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 1.27 2021/02/05 21:33:49 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 unsigned char *nbuf = NULL;
84 file_unichar_t *udefbuf;
85 size_t udeflen;
86
87 if (ubuf == NULL)
88 ubuf = &udefbuf;
89 if (ulen == NULL)
90 ulen = &udeflen;
91
92 *type = "text";
93 *ulen = 0;
94 *code = "unknown";
95 *code_mime = "binary";
96
97 if (nbytes > ms->encoding_max)
98 nbytes = ms->encoding_max;
99
100 mlen = (nbytes + 1) * sizeof((*ubuf)[0]);
101 *ubuf = CAST(file_unichar_t *, ecalloc(CAST(size_t, 1), mlen));
102 if (*ubuf == NULL) {
103 file_oomem(ms, mlen);
104 goto done;
105 }
106 mlen = (nbytes + 1) * sizeof(nbuf[0]);
107 if ((nbuf = CAST(unsigned char *,
108 ecalloc(CAST(size_t, 1), mlen))) == NULL) {
109 file_oomem(ms, mlen);
110 goto done;
111 }
112
113 if (looks_ascii(buf, nbytes, *ubuf, ulen)) {
114 if (looks_utf7(buf, nbytes, *ubuf, ulen) > 0) {
115 DPRINTF(("utf-7 %" SIZE_T_FORMAT "u\n", *ulen));
116 *code = "Unicode text, UTF-7";
117 *code_mime = "utf-7";
118 } else {
119 DPRINTF(("ascii %" SIZE_T_FORMAT "u\n", *ulen));
120 *code = "ASCII";
121 *code_mime = "us-ascii";
122 }
123 } else if (looks_utf8_with_BOM(buf, nbytes, *ubuf, ulen) > 0) {
124 DPRINTF(("utf8/bom %" SIZE_T_FORMAT "u\n", *ulen));
125 *code = "Unicode text, UTF-8 (with BOM)";
126 *code_mime = "utf-8";
127 } else if (file_looks_utf8(buf, nbytes, *ubuf, ulen) > 1) {
128 DPRINTF(("utf8 %" SIZE_T_FORMAT "u\n", *ulen));
129 *code = "Unicode text, UTF-8";
130 *code_mime = "utf-8";
131 } else if ((ucs_type = looks_ucs32(buf, nbytes, *ubuf, ulen)) != 0) {
132 if (ucs_type == 1) {
133 *code = "Unicode text, UTF-32, little-endian";
134 *code_mime = "utf-32le";
135 } else {
136 *code = "Unicode text, UTF-32, big-endian";
137 *code_mime = "utf-32be";
138 }
139 DPRINTF(("ucs32 %" SIZE_T_FORMAT "u\n", *ulen));
140 } else if ((ucs_type = looks_ucs16(buf, nbytes, *ubuf, ulen)) != 0) {
141 if (ucs_type == 1) {
142 *code = "Unicode text, UTF-16, little-endian";
143 *code_mime = "utf-16le";
144 } else {
145 *code = "Unicode text, UTF-16, big-endian";
146 *code_mime = "utf-16be";
147 }
148 DPRINTF(("ucs16 %" SIZE_T_FORMAT "u\n", *ulen));
149 } else if (looks_latin1(buf, nbytes, *ubuf, ulen)) {
150 DPRINTF(("latin1 %" SIZE_T_FORMAT "u\n", *ulen));
151 *code = "ISO-8859";
152 *code_mime = "iso-8859-1";
153 } else if (looks_extended(buf, nbytes, *ubuf, ulen)) {
154 DPRINTF(("extended %" SIZE_T_FORMAT "u\n", *ulen));
155 *code = "Non-ISO extended-ASCII";
156 *code_mime = "unknown-8bit";
157 } else {
158 from_ebcdic(buf, nbytes, nbuf);
159
160 if (looks_ascii(nbuf, nbytes, *ubuf, ulen)) {
161 DPRINTF(("ebcdic %" SIZE_T_FORMAT "u\n", *ulen));
162 *code = "EBCDIC";
163 *code_mime = "ebcdic";
164 } else if (looks_latin1(nbuf, nbytes, *ubuf, ulen)) {
165 DPRINTF(("ebcdic/international %" SIZE_T_FORMAT "u\n",
166 *ulen));
167 *code = "International EBCDIC";
168 *code_mime = "ebcdic";
169 } else { /* Doesn't look like text at all */
170 DPRINTF(("binary\n"));
171 rv = 0;
172 *type = "binary";
173 }
174 }
175
176 done:
177 efree(nbuf);
178 if (ubuf == &udefbuf)
179 efree(udefbuf);
180
181 return rv;
182 }
183
184 /*
185 * This table reflects a particular philosophy about what constitutes
186 * "text," and there is room for disagreement about it.
