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 * Encoding -- determine the character encoding of a text file.
31 * Joerg Wunsch <joerg@freebsd.org> wrote the original support for 8-bit
32 * international characters.
38 FILE_RCSID("@(#)$File: encoding.c,v 1.14 2017/11/02 20:25:39 christos Exp $")
47 private int looks_ascii(const unsigned char *, size_t, unichar *, size_t *);
48 private int looks_utf8_with_BOM(const unsigned char *, size_t, unichar *,
50 private int looks_utf7(const unsigned char *, size_t, unichar *, size_t *);
51 private int looks_ucs16(const unsigned char *, size_t, unichar *, size_t *);
52 private int looks_latin1(const unsigned char *, size_t, unichar *, size_t *);
53 private int looks_extended(const unsigned char *, size_t, unichar *, size_t *);
54 private void from_ebcdic(const unsigned char *, size_t, unsigned char *);
57 #define DPRINTF(a) printf a
63 * Try to determine whether text is in some character code we can
64 * identify. Each of these tests, if it succeeds, will leave
65 * the text converted into one-unichar-per-character Unicode in
66 * ubuf, and the number of characters converted in ulen.
69 file_encoding(struct magic_set *ms, const struct buffer *b, unichar **ubuf,
70 size_t *ulen, const char **code, const char **code_mime, const char **type)
72 const unsigned char *buf = b->fbuf;
73 size_t nbytes = b->flen;
76 unsigned char *nbuf = NULL;
88 *code_mime = "binary";
90 mlen = (nbytes + 1) * sizeof((*ubuf)[0]);
91 if ((*ubuf = CAST(unichar *, calloc((size_t)1, mlen))) == NULL) {
95 mlen = (nbytes + 1) * sizeof(nbuf[0]);
96 if ((nbuf = CAST(unsigned char *, calloc((size_t)1, mlen))) == NULL) {
101 if (looks_ascii(buf, nbytes, *ubuf, ulen)) {
102 if (looks_utf7(buf, nbytes, *ubuf, ulen) > 0) {
103 DPRINTF(("utf-7 %" SIZE_T_FORMAT "u\n", *ulen));
104 *code = "UTF-7 Unicode";
105 *code_mime = "utf-7";
107 DPRINTF(("ascii %" SIZE_T_FORMAT "u\n", *ulen));
109 *code_mime = "us-ascii";
111 } else if (looks_utf8_with_BOM(buf, nbytes, *ubuf, ulen) > 0) {
112 DPRINTF(("utf8/bom %" SIZE_T_FORMAT "u\n", *ulen));
113 *code = "UTF-8 Unicode (with BOM)";
114 *code_mime = "utf-8";
115 } else if (file_looks_utf8(buf, nbytes, *ubuf, ulen) > 1) {
116 DPRINTF(("utf8 %" SIZE_T_FORMAT "u\n", *ulen));
117 *code = "UTF-8 Unicode";
118 *code_mime = "utf-8";
119 } else if ((ucs_type = looks_ucs16(buf, nbytes, *ubuf, ulen)) != 0) {
121 *code = "Little-endian UTF-16 Unicode";
122 *code_mime = "utf-16le";
124 *code = "Big-endian UTF-16 Unicode";
125 *code_mime = "utf-16be";
127 DPRINTF(("ucs16 %" SIZE_T_FORMAT "u\n", *ulen));
128 } else if (looks_latin1(buf, nbytes, *ubuf, ulen)) {
129 DPRINTF(("latin1 %" SIZE_T_FORMAT "u\n", *ulen));
131 *code_mime = "iso-8859-1";
132 } else if (looks_extended(buf, nbytes, *ubuf, ulen)) {
133 DPRINTF(("extended %" SIZE_T_FORMAT "u\n", *ulen));
134 *code = "Non-ISO extended-ASCII";
135 *code_mime = "unknown-8bit";
137 from_ebcdic(buf, nbytes, nbuf);
139 if (looks_ascii(nbuf, nbytes, *ubuf, ulen)) {
140 DPRINTF(("ebcdic %" SIZE_T_FORMAT "u\n", *ulen));
142 *code_mime = "ebcdic";
143 } else if (looks_latin1(nbuf, nbytes, *ubuf, ulen)) {
144 DPRINTF(("ebcdic/international %" SIZE_T_FORMAT "u\n",
146 *code = "International EBCDIC";
147 *code_mime = "ebcdic";
148 } else { /* Doesn't look like text at all */
149 DPRINTF(("binary\n"));
157 if (ubuf == &udefbuf)
164 * This table reflects a particular philosophy about what constitutes
165 * "text," and there is room for disagreement about it.
