1 /*
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.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
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.
15 *
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
26 * SUCH DAMAGE.
27 */
28 /*
29 * Encoding -- determine the character encoding of a text file.
30 *
31 * Joerg Wunsch <joerg@freebsd.org> wrote the original support for 8-bit
32 * international characters.
33 */
34
35 #include "file.h"
36
37 #ifndef lint
38 FILE_RCSID("@(#)$File: encoding.c,v 1.44 2024/12/26 18:41:27 christos Exp $")
39 #endif /* lint */
40
41 #include "magic.h"
42 #include <string.h>
43 #include <stdlib.h>
44
45
46 file_private int looks_ascii(const unsigned char *, size_t, file_unichar_t *,
47 size_t *);
48 file_private int looks_utf8_with_BOM(const unsigned char *, size_t, file_unichar_t *,
49 size_t *);
50 file_private int looks_utf7(const unsigned char *, size_t, file_unichar_t *,
51 size_t *);
52 file_private int looks_ucs16(const unsigned char *, size_t, file_unichar_t *,
53 size_t *);
54 file_private int looks_ucs32(const unsigned char *, size_t, file_unichar_t *,
55 size_t *);
56 file_private int looks_latin1(const unsigned char *, size_t, file_unichar_t *,
57 size_t *);
58 file_private int looks_extended(const unsigned char *, size_t, file_unichar_t *,
59 size_t *);
60 file_private void from_ebcdic(const unsigned char *, size_t, unsigned char *);
61
62 #ifdef DEBUG_ENCODING
63 #define DPRINTF(a) printf a
64 #else
65 #define DPRINTF(a)
66 #endif
67
68 /*
69 * Try to determine whether text is in some character code we can
70 * identify. Each of these tests, if it succeeds, will leave
71 * the text converted into one-file_unichar_t-per-character Unicode in
72 * ubuf, and the number of characters converted in ulen.
73 */
74 file_protected int
file_encoding(struct magic_set * ms,const struct buffer * b,file_unichar_t ** ubuf,size_t * ulen,const char ** code,const char ** code_mime,const char ** type)75 file_encoding(struct magic_set *ms, const struct buffer *b,
76 file_unichar_t **ubuf, size_t *ulen, const char **code,
77 const char **code_mime, const char **type)
78 {
79 const unsigned char *buf = CAST(const unsigned char *, b->fbuf);
80 size_t nbytes = b->flen;
81 size_t mlen;
82 int rv = 1, ucs_type;
83 file_unichar_t *udefbuf;
84 size_t udeflen;
85
86 if (ubuf == NULL)
87 ubuf = &udefbuf;
88 if (ulen == NULL)
89 ulen = &udeflen;
90
91 *type = "text";
92 *ulen = 0;
93 *code = "unknown";
94 *code_mime = "binary";
95
96 if (nbytes > ms->encoding_max)
97 nbytes = ms->encoding_max;
98
99 mlen = (nbytes + 1) * sizeof((*ubuf)[0]);
100 *ubuf = CAST(file_unichar_t *, calloc(CAST(size_t, 1), mlen));
101 if (*ubuf == NULL) {
102 file_oomem(ms, mlen);
103 goto done;
104 }
105 if (looks_ascii(buf, nbytes, *ubuf, ulen)) {
106 if (looks_utf7(buf, nbytes, *ubuf, ulen) > 0) {
107 DPRINTF(("utf-7 %" SIZE_T_FORMAT "u\n", *ulen));
108 *code = "Unicode text, UTF-7";
109 *code_mime = "utf-7";
110 } else {