187 *
188 * Version 3.31 of the file command considered a file to be ASCII if
189 * each of its characters was approved by either the isascii() or
190 * isalpha() function. On most systems, this would mean that any
191 * file consisting only of characters in the range 0x00 ... 0x7F
192 * would be called ASCII text, but many systems might reasonably
193 * consider some characters outside this range to be alphabetic,
194 * so the file command would call such characters ASCII. It might
195 * have been more accurate to call this "considered textual on the
196 * local system" than "ASCII."
197 *
198 * It considered a file to be "International language text" if each
199 * of its characters was either an ASCII printing character (according
200 * to the real ASCII standard, not the above test), a character in
201 * the range 0x80 ... 0xFF, or one of the following control characters:
202 * backspace, tab, line feed, vertical tab, form feed, carriage return,
203 * escape. No attempt was made to determine the language in which files
204 * of this type were written.
205 *
206 *
207 * The table below considers a file to be ASCII if all of its characters
208 * are either ASCII printing characters (again, according to the X3.4
209 * standard, not isascii()) or any of the following controls: bell,
210 * backspace, tab, line feed, form feed, carriage return, esc, nextline.
211 *
212 * I include bell because some programs (particularly shell scripts)
213 * use it literally, even though it is rare in normal text. I exclude
214 * vertical tab because it never seems to be used in real text. I also
215 * include, with hesitation, the X3.64/ECMA-43 control nextline (0x85),
216 * because that's what the dd EBCDIC->ASCII table maps the EBCDIC newline
217 * character to. It might be more appropriate to include it in the 8859
218 * set instead of the ASCII set, but it's got to be included in *something*
219 * we recognize or EBCDIC files aren't going to be considered textual.
220 * Some old Unix source files use SO/SI (^N/^O) to shift between Greek
221 * and Latin characters, so these should possibly be allowed. But they
222 * make a real mess on VT100-style displays if they're not paired properly,
223 * so we are probably better off not calling them text.
224 *
225 * A file is considered to be ISO-8859 text if its characters are all
226 * either ASCII, according to the above definition, or printing characters
227 * from the ISO-8859 8-bit extension, characters 0xA0 ... 0xFF.
228 *
229 * Finally, a file is considered to be international text from some other
230 * character code if its characters are all either ISO-8859 (according to
231 * the above definition) or characters in the range 0x80 ... 0x9F, which
232 * ISO-8859 considers to be control characters but the IBM PC and Macintosh
233 * consider to be printing characters.
