| /* |
| * rdjpgcom.c |
| * |
| * This file was part of the Independent JPEG Group's software: |
| * Copyright (C) 1994-1997, Thomas G. Lane. |
| * Modified 2009 by Bill Allombert, Guido Vollbeding. |
| * libjpeg-turbo Modifications: |
| * Copyright (C) 2022, D. R. Commander. |
| * For conditions of distribution and use, see the accompanying README.ijg |
| * file. |
| * |
| * This file contains a very simple stand-alone application that displays |
| * the text in COM (comment) markers in a JFIF file. |
| * This may be useful as an example of the minimum logic needed to parse |
| * JPEG markers. |
| */ |
| |
| #ifdef _MSC_VER |
| #define _CRT_SECURE_NO_DEPRECATE |
| #endif |
| |
| #define JPEG_CJPEG_DJPEG /* to get the command-line config symbols */ |
| #include "jinclude.h" /* get auto-config symbols, <stdio.h> */ |
| |
| #include <locale.h> /* Bill Allombert: use locale for isprint */ |
| #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 DONT_USE_B_MODE /* define mode parameters for fopen() */ |
| #define READ_BINARY "r" |
| #else |
| #define READ_BINARY "rb" |
| #endif |
| |
| #ifndef EXIT_FAILURE /* define exit() codes if not provided */ |
| #define EXIT_FAILURE 1 |
| #endif |
| #ifndef EXIT_SUCCESS |
| #define EXIT_SUCCESS 0 |
| #endif |
| |
| |
| /* |
| * These macros are used to read the input 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) |
| |
| |
| /* 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); |
| } |
| |
| |
| /* |
| * 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_APP12 0xEC /* (we don't bother to list all 16 APPn's) */ |
| #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. |
| * 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 |
| 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--; |
| } |
| } |
| |
| |
| /* |
| * Process a COM marker. |
| * We want to print out the marker contents as legible text; |
| * we must guard against non-text junk and varying newline representations. |
| */ |
| |
| static void |
| process_COM(int raw) |
| { |
| unsigned int length; |
| int ch; |
| int lastch = 0; |
| |
| /* Bill Allombert: set locale properly for isprint */ |
| setlocale(LC_CTYPE, ""); |
| |
| /* 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; |
| |
| while (length > 0) { |
| ch = read_1_byte(); |
| if (raw) { |
| putc(ch, stdout); |
| /* Emit the character in a readable form. |
| * Nonprintables are converted to \nnn form, |
| * while \ is converted to \\. |
| * Newlines in CR, CR/LF, or LF form will be printed as one newline. |
| */ |
| } else if (ch == '\r') { |
| printf("\n"); |
| } else if (ch == '\n') { |
| if (lastch != '\r') |
| printf("\n"); |
| } else if (ch == '\\') { |
| printf("\\\\"); |
| } else if (isprint(ch)) { |
| putc(ch, stdout); |
| } else { |
| printf("\\%03o", (unsigned int)ch); |
| } |
| lastch = ch; |
| length--; |
| } |
| printf("\n"); |
| |
| /* Bill Allombert: revert to C locale */ |
| setlocale(LC_CTYPE, "C"); |
| } |
| |
| |
| /* |
| * Process a SOFn marker. |
| * This code is only needed if you want to know the image dimensions... |
| */ |
| |
| static void |
| process_SOFn(int marker) |
| { |
| unsigned int length; |
| unsigned int image_height, image_width; |
| int data_precision, num_components; |
| const char *process; |
| int ci; |
| |
| length = read_2_bytes(); /* usual parameter length count */ |
| |
| data_precision = read_1_byte(); |
| image_height = read_2_bytes(); |
| image_width = read_2_bytes(); |
| num_components = read_1_byte(); |
| |
| switch (marker) { |
| case M_SOF0: process = "Baseline"; break; |
| case M_SOF1: process = "Extended sequential"; break; |
| case M_SOF2: process = "Progressive"; break; |
| case M_SOF3: process = "Lossless"; break; |
| case M_SOF5: process = "Differential sequential"; break; |
