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 1.5 2010/07/21 16:47:17 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_ucs16(const unsigned char *, size_t, unichar *, size_t *);
51 private int looks_latin1(const unsigned char *, size_t, unichar *, size_t *);
52 private int looks_extended(const unsigned char *, size_t, unichar *, size_t *);
53 private void from_ebcdic(const unsigned char *, size_t, unsigned char *);
56 #define DPRINTF(a) printf a
62 * Try to determine whether text is in some character code we can
63 * identify. Each of these tests, if it succeeds, will leave
64 * the text converted into one-unichar-per-character Unicode in
65 * ubuf, and the number of characters converted in ulen.
68 file_encoding(struct magic_set *ms, const unsigned char *buf, size_t nbytes, unichar **ubuf, size_t *ulen, const char **code, const char **code_mime, const char **type)
72 unsigned char *nbuf = NULL;
74 mlen = (nbytes + 1) * sizeof(nbuf[0]);
75 if ((nbuf = CAST(unsigned char *, calloc((size_t)1, mlen))) == NULL) {
79 mlen = (nbytes + 1) * sizeof((*ubuf)[0]);
80 if ((*ubuf = CAST(unichar *, calloc((size_t)1, mlen))) == NULL) {
86 if (looks_ascii(buf, nbytes, *ubuf, ulen)) {
87 DPRINTF(("ascii %" SIZE_T_FORMAT "u\n", *ulen));
89 *code_mime = "us-ascii";
90 } else if (looks_utf8_with_BOM(buf, nbytes, *ubuf, ulen) > 0) {
91 DPRINTF(("utf8/bom %" SIZE_T_FORMAT "u\n", *ulen));
92 *code = "UTF-8 Unicode (with BOM)";
94 } else if (file_looks_utf8(buf, nbytes, *ubuf, ulen) > 1) {
95 DPRINTF(("utf8 %" SIZE_T_FORMAT "u\n", *ulen));
96 *code = "UTF-8 Unicode (with BOM)";
97 *code = "UTF-8 Unicode";
99 } else if ((ucs_type = looks_ucs16(buf, nbytes, *ubuf, ulen)) != 0) {
101 *code = "Little-endian UTF-16 Unicode";
102 *code_mime = "utf-16le";
104 *code = "Big-endian UTF-16 Unicode";
105 *code_mime = "utf-16be";
107 DPRINTF(("ucs16 %" SIZE_T_FORMAT "u\n", *ulen));
108 } else if (looks_latin1(buf, nbytes, *ubuf, ulen)) {
109 DPRINTF(("latin1 %" SIZE_T_FORMAT "u\n", *ulen));
111 *code_mime = "iso-8859-1";
112 } else if (looks_extended(buf, nbytes, *ubuf, ulen)) {
113 DPRINTF(("extended %" SIZE_T_FORMAT "u\n", *ulen));
114 *code = "Non-ISO extended-ASCII";
115 *code_mime = "unknown-8bit";
117 from_ebcdic(buf, nbytes, nbuf);
119 if (looks_ascii(nbuf, nbytes, *ubuf, ulen)) {
120 DPRINTF(("ebcdic %" SIZE_T_FORMAT "u\n", *ulen));
122 *code_mime = "ebcdic";
123 } else if (looks_latin1(nbuf, nbytes, *ubuf, ulen)) {
124 DPRINTF(("ebcdic/international %" SIZE_T_FORMAT "u\n",
126 *code = "International EBCDIC";
127 *code_mime = "ebcdic";
128 } else { /* Doesn't look like text at all */
129 DPRINTF(("binary\n"));
143 * This table reflects a particular philosophy about what constitutes
144 * "text," and there is room for disagreement about it.