234 */
235
236 #define F 0 /* character never appears in text */
237 #define T 1 /* character appears in plain ASCII text */
238 #define I 2 /* character appears in ISO-8859 text */
239 #define X 3 /* character appears in non-ISO extended ASCII (Mac, IBM PC) */
240
241 private char text_chars[256] = {
242 /* BEL BS HT LF VT FF CR */
243 F, F, F, F, F, F, F, T, T, T, T, T, T, T, F, F, /* 0x0X */
244 /* ESC */
245 F, F, F, F, F, F, F, F, F, F, F, T, F, F, F, F, /* 0x1X */
246 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x2X */
247 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x3X */
248 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x4X */
249 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x5X */
250 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, /* 0x6X */
251 T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, F, /* 0x7X */
252 /* NEL */
253 X, X, X, X, X, T, X, X, X, X, X, X, X, X, X, X, /* 0x8X */
254 X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, /* 0x9X */
255 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xaX */
256 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xbX */
257 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xcX */
258 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xdX */
259 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, /* 0xeX */
260 I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I /* 0xfX */
261 };
262
263 #define LOOKS(NAME, COND) \
264 private int \
265 looks_ ## NAME(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf, \
266 size_t *ulen) \
267 { \
268 size_t i, u; \
269 unsigned char dist[256]; \
270 memset(dist, 0, sizeof(dist)); \
271 \
272 *ulen = 0; \
273 \
274 for (i = 0; i < nbytes; i++) { \
275 int t = text_chars[buf[i]]; \
276 \
277 if (COND) \
278 return 0; \
279 \
280 ubuf[(*ulen)++] = buf[i]; \
281 dist[buf[i]]++; \
282 } \
283 u = 0; \
284 for (i = 0; i < __arraycount(dist); i++) { \
285 if (dist[i]) \
286 u += dist[i]; \
287 } \
288 if (u < 3) \
289 return 0; \
290 \
291 return 1; \
292 }
293
294 LOOKS(ascii, t != T)
295 LOOKS(latin1, t != T && t != I)
296 LOOKS(extended, t != T && t != I && t != X)
297
298 /*
299 * Decide whether some text looks like UTF-8. Returns:
300 *
301 * -1: invalid UTF-8
302 * 0: uses odd control characters, so doesn't look like text
303 * 1: 7-bit text
304 * 2: definitely UTF-8 text (valid high-bit set bytes)
305 *
306 * If ubuf is non-NULL on entry, text is decoded into ubuf, *ulen;
307 * ubuf must be big enough!
308 */
309
310 // from: https://golang.org/src/unicode/utf8/utf8.go
311
312 #define XX 0xF1 // invalid: size 1
313 #define AS 0xF0 // ASCII: size 1
314 #define S1 0x02 // accept 0, size 2
315 #define S2 0x13 // accept 1, size 3
316 #define S3 0x03 // accept 0, size 3
317 #define S4 0x23 // accept 2, size 3
318 #define S5 0x34 // accept 3, size 4
319 #define S6 0x04 // accept 0, size 4
320 #define S7 0x44 // accept 4, size 4
321
322 #define LOCB 0x80
323 #define HICB 0xBF
324
325 // first is information about the first byte in a UTF-8 sequence.
326 static const uint8_t first[] = {
327 // 1 2 3 4 5 6 7 8 9 A B C D E F
328 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x00-0x0F
329 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x10-0x1F
330 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x20-0x2F
331 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x30-0x3F
332 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x40-0x4F
333 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x50-0x5F
334 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x60-0x6F
335 AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, AS, // 0x70-0x7F
336 // 1 2 3 4 5 6 7 8 9 A B C D E F
337 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0x80-0x8F
338 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0x90-0x9F
339 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xA0-0xAF
340 XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xB0-0xBF
341 XX, XX, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, // 0xC0-0xCF
342 S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, S1, // 0xD0-0xDF
343 S2, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S3, S4, S3, S3, // 0xE0-0xEF
344 S5, S6, S6, S6, S7, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, // 0xF0-0xFF
345 };
346
347 // acceptRange gives the range of valid values for the second byte in a UTF-8
348 // sequence.
349 struct accept_range {
350 uint8_t lo; // lowest value for second byte.
351 uint8_t hi; // highest value for second byte.
352 } accept_ranges[16] = {
353 // acceptRanges has size 16 to avoid bounds checks in the code that uses it.
354 { LOCB, HICB },
355 { 0xA0, HICB },
356 { LOCB, 0x9F },
357 { 0x90, HICB },
358 { LOCB, 0x8F },
359 };
360
361 protected int
file_looks_utf8(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)362 file_looks_utf8(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf,
363 size_t *ulen)
364 {
365 size_t i;
366 int n;
367 file_unichar_t c;
368 int gotone = 0, ctrl = 0;
369
370 if (ubuf)
371 *ulen = 0;
372
373 for (i = 0; i < nbytes; i++) {
374 if ((buf[i] & 0x80) == 0) { /* 0xxxxxxx is plain ASCII */
375 /*
376 * Even if the whole file is valid UTF-8 sequences,
377 * still reject it if it uses weird control characters.
