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 1.43 2005/06/25 15:52:14 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 int last_line_end = -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 = malloc((nbytes + 1) * sizeof(nbuf[0]))) == NULL)
107 if ((ubuf = malloc((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 */
158 * for troff, look for . + letter + letter or .\";
159 * this must be done to disambiguate tar archives' ./file
160 * and other trash from real troff input.
162 * I believe Plan 9 troff allows non-ASCII characters in the names
163 * of macros, so this test might possibly fail on such a file.
166 unichar *tp = ubuf + 1;
169 ++tp; /* skip leading whitespace */
170 if ((tp[0] == '\\' && tp[1] == '\"') ||
171 (isascii((unsigned char)tp[0]) &&
172 isalnum((unsigned char)tp[0]) &&
173 isascii((unsigned char)tp[1]) &&
174 isalnum((unsigned char)tp[1]) &&
176 subtype_mime = "text/troff";
177 subtype = "troff or preprocessor input";
178 goto subtype_identified;
182 if ((*buf == 'c' || *buf == 'C') && ISSPC(buf[1])) {
183 subtype_mime = "text/fortran";
184 subtype = "fortran program";
185 goto subtype_identified;
188 /* look for tokens from names.h - this is expensive! */
195 * skip past any leading space
197 while (i < ulen && ISSPC(ubuf[i]))
203 * find the next whitespace
205 for (end = i + 1; end < nbytes; end++)
206 if (ISSPC(ubuf[end]))
210 * compare the word thus isolated against the token list
212 for (p = names; p < names + NNAMES; p++) {
213 if (ascmatch((const unsigned char *)p->name, ubuf + i,
215 subtype = types[p->type].human;
216 subtype_mime = types[p->type].mime;
217 goto subtype_identified;
227 * Now try to discover other details about the file.
229 for (i = 0; i < ulen; i++) {
230 if (ubuf[i] == '\n') {
239 seen_cr = (ubuf[i] == '\r');
243 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
248 /* If this line is _longer_ than MAXLINELEN, remember it. */
249 if (i > last_line_end + MAXLINELEN)
252 if (ubuf[i] == '\033')
258 /* Beware, if the data has been truncated, the final CR could have
259 been followed by a LF. If we have HOWMANY bytes, it indicates
260 that the data might have been truncated, probably even before
261 this function was called. */
262 if (seen_cr && nbytes < HOWMANY)
265 if ((ms->flags & MAGIC_MIME)) {
267 if (file_printf(ms, subtype_mime) == -1)
270 if (file_printf(ms, "text/plain") == -1)
275 if (file_printf(ms, "; charset=") == -1)
277 if (file_printf(ms, code_mime) == -1)
281 if (file_printf(ms, code) == -1)
285 if (file_printf(ms, " ") == -1)
287 if (file_printf(ms, subtype) == -1)
291 if (file_printf(ms, " ") == -1)
293 if (file_printf(ms, type) == -1)
297 if (file_printf(ms, ", with very long lines") == -1)
301 * Only report line terminators if we find one other than LF,
302 * or if we find none at all.
304 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
305 (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
306 if (file_printf(ms, ", with") == -1)
309 if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
310 if (file_printf(ms, " no") == -1)
314 if (file_printf(ms, " CRLF") == -1)
316 if (n_cr || n_lf || n_nel)
317 if (file_printf(ms, ",") == -1)
321 if (file_printf(ms, " CR") == -1)
324 if (file_printf(ms, ",") == -1)
328 if (file_printf(ms, " LF") == -1)
331 if (file_printf(ms, ",") == -1)
335 if (file_printf(ms, " NEL") == -1)
339 if (file_printf(ms, " line terminators") == -1)
344 if (file_printf(ms, ", with escape sequences") == -1)
347 if (file_printf(ms, ", with overstriking") == -1)
361 ascmatch(const unsigned char *s, const unichar *us, size_t ulen)
365 for (i = 0; i < ulen; i++) {
377 * This table reflects a particular philosophy about what constitutes
378 * "text," and there is room for disagreement about it.
380 * Version 3.31 of the file command considered a file to be ASCII if
381 * each of its characters was approved by either the isascii() or
382 * isalpha() function. On most systems, this would mean that any
383 * file consisting only of characters in the range 0x00 ... 0x7F
384 * would be called ASCII text, but many systems might reasonably
385 * consider some characters outside this range to be alphabetic,
386 * so the file command would call such characters ASCII. It might
387 * have been more accurate to call this "considered textual on the
388 * local system" than "ASCII."
390 * It considered a file to be "International language text" if each
391 * of its characters was either an ASCII printing character (according
392 * to the real ASCII standard, not the above test), a character in
393 * the range 0x80 ... 0xFF, or one of the following control characters:
394 * backspace, tab, line feed, vertical tab, form feed, carriage return,
395 * escape. No attempt was made to determine the language in which files
396 * of this type were written.
399 * The table below considers a file to be ASCII if all of its characters
400 * are either ASCII printing characters (again, according to the X3.4
401 * standard, not isascii()) or any of the following controls: bell,
402 * backspace, tab, line feed, form feed, carriage return, esc, nextline.
404 * I include bell because some programs (particularly shell scripts)
405 * use it literally, even though it is rare in normal text. I exclude
406 * vertical tab because it never seems to be used in real text. I also
407 * include, with hesitation, the X3.64/ECMA-43 control nextline (0x85),
408 * because that's what the dd EBCDIC->ASCII table maps the EBCDIC newline
409 * character to. It might be more appropriate to include it in the 8859
410 * set instead of the ASCII set, but it's got to be included in *something*
411 * we recognize or EBCDIC files aren't going to be considered textual.
