt != LIST)
           {
              /* find_val sets 'dp->entry[j]' to a non-zero value: */
              val = find_val(dp, j, list, strlen(list));
  
              if (negate)
              {
                 if (options[j].opt < OPTION)
                    val = !val;
  
                 else
                 {
                    display_log(dp, USER_ERROR,
                          "%.*s: option=arg cannot be negated", i, arg);
                    abort(); /* NOT REACHED */
                 }
              }
           }
  
           else /* multiple options separated by ',' characters */
           {
              /* --no-option negates list values from the default, which should
               * therefore be 'all'.  Notice that if the option list is empty in
               * this case nothing will be removed and therefore --no-option= is
               * the same as --option.
               */
              if (negate)
                 val = options[j].values[0].value;
  
              else
                 val = 0;
  
              while (*list != 0) /* allows option= which sets 0 */
              {
                 /* A value is terminated by the end of the list or a ','
                  * character.
                  */
                 int v, iv;
  
                 iv = 0; /* an index into 'list' */
                 while (list[++iv] != 0 && list[iv] != ',') {}
  
                 v = find_val(dp, j, list, iv);
  
                 if (negate)
                    val &= ~v;
  
                 else
                    val |= v;
  
                 list += iv;
                 if (*list != 0)
                    ++list; /* skip the ',' */
              }
           }
        }
  
        /* 'val' is the new value, store it for use later and debugging: */
        dp->value[j] = val;
  
        if (options[j].opt < LEVEL_MASK)
        {
           /* The handling for error levels is to set the level. */
           if (val) /* Set this level */
              dp->options = (dp->options & ~LEVEL_MASK) | options[j].opt;
  
           else
              display_log(dp, USER_ERROR,
        "%.*s: messages cannot be turned off individually; set a message level",
                    i, arg);
        }
  
        else if (options[j].opt < OPTION)
        {
           if (val)
              dp->options |= options[j].opt;
  
           else
              dp->options &= ~options[j].opt;
        }
  
        return 1; /* this is an option */
     }
  
     else
        return 0; /* not an option */
  }
  
  #ifdef PNG_PNGCP_TIMING_SUPPORTED
  static void
  set_timer(struct display *dp, struct timespec *timer)
  {
     /* Do the timing using clock_gettime and the per-process timer. */
     if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, timer))
     {
        display_log(dp, APP_ERROR,
              "CLOCK_PROCESS_CPUTIME_ID: %s: timing disabled\n", strerror(errno));
        dp->value[OPTIND(dp,time)] = 0; /* i.e. off */
     }
  }
  
  static void
  start_timer(struct display *dp, int what)
  {
     if ((dp->value[OPTIND(dp,time)] & what) != 0)
        set_timer(dp, what == PNGCP_TIME_READ ? &dp->read_time : &dp->write_time);
  }
  
  static void
  end_timer(struct display *dp, int what)
  {
     if ((dp->value[OPTIND(dp,time)] & what) != 0)
     {
        struct timespec t, tmp;
  
        set_timer(dp, &t);
  
        if (what == PNGCP_TIME_READ)
           tmp = dp->read_time;
  
        else
           tmp = dp->write_time;
  
        t.tv_sec -= tmp.tv_sec;
        t.tv_nsec -= tmp.tv_nsec;
  
        if (t.tv_nsec < 0)
        {
           --(t.tv_sec);
           t.tv_nsec += 1000000000L;
        }
  
        if (what == PNGCP_TIME_READ)
           dp->read_time = t, tmp = dp->read_time_total;
  
        else
           dp->write_time = t, tmp = dp->write_time_total;
  
        tmp.tv_sec += t.tv_sec;
        tmp.tv_nsec += t.tv_nsec;
  
        if (tmp.tv_nsec >= 1000000000L)
        {
           ++(tmp.tv_sec);
           tmp.tv_nsec -= 1000000000L;
        }
  
        if (what == PNGCP_TIME_READ)
           dp->read_time_total = tmp;
  
        else
           dp->write_time_total = tmp;
     }
  }
  
  static void
  print_time(const char *what, struct timespec t)
  {
     printf("%s %.2lu.%.9ld", what, (unsigned long)t.tv_sec, t.tv_nsec);
  }
  #else /* !PNGCP_TIMING */
  #define start_timer(dp, what) ((void)0)
  #define end_timer(dp, what) ((void)0)
  #endif /* !PNGCP_TIMING */
  