146 * Version 3.31 of the file command considered a file to be ASCII if
147 * each of its characters was approved by either the isascii() or
148 * isalpha() function. On most systems, this would mean that any
149 * file consisting only of characters in the range 0x00 ... 0x7F
150 * would be called ASCII text, but many systems might reasonably
151 * consider some characters outside this range to be alphabetic,
152 * so the file command would call such characters ASCII. It might
153 * have been more accurate to call this "considered textual on the
154 * local system" than "ASCII."
156 * It considered a file to be "International language text" if each
157 * of its characters was either an ASCII printing character (according
158 * to the real ASCII standard, not the above test), a character in
159 * the range 0x80 ... 0xFF, or one of the following control characters:
160 * backspace, tab, line feed, vertical tab, form feed, carriage return,
161 * escape. No attempt was made to determine the language in which files
162 * of this type were written.
165 * The table below considers a file to be ASCII if all of its characters
166 * are either ASCII printing characters (again, according to the X3.4
167 * standard, not isascii()) or any of the following controls: bell,
168 * backspace, tab, line feed, form feed, carriage return, esc, nextline.
170 * I include bell because some programs (particularly shell scripts)
171 * use it literally, even though it is rare in normal text. I exclude
172 * vertical tab because it never seems to be used in real text. I also
173 * include, with hesitation, the X3.64/ECMA-43 control nextline (0x85),
174 * because that's what the dd EBCDIC->ASCII table maps the EBCDIC newline
175 * character to. It might be more appropriate to include it in the 8859
176 * set instead of the ASCII set, but it's got to be included in *something*
177 * we recognize or EBCDIC files aren't going to be considered textual.
178 * Some old Unix source files use SO/SI (^N/^O) to shift between Greek
179 * and Latin characters, so these should possibly be allowed. But they
180 * make a real mess on VT100-style displays if they're not paired properly,
181 * so we are probably better off not calling them text.
183 * A file is considered to be ISO-8859 text if its characters are all
184 * either ASCII, according to the above definition, or printing characters
185 * from the ISO-8859 8-bit extension, characters 0xA0 ... 0xFF.
187 * Finally, a file is considered to be international text from some other
188 * character code if its characters are all either ISO-8859 (according to
189 * the above definition) or characters in the range 0x80 ... 0x9F, which
190 * ISO-8859 considers to be control characters but the IBM PC and Macintosh
191 * consider to be printing characters.
194 #define F 0 /* character never appears in text */
195 #define T 1 /* character appears in plain ASCII text */
196 #define I 2 /* character appears in ISO-8859 text */
197 #define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
199 private char text_chars[256] = {
200 /* BEL BS HT LF FF CR */
201 F, F, F, F, F, F, F, T, T, T, T, F, T, T, F, F, /* 0x0X */
203 F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
204 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
205 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
206 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
207 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
208 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
209 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
211 X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
212 X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
213 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
214 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
215 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
216 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
217 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
218 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
222 looks_ascii(const unsigned char *buf, size_t nbytes, unichar *ubuf,
229 for (i = 0; i < nbytes; i++) {
230 int t = text_chars[buf[i]];
235 ubuf[(*ulen)++] = buf[i];
242 looks_latin1(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
248 for (i = 0; i < nbytes; i++) {
249 int t = text_chars[buf[i]];
251 if (t != T && t != I)
254 ubuf[(*ulen)++] = buf[i];
261 looks_extended(const unsigned char *buf, size_t nbytes, unichar *ubuf,
268 for (i = 0; i < nbytes; i++) {
269 int t = text_chars[buf[i]];
271 if (t != T && t != I && t != X)
274 ubuf[(*ulen)++] = buf[i];
281 * Decide whether some text looks like UTF-8. Returns:
284 * 0: uses odd control characters, so doesn't look like text
286 * 2: definitely UTF-8 text (valid high-bit set bytes)
288 * If ubuf is non-NULL on entry, text is decoded into ubuf, *ulen;
289 * ubuf must be big enough!
292 file_looks_utf8(const unsigned char *buf, size_t nbytes, unichar *ubuf, size_t *ulen)
297 int gotone = 0, ctrl = 0;
302 for (i = 0; i < nbytes; i++) {
303 if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
305 * Even if the whole file is valid UTF-8 sequences,
306 * still reject it if it uses weird control characters.
