/*

* wrjpgcom.c

*

* Copyright (C) 1994-1997, Thomas G. Lane.

* Modified 2015 by Guido Vollbeding.

* 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");

if (strlen(argv[argn]+1) >= (size_t) MAX_COM_LENGTH) {

fprintf(stderr, "Comment text may not exceed %u bytes\n",

(unsigned int) MAX_COM_LENGTH);

exit(EXIT_FAILURE);

}

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");

if (strlen(comment_arg) + 1 + strlen(argv[argn]) >=

(size_t) MAX_COM_LENGTH) {

fprintf(stderr, "Comment text may not exceed %u bytes\n",

(unsigned int) MAX_COM_LENGTH);

exit(EXIT_FAILURE);

}

strcat(comment_arg, " ");

strcat(comment_arg, argv[argn]);

}

} else if (strlen(comment_arg) >= (size_t) MAX_COM_LENGTH) {

fprintf(stderr, "Comment text may not exceed %u bytes\n",

(unsigned int) MAX_COM_LENGTH);

exit(EXIT_FAILURE);

}

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 */

}