text: /*
   * wrjpgcom.c
   *
   * Copyright (C) 1994-1997, Thomas G. Lane.
   * This file is part of the Independent JPEG Group's software.
   * For conditions of distribution and use, see the accompanying README file.
   *
   * This file contains a very simple stand-alone application that inserts
   * user-supplied text as a COM (comment) marker in a JFIF file.
   * This may be useful as an example of the minimum logic needed to parse
   * JPEG markers.
   */
  
  #define JPEG_CJPEG_DJPEG	/* to get the command-line config symbols */
  #include "jinclude.h"		/* get auto-config symbols, <stdio.h> */
  
  #ifndef HAVE_STDLIB_H		/* <stdlib.h> should declare malloc() */
  extern void * malloc ();
  #endif
  #include <ctype.h>		/* to declare isupper(), tolower() */
  #ifdef USE_SETMODE
  #include <fcntl.h>		/* to declare setmode()'s parameter macros */
  /* If you have setmode() but not <io.h>, just delete this line: */
  #include <io.h>			/* to declare setmode() */
  #endif
  
  #ifdef USE_CCOMMAND		/* command-line reader for Macintosh */
  #ifdef __MWERKS__
  #include <SIOUX.h>              /* Metrowerks needs this */
  #include <console.h>		/* ... and this */
  #endif
  #ifdef THINK_C
  #include <console.h>		/* Think declares it here */
  #endif
  #endif
  
  #ifdef DONT_USE_B_MODE		/* define mode parameters for fopen() */
  #define READ_BINARY	"r"
  #define WRITE_BINARY	"w"
  #else
  #ifdef VMS			/* VMS is very nonstandard */
  #define READ_BINARY	"rb", "ctx=stm"
  #define WRITE_BINARY	"wb", "ctx=stm"
  #else				/* standard ANSI-compliant case */
  #define READ_BINARY	"rb"
  #define WRITE_BINARY	"wb"
  #endif
  #endif
  
  #ifndef EXIT_FAILURE		/* define exit() codes if not provided */
  #define EXIT_FAILURE  1
  #endif
  #ifndef EXIT_SUCCESS
  #ifdef VMS
  #define EXIT_SUCCESS  1		/* VMS is very nonstandard */
  #else
  #define EXIT_SUCCESS  0
  #endif
  #endif
  
  /* Reduce this value if your malloc() can't allocate blocks up to 64K.
   * On DOS, compiling in large model is usually a better solution.
   */
  
  #ifndef MAX_COM_LENGTH
  #define MAX_COM_LENGTH 65000L	/* must be <= 65533 in any case */
  #endif
  
  
  /*
   * These macros are used to read the input file and write the output file.
   * To reuse this code in another application, you might need to change these.
   */
  
  static FILE * infile;		/* input JPEG file */
  
  /* Return next input byte, or EOF if no more */
  #define NEXTBYTE()  getc(infile)
  
  static FILE * outfile;		/* output JPEG file */
  
  /* Emit an output byte */
  #define PUTBYTE(x)  putc((x), outfile)
  
  
  /* Error exit handler */
  #define ERREXIT(msg)  (fprintf(stderr, "%s\n", msg), exit(EXIT_FAILURE))
  
  
  /* Read one byte, testing for EOF */
  static int
  read_1_byte (void)
  {
    int c;
  
    c = NEXTBYTE();
    if (c == EOF)
      ERREXIT("Premature EOF in JPEG file");
    return c;
  }
  
  /* Read 2 bytes, convert to unsigned int */
  /* All 2-byte quantities in JPEG markers are MSB first */
  static unsigned int
  read_2_bytes (void)
  {
    int c1, c2;
  
    c1 = NEXTBYTE();
    if (c1 == EOF)
      ERREXIT("Premature EOF in JPEG file");
    c2 = NEXTBYTE();
    if (c2 == EOF)
      ERREXIT("Premature EOF in JPEG file");
    return (((unsigned int) c1) << 8) + ((unsigned int) c2);
  }
  