412 * Some old Unix source files use SO/SI (^N/^O) to shift between Greek
413 * and Latin characters, so these should possibly be allowed. But they
414 * make a real mess on VT100-style displays if they're not paired properly,
415 * so we are probably better off not calling them text.
417 * A file is considered to be ISO-8859 text if its characters are all
418 * either ASCII, according to the above definition, or printing characters
419 * from the ISO-8859 8-bit extension, characters 0xA0 ... 0xFF.
421 * Finally, a file is considered to be international text from some other
422 * character code if its characters are all either ISO-8859 (according to
423 * the above definition) or characters in the range 0x80 ... 0x9F, which
424 * ISO-8859 considers to be control characters but the IBM PC and Macintosh
425 * consider to be printing characters.
428 #define F 0 /* character never appears in text */
429 #define T 1 /* character appears in plain ASCII text */
430 #define I 2 /* character appears in ISO-8859 text */
431 #define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
433 private char text_chars[256] = {
434 /* BEL BS HT LF FF CR */
435 F, F, F, F, F, F, F, T, T, T, T, F, T, T, F, F, /* 0x0X */
437 F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
438 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
439 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
440 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
441 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
442 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
443 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
445 X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
446 X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
447 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
448 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
449 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
450 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
451 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
452 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
456 looks_ascii(const unsigned char *buf, size_t nbytes, unichar *ubuf,
463 for (i = 0; i < nbytes; i++) {
464 int t = text_chars[buf[i]];
469 ubuf[(*ulen)++] = buf[i];
476 looks_latin1(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
482 for (i = 0; i < nbytes; i++) {
483 int t = text_chars[buf[i]];
485 if (t != T && t != I)
488 ubuf[(*ulen)++] = buf[i];
495 looks_extended(const unsigned char *buf, size_t nbytes, unichar *ubuf,
502 for (i = 0; i < nbytes; i++) {
503 int t = text_chars[buf[i]];
505 if (t != T && t != I && t != X)
508 ubuf[(*ulen)++] = buf[i];
515 looks_utf8(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
523 for (i = 0; i < nbytes; i++) {
524 if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
526 * Even if the whole file is valid UTF-8 sequences,
527 * still reject it if it uses weird control characters.
530 if (text_chars[buf[i]] != T)
533 ubuf[(*ulen)++] = buf[i];
534 } else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
536 } else { /* 11xxxxxx begins UTF-8 */
539 if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
542 } else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
545 } else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
548 } else if ((buf[i] & 0x04) == 0) { /* 111110xx */
551 } else if ((buf[i] & 0x02) == 0) { /* 1111110x */
557 for (n = 0; n < following; n++) {
562 if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
565 c = (c << 6) + (buf[i] & 0x3f);
573 return gotone; /* don't claim it's UTF-8 if it's all 7-bit */
577 looks_unicode(const unsigned char *buf, size_t nbytes, unichar *ubuf,
586 if (buf[0] == 0xff && buf[1] == 0xfe)
588 else if (buf[0] == 0xfe && buf[1] == 0xff)
595 for (i = 2; i + 1 < nbytes; i += 2) {
596 /* XXX fix to properly handle chars > 65536 */
599 ubuf[(*ulen)++] = buf[i + 1] + 256 * buf[i];
601 ubuf[(*ulen)++] = buf[i] + 256 * buf[i + 1];
603 if (ubuf[*ulen - 1] == 0xfffe)
605 if (ubuf[*ulen - 1] < 128 &&
606 text_chars[(size_t)ubuf[*ulen - 1]] != T)
619 * This table maps each EBCDIC character to an (8-bit extended) ASCII
620 * character, as specified in the rationale for the dd(1) command in
621 * draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
623 * Unfortunately it does not seem to correspond exactly to any of the
624 * five variants of EBCDIC documented in IBM's _Enterprise Systems
625 * Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
626 * Edition, July, 1999, pp. I-1 - I-4.
628 * Fortunately, though, all versions of EBCDIC, including this one, agree
629 * on most of the printing characters that also appear in (7-bit) ASCII.
630 * Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
632 * Fortunately too, there is general agreement that codes 0x00 through
633 * 0x3F represent control characters, 0x41 a nonbreaking space, and the
634 * remainder printing characters.
636 * This is sufficient to allow us to identify EBCDIC text and to distinguish
637 * between old-style and internationalized examples of text.
640 private unsigned char ebcdic_to_ascii[] = {
641 0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
642 16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
643 128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
644 144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
645 ' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
646 '&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
647 '-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
648 186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
649 195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
650 202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
651 209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
652 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
653 '{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
654 '}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
655 '\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
656 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
661 * The following EBCDIC-to-ASCII table may relate more closely to reality,
662 * or at least to modern reality. It comes from
664 * http://ftp.s390.ibm.com/products/oe/bpxqp9.html
666 * and maps the characters of EBCDIC code page 1047 (the code used for
667 * Unix-derived software on IBM's 390 systems) to the corresponding
668 * characters from ISO 8859-1.
670 * If this table is used instead of the above one, some of the special
671 * cases for the NEL character can be taken out of the code.
674 private unsigned char ebcdic_1047_to_8859[] = {
675 0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
676 0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
677 0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
678 0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
679 0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
680 0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
681 0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
682 0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
683 0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
684 0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
685 0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
686 0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
687 0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
688 0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
689 0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
690 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
695 * Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
698 from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
702 for (i = 0; i < nbytes; i++) {
703 out[i] = ebcdic_to_ascii[buf[i]];