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("@(#)$Id: ascmagic.c,v 1.41 2004/09/11 19:15:57 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[HOWMANY+1]; /* one extra for terminating '\0' */
75 unichar ubuf[HOWMANY+1]; /* one extra for terminating '\0' */
79 const char *code = NULL;
80 const char *code_mime = NULL;
81 const char *type = NULL;
82 const char *subtype = NULL;
83 const char *subtype_mime = NULL;
86 int has_backspace = 0;
93 int last_line_end = -1;
94 int has_long_lines = 0;
97 * Undo the NUL-termination kindly provided by process()
98 * but leave at least one byte to look at
101 while (nbytes > 1 && buf[nbytes - 1] == '\0')
104 /* nbuf and ubuf relies on this */
105 if (nbytes > HOWMANY)
109 * Then try to determine whether it's any character code we can
110 * identify. Each of these tests, if it succeeds, will leave
111 * the text converted into one-unichar-per-character Unicode in
112 * ubuf, and the number of characters converted in ulen.
114 if (looks_ascii(buf, nbytes, ubuf, &ulen)) {
116 code_mime = "us-ascii";
118 } else if (looks_utf8(buf, nbytes, ubuf, &ulen)) {
119 code = "UTF-8 Unicode";
122 } else if ((i = looks_unicode(buf, nbytes, ubuf, &ulen)) != 0) {
124 code = "Little-endian UTF-16 Unicode";
126 code = "Big-endian UTF-16 Unicode";
128 type = "character data";
129 code_mime = "utf-16"; /* is this defined? */
130 } else if (looks_latin1(buf, nbytes, ubuf, &ulen)) {
133 code_mime = "iso-8859-1";
134 } else if (looks_extended(buf, nbytes, ubuf, &ulen)) {
135 code = "Non-ISO extended-ASCII";
137 code_mime = "unknown";
139 from_ebcdic(buf, nbytes, nbuf);
141 if (looks_ascii(nbuf, nbytes, ubuf, &ulen)) {
143 type = "character data";
144 code_mime = "ebcdic";
145 } else if (looks_latin1(nbuf, nbytes, ubuf, &ulen)) {
146 code = "International EBCDIC";
147 type = "character data";
148 code_mime = "ebcdic";
150 return 0; /* doesn't look like text at all */
155 * for troff, look for . + letter + letter or .\";
156 * this must be done to disambiguate tar archives' ./file
157 * and other trash from real troff input.
159 * I believe Plan 9 troff allows non-ASCII characters in the names
160 * of macros, so this test might possibly fail on such a file.
163 unichar *tp = ubuf + 1;
166 ++tp; /* skip leading whitespace */
167 if ((tp[0] == '\\' && tp[1] == '\"') ||
168 (isascii((unsigned char)tp[0]) &&
169 isalnum((unsigned char)tp[0]) &&
170 isascii((unsigned char)tp[1]) &&
171 isalnum((unsigned char)tp[1]) &&
173 subtype_mime = "text/troff";
174 subtype = "troff or preprocessor input";
175 goto subtype_identified;
179 if ((*buf == 'c' || *buf == 'C') && ISSPC(buf[1])) {
180 subtype_mime = "text/fortran";
181 subtype = "fortran program";
182 goto subtype_identified;
185 /* look for tokens from names.h - this is expensive! */
192 * skip past any leading space
194 while (i < ulen && ISSPC(ubuf[i]))
200 * find the next whitespace
202 for (end = i + 1; end < nbytes; end++)
203 if (ISSPC(ubuf[end]))
207 * compare the word thus isolated against the token list
209 for (p = names; p < names + NNAMES; p++) {
210 if (ascmatch((const unsigned char *)p->name, ubuf + i,
212 subtype = types[p->type].human;
213 subtype_mime = types[p->type].mime;
214 goto subtype_identified;
224 * Now try to discover other details about the file.