  
  /* Routines to write data to output file */
  
  static void
  write_1_byte (int c)
  {
    PUTBYTE(c);
  }
  
  static void
  write_2_bytes (unsigned int val)
  {
    PUTBYTE((val >> 8) & 0xFF);
    PUTBYTE(val & 0xFF);
  }
  
  static void
  write_marker (int marker)
  {
    PUTBYTE(0xFF);
    PUTBYTE(marker);
  }
  
  static void
  copy_rest_of_file (void)
  {
    int c;
  
    while ((c = NEXTBYTE()) != EOF)
      PUTBYTE(c);
  }
  
  
  /*
   * JPEG markers consist of one or more 0xFF bytes, followed by a marker
   * code byte (which is not an FF).  Here are the marker codes of interest
   * in this program.  (See jdmarker.c for a more complete list.)
   */
  
  #define M_SOF0  0xC0		/* Start Of Frame N */
  #define M_SOF1  0xC1		/* N indicates which compression process */
  #define M_SOF2  0xC2		/* Only SOF0-SOF2 are now in common use */
  #define M_SOF3  0xC3
  #define M_SOF5  0xC5		/* NB: codes C4 and CC are NOT SOF markers */
  #define M_SOF6  0xC6
  #define M_SOF7  0xC7
  #define M_SOF9  0xC9
  #define M_SOF10 0xCA
  #define M_SOF11 0xCB
  #define M_SOF13 0xCD
  #define M_SOF14 0xCE
  #define M_SOF15 0xCF
  #define M_SOI   0xD8		/* Start Of Image (beginning of datastream) */
  #define M_EOI   0xD9		/* End Of Image (end of datastream) */
  #define M_SOS   0xDA		/* Start Of Scan (begins compressed data) */
  #define M_COM   0xFE		/* COMment */
  
  
  /*
   * Find the next JPEG marker and return its marker code.
   * We expect at least one FF byte, possibly more if the compressor used FFs
   * to pad the file.  (Padding FFs will NOT be replicated in the output file.)
   * There could also be non-FF garbage between markers.  The treatment of such
   * garbage is unspecified; we choose to skip over it but emit a warning msg.
   * NB: this routine must not be used after seeing SOS marker, since it will
   * not deal correctly with FF/00 sequences in the compressed image data...
   */
  
  static int
  next_marker (void)
  {
    int c;
    int discarded_bytes = 0;
  
    /* Find 0xFF byte; count and skip any non-FFs. */
    c = read_1_byte();
    while (c != 0xFF) {
      discarded_bytes++;
      c = read_1_byte();
    }
    /* Get marker code byte, swallowing any duplicate FF bytes.  Extra FFs
     * are legal as pad bytes, so don't count them in discarded_bytes.
     */
    do {
      c = read_1_byte();
    } while (c == 0xFF);
  
    if (discarded_bytes != 0) {
      fprintf(stderr, "Warning: garbage data found in JPEG file\n");
    }
  
    return c;
  }
  
  
  /*
   * Read the initial marker, which should be SOI.
   * For a JFIF file, the first two bytes of the file should be literally
   * 0xFF M_SOI.  To be more general, we could use next_marker, but if the
   * input file weren't actually JPEG at all, next_marker might read the whole
   * file and then return a misleading error message...
   */
  
  static int
  first_marker (void)
  {
    int c1, c2;
  
    c1 = NEXTBYTE();
    c2 = NEXTBYTE();
    if (c1 != 0xFF || c2 != M_SOI)
      ERREXIT("Not a JPEG file");
    return c2;
  }
  
  
  /*
   * Most types of marker are followed by a variable-length parameter segment.
   * This routine skips over the parameters for any marker we don't otherwise
   * want to process.
   * Note that we MUST skip the parameter segment explicitly in order not to
   * be fooled by 0xFF bytes that might appear within the parameter segment;
   * such bytes do NOT introduce new markers.
   */
  
  static void
  copy_variable (void)
  /* Copy an unknown or uninteresting variable-length marker */
  {
    unsigned int length;
  