111 DPRINTF(("ascii %" SIZE_T_FORMAT "u\n", *ulen));
112 *code = "ASCII";
113 *code_mime = "us-ascii";
114 }
115 } else if (looks_utf8_with_BOM(buf, nbytes, *ubuf, ulen) > 0) {
116 DPRINTF(("utf8/bom %" SIZE_T_FORMAT "u\n", *ulen));
117 *code = "Unicode text, UTF-8 (with BOM)";
118 *code_mime = "utf-8";
119 } else if (file_looks_utf8(buf, nbytes, *ubuf, ulen) > 1) {
120 DPRINTF(("utf8 %" SIZE_T_FORMAT "u\n", *ulen));
121 *code = "Unicode text, UTF-8";
122 *code_mime = "utf-8";
123 } else if ((ucs_type = looks_ucs32(buf, nbytes, *ubuf, ulen)) != 0) {
124 if (ucs_type == 1) {
125 *code = "Unicode text, UTF-32, little-endian";
126 *code_mime = "utf-32le";
127 } else {
128 *code = "Unicode text, UTF-32, big-endian";
129 *code_mime = "utf-32be";
130 }
131 DPRINTF(("ucs32 %" SIZE_T_FORMAT "u\n", *ulen));
132 } else if ((ucs_type = looks_ucs16(buf, nbytes, *ubuf, ulen)) != 0) {
133 if (ucs_type == 1) {
134 *code = "Unicode text, UTF-16, little-endian";
135 *code_mime = "utf-16le";
136 } else {
137 *code = "Unicode text, UTF-16, big-endian";
138 *code_mime = "utf-16be";
139 }
140 DPRINTF(("ucs16 %" SIZE_T_FORMAT "u\n", *ulen));
141 } else if (looks_latin1(buf, nbytes, *ubuf, ulen)) {
142 DPRINTF(("latin1 %" SIZE_T_FORMAT "u\n", *ulen));
143 *code = "ISO-8859";
144 *code_mime = "iso-8859-1";
145 } else if (looks_extended(buf, nbytes, *ubuf, ulen)) {
146 DPRINTF(("extended %" SIZE_T_FORMAT "u\n", *ulen));
147 *code = "Non-ISO extended-ASCII";
148 *code_mime = "unknown-8bit";
149 } else {
150 unsigned char *nbuf;
151
152 mlen = (nbytes + 1) * sizeof(nbuf[0]);
153 if ((nbuf = CAST(unsigned char *, malloc(mlen))) == NULL) {
154 file_oomem(ms, mlen);
155 goto done;
156 }
157 from_ebcdic(buf, nbytes, nbuf);
158
159 if (looks_ascii(nbuf, nbytes, *ubuf, ulen)) {
160 DPRINTF(("ebcdic %" SIZE_T_FORMAT "u\n", *ulen));
161 *code = "EBCDIC";
162 *code_mime = "ebcdic";
163 } else if (looks_latin1(nbuf, nbytes, *ubuf, ulen)) {
164 DPRINTF(("ebcdic/international %" SIZE_T_FORMAT "u\n",
165 *ulen));
166 *code = "International EBCDIC";
167 *code_mime = "ebcdic";
168 } else { /* Doesn't look like text at all */
169 DPRINTF(("binary\n"));
170 rv = 0;
171 *type = "binary";
172 }
173 free(nbuf);
174 }
175
176 done:
177 if (ubuf == &udefbuf)
178 free(udefbuf);
179
180 return rv;
181 }
182
183 /*
184 * This table reflects a particular philosophy about what constitutes
185 * "text," and there is room for disagreement about it.
186 *
187 * Version 3.31 of the file command considered a file to be ASCII if
188 * each of its characters was approved by either the isascii() or
189 * isalpha() function. On most systems, this would mean that any
190 * file consisting only of characters in the range 0x00 ... 0x7F
191 * would be called ASCII text, but many systems might reasonably
192 * consider some characters outside this range to be alphabetic,
193 * so the file command would call such characters ASCII. It might
194 * have been more accurate to call this "considered textual on the
195 * local system" than "ASCII."