378 */
379
380 if (text_chars[buf[i]] != T)
381 ctrl = 1;
382
383 if (ubuf)
384 ubuf[(*ulen)++] = buf[i];
385 } else if ((buf[i] & 0x40) == 0) { /* 10xxxxxx never 1st byte */
386 return -1;
387 } else { /* 11xxxxxx begins UTF-8 */
388 int following;
389 uint8_t x = first[buf[i]];
390 const struct accept_range *ar = &accept_ranges[x >> 4];
391 if (x == XX)
392 return -1;
393
394 if ((buf[i] & 0x20) == 0) { /* 110xxxxx */
395 c = buf[i] & 0x1f;
396 following = 1;
397 } else if ((buf[i] & 0x10) == 0) { /* 1110xxxx */
398 c = buf[i] & 0x0f;
399 following = 2;
400 } else if ((buf[i] & 0x08) == 0) { /* 11110xxx */
401 c = buf[i] & 0x07;
402 following = 3;
403 } else if ((buf[i] & 0x04) == 0) { /* 111110xx */
404 c = buf[i] & 0x03;
405 following = 4;
406 } else if ((buf[i] & 0x02) == 0) { /* 1111110x */
407 c = buf[i] & 0x01;
408 following = 5;
409 } else
410 return -1;
411
412 for (n = 0; n < following; n++) {
413 i++;
414 if (i >= nbytes)
415 goto done;
416
417 if (n == 0 &&
418 (buf[i] < ar->lo || buf[i] > ar->hi))
419 return -1;
420
421 if ((buf[i] & 0x80) == 0 || (buf[i] & 0x40))
422 return -1;
423
424 c = (c << 6) + (buf[i] & 0x3f);
425 }
426
427 if (ubuf)
428 ubuf[(*ulen)++] = c;
429 gotone = 1;
430 }
431 }
432 done:
433 return ctrl ? 0 : (gotone ? 2 : 1);
434 }
435
436 /*
437 * Decide whether some text looks like UTF-8 with BOM. If there is no
438 * BOM, return -1; otherwise return the result of looks_utf8 on the
439 * rest of the text.
440 */
441 private int
looks_utf8_with_BOM(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)442 looks_utf8_with_BOM(const unsigned char *buf, size_t nbytes,
443 file_unichar_t *ubuf, size_t *ulen)
444 {
445 if (nbytes > 3 && buf[0] == 0xef && buf[1] == 0xbb && buf[2] == 0xbf)
446 return file_looks_utf8(buf + 3, nbytes - 3, ubuf, ulen);
447 else
448 return -1;
449 }
450
451 private int
looks_utf7(const unsigned char * buf,size_t nbytes,file_unichar_t * ubuf,size_t * ulen)452 looks_utf7(const unsigned char *buf, size_t nbytes, file_unichar_t *ubuf,
453 size_t *ulen)
454 {
455 if (nbytes > 4 && buf[0] == '+' && buf[1] == '/' && buf[2] == 'v')
456 switch (buf[3]) {
457 case '8':
458 case '9':
459 case '+':
460 case '/':
461 if (ubuf)
462 *ulen = 0;
463 return 1;
464 default:
465 return -1;
466 }
467 else
468 return -1;
469 }
470
471 private int
looks_ucs16(const unsigned char * bf,size_t nbytes,file_unichar_t * ubf,size_t * ulen)472 looks_ucs16(const unsigned char *bf, size_t nbytes, file_unichar_t *ubf,
473 size_t *ulen)
474 {
475 int bigend;
476 size_t i;
477
478 if (nbytes < 2)
479 return 0;
480
481 if (bf[0] == 0xff && bf[1] == 0xfe)
482 bigend = 0;
483 else if (bf[0] == 0xfe && bf[1] == 0xff)
484 bigend = 1;
485 else
486 return 0;
487
488 *ulen = 0;
489
490 for (i = 2; i + 1 < nbytes; i += 2) {
491 /* XXX fix to properly handle chars > 65536 */
492
493 if (bigend)
494 ubf[(*ulen)++] = bf[i + 1]
495 | (CAST(file_unichar_t, bf[i]) << 8);
496 else
497 ubf[(*ulen)++] = bf[i]
498 | (CAST(file_unichar_t, bf[i + 1]) << 8);
499
500 if (ubf[*ulen - 1] == 0xfffe)
501 return 0;
502 if (ubf[*ulen - 1] < 128 &&
503 text_chars[CAST(size_t, ubf[*ulen - 1])] != T)
504 return 0;
505 }
506
507 return 1 + bigend;
508 }
509
510 private int
looks_ucs32(const unsigned char * bf,size_t nbytes,file_unichar_t * ubf,size_t * ulen)511 looks_ucs32(const unsigned char *bf, size_t nbytes, file_unichar_t *ubf,
512 size_t *ulen)
513 {
514 int bigend;
515 size_t i;
516
517 if (nbytes < 4)
518 return 0;
519
520 if (bf[0] == 0xff && bf[1] == 0xfe && bf[2] == 0 && bf[3] == 0)
521 bigend = 0;
522 else if (bf[0] == 0 && bf[1] == 0 && bf[2] == 0xfe && bf[3] == 0xff)
523 bigend = 1;
524 else