    /* Get the marker parameter length count */
    length = read_2_bytes();
    write_2_bytes(length);
    /* Length includes itself, so must be at least 2 */
    if (length < 2)
      ERREXIT("Erroneous JPEG marker length");
    length -= 2;
    /* Skip over the remaining bytes */
    while (length > 0) {
      write_1_byte(read_1_byte());
      length--;
    }
  }
  
  static void
  skip_variable (void)
  /* Skip over an unknown or uninteresting variable-length marker */
  {
    unsigned int length;
  
    /* Get the marker parameter length count */
    length = read_2_bytes();
    /* Length includes itself, so must be at least 2 */
    if (length < 2)
      ERREXIT("Erroneous JPEG marker length");
    length -= 2;
    /* Skip over the remaining bytes */
    while (length > 0) {
      (void) read_1_byte();
      length--;
    }
  }
  
  
  /*
   * Parse the marker stream until SOFn or EOI is seen;
   * copy data to output, but discard COM markers unless keep_COM is true.
   */
  
  static int
  scan_JPEG_header (int keep_COM)
  {
    int marker;
  
    /* Expect SOI at start of file */
    if (first_marker() != M_SOI)
      ERREXIT("Expected SOI marker first");
    write_marker(M_SOI);
  
    /* Scan miscellaneous markers until we reach SOFn. */
    for (;;) {
      marker = next_marker();
      switch (marker) {
        /* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,
         * treated as SOFn.  C4 in particular is actually DHT.
         */
      case M_SOF0:		/* Baseline */
      case M_SOF1:		/* Extended sequential, Huffman */
      case M_SOF2:		/* Progressive, Huffman */
      case M_SOF3:		/* Lossless, Huffman */
      case M_SOF5:		/* Differential sequential, Huffman */
      case M_SOF6:		/* Differential progressive, Huffman */
      case M_SOF7:		/* Differential lossless, Huffman */
      case M_SOF9:		/* Extended sequential, arithmetic */
      case M_SOF10:		/* Progressive, arithmetic */
      case M_SOF11:		/* Lossless, arithmetic */
      case M_SOF13:		/* Differential sequential, arithmetic */
      case M_SOF14:		/* Differential progressive, arithmetic */
      case M_SOF15:		/* Differential lossless, arithmetic */
        return marker;
  
      case M_SOS:			/* should not see compressed data before SOF */
        ERREXIT("SOS without prior SOFn");
        break;
  
      case M_EOI:			/* in case it's a tables-only JPEG stream */
        return marker;
  
      case M_COM:			/* Existing COM: conditionally discard */
        if (keep_COM) {
  	write_marker(marker);
  	copy_variable();
        } else {
  	skip_variable();
        }
        break;
  
      default:			/* Anything else just gets copied */
        write_marker(marker);
        copy_variable();		/* we assume it has a parameter count... */
        break;
      }
    } /* end loop */
  }
  
  
  /* Command line parsing code */
  
  static const char * progname;	/* program name for error messages */
  
  
  static void
  usage (void)
  /* complain about bad command line */
  {
    fprintf(stderr, "wrjpgcom inserts a textual comment in a JPEG file.\n");
    fprintf(stderr, "You can add to or replace any existing comment(s).\n");
  
    fprintf(stderr, "Usage: %s [switches] ", progname);
  #ifdef TWO_FILE_COMMANDLINE
    fprintf(stderr, "inputfile outputfile\n");
  #else
    fprintf(stderr, "[inputfile]\n");
  #endif
  
