/*
* 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 */
}