309 if (text_chars[buf[i]] != T)
313 ubuf[(*ulen)++] = buf[i];
314 } else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
316 } else { /* 11xxxxxx begins UTF-8 */
319 if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
322 } else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
325 } else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
328 } else if ((buf[i] & 0x04) == 0) { /* 111110xx */
331 } else if ((buf[i] & 0x02) == 0) { /* 1111110x */
337 for (n = 0; n < following; n++) {
342 if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
345 c = (c << 6) + (buf[i] & 0x3f);
354 return ctrl ? 0 : (gotone ? 2 : 1);
358 * Decide whether some text looks like UTF-8 with BOM. If there is no
359 * BOM, return -1; otherwise return the result of looks_utf8 on the
363 looks_utf8_with_BOM(const unsigned char *buf, size_t nbytes, unichar *ubuf,
366 if (nbytes > 3 && buf[0] == 0xef && buf[1] == 0xbb && buf[2] == 0xbf)
367 return file_looks_utf8(buf + 3, nbytes - 3, ubuf, ulen);
373 looks_ucs16(const unsigned char *buf, size_t nbytes, unichar *ubuf,
382 if (buf[0] == 0xff && buf[1] == 0xfe)
384 else if (buf[0] == 0xfe && buf[1] == 0xff)
391 for (i = 2; i + 1 < nbytes; i += 2) {
392 /* XXX fix to properly handle chars > 65536 */
395 ubuf[(*ulen)++] = buf[i + 1] + 256 * buf[i];
397 ubuf[(*ulen)++] = buf[i] + 256 * buf[i + 1];
399 if (ubuf[*ulen - 1] == 0xfffe)
401 if (ubuf[*ulen - 1] < 128 &&
402 text_chars[(size_t)ubuf[*ulen - 1]] != T)
415 * This table maps each EBCDIC character to an (8-bit extended) ASCII
416 * character, as specified in the rationale for the dd(1) command in
417 * draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
419 * Unfortunately it does not seem to correspond exactly to any of the
420 * five variants of EBCDIC documented in IBM's _Enterprise Systems
421 * Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
422 * Edition, July, 1999, pp. I-1 - I-4.
424 * Fortunately, though, all versions of EBCDIC, including this one, agree
425 * on most of the printing characters that also appear in (7-bit) ASCII.
426 * Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
428 * Fortunately too, there is general agreement that codes 0x00 through
429 * 0x3F represent control characters, 0x41 a nonbreaking space, and the
430 * remainder printing characters.
432 * This is sufficient to allow us to identify EBCDIC text and to distinguish
433 * between old-style and internationalized examples of text.
436 private unsigned char ebcdic_to_ascii[] = {
437 0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
438 16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
439 128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
440 144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
441 ' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
442 '&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
443 '-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
444 186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
445 195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
446 202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
447 209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
448 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
449 '{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
450 '}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
451 '\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
452 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
457 * The following EBCDIC-to-ASCII table may relate more closely to reality,
458 * or at least to modern reality. It comes from
460 * http://ftp.s390.ibm.com/products/oe/bpxqp9.html
462 * and maps the characters of EBCDIC code page 1047 (the code used for
463 * Unix-derived software on IBM's 390 systems) to the corresponding
464 * characters from ISO 8859-1.
466 * If this table is used instead of the above one, some of the special
467 * cases for the NEL character can be taken out of the code.
470 private unsigned char ebcdic_1047_to_8859[] = {
471 0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
472 0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
473 0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
474 0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
475 0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
476 0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
477 0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
478 0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
479 0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
480 0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
481 0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
482 0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
483 0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
484 0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
485 0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
486 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
491 * Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
494 from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
498 for (i = 0; i < nbytes; i++) {
499 out[i] = ebcdic_to_ascii[buf[i]];