226 for (i = 0; i < ulen; i++) {
227 if (i > last_line_end + MAXLINELEN)
230 if (ubuf[i] == '\033')
235 if (ubuf[i] == '\r' && (i + 1 < ulen && ubuf[i + 1] == '\n')) {
239 if (ubuf[i] == '\r' && (i + 1 >= ulen || ubuf[i + 1] != '\n')) {
243 if (ubuf[i] == '\n' && ((int)i - 1 < 0 || ubuf[i - 1] != '\r')){
247 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
253 if ((ms->flags & MAGIC_MIME)) {
255 if (file_printf(ms, subtype_mime) == -1)
258 if (file_printf(ms, "text/plain") == -1)
263 if (file_printf(ms, "; charset=") == -1)
265 if (file_printf(ms, code_mime) == -1)
269 if (file_printf(ms, code) == -1)
273 if (file_printf(ms, " ") == -1)
275 if (file_printf(ms, subtype) == -1)
279 if (file_printf(ms, " ") == -1)
281 if (file_printf(ms, type) == -1)
285 if (file_printf(ms, ", with very long lines") == -1)
289 * Only report line terminators if we find one other than LF,
290 * or if we find none at all.
292 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
293 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
294 if (file_printf(ms, ", with") == -1)
297 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
298 if (file_printf(ms, " no") == -1)
302 if (file_printf(ms, " CRLF") == -1)
304 if (n_cr || n_lf || n_nel)
305 if (file_printf(ms, ",") == -1)
309 if (file_printf(ms, " CR") == -1)
312 if (file_printf(ms, ",") == -1)
316 if (file_printf(ms, " LF") == -1)
319 if (file_printf(ms, ",") == -1)
323 if (file_printf(ms, " NEL") == -1)
327 if (file_printf(ms, " line terminators") == -1)
332 if (file_printf(ms, ", with escape sequences") == -1)
335 if (file_printf(ms, ", with overstriking") == -1)
343 ascmatch(const unsigned char *s, const unichar *us, size_t ulen)
347 for (i = 0; i < ulen; i++) {
359 * This table reflects a particular philosophy about what constitutes
360 * "text," and there is room for disagreement about it.
362 * Version 3.31 of the file command considered a file to be ASCII if
363 * each of its characters was approved by either the isascii() or
364 * isalpha() function. On most systems, this would mean that any
365 * file consisting only of characters in the range 0x00 ... 0x7F
366 * would be called ASCII text, but many systems might reasonably
367 * consider some characters outside this range to be alphabetic,
368 * so the file command would call such characters ASCII. It might
369 * have been more accurate to call this "considered textual on the
370 * local system" than "ASCII."
372 * It considered a file to be "International language text" if each
373 * of its characters was either an ASCII printing character (according
374 * to the real ASCII standard, not the above test), a character in
375 * the range 0x80 ... 0xFF, or one of the following control characters:
376 * backspace, tab, line feed, vertical tab, form feed, carriage return,
377 * escape. No attempt was made to determine the language in which files
378 * of this type were written.
381 * The table below considers a file to be ASCII if all of its characters
382 * are either ASCII printing characters (again, according to the X3.4
383 * standard, not isascii()) or any of the following controls: bell,
384 * backspace, tab, line feed, form feed, carriage return, esc, nextline.
386 * I include bell because some programs (particularly shell scripts)
387 * use it literally, even though it is rare in normal text. I exclude
388 * vertical tab because it never seems to be used in real text. I also
389 * include, with hesitation, the X3.64/ECMA-43 control nextline (0x85),
390 * because that's what the dd EBCDIC->ASCII table maps the EBCDIC newline
391 * character to. It might be more appropriate to include it in the 8859
392 * set instead of the ASCII set, but it's got to be included in *something*
393 * we recognize or EBCDIC files aren't going to be considered textual.
394 * Some old Unix source files use SO/SI (^N/^O) to shift between Greek
395 * and Latin characters, so these should possibly be allowed. But they
396 * make a real mess on VT100-style displays if they're not paired properly,
397 * so we are probably better off not calling them text.
399 * A file is considered to be ISO-8859 text if its characters are all
400 * either ASCII, according to the above definition, or printing characters
401 * from the ISO-8859 8-bit extension, characters 0xA0 ... 0xFF.
403 * Finally, a file is considered to be international text from some other
404 * character code if its characters are all either ISO-8859 (according to
405 * the above definition) or characters in the range 0x80 ... 0x9F, which
406 * ISO-8859 considers to be control characters but the IBM PC and Macintosh
407 * consider to be printing characters.