    fprintf(stderr, "Switches (names may be abbreviated):\n");
    fprintf(stderr, "  -replace         Delete any existing comments\n");
    fprintf(stderr, "  -comment \"text\"  Insert comment with given text\n");
    fprintf(stderr, "  -cfile name      Read comment from named file\n");
    fprintf(stderr, "Notice that you must put quotes around the comment text\n");
    fprintf(stderr, "when you use -comment.\n");
    fprintf(stderr, "If you do not give either -comment or -cfile on the command line,\n");
    fprintf(stderr, "then the comment text is read from standard input.\n");
    fprintf(stderr, "It can be multiple lines, up to %u characters total.\n",
  	  (unsigned int) MAX_COM_LENGTH);
  #ifndef TWO_FILE_COMMANDLINE
    fprintf(stderr, "You must specify an input JPEG file name when supplying\n");
    fprintf(stderr, "comment text from standard input.\n");
  #endif
  
    exit(EXIT_FAILURE);
  }
  
  
  static int
  keymatch (char * arg, const char * keyword, int minchars)
  /* Case-insensitive matching of (possibly abbreviated) keyword switches. */
  /* keyword is the constant keyword (must be lower case already), */
  /* minchars is length of minimum legal abbreviation. */
  {
    register int ca, ck;
    register int nmatched = 0;
  
    while ((ca = *arg++) != '\0') {
      if ((ck = *keyword++) == '\0')
        return 0;			/* arg longer than keyword, no good */
      if (isupper(ca))		/* force arg to lcase (assume ck is already) */
        ca = tolower(ca);
      if (ca != ck)
        return 0;			/* no good */
      nmatched++;			/* count matched characters */
    }
    /* reached end of argument; fail if it's too short for unique abbrev */
    if (nmatched < minchars)
      return 0;
    return 1;			/* A-OK */
  }
  
  
  /*
   * The main program.
   */
  
  int
  main (int argc, char **argv)
  {
    int argn;
    char * arg;
    int keep_COM = 1;
    char * comment_arg = NULL;
    FILE * comment_file = NULL;
    unsigned int comment_length = 0;
    int marker;
  
    /* On Mac, fetch a command line. */
  #ifdef USE_CCOMMAND
    argc = ccommand(&argv);
  #endif
  
    progname = argv[0];
    if (progname == NULL || progname[0] == 0)
      progname = "wrjpgcom";	/* in case C library doesn't provide it */
  
    /* Parse switches, if any */
    for (argn = 1; argn < argc; argn++) {
      arg = argv[argn];
      if (arg[0] != '-')
        break;			/* not switch, must be file name */
      arg++;			/* advance over '-' */
      if (keymatch(arg, "replace", 1)) {
        keep_COM = 0;
      } else if (keymatch(arg, "cfile", 2)) {
        if (++argn >= argc) usage();
        if ((comment_file = fopen(argv[argn], "r")) == NULL) {
  	fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);
  	exit(EXIT_FAILURE);
        }
      } else if (keymatch(arg, "comment", 1)) {
        if (++argn >= argc) usage();
        comment_arg = argv[argn];
        /* If the comment text starts with '"', then we are probably running
         * under MS-DOG and must parse out the quoted string ourselves.  Sigh.
         */
        if (comment_arg[0] == '"') {
  	comment_arg = (char *) malloc((size_t) MAX_COM_LENGTH);
  	if (comment_arg == NULL)
  	  ERREXIT("Insufficient memory");
  	strcpy(comment_arg, argv[argn]+1);
  	for (;;) {
  	  comment_length = (unsigned int) strlen(comment_arg);
  	  if (comment_length > 0 && comment_arg[comment_length-1] == '"') {
  	    comment_arg[comment_length-1] = '\0'; /* zap terminating quote */
  	    break;
  	  }
  	  if (++argn >= argc)
  	    ERREXIT("Missing ending quote mark");
  	  strcat(comment_arg, " ");
  	  strcat(comment_arg, argv[argn]);
  	}
        }
        comment_length = (unsigned int) strlen(comment_arg);
      } else
        usage();
    }
  