  /* The following is used in main to verify that the final argument is a
   * directory:
   */
  static int
  checkdir(const char *pathname)
  {
     struct stat buf;
     return stat(pathname, &buf) == 0 && S_ISDIR(buf.st_mode);
  }
  
  /* Work out whether a path is valid (if not a display_log occurs), a directory
   * (1 is returned) or a file *or* non-existent (0 is returned).
   *
   * Used for a write path.
   */
  static int
  isdir(struct display *dp, const char *pathname)
  {
     if (pathname == NULL)
        return 0; /* stdout */
  
     else if (pathname[0] == 0)
        return 1; /* empty string */
  
     else
     {
        struct stat buf;
        int ret = stat(pathname, &buf);
  
        if (ret == 0) /* the entry exists */
        {
           if (S_ISDIR(buf.st_mode))
              return 1;
  
           /* Else expect an object that exists and can be written: */
           if (access(pathname, W_OK) != 0)
              display_log(dp, USER_ERROR, "%s: cannot be written (%s)", pathname,
                    strerror(errno));
  
           return 0; /* file (exists, can be written) */
        }
  
        else /* an error */
        {
           /* Non-existence is fine, other errors are not: */
           if (errno != ENOENT)
              display_log(dp, USER_ERROR, "%s: invalid output name (%s)",
                    pathname, strerror(errno));
  
           return 0; /* file (does not exist) */
        }
     }
  }
  
  static void
  makename(struct display *dp, const char *dir, const char *infile)
  {
     /* Make a name for an output file (and check it). */
     dp->namebuf[0] = 0;
  
     if (dir == NULL || infile == NULL)
        display_log(dp, INTERNAL_ERROR, "NULL name to makename");
  
     else
     {
        size_t dsize = strlen(dir);
  
        if (dsize <= (sizeof dp->namebuf)-2) /* Allow for name + '/' + '\0' */
        {
           size_t isize = strlen(infile);
           size_t istart = isize-1;
  
           /* This should fail before here: */
           if (infile[istart] == '/')
              display_log(dp, INTERNAL_ERROR, "infile with trailing /");
  
           memcpy(dp->namebuf, dir, dsize);
           if (dsize > 0 && dp->namebuf[dsize-1] != '/')
              dp->namebuf[dsize++] = '/';
  
           /* Find the rightmost non-/ character: */
           while (istart > 0 && infile[istart-1] != '/')
              --istart;
  
           isize -= istart;
           infile += istart;
  
           if (dsize+isize < (sizeof dp->namebuf)) /* dsize + infile + '\0' */
           {
              memcpy(dp->namebuf+dsize, infile, isize+1);
  
              if (isdir(dp, dp->namebuf))
                 display_log(dp, USER_ERROR, "%s: output file is a directory",
                       dp->namebuf);
           }
  
           else
           {
              dp->namebuf[dsize] = 0; /* allowed for: -2 at start */
              display_log(dp, USER_ERROR, "%s%s: output file name too long",
                    dp->namebuf, infile);
           }
        }
  
        else
           display_log(dp, USER_ERROR, "%s: output directory name too long", dir);
     }
  }
  
  /* error handler callbacks for libpng */
  static void PNGCBAPI
  display_warning(png_structp pp, png_const_charp warning)
  {
     struct display *dp = get_dp(pp);
  
