2 * Copyright (c) Ian F. Darwin 1986-1995.
3 * Software written by Ian F. Darwin and others;
4 * maintained 1995-present by Christos Zoulas and others.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice immediately at the beginning of the file, without modification,
11 * this list of conditions, and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * ASCII magic -- file types that we know based on keywords
30 * that can appear anywhere in the file.
32 * Extensively modified by Eric Fischer <enf@pobox.com> in July, 2000,
33 * to handle character codes other than ASCII on a unified basis.
35 * Joerg Wunsch <joerg@freebsd.org> wrote the original support for 8-bit
36 * international characters, now subsumed into this file.
52 FILE_RCSID("@(#)$File: ascmagic.c,v 1.50 2007/03/15 14:51:00 christos Exp $")
55 typedef unsigned long unichar;
57 #define MAXLINELEN 300 /* longest sane line length */
58 #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \
59 || (x) == 0x85 || (x) == '\f')
61 private int looks_ascii(const unsigned char *, size_t, unichar *, size_t *);
62 private int looks_utf8(const unsigned char *, size_t, unichar *, size_t *);
63 private int looks_unicode(const unsigned char *, size_t, unichar *, size_t *);
64 private int looks_latin1(const unsigned char *, size_t, unichar *, size_t *);
65 private int looks_extended(const unsigned char *, size_t, unichar *, size_t *);
66 private void from_ebcdic(const unsigned char *, size_t, unsigned char *);
67 private int ascmatch(const unsigned char *, const unichar *, size_t);
71 file_ascmagic(struct magic_set *ms, const unsigned char *buf, size_t nbytes)
74 unsigned char *nbuf = NULL;
80 const char *code = NULL;
81 const char *code_mime = NULL;
82 const char *type = NULL;
83 const char *subtype = NULL;
84 const char *subtype_mime = NULL;
87 int has_backspace = 0;
95 size_t last_line_end = (size_t)-1;
96 int has_long_lines = 0;
99 * Undo the NUL-termination kindly provided by process()
100 * but leave at least one byte to look at
102 while (nbytes > 1 && buf[nbytes - 1] == '\0')
105 if ((nbuf = calloc(1, (nbytes + 1) * sizeof(nbuf[0]))) == NULL)
107 if ((ubuf = calloc(1, (nbytes + 1) * sizeof(ubuf[0]))) == NULL)
111 * Then try to determine whether it's any character code we can
112 * identify. Each of these tests, if it succeeds, will leave
113 * the text converted into one-unichar-per-character Unicode in
114 * ubuf, and the number of characters converted in ulen.
116 if (looks_ascii(buf, nbytes, ubuf, &ulen)) {
118 code_mime = "us-ascii";
120 } else if (looks_utf8(buf, nbytes, ubuf, &ulen)) {
121 code = "UTF-8 Unicode";
124 } else if ((i = looks_unicode(buf, nbytes, ubuf, &ulen)) != 0) {
126 code = "Little-endian UTF-16 Unicode";
128 code = "Big-endian UTF-16 Unicode";
130 type = "character data";
131 code_mime = "utf-16"; /* is this defined? */
132 } else if (looks_latin1(buf, nbytes, ubuf, &ulen)) {
135 code_mime = "iso-8859-1";
136 } else if (looks_extended(buf, nbytes, ubuf, &ulen)) {
137 code = "Non-ISO extended-ASCII";
139 code_mime = "unknown";
141 from_ebcdic(buf, nbytes, nbuf);
143 if (looks_ascii(nbuf, nbytes, ubuf, &ulen)) {
145 type = "character data";
146 code_mime = "ebcdic";
147 } else if (looks_latin1(nbuf, nbytes, ubuf, &ulen)) {
148 code = "International EBCDIC";
149 type = "character data";
150 code_mime = "ebcdic";
153 goto done; /* doesn't look like text at all */
163 * for troff, look for . + letter + letter or .\";
164 * this must be done to disambiguate tar archives' ./file
165 * and other trash from real troff input.
167 * I believe Plan 9 troff allows non-ASCII characters in the names
168 * of macros, so this test might possibly fail on such a file.
170 if ((ms->flags & MAGIC_NO_CHECK_TROFF) == 0 && *ubuf == '.') {
171 unichar *tp = ubuf + 1;
174 ++tp; /* skip leading whitespace */
175 if ((tp[0] == '\\' && tp[1] == '\"') ||
176 (isascii((unsigned char)tp[0]) &&
177 isalnum((unsigned char)tp[0]) &&
178 isascii((unsigned char)tp[1]) &&
179 isalnum((unsigned char)tp[1]) &&
181 subtype_mime = "text/troff";
182 subtype = "troff or preprocessor input";
183 goto subtype_identified;
187 if ((ms->flags & MAGIC_NO_CHECK_FORTRAN) == 0 &&
188 (*buf == 'c' || *buf == 'C') && ISSPC(buf[1])) {
189 subtype_mime = "text/fortran";
190 subtype = "fortran program";
191 goto subtype_identified;
194 /* look for tokens from names.h - this is expensive! */
196 if ((ms->flags & MAGIC_NO_CHECK_TOKENS) != 0)
197 goto subtype_identified;
204 * skip past any leading space
206 while (i < ulen && ISSPC(ubuf[i]))
212 * find the next whitespace
214 for (end = i + 1; end < nbytes; end++)
215 if (ISSPC(ubuf[end]))
219 * compare the word thus isolated against the token list
221 for (p = names; p < names + NNAMES; p++) {
222 if (ascmatch((const unsigned char *)p->name, ubuf + i,
224 subtype = types[p->type].human;
225 subtype_mime = types[p->type].mime;
226 goto subtype_identified;
236 * Now try to discover other details about the file.
