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 1.39 2022/09/13 18:46:07 christos Exp $")
39 #endif /* lint */
40
41 #include "magic.h"
42 #include <string.h>
43 #include <stdlib.h>
44
45
46 private int looks_ascii(const unsigned char *, size_t, file_unichar_t *,
47 size_t *);
48 private int looks_utf8_with_BOM(const unsigned char *, size_t, file_unichar_t *,
49 size_t *);
50 private int looks_utf7(const unsigned char *, size_t, file_unichar_t *,
51 size_t *);
52 private int looks_ucs16(const unsigned char *, size_t, file_unichar_t *,
53 size_t *);
54 private int looks_ucs32(const unsigned char *, size_t, file_unichar_t *,
55 size_t *);
56 private int looks_latin1(const unsigned char *, size_t, file_unichar_t *,
57 size_t *);
58 private int looks_extended(const unsigned char *, size_t, file_unichar_t *,
59 size_t *);
60 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 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 private char text_chars[256] = {
241 /* BEL BS HT LF VT FF CR */
242 F, F, F, F, F, F, F, T, T, T, T, T, T, T, F, F, /* 0x0X */
243 /* ESC */
244 F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
245 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
246 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
247 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
248 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
249 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
250 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
251 /* NEL */
252 X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
253 X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
254 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
255 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
256 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
257 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
258 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
259 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
260 };
261
262 #define LOOKS(NAME, COND) \
263 private int \
264 looks_ ## NAME(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf, \
265 size_t *ulen) \
266 { \
267 size_t i; \
268 \
269 *ulen = 0; \
270 \
271 for (i = 0; i < nbytes; i++) { \
272 int t = text_chars[buf[i]]; \
273 \
274 if (COND) \
275 return 0; \
276 \
277 ubuf[(*ulen)++] = buf[i]; \
278 } \
279 return 1; \
280 }
281
282 LOOKS(ascii, t != T)
283 LOOKS(latin1, t != T && t != I)
284 LOOKS(extended, t != T && t != I && t != X)
285
286 /*
287 * Decide whether some text looks like UTF-8. Returns:
288 *
289 * -1: invalid UTF-8
290 * 0: uses odd control characters, so doesn't look like text
291 * 1: 7-bit text
292 * 2: definitely UTF-8 text (valid high-bit set bytes)
293 *
294 * If ubuf is non-NULL on entry, text is decoded into ubuf, *ulen;
295 * ubuf must be big enough!
296 */
297
298 // from: https://golang.org/src/unicode/utf8/utf8.go
299
300 #define XX 0xF1 // invalid: size 1
301 #define AS 0xF0 // ASCII: size 1
302 #define S1 0x02 // accept 0, size 2
303 #define S2 0x13 // accept 1, size 3
304 #define S3 0x03 // accept 0, size 3
305 #define S4 0x23 // accept 2, size 3
306 #define S5 0x34 // accept 3, size 4
307 #define S6 0x04 // accept 0, size 4
308 #define S7 0x44 // accept 4, size 4
309
310 #define LOCB 0x80
311 #define HICB 0xBF
312
313 // first is information about the first byte in a UTF-8 sequence.
314 static const uint8_t first[] = {
315 // 1 2 3 4 5 6 7 8 9 A B C D E F
316 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x00-0x0F
317 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x10-0x1F
318 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x20-0x2F
319 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x30-0x3F
320 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x40-0x4F
321 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x50-0x5F
322 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x60-0x6F
323 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x70-0x7F
324 // 1 2 3 4 5 6 7 8 9 A B C D E F
325 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0x80-0x8F
326 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0x90-0x9F
327 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xA0-0xAF
328 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xB0-0xBF
329 XX, XX, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, // 0xC0-0xCF
330 S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, // 0xD0-0xDF
331 S2, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S4, S3, S3, // 0xE0-0xEF
332 S5, S6, S6, S6, S7, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xF0-0xFF
333 };
334
335 // acceptRange gives the range of valid values for the second byte in a UTF-8
336 // sequence.
337 struct accept_range {
338 uint8_t lo; // lowest value for second byte.
339 uint8_t hi; // highest value for second byte.
340 } accept_ranges[16] = {
341 // acceptRanges has size 16 to avoid bounds checks in the code that uses it.
342 { LOCB, HICB },
343 { 0xA0, HICB },
344 { LOCB, 0x9F },
345 { 0x90, HICB },
346 { LOCB, 0x8F },
347 };
348
349 protected int
file_looks_utf8(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)350 file_looks_utf8(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf,
351 size_t *ulen)
352 {
353 size_t i;
354 int n;
355 file_unichar_t c;
356 int gotone = 0, ctrl = 0;
357
358 if (ubuf)
359 *ulen = 0;
360
361 for (i = 0; i < nbytes; i++) {
362 if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
363 /*
364 * Even if the whole file is valid UTF-8 sequences,
365 * still reject it if it uses weird control characters.