     /* This is used to prevent repeated warnings while searching */
     if (!dp->no_warnings)
        display_log(get_dp(pp), LIBPNG_WARNING, "%s", warning);
  }
  
  static void PNGCBAPI
  display_error(png_structp pp, png_const_charp error)
  {
     struct display *dp = get_dp(pp);
  
     display_log(dp, LIBPNG_ERROR, "%s", error);
  }
  
  static void
  display_start_read(struct display *dp, const char *filename)
  {
     if (filename != NULL)
     {
        dp->filename = filename;
        dp->fp = fopen(filename, "rb");
     }
  
     else
     {
        dp->filename = "<stdin>";
        dp->fp = stdin;
     }
  
     dp->w = dp->h = 0U;
     dp->bpp = 0U;
     dp->size = 0U;
     dp->read_size = 0U;
  
     if (dp->fp == NULL)
        display_log(dp, USER_ERROR, "file open failed (%s)", strerror(errno));
  }
  
  static void PNGCBAPI
  read_function(png_structp pp, png_bytep data, size_t size)
  {
     struct display *dp = get_dp(pp);
  
     if (size == 0U || fread(data, size, 1U, dp->fp) == 1U)
        dp->read_size += size;
  
     else
     {
        if (feof(dp->fp))
           display_log(dp, LIBPNG_ERROR, "PNG file truncated");
        else
           display_log(dp, LIBPNG_ERROR, "PNG file read failed (%s)",
                 strerror(errno));
     }
  }
  
  static void
  read_png(struct display *dp, const char *filename)
  {
     display_clean_read(dp); /* safety */
     display_start_read(dp, filename);
  
     dp->read_pp = png_create_read_struct(PNG_LIBPNG_VER_STRING, dp,
        display_error, display_warning);
     if (dp->read_pp == NULL)
        display_log(dp, LIBPNG_ERROR, "failed to create read struct");
  
  #  ifdef PNG_BENIGN_ERRORS_SUPPORTED
        png_set_benign_errors(dp->read_pp, 1/*allowed*/);
  #  endif /* BENIGN_ERRORS */
  
  #  ifdef FIX_INDEX
        if ((dp->options & FIX_INDEX) != 0)
           png_set_check_for_invalid_index(dp->read_pp, 1/*on, no warning*/);
  #     ifdef IGNORE_INDEX
           else
  #     endif /* IGNORE_INDEX */
  #  endif /* FIX_INDEX */
  #  ifdef IGNORE_INDEX
        if ((dp->options & IGNORE_INDEX) != 0) /* DANGEROUS */
           png_set_check_for_invalid_index(dp->read_pp, -1/*off completely*/);
  #  endif /* IGNORE_INDEX */
  
     /* The png_read_png API requires us to make the info struct, but it does the
      * call to png_read_info.
      */
     dp->ip = png_create_info_struct(dp->read_pp);
     if (dp->ip == NULL)
        png_error(dp->read_pp, "failed to create info struct");
  
     /* Set the IO handling */
     png_set_read_fn(dp->read_pp, dp, read_function);
  
  #  ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
        png_set_keep_unknown_chunks(dp->read_pp, PNG_HANDLE_CHUNK_ALWAYS, NULL,
              0);
  #  endif /* HANDLE_AS_UNKNOWN */
  
  #  ifdef PNG_SET_USER_LIMITS_SUPPORTED
        /* Remove the user limits, if any */
        png_set_user_limits(dp->read_pp, 0x7fffffff, 0x7fffffff);
  #  endif /* SET_USER_LIMITS */
  
     /* Now read the PNG. */
     start_timer(dp, PNGCP_TIME_READ);
     png_read_png(dp->read_pp, dp->ip, 0U/*transforms*/, NULL/*params*/);
     end_timer(dp, PNGCP_TIME_READ);
     dp->w = png_get_image_width(dp->read_pp, dp->ip);
     dp->h = png_get_image_height(dp->read_pp, dp->ip);
     dp->ct = png_get_color_type(dp->read_pp, dp->ip);
     dp->bpp = png_get_bit_depth(dp->read_pp, dp->ip) *
               png_get_channels(dp->read_pp, dp->ip);
     {
        /* png_get_rowbytes should never return 0 because the value is set by the
         * first call to png_set_IHDR, which should have happened by now, but just
         * in case:
         */
        png_alloc_size_t rb = png_get_rowbytes(dp->read_pp, dp->ip);
  
        if (rb == 0)
           png_error(dp->read_pp, "invalid row byte count from libpng");
  