196 *
197 * It considered a file to be "International language text" if each
198 * of its characters was either an ASCII printing character (according
199 * to the real ASCII standard, not the above test), a character in
200 * the range 0x80 ... 0xFF, or one of the following control characters:
201 * backspace, tab, line feed, vertical tab, form feed, carriage return,
202 * escape. No attempt was made to determine the language in which files
203 * of this type were written.
204 *
205 *
206 * The table below considers a file to be ASCII if all of its characters
207 * are either ASCII printing characters (again, according to the X3.4
208 * standard, not isascii()) or any of the following controls: bell,
209 * backspace, tab, line feed, form feed, carriage return, esc, nextline.
210 *
211 * I include bell because some programs (particularly shell scripts)
212 * use it literally, even though it is rare in normal text. I exclude
213 * vertical tab because it never seems to be used in real text. I also
214 * include, with hesitation, the X3.64/ECMA-43 control nextline (0x85),
215 * because that's what the dd EBCDIC->ASCII table maps the EBCDIC newline
216 * character to. It might be more appropriate to include it in the 8859
217 * set instead of the ASCII set, but it's got to be included in *something*
218 * we recognize or EBCDIC files aren't going to be considered textual.
219 * Some old Unix source files use SO/SI (^N/^O) to shift between Greek
220 * and Latin characters, so these should possibly be allowed. But they
221 * make a real mess on VT100-style displays if they're not paired properly,
222 * so we are probably better off not calling them text.
223 *
224 * A file is considered to be ISO-8859 text if its characters are all
225 * either ASCII, according to the above definition, or printing characters
226 * from the ISO-8859 8-bit extension, characters 0xA0 ... 0xFF.
227 *
228 * Finally, a file is considered to be international text from some other
229 * character code if its characters are all either ISO-8859 (according to
230 * the above definition) or characters in the range 0x80 ... 0x9F, which
231 * ISO-8859 considers to be control characters but the IBM PC and Macintosh
232 * consider to be printing characters.
233 */
234
235 #define F 0 /* character never appears in text */
236 #define T 1 /* character appears in plain ASCII text */
237 #define I 2 /* character appears in ISO-8859 text */
238 #define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
239
240 /*
241 * SUB (substitute character ^Z) was used as EOF in DOS and early Windows
242 * NEL (next line 0x85) is considered in ECMAScript as whitespace
243 */
244 file_private char text_chars[256] = {
245 /* BEL BS HT LF VT FF CR */
246 F, F, F, F, F, F, F, T, T, T, T, T, T, T, F, F, /* 0x0X */
247 /* SUB ESC */
248 F, F, F, F, F, F, F, F, F, F, T, T, F, F, F, F, /* 0x1X */
249 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
250 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
251 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
252 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
253 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
254 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
255 /* NEL */
256 X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
257 X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
258 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
259 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
260 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
261 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
262 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
263 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
264 };
265
266 #define LOOKS(NAME, COND) \
267 file_private int \
268 looks_ ## NAME(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf, \
269 size_t *ulen) \
270 { \
271 size_t i; \
272 \
273 *ulen = 0; \
274 \
275 for (i = 0; i < nbytes; i++) { \
276 int t = text_chars[buf[i]]; \
277 \
278 if (COND) \
279 return 0; \
280 \
281 ubuf[(*ulen)++] = buf[i]; \
282 } \
283 return 1; \
284 }
285
286 LOOKS(ascii, t != T)
287 LOOKS(latin1, t != T && t != I)
288 LOOKS(extended, t != T && t != I && t != X)
289
290 /*
291 * Decide whether some text looks like UTF-8. Returns:
292 *
293 * -1: invalid UTF-8
294 * 0: uses odd control characters, so doesn't look like text
295 * 1: 7-bit text
296 * 2: definitely UTF-8 text (valid high-bit set bytes)
297 *
298 * If ubuf is non-NULL on entry, text is decoded into ubuf, *ulen;
299 * ubuf must be big enough!