167 * Version 3.31 of the file command considered a file to be ASCII if
168 * each of its characters was approved by either the isascii() or
169 * isalpha() function. On most systems, this would mean that any
170 * file consisting only of characters in the range 0x00 ... 0x7F
171 * would be called ASCII text, but many systems might reasonably
172 * consider some characters outside this range to be alphabetic,
173 * so the file command would call such characters ASCII. It might
174 * have been more accurate to call this "considered textual on the
175 * local system" than "ASCII."
177 * It considered a file to be "International language text" if each
178 * of its characters was either an ASCII printing character (according
179 * to the real ASCII standard, not the above test), a character in
180 * the range 0x80 ... 0xFF, or one of the following control characters:
181 * backspace, tab, line feed, vertical tab, form feed, carriage return,
182 * escape. No attempt was made to determine the language in which files
183 * of this type were written.
186 * The table below considers a file to be ASCII if all of its characters
187 * are either ASCII printing characters (again, according to the X3.4
188 * standard, not isascii()) or any of the following controls: bell,
189 * backspace, tab, line feed, form feed, carriage return, esc, nextline.
191 * I include bell because some programs (particularly shell scripts)
192 * use it literally, even though it is rare in normal text. I exclude
193 * vertical tab because it never seems to be used in real text. I also
194 * include, with hesitation, the X3.64/ECMA-43 control nextline (0x85),
195 * because that's what the dd EBCDIC->ASCII table maps the EBCDIC newline
196 * character to. It might be more appropriate to include it in the 8859
197 * set instead of the ASCII set, but it's got to be included in *something*
198 * we recognize or EBCDIC files aren't going to be considered textual.
199 * Some old Unix source files use SO/SI (^N/^O) to shift between Greek
200 * and Latin characters, so these should possibly be allowed. But they
201 * make a real mess on VT100-style displays if they're not paired properly,
202 * so we are probably better off not calling them text.
204 * A file is considered to be ISO-8859 text if its characters are all
205 * either ASCII, according to the above definition, or printing characters
206 * from the ISO-8859 8-bit extension, characters 0xA0 ... 0xFF.
208 * Finally, a file is considered to be international text from some other
209 * character code if its characters are all either ISO-8859 (according to
210 * the above definition) or characters in the range 0x80 ... 0x9F, which
211 * ISO-8859 considers to be control characters but the IBM PC and Macintosh
212 * consider to be printing characters.
215 #define F 0 /* character never appears in text */
216 #define T 1 /* character appears in plain ASCII text */
217 #define I 2 /* character appears in ISO-8859 text */
218 #define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
220 private char text_chars[256] = {
221 /* BEL BS HT LF VT FF CR */
222 F, F, F, F, F, F, F, T, T, T, T, T, T, T, F, F, /* 0x0X */
224 F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
225 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
226 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
227 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
228 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
229 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
230 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
232 X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
233 X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
234 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
235 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
236 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
237 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
238 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
239 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
243 looks_ascii(const unsigned char *buf, size_t nbytes, unichar *ubuf,
250 for (i = 0; i < nbytes; i++) {
251 int t = text_chars[buf[i]];
256 ubuf[(*ulen)++] = buf[i];
263 looks_latin1(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
269 for (i = 0; i < nbytes; i++) {
270 int t = text_chars[buf[i]];
272 if (t != T && t != I)
275 ubuf[(*ulen)++] = buf[i];
282 looks_extended(const unsigned char *buf, size_t nbytes, unichar *ubuf,
289 for (i = 0; i < nbytes; i++) {
290 int t = text_chars[buf[i]];
292 if (t != T && t != I && t != X)
295 ubuf[(*ulen)++] = buf[i];
302 * Decide whether some text looks like UTF-8. Returns:
305 * 0: uses odd control characters, so doesn't look like text
307 * 2: definitely UTF-8 text (valid high-bit set bytes)
309 * If ubuf is non-NULL on entry, text is decoded into ubuf, *ulen;
310 * ubuf must be big enough!