        /* The size calc can overflow. */
        if ((MAX_SIZE-dp->h)/rb < dp->h)
           png_error(dp->read_pp, "image too large");
  
        dp->size = rb * dp->h + dp->h/*filter byte*/;
     }
  
  #ifdef FIX_INDEX
     if (dp->ct == PNG_COLOR_TYPE_PALETTE && (dp->options & FIX_INDEX) != 0)
     {
        int max = png_get_palette_max(dp->read_pp, dp->ip);
        png_colorp palette = NULL;
        int num = -1;
  
        if (png_get_PLTE(dp->read_pp, dp->ip, &palette, &num) != PNG_INFO_PLTE
            || max < 0 || num <= 0 || palette == NULL)
           display_log(dp, LIBPNG_ERROR, "invalid png_get_PLTE result");
  
        if (max >= num)
        {
           /* 'Fix' the palette. */
           int i;
           png_color newpal[256];
  
           for (i=0; i<num; ++i)
              newpal[i] = palette[i];
  
           /* Fill in any remainder with a warning color: */
           for (; i<=max; ++i)
           {
              newpal[i].red = 0xbe;
              newpal[i].green = 0xad;
              newpal[i].blue = 0xed;
           }
  
           png_set_PLTE(dp->read_pp, dp->ip, newpal, i);
        }
     }
  #endif /* FIX_INDEX */
  
     display_clean_read(dp);
     dp->operation = "none";
  }
  
  static void
  display_start_write(struct display *dp, const char *filename)
  {
     assert(dp->fp == NULL);
  
     if ((dp->options & NOWRITE) != 0)
        dp->output_file = "<no write>";
  
     else
     {
        if (filename != NULL)
        {
           dp->output_file = filename;
           dp->fp = fopen(filename, "wb");
        }
  
        else
        {
           dp->output_file = "<stdout>";
           dp->fp = stdout;
        }
  
        if (dp->fp == NULL)
           display_log(dp, USER_ERROR, "%s: file open failed (%s)",
                 dp->output_file, strerror(errno));
     }
  }
  
  static void PNGCBAPI
  write_function(png_structp pp, png_bytep data, size_t size)
  {
     struct display *dp = get_dp(pp);
  
     /* The write fail is classed as a USER_ERROR, so --quiet does not turn it
      * off, this seems more likely to be correct.
      */
     if (dp->fp == NULL || fwrite(data, size, 1U, dp->fp) == 1U)
     {
        dp->write_size += size;
        if (dp->write_size < size || dp->write_size == MAX_SIZE)
           png_error(pp, "IDAT size overflow");
     }
  
     else
        display_log(dp, USER_ERROR, "%s: PNG file write failed (%s)",
              dp->output_file, strerror(errno));
  }
  
  /* Compression option, 'method' is never set: there is no choice.
   *
   * IMPORTANT: the order of the entries in this macro determines the preference
   * order when two different combos of two of these options produce an IDAT of
   * the same size.  The logic here is to put the things that affect the decoding
   * of the PNG image ahead of those that are relevant only to the encoding.
   */
  #define SET_COMPRESSION\
     SET(strategy, strategy);\
     SET(windowBits, window_bits);\
     SET(level, level);\
     SET(memLevel, mem_level);
  
  #ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
  static void
  search_compression(struct display *dp)
  {
     /* Like set_compression below but use a more restricted search than 'all' */
     int val;
  
  #  define SET(name, func) if (getsearchopts(dp, #name, &val))\
        png_set_compression_ ## func(dp->write_pp, val);
     SET_COMPRESSION
  #  undef SET
  }
  
  static void
  set_compression(struct display *dp)
  {
     int val;
  
  #  define SET(name, func) if (getallopts(dp, #name, &val))\
        png_set_compression_ ## func(dp->write_pp, val);
     SET_COMPRESSION
  #  undef SET
  }
  