525 return 0;
526
527 *ulen = 0;
528
529 for (i = 4; i + 3 < nbytes; i += 4) {
530 /* XXX fix to properly handle chars > 65536 */
531
532 if (bigend)
533 ubf[(*ulen)++] = CAST(file_unichar_t, bf[i + 3])
534 | (CAST(file_unichar_t, bf[i + 2]) << 8)
535 | (CAST(file_unichar_t, bf[i + 1]) << 16)
536 | (CAST(file_unichar_t, bf[i]) << 24);
537 else
538 ubf[(*ulen)++] = CAST(file_unichar_t, bf[i + 0])
539 | (CAST(file_unichar_t, bf[i + 1]) << 8)
540 | (CAST(file_unichar_t, bf[i + 2]) << 16)
541 | (CAST(file_unichar_t, bf[i + 3]) << 24);
542
543 if (ubf[*ulen - 1] == 0xfffe)
544 return 0;
545 if (ubf[*ulen - 1] < 128 &&
546 text_chars[CAST(size_t, ubf[*ulen - 1])] != T)
547 return 0;
548 }
549
550 return 1 + bigend;
551 }
552 #undef F
553 #undef T
554 #undef I
555 #undef X
556
557 /*
558 * This table maps each EBCDIC character to an (8-bit extended) ASCII
559 * character, as specified in the rationale for the dd(1) command in
560 * draft 11.2 (September, 1991) of the POSIX P1003.2 standard.
561 *
562 * Unfortunately it does not seem to correspond exactly to any of the
563 * five variants of EBCDIC documented in IBM's _Enterprise Systems
564 * Architecture/390: Principles of Operation_, SA22-7201-06, Seventh
565 * Edition, July, 1999, pp. I-1 - I-4.
566 *
567 * Fortunately, though, all versions of EBCDIC, including this one, agree
568 * on most of the printing characters that also appear in (7-bit) ASCII.
569 * Of these, only '|', '!', '~', '^', '[', and ']' are in question at all.
570 *
571 * Fortunately too, there is general agreement that codes 0x00 through
572 * 0x3F represent control characters, 0x41 a nonbreaking space, and the
573 * remainder printing characters.
574 *
575 * This is sufficient to allow us to identify EBCDIC text and to distinguish
576 * between old-style and internationalized examples of text.
577 */
578
579 private unsigned char ebcdic_to_ascii[] = {
580 0, 1, 2, 3, 156, 9, 134, 127, 151, 141, 142, 11, 12, 13, 14, 15,
581 16, 17, 18, 19, 157, 133, 8, 135, 24, 25, 146, 143, 28, 29, 30, 31,
582 128, 129, 130, 131, 132, 10, 23, 27, 136, 137, 138, 139, 140, 5, 6, 7,
583 144, 145, 22, 147, 148, 149, 150, 4, 152, 153, 154, 155, 20, 21, 158, 26,
584 ' ', 160, 161, 162, 163, 164, 165, 166, 167, 168, 213, '.', '<', '(', '+', '|',
585 '&', 169, 170, 171, 172, 173, 174, 175, 176, 177, '!', '$', '*', ')', ';', '~',
586 '-', '/', 178, 179, 180, 181, 182, 183, 184, 185, 203, ',', '%', '_', '>', '?',
587 186, 187, 188, 189, 190, 191, 192, 193, 194, '`', ':', '#', '@', '\'','=', '"',
588 195, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 196, 197, 198, 199, 200, 201,
589 202, 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', '^', 204, 205, 206, 207, 208,
590 209, 229, 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 210, 211, 212, '[', 214, 215,
591 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, ']', 230, 231,
592 '{', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 232, 233, 234, 235, 236, 237,
593 '}', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 238, 239, 240, 241, 242, 243,
594 '\\',159, 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 244, 245, 246, 247, 248, 249,
595 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 250, 251, 252, 253, 254, 255
596 };
597
598 #ifdef notdef
599 /*
600 * The following EBCDIC-to-ASCII table may relate more closely to reality,
601 * or at least to modern reality. It comes from
602 *
603 * http://ftp.s390.ibm.com/products/oe/bpxqp9.html
604 *
605 * and maps the characters of EBCDIC code page 1047 (the code used for
606 * Unix-derived software on IBM's 390 systems) to the corresponding
607 * characters from ISO 8859-1.