366 */
367
368 if (text_chars[buf[i]] != T)
369 ctrl = 1;
370
371 if (ubuf)
372 ubuf[(*ulen)++] = buf[i];
373 } else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
374 return -1;
375 } else { /* 11xxxxxx begins UTF-8 */
376 int following;
377 uint8_t x = first[buf[i]];
378 const struct accept_range *ar =
379 &accept_ranges[(unsigned int)x >> 4];
380 if (x == XX)
381 return -1;
382
383 if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
384 c = buf[i] & 0x1f;
385 following = 1;
386 } else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
387 c = buf[i] & 0x0f;
388 following = 2;
389 } else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
390 c = buf[i] & 0x07;
391 following = 3;
392 } else if ((buf[i] & 0x04) == 0) { /* 111110xx */
393 c = buf[i] & 0x03;
394 following = 4;
395 } else if ((buf[i] & 0x02) == 0) { /* 1111110x */
396 c = buf[i] & 0x01;
397 following = 5;
398 } else
399 return -1;
400
401 for (n = 0; n < following; n++) {
402 i++;
403 if (i >= nbytes)
404 goto done;
405
406 if (n == 0 &&
407 (buf[i] < ar->lo || buf[i] > ar->hi))
408 return -1;
409
410 if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
411 return -1;
412
413 c = (c << 6) + (buf[i] & 0x3f);
414 }
415
416 if (ubuf)
417 ubuf[(*ulen)++] = c;
418 gotone = 1;
419 }
420 }
421 done:
422 return ctrl ? 0 : (gotone ? 2 : 1);
423 }
424
425 /*
426 * Decide whether some text looks like UTF-8 with BOM. If there is no
427 * BOM, return -1; otherwise return the result of looks_utf8 on the
428 * rest of the text.
429 */
430 private int
looks_utf8_with_BOM(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)431 looks_utf8_with_BOM(const unsigned char *buf, size_t nbytes,
432 file_unichar_t *ubuf, size_t *ulen)
433 {
434 if (nbytes > 3 && buf[0] == 0xef && buf[1] == 0xbb && buf[2] == 0xbf)
435 return file_looks_utf8(buf + 3, nbytes - 3, ubuf, ulen);
436 else
437 return -1;
438 }
439
440 private int
looks_utf7(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)441 looks_utf7(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf,
442 size_t *ulen)
443 {
444 if (nbytes > 4 && buf[0] == '+' && buf[1] == '/' && buf[2] == 'v')
445 switch (buf[3]) {
446 case '8':
447 case '9':
448 case '+':
449 case '/':
450 if (ubuf)
451 *ulen = 0;
452 return 1;
453 default:
454 return -1;
455 }
456 else
457 return -1;
458 }
459
460 #define UCS16_NOCHAR(c) ((c) >= 0xfdd0 && (c) <= 0xfdef)
461 #define UCS16_HISURR(c) ((c) >= 0xd800 && (c) <= 0xdbff)
462 #define UCS16_LOSURR(c) ((c) >= 0xdc00 && (c) <= 0xdfff)
463
464 private int
looks_ucs16(const unsigned char * bf,size_t nbytes,file_unichar_t * ubf,size_t * ulen)465 looks_ucs16(const unsigned char *bf, size_t nbytes, file_unichar_t *ubf,
466 size_t *ulen)
467 {
468 int bigend;
469 uint32_t hi;
470 size_t i;
471
472 if (nbytes < 2)
473 return 0;
474
475 if (bf[0] == 0xff && bf[1] == 0xfe)
476 bigend = 0;
477 else if (bf[0] == 0xfe && bf[1] == 0xff)
478 bigend = 1;
479 else
480 return 0;
481
482 *ulen = 0;
483 hi = 0;
484
485 for (i = 2; i + 1 < nbytes; i += 2) {
486 uint32_t uc;
487
488 if (bigend)
489 uc = CAST(uint32_t,
490 bf[i + 1] | (CAST(file_unichar_t, bf[i]) << 8));
491 else
492 uc = CAST(uint32_t,
493 bf[i] | (CAST(file_unichar_t, bf[i + 1]) << 8));
494
495 uc &= 0xffff;
496
497 switch (uc) {
498 case 0xfffe:
499 case 0xffff:
500 return 0;
501 default:
502 if (UCS16_NOCHAR(uc))
503 return 0;
504 break;
505 }
506 if (hi) {
507 if (!UCS16_LOSURR(uc))
508 return 0;
509 uc = 0x10000 + 0x400 * (hi - 1) + (uc - 0xdc00);
510 hi = 0;
511 }
512 if (uc < 128 && text_chars[CAST(size_t, uc)] != T)
513 return 0;
514 ubf[(*ulen)++] = uc;
515 if (UCS16_HISURR(uc))
516 hi = uc - 0xd800 + 1;
517 if (UCS16_LOSURR(uc))
518 return 0;
519 }
520
521 return 1 + bigend;
522 }
523
524 private int
looks_ucs32(const unsigned char * bf,size_t nbytes,file_unichar_t * ubf,size_t * ulen)525 looks_ucs32(const unsigned char *bf, size_t nbytes, file_unichar_t *ubf,
526 size_t *ulen)
527 {
528 int bigend;
529 size_t i;
530
531 if (nbytes < 4)
532 return 0;
533
534 if (bf[0] == 0xff && bf[1] == 0xfe && bf[2] == 0 && bf[3] == 0)
535 bigend = 0;
536 else if (bf[0] == 0 && bf[1] == 0 && bf[2] == 0xfe && bf[3] == 0xff)
537 bigend = 1;
538 else
539 return 0;
540
541 *ulen = 0;
542
543 for (i = 4; i + 3 < nbytes; i += 4) {
544 /* XXX fix to properly handle chars > 65536 */
545
546 if (bigend)
547 ubf[(*ulen)++] = CAST(file_unichar_t, bf[i + 3])
548 | (CAST(file_unichar_t, bf[i + 2]) << 8)