  #ifdef PNG_SW_COMPRESS_level /* 1.7.0+ */
  static void
  set_ICC_profile_compression(struct display *dp)
  {
     int val;
  
  #  define SET(name, func) if (getallopts(dp, "ICC-profile-" #name, &val))\
        png_set_ICC_profile_compression_ ## func(dp->write_pp, val);
     SET_COMPRESSION
  #  undef SET
  }
  #else
  #  define set_ICC_profile_compression(dp) ((void)0)
  #endif
  #else
  #  define search_compression(dp) ((void)0)
  #  define set_compression(dp) ((void)0)
  #  define set_ICC_profile_compression(dp) ((void)0)
  #endif /* WRITE_CUSTOMIZE_COMPRESSION */
  
  #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
  static void
  set_text_compression(struct display *dp)
  {
     int val;
  
  #  define SET(name, func) if (getallopts(dp, "text-" #name, &val))\
        png_set_text_compression_ ## func(dp->write_pp, val);
     SET_COMPRESSION
  #  undef SET
  }
  #else
  #  define set_text_compression(dp) ((void)0)
  #endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
  
  static void
  write_png(struct display *dp, const char *destname)
  {
     display_clean_write(dp); /* safety */
     display_start_write(dp, destname);
  
     dp->write_pp = png_create_write_struct(PNG_LIBPNG_VER_STRING, dp,
        display_error, display_warning);
  
     if (dp->write_pp == NULL)
        display_log(dp, LIBPNG_ERROR, "failed to create write png_struct");
  
  #  ifdef PNG_BENIGN_ERRORS_SUPPORTED
        png_set_benign_errors(dp->write_pp, 1/*allowed*/);
  #  endif /* BENIGN_ERRORS */
  
     png_set_write_fn(dp->write_pp, dp, write_function, NULL/*flush*/);
  
  #ifdef IGNORE_INDEX
     if ((dp->options & IGNORE_INDEX) != 0) /* DANGEROUS */
        png_set_check_for_invalid_index(dp->write_pp, -1/*off completely*/);
  #endif /* IGNORE_INDEX */
  
     /* Restore the text chunks when using libpng 1.6 or less; this is a macro
      * which expands to nothing in 1.7+  In earlier versions it tests
      * dp->text_stashed, which is only set (below) *after* the first write.
      */
     text_restore(dp);
  
  #  ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
        png_set_keep_unknown_chunks(dp->write_pp, PNG_HANDLE_CHUNK_ALWAYS, NULL,
              0);
  #  endif /* HANDLE_AS_UNKNOWN */
  
  #  ifdef PNG_SET_USER_LIMITS_SUPPORTED
        /* Remove the user limits, if any */
        png_set_user_limits(dp->write_pp, 0x7fffffff, 0x7fffffff);
  #  endif
  
     /* OPTION HANDLING */
     /* compression outputs, IDAT and zTXt/iTXt: */
     dp->tsp = dp->nsp;
     dp->nsp = dp->csp = 0;
  #  ifdef PNG_SW_COMPRESS_png_level
        {
           int val;
  
           /* This sets everything, but then the following options just override
            * the specific settings for ICC profiles and text.
            */
           if (getallopts(dp, "compression", &val))
              png_set_compression(dp->write_pp, val);
  
           if (getallopts(dp, "ICC-profile-compression", &val))
              png_set_ICC_profile_compression(dp->write_pp, val);
  
           if (getallopts(dp, "text-compression", &val))
              png_set_text_compression(dp->write_pp, val);
        }
  #  endif /* png_level support */
     if (dp->options & SEARCH)
        search_compression(dp);
     else
        set_compression(dp);
     set_ICC_profile_compression(dp);
     set_text_compression(dp);
  
     {
        int val;
  
        /* The permitted range is 1..0x7FFFFFFF, so the cast is safe */
        if (get_option(dp, "IDAT-size", &val))
           png_set_IDAT_size(dp->write_pp, val);
     }
  