300 */
301
302 // from: https://golang.org/src/unicode/utf8/utf8.go
303
304 #define XX 0xF1 // invalid: size 1
305 #define AS 0xF0 // ASCII: size 1
306 #define S1 0x02 // accept 0, size 2
307 #define S2 0x13 // accept 1, size 3
308 #define S3 0x03 // accept 0, size 3
309 #define S4 0x23 // accept 2, size 3
310 #define S5 0x34 // accept 3, size 4
311 #define S6 0x04 // accept 0, size 4
312 #define S7 0x44 // accept 4, size 4
313
314 #define LOCB 0x80
315 #define HICB 0xBF
316
317 // first is information about the first byte in a UTF-8 sequence.
318 static const uint8_t first[] = {
319 // 1 2 3 4 5 6 7 8 9 A B C D E F
320 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x00-0x0F
321 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x10-0x1F
322 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x20-0x2F
323 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x30-0x3F
324 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x40-0x4F
325 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x50-0x5F
326 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x60-0x6F
327 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x70-0x7F
328 // 1 2 3 4 5 6 7 8 9 A B C D E F
329 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0x80-0x8F
330 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0x90-0x9F
331 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xA0-0xAF
332 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xB0-0xBF
333 XX, XX, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, // 0xC0-0xCF
334 S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, // 0xD0-0xDF
335 S2, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S4, S3, S3, // 0xE0-0xEF
336 S5, S6, S6, S6, S7, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xF0-0xFF
337 };
338
339 // acceptRange gives the range of valid values for the second byte in a UTF-8
340 // sequence.
341 static struct accept_range {
342 uint8_t lo; // lowest value for second byte.
343 uint8_t hi; // highest value for second byte.
344 } accept_ranges[16] = {
345 // acceptRanges has size 16 to avoid bounds checks in the code that uses it.
346 { LOCB, HICB },
347 { 0xA0, HICB },
348 { LOCB, 0x9F },
349 { 0x90, HICB },
350 { LOCB, 0x8F },
351 };
352
353 file_protected int
file_looks_utf8(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)354 file_looks_utf8(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf,
355 size_t *ulen)
356 {
357 size_t i;
358 int n;
359 file_unichar_t c;
360 int gotone = 0, ctrl = 0;
361
362 if (ubuf)
363 *ulen = 0;
364
365 for (i = 0; i < nbytes; i++) {
366 if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
367 /*
368 * Even if the whole file is valid UTF-8 sequences,
369 * still reject it if it uses weird control characters.
370 */
371
372 if (text_chars[buf[i]] != T)
373 ctrl = 1;
374
375 if (ubuf)
376 ubuf[(*ulen)++] = buf[i];
377 } else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
378 return -1;
379 } else { /* 11xxxxxx begins UTF-8 */
380 int following;
381 uint8_t x = first[buf[i]];
382 const struct accept_range *ar =
383 &accept_ranges[(unsigned int)x >> 4];
384 if (x == XX)
385 return -1;
386
387 if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
388 c = buf[i] & 0x1f;
389 following = 1;
390 } else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
391 c = buf[i] & 0x0f;
392 following = 2;
393 } else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
394 c = buf[i] & 0x07;
395 following = 3;
396 } else if ((buf[i] & 0x04) == 0) { /* 111110xx */
397 c = buf[i] & 0x03;
398 following = 4;
399 } else if ((buf[i] & 0x02) == 0) { /* 1111110x */
400 c = buf[i] & 0x01;
401 following = 5;
402 } else
403 return -1;
404
405 for (n = 0; n < following; n++) {
406 i++;
407 if (i >= nbytes)
408 goto done;
409
410 if (n == 0 &&
411 (buf[i] < ar->lo || buf[i] > ar->hi))
412 return -1;
413
414 if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
415 return -1;
416
417 c = (c << 6) + (buf[i] & 0x3f);
418 }
419
420 if (ubuf)
421 ubuf[(*ulen)++] = c;
422 gotone = 1;
423 }
424 }
425 done:
426 return ctrl ? 0 : (gotone ? 2 : 1);
427 }
428
429 /*
430 * Decide whether some text looks like UTF-8 with BOM. If there is no
431 * BOM, return -1; otherwise return the result of looks_utf8 on the
432 * rest of the text.