549 | (CAST(file_unichar_t, bf[i + 1]) << 16)
550 | (CAST(file_unichar_t, bf[i]) << 24);
551 else
552 ubf[(*ulen)++] = CAST(file_unichar_t, bf[i + 0])
553 | (CAST(file_unichar_t, bf[i + 1]) << 8)
554 | (CAST(file_unichar_t, bf[i + 2]) << 16)
555 | (CAST(file_unichar_t, bf[i + 3]) << 24);
556
557 if (ubf[*ulen - 1] == 0xfffe)
558 return 0;
559 if (ubf[*ulen - 1] < 128 &&
560 text_chars[CAST(size_t, ubf[*ulen - 1])] != T)
561 return 0;
562 }
563
564 return 1 + bigend;
565 }
566 #undef F
567 #undef T
568 #undef I
569 #undef X
570
571 /*
572 * This table maps each EBCDIC character to an (8-bit extended) ASCII
573 * character, as specified in the rationale for the dd(1) command in
574 * draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
575 *
576 * Unfortunately it does not seem to correspond exactly to any of the
577 * five variants of EBCDIC documented in IBM's _Enterprise Systems
578 * Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
579 * Edition, July, 1999, pp. I-1 - I-4.
580 *
581 * Fortunately, though, all versions of EBCDIC, including this one, agree
582 * on most of the printing characters that also appear in (7-bit) ASCII.
583 * Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
584 *
585 * Fortunately too, there is general agreement that codes 0x00 through
586 * 0x3F represent control characters, 0x41 a nonbreaking space, and the
587 * remainder printing characters.
588 *
589 * This is sufficient to allow us to identify EBCDIC text and to distinguish
590 * between old-style and internationalized examples of text.
591 */
592
593 private unsigned char ebcdic_to_ascii[] = {
594 0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
595 16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
596 128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
597 144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
598 ' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
599 '&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
600 '-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
601 186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
602 195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
603 202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
604 209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
605 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
606 '{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
607 '}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
608 '\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
609 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
610 };
611
612 #ifdef notdef
613 /*
614 * The following EBCDIC-to-ASCII table may relate more closely to reality,
615 * or at least to modern reality. It comes from
616 *
617 * http://ftp.s390.ibm.com/products/oe/bpxqp9.html
618 *
619 * and maps the characters of EBCDIC code page 1047 (the code used for
620 * Unix-derived software on IBM's 390 systems) to the corresponding
621 * characters from ISO 8859-1.
622 *
623 * If this table is used instead of the above one, some of the special
624 * cases for the NEL character can be taken out of the code.
625 */
626
627 private unsigned char ebcdic_1047_to_8859[] = {
628 0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
629 0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
630 0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
631 0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
632 0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
633 0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
634 0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
635 0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
636 0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
637 0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
638 0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
639 0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
640 0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
641 0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
642 0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
643 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
644 };
645 #endif
646
647 /*
648 * Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
649 */
650 private void
from_ebcdic(const unsigned char * buf,size_t nbytes,unsigned char * out)651 from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
652 {
653 size_t i;
654
655 for (i = 0; i < nbytes; i++) {
656 out[i] = ebcdic_to_ascii[buf[i]];
657 }
658 }
659