| case M_SOF6: process = "Differential progressive"; break; |
| case M_SOF7: process = "Differential lossless"; break; |
| case M_SOF9: process = "Extended sequential, arithmetic coding"; break; |
| case M_SOF10: process = "Progressive, arithmetic coding"; break; |
| case M_SOF11: process = "Lossless, arithmetic coding"; break; |
| case M_SOF13: process = "Differential sequential, arithmetic coding"; break; |
| case M_SOF14: |
| process = "Differential progressive, arithmetic coding"; break; |
| case M_SOF15: process = "Differential lossless, arithmetic coding"; break; |
| default: process = "Unknown"; break; |
| } |
| |
| printf("JPEG image is %uw * %uh, %d color components, %d bits per sample\n", |
| image_width, image_height, num_components, data_precision); |
| printf("JPEG process: %s\n", process); |
| |
| if (length != (unsigned int)(8 + num_components * 3)) |
| ERREXIT("Bogus SOF marker length"); |
| |
| for (ci = 0; ci < num_components; ci++) { |
| (void)read_1_byte(); /* Component ID code */ |
| (void)read_1_byte(); /* H, V sampling factors */ |
| (void)read_1_byte(); /* Quantization table number */ |
| } |
| } |
| |
| |
| /* |
| * Parse the marker stream until SOS or EOI is seen; |
| * display any COM markers. |
| * While the companion program wrjpgcom will always insert COM markers before |
| * SOFn, other implementations might not, so we scan to SOS before stopping. |
| * If we were only interested in the image dimensions, we would stop at SOFn. |
| * (Conversely, if we only cared about COM markers, there would be no need |
| * for special code to handle SOFn; we could treat it like other markers.) |
| */ |
| |
| static int |
| scan_JPEG_header(int verbose, int raw) |
| { |
| int marker; |
| |
| /* Expect SOI at start of file */ |
| if (first_marker() != M_SOI) |
| ERREXIT("Expected SOI marker first"); |
| |
| /* Scan miscellaneous markers until we reach SOS. */ |
| 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 */ |
| if (verbose) |
| process_SOFn(marker); |
| else |
| skip_variable(); |
| break; |
| |
| case M_SOS: /* stop before hitting compressed data */ |
| return marker; |
| |
| case M_EOI: /* in case it's a tables-only JPEG stream */ |
| return marker; |
| |
| case M_COM: |
| process_COM(raw); |
| break; |
| |
| case M_APP12: |
| /* Some digital camera makers put useful textual information into |
| * APP12 markers, so we print those out too when in -verbose mode. |
| */ |
| if (verbose) { |
| printf("APP12 contains:\n"); |
| process_COM(raw); |
| } else |
| skip_variable(); |
| break; |
| |
| default: /* Anything else just gets skipped */ |
| skip_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, "rdjpgcom displays any textual comments in a JPEG file.\n"); |
| |
| fprintf(stderr, "Usage: %s [switches] [inputfile]\n", progname); |
| |
| fprintf(stderr, "Switches (names may be abbreviated):\n"); |
| fprintf(stderr, " -raw Display non-printable characters in comments (unsafe)\n"); |
| fprintf(stderr, " -verbose Also display dimensions of JPEG image\n"); |
| |
| 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 verbose = 0, raw = 0; |
| |
| progname = argv[0]; |
| if (progname == NULL || progname[0] == 0) |
| progname = "rdjpgcom"; /* 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, "verbose", 1)) { |
| verbose++; |
| } else if (keymatch(arg, "raw", 1)) { |
| raw = 1; |
| } else |
| usage(); |
| } |
| |
| /* Open the input file. */ |
| /* Unix style: expect zero or one file name */ |
| if (argn < argc - 1) { |
| fprintf(stderr, "%s: only one input file\n", progname); |
| usage(); |
| } |
| 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 |
| } |
| |
| /* Scan the JPEG headers. */ |
| (void)scan_JPEG_header(verbose, raw); |
| |
| /* All done. */ |
| exit(EXIT_SUCCESS); |
| return 0; /* suppress no-return-value warnings */ |
| } |