433 */
434 file_private int
looks_utf8_with_BOM(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)435 looks_utf8_with_BOM(const unsigned char *buf, size_t nbytes,
436 file_unichar_t *ubuf, size_t *ulen)
437 {
438 if (nbytes > 3 && buf[0] == 0xef && buf[1] == 0xbb && buf[2] == 0xbf)
439 return file_looks_utf8(buf + 3, nbytes - 3, ubuf, ulen);
440 else
441 return -1;
442 }
443
444 file_private int
looks_utf7(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)445 looks_utf7(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf,
446 size_t *ulen)
447 {
448 if (nbytes > 4 && buf[0] == '+' && buf[1] == '/' && buf[2] == 'v')
449 switch (buf[3]) {
450 case '8':
451 case '9':
452 case '+':
453 case '/':
454 if (ubuf)
455 *ulen = 0;
456 return 1;
457 default:
458 return -1;
459 }
460 else
461 return -1;
462 }
463
464 #define UCS16_NOCHAR(c) ((c) >= 0xfdd0 && (c) <= 0xfdef)
465 #define UCS16_HISURR(c) ((c) >= 0xd800 && (c) <= 0xdbff)
466 #define UCS16_LOSURR(c) ((c) >= 0xdc00 && (c) <= 0xdfff)
467
468 file_private int
looks_ucs16(const unsigned char * bf,size_t nbytes,file_unichar_t * ubf,size_t * ulen)469 looks_ucs16(const unsigned char *bf, size_t nbytes, file_unichar_t *ubf,
470 size_t *ulen)
471 {
472 int bigend;
473 uint32_t hi;
474 size_t i;
475
476 if (nbytes < 2)
477 return 0;
478
479 if (bf[0] == 0xff && bf[1] == 0xfe)
480 bigend = 0;
481 else if (bf[0] == 0xfe && bf[1] == 0xff)
482 bigend = 1;
483 else
484 return 0;
485
486 *ulen = 0;
487 hi = 0;
488
489 for (i = 2; i + 1 < nbytes; i += 2) {
490 uint32_t uc;
491
492 if (bigend)
493 uc = CAST(uint32_t,
494 bf[i + 1] | (CAST(file_unichar_t, bf[i]) << 8));
495 else
496 uc = CAST(uint32_t,
497 bf[i] | (CAST(file_unichar_t, bf[i + 1]) << 8));
498
499 uc &= 0xffff;
500
501 switch (uc) {
502 case 0xfffe:
503 case 0xffff:
504 return 0;
505 default:
506 if (UCS16_NOCHAR(uc))
507 return 0;
508 break;
509 }
510 if (hi) {
511 if (!UCS16_LOSURR(uc))
512 return 0;
513 uc = 0x10000 + 0x400 * (hi - 1) + (uc - 0xdc00);
514 hi = 0;
515 }
516 if (uc < 128 && text_chars[CAST(size_t, uc)] != T)
517 return 0;
518 ubf[(*ulen)++] = uc;
519 if (UCS16_HISURR(uc))
520 hi = uc - 0xd800 + 1;
521 if (UCS16_LOSURR(uc))
522 return 0;
523 }
524
525 return 1 + bigend;
526 }
527
528 file_private int
looks_ucs32(const unsigned char * bf,size_t nbytes,file_unichar_t * ubf,size_t * ulen)529 looks_ucs32(const unsigned char *bf, size_t nbytes, file_unichar_t *ubf,
530 size_t *ulen)
531 {
532 int bigend;
533 size_t i;
534
535 if (nbytes < 4)
536 return 0;
537
538 if (bf[0] == 0xff && bf[1] == 0xfe && bf[2] == 0 && bf[3] == 0)
539 bigend = 0;
540 else if (bf[0] == 0 && bf[1] == 0 && bf[2] == 0xfe && bf[3] == 0xff)
541 bigend = 1;
542 else
543 return 0;
544
545 *ulen = 0;
546
547 for (i = 4; i + 3 < nbytes; i += 4) {
548 /* XXX fix to properly handle chars > 65536 */
549
550 if (bigend)
551 ubf[(*ulen)++] = CAST(file_unichar_t, bf[i + 3])
552 | (CAST(file_unichar_t, bf[i + 2]) << 8)
553 | (CAST(file_unichar_t, bf[i + 1]) << 16)
554 | (CAST(file_unichar_t, bf[i]) << 24);
555 else
556 ubf[(*ulen)++] = CAST(file_unichar_t, bf[i + 0])
557 | (CAST(file_unichar_t, bf[i + 1]) << 8)
558 | (CAST(file_unichar_t, bf[i + 2]) << 16)
559 | (CAST(file_unichar_t, bf[i + 3]) << 24);
560
561 if (ubf[*ulen - 1] == 0xfffe)
562 return 0;
563 if (ubf[*ulen - 1] < 128 &&
564 text_chars[CAST(size_t, ubf[*ulen - 1])] != T)
565 return 0;
566 }
567
568 return 1 + bigend;
569 }
570 #undef F
571 #undef T
572 #undef I
573 #undef X
574
575 /*
576 * This table maps each EBCDIC character to an (8-bit extended) ASCII
577 * character, as specified in the rationale for the dd(1) command in
578 * draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
579 *