238 for (i = 0; i < ulen; i++) {
239 if (ubuf[i] == '\n') {
248 seen_cr = (ubuf[i] == '\r');
252 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
257 /* If this line is _longer_ than MAXLINELEN, remember it. */
258 if (i > last_line_end + MAXLINELEN)
261 if (ubuf[i] == '\033')
267 /* Beware, if the data has been truncated, the final CR could have
268 been followed by a LF. If we have HOWMANY bytes, it indicates
269 that the data might have been truncated, probably even before
270 this function was called. */
271 if (seen_cr && nbytes < HOWMANY)
274 if ((ms->flags & MAGIC_MIME)) {
276 if (file_printf(ms, subtype_mime) == -1)
279 if (file_printf(ms, "text/plain") == -1)
284 if (file_printf(ms, "; charset=") == -1)
286 if (file_printf(ms, code_mime) == -1)
290 if (file_printf(ms, code) == -1)
294 if (file_printf(ms, " ") == -1)
296 if (file_printf(ms, subtype) == -1)
300 if (file_printf(ms, " ") == -1)
302 if (file_printf(ms, type) == -1)
306 if (file_printf(ms, ", with very long lines") == -1)
310 * Only report line terminators if we find one other than LF,
311 * or if we find none at all.
313 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
314 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
315 if (file_printf(ms, ", with") == -1)
318 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
319 if (file_printf(ms, " no") == -1)
323 if (file_printf(ms, " CRLF") == -1)
325 if (n_cr || n_lf || n_nel)
326 if (file_printf(ms, ",") == -1)
330 if (file_printf(ms, " CR") == -1)
333 if (file_printf(ms, ",") == -1)
337 if (file_printf(ms, " LF") == -1)
340 if (file_printf(ms, ",") == -1)
344 if (file_printf(ms, " NEL") == -1)
348 if (file_printf(ms, " line terminators") == -1)
353 if (file_printf(ms, ", with escape sequences") == -1)
356 if (file_printf(ms, ", with overstriking") == -1)
370 ascmatch(const unsigned char *s, const unichar *us, size_t ulen)
374 for (i = 0; i < ulen; i++) {
386 * This table reflects a particular philosophy about what constitutes
387 * "text," and there is room for disagreement about it.
389 * Version 3.31 of the file command considered a file to be ASCII if
390 * each of its characters was approved by either the isascii() or
391 * isalpha() function. On most systems, this would mean that any
392 * file consisting only of characters in the range 0x00 ... 0x7F
393 * would be called ASCII text, but many systems might reasonably
394 * consider some characters outside this range to be alphabetic,
395 * so the file command would call such characters ASCII. It might
396 * have been more accurate to call this "considered textual on the
397 * local system" than "ASCII."
399 * It considered a file to be "International language text" if each
400 * of its characters was either an ASCII printing character (according
401 * to the real ASCII standard, not the above test), a character in
402 * the range 0x80 ... 0xFF, or one of the following control characters:
403 * backspace, tab, line feed, vertical tab, form feed, carriage return,
404 * escape. No attempt was made to determine the language in which files
405 * of this type were written.
408 * The table below considers a file to be ASCII if all of its characters
409 * are either ASCII printing characters (again, according to the X3.4
410 * standard, not isascii()) or any of the following controls: bell,
411 * backspace, tab, line feed, form feed, carriage return, esc, nextline.
413 * I include bell because some programs (particularly shell scripts)
414 * use it literally, even though it is rare in normal text. I exclude
415 * vertical tab because it never seems to be used in real text. I also
416 * include, with hesitation, the X3.64/ECMA-43 control nextline (0x85),
417 * because that's what the dd EBCDIC->ASCII table maps the EBCDIC newline
418 * character to. It might be more appropriate to include it in the 8859
419 * set instead of the ASCII set, but it's got to be included in *something*
420 * we recognize or EBCDIC files aren't going to be considered textual.
421 * Some old Unix source files use SO/SI (^N/^O) to shift between Greek
422 * and Latin characters, so these should possibly be allowed. But they
423 * make a real mess on VT100-style displays if they're not paired properly,
424 * so we are probably better off not calling them text.
426 * A file is considered to be ISO-8859 text if its characters are all
427 * either ASCII, according to the above definition, or printing characters
428 * from the ISO-8859 8-bit extension, characters 0xA0 ... 0xFF.