     /* filter handling */
  #  ifdef PNG_WRITE_FILTER_SUPPORTED
        {
           int val;
  
           if (get_option(dp, "filter", &val))
              png_set_filter(dp->write_pp, PNG_FILTER_TYPE_BASE, val);
        }
  #  endif /* WRITE_FILTER */
  
     /* This just uses the 'read' info_struct directly, it contains the image. */
     dp->write_size = 0U;
     start_timer(dp, PNGCP_TIME_WRITE);
     png_write_png(dp->write_pp, dp->ip, 0U/*transforms*/, NULL/*params*/);
     end_timer(dp, PNGCP_TIME_WRITE);
  
     /* Make sure the file was written ok: */
     if (dp->fp != NULL)
     {
        FILE *fp = dp->fp;
        dp->fp = NULL;
        if (fclose(fp))
           display_log(dp, APP_ERROR, "%s: write failed (%s)",
                 destname == NULL ? "stdout" : destname, strerror(errno));
     }
  
     /* Clean it on the way out - if control returns to the caller then the
      * written_file contains the required data.
      */
     display_clean_write(dp);
     dp->operation = "none";
  }
  
  static void
  set_windowBits_hi(struct display *dp)
  {
     /* windowBits is in the range 8..15 but zlib maps '8' to '9' so it is only
      * worth using if the data size is 256 byte or less.
      */
     int wb = MAX_WBITS; /* for large images */
     int i = VLSIZE(windowBits_IDAT);
  
     while (wb > 8 && dp->size <= 1U<<(wb-1)) --wb;
  
     while (--i >= 0) if (VLNAME(windowBits_IDAT)[i].name == range_hi) break;
  
     assert(i > 1); /* vl_windowBits_IDAT always has a RANGE() */
     VLNAME(windowBits_IDAT)[i].value = wb;
  
     assert(VLNAME(windowBits_IDAT)[--i].name == range_lo);
     VLNAME(windowBits_IDAT)[i].value = wb > 8 ? 9 : 8;
  
     /* If wb == 8 then any search has been restricted to just one windowBits
      * entry.  Record that here to avoid producing a spurious app-level warning
      * above.
      */
     if (wb == 8)
        dp->min_windowBits = OPTIND(dp, windowBits);
  }
  
  static int
  better_options(const struct display *dp)
  {
     /* Are these options better than the best found so far?  Normally the
      * options are tested in preference order, best first, however when doing a
      * search operation on a range the range values are tested out of order.  In
      * that case preferable options will get tested later.
      *
      * This function looks through the stack from the bottom up looking for an
      * option that does not match the current best value.  When it finds one it
      * checks to see if it is more or less desirable and returns true or false
      * as appropriate.
      *
      * Notice that this means that the order options are pushed onto the stack
      * conveys a priority; lower/earlier options are more important than later
      * ones.
      */
     unsigned int sp;
  
     for (sp=0; sp<dp->csp; ++sp)
     {
        int c = compare_option(dp, sp);
  
        if (c < 0)
           return 0; /* worse */
  
        else if (c > 0)
           return 1; /* better */
     }
  
     assert(0 && "unreached");
  }
  
  static void
  print_search_results(struct display *dp)
  {
     assert(dp->filename != NULL);
     printf("%s [%ld x %ld %d bpp %s, %lu bytes] %lu -> %lu with '%s'\n",
        dp->filename, (unsigned long)dp->w, (unsigned long)dp->h, dp->bpp,
        cts(dp->ct), (unsigned long)dp->size, (unsigned long)dp->read_size,
        (unsigned long)dp->best_size, dp->best);
     fflush(stdout);
  }
  
  static void
  log_search(struct display *dp, unsigned int log_depth)
  {
     /* Log, and reset, the search so far: */
     if (dp->nsp/*next entry to change*/ <= log_depth)
     {
        print_search_results(dp);
        /* Start again with this entry: */
        dp->best_size = MAX_SIZE;
     }
  }
  
  static void
  cp_one_file(struct display *dp, const char *filename, const char *destname)
  {
     unsigned int log_depth;
  
     dp->filename = filename;
     dp->operation = "read";
     dp->no_warnings = 0;
  