580 * Unfortunately it does not seem to correspond exactly to any of the
581 * five variants of EBCDIC documented in IBM's _Enterprise Systems
582 * Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
583 * Edition, July, 1999, pp. I-1 - I-4.
584 *
585 * Fortunately, though, all versions of EBCDIC, including this one, agree
586 * on most of the printing characters that also appear in (7-bit) ASCII.
587 * Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
588 *
589 * Fortunately too, there is general agreement that codes 0x00 through
590 * 0x3F represent control characters, 0x41 a nonbreaking space, and the
591 * remainder printing characters.
592 *
593 * This is sufficient to allow us to identify EBCDIC text and to distinguish
594 * between old-style and internationalized examples of text.
595 */
596
597 file_private unsigned char ebcdic_to_ascii[] = {
598 0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
599 16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
600 128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
601 144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
602 ' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
603 '&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
604 '-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
605 186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
606 195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
607 202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
608 209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
609 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
610 '{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
611 '}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
612 '\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
613 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
614 };
615
616 #ifdef notdef
617 /*
618 * The following EBCDIC-to-ASCII table may relate more closely to reality,
619 * or at least to modern reality. It comes from
620 *
621 * http://ftp.s390.ibm.com/products/oe/bpxqp9.html
622 *
623 * and maps the characters of EBCDIC code page 1047 (the code used for
624 * Unix-derived software on IBM's 390 systems) to the corresponding
625 * characters from ISO 8859-1.
626 *
627 * If this table is used instead of the above one, some of the special
628 * cases for the NEL character can be taken out of the code.
629 */
630
631 file_private unsigned char ebcdic_1047_to_8859[] = {
632 0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
633 0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
634 0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
635 0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
636 0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
637 0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
638 0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
639 0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
640 0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
641 0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
642 0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
643 0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
644 0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
645 0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
646 0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
647 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
648 };
649 #endif
650
651 /*
652 * Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
653 */
654 file_private void
from_ebcdic(const unsigned char * buf,size_t nbytes,unsigned char * out)655 from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
656 {
657 size_t i;
658
659 for (i = 0; i < nbytes; i++) {
660 out[i] = ebcdic_to_ascii[buf[i]];
661 }
662 }
663