    /* Cannot use both -comment and -cfile. */
    if (comment_arg != NULL && comment_file != NULL)
      usage();
    /* If there is neither -comment nor -cfile, we will read the comment text
     * from stdin; in this case there MUST be an input JPEG file name.
     */
    if (comment_arg == NULL && comment_file == NULL && argn >= argc)
      usage();
  
    /* Open the input file. */
    if (argn < argc) {
      if ((infile = fopen(argv[argn], READ_BINARY)) == NULL) {
        fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);
        exit(EXIT_FAILURE);
      }
    } else {
      /* default input file is stdin */
  #ifdef USE_SETMODE		/* need to hack file mode? */
      setmode(fileno(stdin), O_BINARY);
  #endif
  #ifdef USE_FDOPEN		/* need to re-open in binary mode? */
      if ((infile = fdopen(fileno(stdin), READ_BINARY)) == NULL) {
        fprintf(stderr, "%s: can't open stdin\n", progname);
        exit(EXIT_FAILURE);
      }
  #else
      infile = stdin;
  #endif
    }
  
    /* Open the output file. */
  #ifdef TWO_FILE_COMMANDLINE
    /* Must have explicit output file name */
    if (argn != argc-2) {
      fprintf(stderr, "%s: must name one input and one output file\n",
  	    progname);
      usage();
    }
    if ((outfile = fopen(argv[argn+1], WRITE_BINARY)) == NULL) {
      fprintf(stderr, "%s: can't open %s\n", progname, argv[argn+1]);
      exit(EXIT_FAILURE);
    }
  #else
    /* Unix style: expect zero or one file name */
    if (argn < argc-1) {
      fprintf(stderr, "%s: only one input file\n", progname);
      usage();
    }
    /* default output file is stdout */
  #ifdef USE_SETMODE		/* need to hack file mode? */
    setmode(fileno(stdout), O_BINARY);
  #endif
  #ifdef USE_FDOPEN		/* need to re-open in binary mode? */
    if ((outfile = fdopen(fileno(stdout), WRITE_BINARY)) == NULL) {
      fprintf(stderr, "%s: can't open stdout\n", progname);
      exit(EXIT_FAILURE);
    }
  #else
    outfile = stdout;
  #endif
  #endif /* TWO_FILE_COMMANDLINE */
  
    /* Collect comment text from comment_file or stdin, if necessary */
    if (comment_arg == NULL) {
      FILE * src_file;
      int c;
  
      comment_arg = (char *) malloc((size_t) MAX_COM_LENGTH);
      if (comment_arg == NULL)
        ERREXIT("Insufficient memory");
      comment_length = 0;
      src_file = (comment_file != NULL ? comment_file : stdin);
      while ((c = getc(src_file)) != EOF) {
        if (comment_length >= (unsigned int) MAX_COM_LENGTH) {
  	fprintf(stderr, "Comment text may not exceed %u bytes\n",
  		(unsigned int) MAX_COM_LENGTH);
  	exit(EXIT_FAILURE);
        }
        comment_arg[comment_length++] = (char) c;
      }
      if (comment_file != NULL)
        fclose(comment_file);
    }
  
    /* Copy JPEG headers until SOFn marker;
     * we will insert the new comment marker just before SOFn.
     * This (a) causes the new comment to appear after, rather than before,
     * existing comments; and (b) ensures that comments come after any JFIF
     * or JFXX markers, as required by the JFIF specification.
     */
    marker = scan_JPEG_header(keep_COM);
    /* Insert the new COM marker, but only if nonempty text has been supplied */
    if (comment_length > 0) {
      write_marker(M_COM);
      write_2_bytes(comment_length + 2);
      while (comment_length > 0) {
        write_1_byte(*comment_arg++);
        comment_length--;
      }
    }
    /* Duplicate the remainder of the source file.
     * Note that any COM markers occuring after SOF will not be touched.
     */
    write_marker(marker);
    copy_rest_of_file();
  
    /* All done. */
    exit(EXIT_SUCCESS);
    return 0;			/* suppress no-return-value warnings */
  }
  