430 * Finally, a file is considered to be international text from some other
431 * character code if its characters are all either ISO-8859 (according to
432 * the above definition) or characters in the range 0x80 ... 0x9F, which
433 * ISO-8859 considers to be control characters but the IBM PC and Macintosh
434 * consider to be printing characters.
437 #define F 0 /* character never appears in text */
438 #define T 1 /* character appears in plain ASCII text */
439 #define I 2 /* character appears in ISO-8859 text */
440 #define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
442 private char text_chars[256] = {
443 /* BEL BS HT LF FF CR */
444 F, F, F, F, F, F, F, T, T, T, T, F, T, T, F, F, /* 0x0X */
446 F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
447 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
448 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
449 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
450 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
451 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
452 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
454 X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
455 X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
456 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
457 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
458 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
459 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
460 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
461 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
465 looks_ascii(const unsigned char *buf, size_t nbytes, unichar *ubuf,
472 for (i = 0; i < nbytes; i++) {
473 int t = text_chars[buf[i]];
478 ubuf[(*ulen)++] = buf[i];
485 looks_latin1(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
491 for (i = 0; i < nbytes; i++) {
492 int t = text_chars[buf[i]];
494 if (t != T && t != I)
497 ubuf[(*ulen)++] = buf[i];
504 looks_extended(const unsigned char *buf, size_t nbytes, unichar *ubuf,
511 for (i = 0; i < nbytes; i++) {
512 int t = text_chars[buf[i]];
514 if (t != T && t != I && t != X)
517 ubuf[(*ulen)++] = buf[i];
524 looks_utf8(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
533 for (i = 0; i < nbytes; i++) {
534 if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
536 * Even if the whole file is valid UTF-8 sequences,
537 * still reject it if it uses weird control characters.
540 if (text_chars[buf[i]] != T)
543 ubuf[(*ulen)++] = buf[i];
544 } else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
546 } else { /* 11xxxxxx begins UTF-8 */
549 if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
552 } else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
555 } else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
558 } else if ((buf[i] & 0x04) == 0) { /* 111110xx */
561 } else if ((buf[i] & 0x02) == 0) { /* 1111110x */
567 for (n = 0; n < following; n++) {
572 if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
575 c = (c << 6) + (buf[i] & 0x3f);
583 return gotone; /* don't claim it's UTF-8 if it's all 7-bit */
587 looks_unicode(const unsigned char *buf, size_t nbytes, unichar *ubuf,
596 if (buf[0] == 0xff && buf[1] == 0xfe)
598 else if (buf[0] == 0xfe && buf[1] == 0xff)
605 for (i = 2; i + 1 < nbytes; i += 2) {
606 /* XXX fix to properly handle chars > 65536 */
609 ubuf[(*ulen)++] = buf[i + 1] + 256 * buf[i];
611 ubuf[(*ulen)++] = buf[i] + 256 * buf[i + 1];
613 if (ubuf[*ulen - 1] == 0xfffe)
615 if (ubuf[*ulen - 1] < 128 &&
616 text_chars[(size_t)ubuf[*ulen - 1]] != T)
629 * This table maps each EBCDIC character to an (8-bit extended) ASCII
630 * character, as specified in the rationale for the dd(1) command in
631 * draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
633 * Unfortunately it does not seem to correspond exactly to any of the
634 * five variants of EBCDIC documented in IBM's _Enterprise Systems
635 * Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
636 * Edition, July, 1999, pp. I-1 - I-4.
638 * Fortunately, though, all versions of EBCDIC, including this one, agree
639 * on most of the printing characters that also appear in (7-bit) ASCII.
640 * Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
642 * Fortunately too, there is general agreement that codes 0x00 through
643 * 0x3F represent control characters, 0x41 a nonbreaking space, and the
644 * remainder printing characters.
646 * This is sufficient to allow us to identify EBCDIC text and to distinguish
647 * between old-style and internationalized examples of text.
650 private unsigned char ebcdic_to_ascii[] = {
651 0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
652 16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
653 128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
654 144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
655 ' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
656 '&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
657 '-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
658 186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
659 195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
660 202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
661 209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
662 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
663 '{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
664 '}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
665 '\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
666 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
671 * The following EBCDIC-to-ASCII table may relate more closely to reality,
672 * or at least to modern reality. It comes from
674 * http://ftp.s390.ibm.com/products/oe/bpxqp9.html
676 * and maps the characters of EBCDIC code page 1047 (the code used for
677 * Unix-derived software on IBM's 390 systems) to the corresponding
678 * characters from ISO 8859-1.
680 * If this table is used instead of the above one, some of the special
681 * cases for the NEL character can be taken out of the code.
684 private unsigned char ebcdic_1047_to_8859[] = {
685 0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
686 0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
687 0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
688 0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
689 0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
690 0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
691 0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
692 0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
693 0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
694 0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
695 0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
696 0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
697 0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
698 0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
699 0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
700 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
705 * Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
708 from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
712 for (i = 0; i < nbytes; i++) {
713 out[i] = ebcdic_to_ascii[buf[i]];