     /* Read it then write it: */
     if (filename != NULL && access(filename, R_OK) != 0)
        display_log(dp, USER_ERROR, "%s: invalid file name (%s)",
              filename, strerror(errno));
  
     read_png(dp, filename);
  
     /* But 'destname' may be a directory. */
     dp->operation = "write";
  
     /* Limit the upper end of the windowBits range for this file */
     set_windowBits_hi(dp);
  
     /* For logging, depth to log: */
     {
        int val;
  
        if (get_option(dp, "log-depth", &val) && val >= 0)
           log_depth = (unsigned int)/*SAFE*/val;
  
        else
           log_depth = 0U;
     }
  
     if (destname != NULL) /* else stdout */
     {
        if (isdir(dp, destname))
        {
           makename(dp, destname, filename);
           destname = dp->namebuf;
        }
  
        else if (access(destname, W_OK) != 0 && errno != ENOENT)
           display_log(dp, USER_ERROR, "%s: invalid output name (%s)", destname,
                 strerror(errno));
     }
  
     dp->nsp = 0;
     dp->curr[0] = 0; /* acts as a flag for the caller */
     dp->opt_string_start = 0;
     dp->best[0] = 0; /* safety */
     dp->best_size = MAX_SIZE;
     write_png(dp, destname);
  
     /* Initialize the 'best' fields: */
     strcpy(dp->best, dp->curr);
     dp->best_size = dp->write_size;
  
     if (dp->nsp > 0) /* iterating over lists */
     {
        char *tmpname, tmpbuf[(sizeof dp->namebuf) + 4];
        assert(dp->curr[0] == ' ' && dp->tsp > 0);
  
        /* Cancel warnings on subsequent writes */
        log_search(dp, log_depth);
        dp->no_warnings = 1;
  
        /* Make a temporary name for the subsequent tests: */
        if (destname != NULL)
        {
           strcpy(tmpbuf, destname);
           strcat(tmpbuf, ".tmp"); /* space for .tmp allocated above */
           tmpname = tmpbuf;
        }
  
        else
           tmpname = NULL; /* stdout */
  
        /* Loop to find the best option. */
        do
        {
           write_png(dp, tmpname);
  
           /* And compare the sizes (the write function makes sure write_size
            * doesn't overflow.)
            */
           assert(dp->csp > 0);
  
           if (dp->write_size < dp->best_size ||
               (dp->write_size == dp->best_size && better_options(dp)))
           {
              if (destname != NULL && rename(tmpname, destname) != 0)
                 display_log(dp, APP_ERROR, "rename %s %s failed (%s)", tmpname,
                       destname, strerror(errno));
  
              strcpy(dp->best, dp->curr);
              dp->best_size = dp->write_size;
           }
  
           else if (tmpname != NULL && unlink(tmpname) != 0)
              display_log(dp, APP_WARNING, "unlink %s failed (%s)", tmpname,
                    strerror(errno));
  
           log_search(dp, log_depth);
        }
        while (dp->nsp > 0);
  
        /* Do this for the 'sizes' option so that it reports the correct size. */
        dp->write_size = dp->best_size;
     }
  }
  
  static int
  cppng(struct display *dp, const char *file, const char *gv dest)
     /* Exists solely to isolate the setjmp clobbers which some versions of GCC
      * erroneously generate.
      */
  {
     int ret = setjmp(dp->error_return);
  
     if (ret == 0)
     {
        dp->errset = 1;
        cp_one_file(dp, file, dest);
        dp->errset = 0;
        return 0;
     }
  
     else
     {
        dp->errset = 0;
  
        if (ret < ERRORS) /* shouldn't longjmp on warnings */
           display_log(dp, INTERNAL_ERROR, "unexpected return code %d", ret);
  
        return ret;
     }
  }
  
  int
  main(int argc, char **argv)
  {
     /* For each file on the command line test it with a range of transforms */
     int option_end;
     struct display d;
  
     display_init(&d);
  
     d.operation = "options";
     for (option_end = 1;
          option_end < argc && opt_check(&d, argv[option_end]);
          ++option_end)
     {
     }
  