608 *
609 * If this table is used instead of the above one, some of the special
610 * cases for the NEL character can be taken out of the code.
611 */
612
613 private unsigned char ebcdic_1047_to_8859[] = {
614 0x00,0x01,0x02,0x03,0x9C,0x09,0x86,0x7F,0x97,0x8D,0x8E,0x0B,0x0C,0x0D,0x0E,0x0F,
615 0x10,0x11,0x12,0x13,0x9D,0x0A,0x08,0x87,0x18,0x19,0x92,0x8F,0x1C,0x1D,0x1E,0x1F,
616 0x80,0x81,0x82,0x83,0x84,0x85,0x17,0x1B,0x88,0x89,0x8A,0x8B,0x8C,0x05,0x06,0x07,
617 0x90,0x91,0x16,0x93,0x94,0x95,0x96,0x04,0x98,0x99,0x9A,0x9B,0x14,0x15,0x9E,0x1A,
618 0x20,0xA0,0xE2,0xE4,0xE0,0xE1,0xE3,0xE5,0xE7,0xF1,0xA2,0x2E,0x3C,0x28,0x2B,0x7C,
619 0x26,0xE9,0xEA,0xEB,0xE8,0xED,0xEE,0xEF,0xEC,0xDF,0x21,0x24,0x2A,0x29,0x3B,0x5E,
620 0x2D,0x2F,0xC2,0xC4,0xC0,0xC1,0xC3,0xC5,0xC7,0xD1,0xA6,0x2C,0x25,0x5F,0x3E,0x3F,
621 0xF8,0xC9,0xCA,0xCB,0xC8,0xCD,0xCE,0xCF,0xCC,0x60,0x3A,0x23,0x40,0x27,0x3D,0x22,
622 0xD8,0x61,0x62,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0xAB,0xBB,0xF0,0xFD,0xFE,0xB1,
623 0xB0,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F,0x70,0x71,0x72,0xAA,0xBA,0xE6,0xB8,0xC6,0xA4,
624 0xB5,0x7E,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7A,0xA1,0xBF,0xD0,0x5B,0xDE,0xAE,
625 0xAC,0xA3,0xA5,0xB7,0xA9,0xA7,0xB6,0xBC,0xBD,0xBE,0xDD,0xA8,0xAF,0x5D,0xB4,0xD7,
626 0x7B,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0xAD,0xF4,0xF6,0xF2,0xF3,0xF5,
627 0x7D,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F,0x50,0x51,0x52,0xB9,0xFB,0xFC,0xF9,0xFA,0xFF,
628 0x5C,0xF7,0x53,0x54,0x55,0x56,0x57,0x58,0x59,0x5A,0xB2,0xD4,0xD6,0xD2,0xD3,0xD5,
629 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0xB3,0xDB,0xDC,0xD9,0xDA,0x9F
630 };
631 #endif
632
633 /*
634 * Copy buf[0 ... nbytes-1] into out[], translating EBCDIC to ASCII.
635 */
636 private void
from_ebcdic(const unsigned char * buf,size_t nbytes,unsigned char * out)637 from_ebcdic(const unsigned char *buf, size_t nbytes, unsigned char *out)
638 {
639 size_t i;
640
641 for (i = 0; i < nbytes; i++) {
642 out[i] = ebcdic_to_ascii[buf[i]];
643 }
644 }
645