313 file_looks_utf8(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
318 int gotone = 0, ctrl = 0;
323 for (i = 0; i < nbytes; i++) {
324 if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
326 * Even if the whole file is valid UTF-8 sequences,
327 * still reject it if it uses weird control characters.
330 if (text_chars[buf[i]] != T)
334 ubuf[(*ulen)++] = buf[i];
335 } else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
337 } else { /* 11xxxxxx begins UTF-8 */
340 if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
343 } else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
346 } else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
349 } else if ((buf[i] & 0x04) == 0) { /* 111110xx */
352 } else if ((buf[i] & 0x02) == 0) { /* 1111110x */
358 for (n = 0; n < following; n++) {
363 if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
366 c = (c << 6) + (buf[i] & 0x3f);
375 return ctrl ? 0 : (gotone ? 2 : 1);
379 * Decide whether some text looks like UTF-8 with BOM. If there is no
380 * BOM, return -1; otherwise return the result of looks_utf8 on the
384 looks_utf8_with_BOM(const unsigned char *buf, size_t nbytes, unichar *ubuf,
387 if (nbytes > 3 && buf[0] == 0xef && buf[1] == 0xbb && buf[2] == 0xbf)
388 return file_looks_utf8(buf + 3, nbytes - 3, ubuf, ulen);
394 looks_utf7(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
396 if (nbytes > 4 && buf[0] == '+' && buf[1] == '/' && buf[2] == 'v')
413 looks_ucs16(const unsigned char *buf, size_t nbytes, unichar *ubuf,
422 if (buf[0] == 0xff && buf[1] == 0xfe)
424 else if (buf[0] == 0xfe && buf[1] == 0xff)
431 for (i = 2; i + 1 < nbytes; i += 2) {
432 /* XXX fix to properly handle chars > 65536 */
435 ubuf[(*ulen)++] = buf[i + 1] + 256 * buf[i];
437 ubuf[(*ulen)++] = buf[i] + 256 * buf[i + 1];
439 if (ubuf[*ulen - 1] == 0xfffe)
441 if (ubuf[*ulen - 1] < 128 &&
442 text_chars[(size_t)ubuf[*ulen - 1]] != T)
455 * This table maps each EBCDIC character to an (8-bit extended) ASCII
456 * character, as specified in the rationale for the dd(1) command in
457 * draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
459 * Unfortunately it does not seem to correspond exactly to any of the
460 * five variants of EBCDIC documented in IBM's _Enterprise Systems
461 * Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
462 * Edition, July, 1999, pp. I-1 - I-4.
464 * Fortunately, though, all versions of EBCDIC, including this one, agree
465 * on most of the printing characters that also appear in (7-bit) ASCII.
466 * Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
468 * Fortunately too, there is general agreement that codes 0x00 through
469 * 0x3F represent control characters, 0x41 a nonbreaking space, and the
470 * remainder printing characters.
472 * This is sufficient to allow us to identify EBCDIC text and to distinguish
473 * between old-style and internationalized examples of text.
476 private unsigned char ebcdic_to_ascii[] = {
477 0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
478 16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
479 128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
480 144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
481 ' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
482 '&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
483 '-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
484 186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
485 195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
486 202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
487 209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
488 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
489 '{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
490 '}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
491 '\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
492 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
497 * The following EBCDIC-to-ASCII table may relate more closely to reality,
498 * or at least to modern reality. It comes from
500 * http://ftp.s390.ibm.com/products/oe/bpxqp9.html
502 * and maps the characters of EBCDIC code page 1047 (the code used for
503 * Unix-derived software on IBM's 390 systems) to the corresponding
504 * characters from ISO 8859-1.
506 * If this table is used instead of the above one, some of the special
507 * cases for the NEL character can be taken out of the code.
510 private unsigned char ebcdic_1047_to_8859[] = {
511 0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
512 0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
513 0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
514 0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
515 0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
516 0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
517 0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
518 0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
519 0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
520 0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
521 0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
522 0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
523 0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
524 0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
525 0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
526 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
531 * Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
534 from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
538 for (i = 0; i < nbytes; i++) {
539 out[i] = ebcdic_to_ascii[buf[i]];