410 #define F 0 /* character never appears in text */
411 #define T 1 /* character appears in plain ASCII text */
412 #define I 2 /* character appears in ISO-8859 text */
413 #define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
415 private char text_chars[256] = {
416 /* BEL BS HT LF FF CR */
417 F, F, F, F, F, F, F, T, T, T, T, F, T, T, F, F, /* 0x0X */
419 F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
420 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
421 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
422 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
423 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
424 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
425 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
427 X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
428 X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
429 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
430 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
431 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
432 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
433 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
434 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
438 looks_ascii(const unsigned char *buf, size_t nbytes, unichar *ubuf,
445 for (i = 0; i < nbytes; i++) {
446 int t = text_chars[buf[i]];
451 ubuf[(*ulen)++] = buf[i];
458 looks_latin1(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
464 for (i = 0; i < nbytes; i++) {
465 int t = text_chars[buf[i]];
467 if (t != T && t != I)
470 ubuf[(*ulen)++] = buf[i];
477 looks_extended(const unsigned char *buf, size_t nbytes, unichar *ubuf,
484 for (i = 0; i < nbytes; i++) {
485 int t = text_chars[buf[i]];
487 if (t != T && t != I && t != X)
490 ubuf[(*ulen)++] = buf[i];
497 looks_utf8(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
505 for (i = 0; i < nbytes; i++) {
506 if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
508 * Even if the whole file is valid UTF-8 sequences,
509 * still reject it if it uses weird control characters.
512 if (text_chars[buf[i]] != T)
515 ubuf[(*ulen)++] = buf[i];
516 } else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
518 } else { /* 11xxxxxx begins UTF-8 */
521 if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
524 } else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
527 } else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
530 } else if ((buf[i] & 0x04) == 0) { /* 111110xx */
533 } else if ((buf[i] & 0x02) == 0) { /* 1111110x */
539 for (n = 0; n < following; n++) {
544 if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
547 c = (c << 6) + (buf[i] & 0x3f);
555 return gotone; /* don't claim it's UTF-8 if it's all 7-bit */
559 looks_unicode(const unsigned char *buf, size_t nbytes, unichar *ubuf,
568 if (buf[0] == 0xff && buf[1] == 0xfe)
570 else if (buf[0] == 0xfe && buf[1] == 0xff)
577 for (i = 2; i + 1 < nbytes; i += 2) {
578 /* XXX fix to properly handle chars > 65536 */
581 ubuf[(*ulen)++] = buf[i + 1] + 256 * buf[i];
583 ubuf[(*ulen)++] = buf[i] + 256 * buf[i + 1];
585 if (ubuf[*ulen - 1] == 0xfffe)
587 if (ubuf[*ulen - 1] < 128 &&
588 text_chars[(size_t)ubuf[*ulen - 1]] != T)
601 * This table maps each EBCDIC character to an (8-bit extended) ASCII
602 * character, as specified in the rationale for the dd(1) command in
603 * draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
605 * Unfortunately it does not seem to correspond exactly to any of the
606 * five variants of EBCDIC documented in IBM's _Enterprise Systems
607 * Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
608 * Edition, July, 1999, pp. I-1 - I-4.
610 * Fortunately, though, all versions of EBCDIC, including this one, agree
611 * on most of the printing characters that also appear in (7-bit) ASCII.
612 * Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
614 * Fortunately too, there is general agreement that codes 0x00 through
615 * 0x3F represent control characters, 0x41 a nonbreaking space, and the
616 * remainder printing characters.
618 * This is sufficient to allow us to identify EBCDIC text and to distinguish
619 * between old-style and internationalized examples of text.
622 private unsigned char ebcdic_to_ascii[] = {
623 0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
624 16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
625 128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
626 144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
627 ' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
628 '&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
629 '-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
630 186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
631 195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
632 202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
633 209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
634 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
635 '{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
636 '}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
637 '\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
638 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
643 * The following EBCDIC-to-ASCII table may relate more closely to reality,
644 * or at least to modern reality. It comes from
646 * http://ftp.s390.ibm.com/products/oe/bpxqp9.html
648 * and maps the characters of EBCDIC code page 1047 (the code used for
649 * Unix-derived software on IBM's 390 systems) to the corresponding
650 * characters from ISO 8859-1.
652 * If this table is used instead of the above one, some of the special
653 * cases for the NEL character can be taken out of the code.
656 private unsigned char ebcdic_1047_to_8859[] = {
657 0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
658 0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
659 0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
660 0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
661 0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
662 0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
663 0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
664 0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
665 0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
666 0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
667 0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
668 0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
669 0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
670 0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
671 0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
672 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
677 * Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
680 from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
684 for (i = 0; i < nbytes; i++) {
685 out[i] = ebcdic_to_ascii[buf[i]];