     /* Do a quick check on the directory target case; when there are more than
      * two arguments the last one must be a directory.
      */
     if (!(d.options & NOWRITE) && option_end+2 < argc && !checkdir(argv[argc-1]))
     {
        fprintf(stderr,
              "pngcp: %s: directory required with more than two arguments\n",
              argv[argc-1]);
        return 99;
     }
  
     {
        int errors = 0;
        int i = option_end;
  
        /* Do this at least once; if there are no arguments stdin/stdout are used.
         */
        d.operation = "files";
        do
        {
           const char *infile = NULL;
           const char *outfile = NULL;
           int ret;
  
           if (i < argc)
           {
              infile = argv[i++];
              if (!(d.options & NOWRITE) && i < argc)
                 outfile = argv[argc-1];
           }
  
           ret = cppng(&d, infile, outfile);
  
           if (ret)
           {
              if (ret > QUIET) /* abort on user or internal error */
                 return 99;
  
              /* An error: the output is meaningless */
           }
  
           else if (d.best[0] != 0)
           {
              /* This result may already have been output, in which case best_size
               * has been reset.
               */
              if (d.best_size < MAX_SIZE)
                 print_search_results(&d);
           }
  
           else if (d.options & SIZES)
           {
              printf("%s [%ld x %ld %d bpp %s, %lu bytes] %lu -> %lu [0x%lx]\n",
                    infile, (unsigned long)d.w, (unsigned long)d.h, d.bpp,
                    cts(d.ct), (unsigned long)d.size, (unsigned long)d.read_size,
                    (unsigned long)d.write_size, (unsigned long)d.results);
              fflush(stdout);
           }
  
           /* Here on any return, including failures, except user/internal issues
            */
           {
              int pass = (d.options & STRICT) ?
                 RESULT_STRICT(d.results) : RESULT_RELAXED(d.results);
  
              if (!pass)
                 ++errors;
  
              if (d.options & LOG)
              {
                 int j;
  
                 printf("%s: pngcp", pass ? "PASS" : "FAIL");
  
                 for (j=1; j<option_end; ++j)
                    printf(" %s", argv[j]);
  
                 if (infile != NULL)
                    printf(" %s", infile);
  
  #              ifdef PNG_PNGCP_TIMING_SUPPORTED
                    /* When logging output the files for each file, if enabled. */
                    if ((d.value[OPTIND(&d,time)] & PNGCP_TIME_READ) != 0)
                       print_time(" read", d.read_time);
  
                    if ((d.value[OPTIND(&d,time)] & PNGCP_TIME_WRITE) != 0)
                       print_time(" write", d.write_time);
  #              endif /* PNGCP_TIMING */
  
                 printf("\n");
                 fflush(stdout);
              }
           }
  
           display_clean(&d);
        }
        while (i+!(d.options & NOWRITE) < argc);
           /* I.e. for write cases after the first time through the loop require
            * there to be at least two arguments left and for the last one to be a
            * directory (this was checked above).
            */
  
        /* Release allocated memory */
        display_destroy(&d);
  
  #     ifdef PNG_PNGCP_TIMING_SUPPORTED
           {
              int output = 0;
  
              if ((d.value[OPTIND(&d,time)] & PNGCP_TIME_READ) != 0)
                 print_time("read", d.read_time_total), output = 1;
  
              if ((d.value[OPTIND(&d,time)] & PNGCP_TIME_WRITE) != 0)
              {
                 if (output) putchar(' ');
                 print_time("write", d.write_time_total);
                 output = 1;
              }
  
              if (output) putchar('\n');
           }
  #     endif /* PNGCP_TIMING */
  
        return errors != 0;
     }
  }
  #else /* !READ_PNG || !WRITE_PNG */
  int
  main(void)
  {
     fprintf(stderr, "pngcp: no support for png_read/write_image\n");
     return 77;
  }
  #endif /* !READ_PNG || !WRITE_PNG */
  