2 * Copyright (C) 2001 Edmund Grimley Evans <edmundo@rano.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 * See the corresponding header file for a description of the functions
21 * that this file provides.
23 * This was first written for Ogg Vorbis but could be of general use.
25 * The only deliberate assumption about data sizes is that a short has
26 * at least 16 bits, but this code has only been tested on systems with
27 * 8-bit char, 16-bit short and 32-bit int.
34 #ifndef HAVE_ICONV /* should be ifdef USE_CHARSET_CONVERT */
43 * This is like the standard strcasecmp, but it does not depend
44 * on the locale. Locale-dependent functions can be dangerous:
45 * we once had a bug involving strcasecmp("iso", "ISO") in a
48 * (I'm not really sure what the official standard says
49 * about the sign of strcasecmp("Z", "["), but usually
50 * we're only interested in whether it's zero.)
53 static int ascii_strcasecmp(const char *s1, const char *s2)
63 if ('a' <= c1 && c1 <= 'z')
66 if ('a' <= c2 && c2 <= 'z')
71 return (unsigned char)*s1 - (unsigned char)*s2;
75 * UTF-8 equivalents of the C library's wctomb() and mbtowc().
78 int utf8_mbtowc(int *pwc, const char *s, size_t n)
95 if (n >= 2 && (s[1] & 0xc0) == 0x80) {
97 *pwc = ((c & 0x1f) << 6) | (s[1] & 0x3f);
116 wc = *s++ & ((1 << (7 - k)) - 1);
117 for (i = 1; i < k; i++) {
118 if ((*s & 0xc0) != 0x80)
120 wc = (wc << 6) | (*s++ & 0x3f);
122 if (wc < (1 << (5 * k - 4)))
129 int utf8_wctomb(char *s, int wc1)
131 unsigned int wc = wc1;
139 else if (wc < (1 << 11)) {
140 *s++ = 0xc0 | (wc >> 6);
141 *s++ = 0x80 | (wc & 0x3f);
144 else if (wc < (1 << 16)) {
145 *s++ = 0xe0 | (wc >> 12);
146 *s++ = 0x80 | ((wc >> 6) & 0x3f);
147 *s++ = 0x80 | (wc & 0x3f);
150 else if (wc < (1 << 21)) {
151 *s++ = 0xf0 | (wc >> 18);
152 *s++ = 0x80 | ((wc >> 12) & 0x3f);
153 *s++ = 0x80 | ((wc >> 6) & 0x3f);
154 *s++ = 0x80 | (wc & 0x3f);
157 else if (wc < (1 << 26)) {
158 *s++ = 0xf8 | (wc >> 24);
159 *s++ = 0x80 | ((wc >> 18) & 0x3f);
160 *s++ = 0x80 | ((wc >> 12) & 0x3f);
161 *s++ = 0x80 | ((wc >> 6) & 0x3f);
162 *s++ = 0x80 | (wc & 0x3f);
165 else if (wc < (1 << 31)) {
166 *s++ = 0xfc | (wc >> 30);
167 *s++ = 0x80 | ((wc >> 24) & 0x3f);
168 *s++ = 0x80 | ((wc >> 18) & 0x3f);
169 *s++ = 0x80 | ((wc >> 12) & 0x3f);
170 *s++ = 0x80 | ((wc >> 6) & 0x3f);
171 *s++ = 0x80 | (wc & 0x3f);
179 * The charset "object" and methods.
184 int (*mbtowc)(void *table, int *pwc, const char *s, size_t n);
185 int (*wctomb)(void *table, char *s, int wc);
189 int charset_mbtowc(struct charset *charset, int *pwc, const char *s, size_t n)
191 return (*charset->mbtowc)(charset->map, pwc, s, n);
194 int charset_wctomb(struct charset *charset, char *s, int wc)
196 return (*charset->wctomb)(charset->map, s, wc);
199 int charset_max(struct charset *charset)
205 * Implementation of UTF-8.
208 static int mbtowc_utf8(void *map, int *pwc, const char *s, size_t n)
210 return utf8_mbtowc(pwc, s, n);
213 static int wctomb_utf8(void *map, char *s, int wc)
215 return utf8_wctomb(s, wc);
219 * Implementation of US-ASCII.
220 * Probably on most architectures this compiles to less than 256 bytes
221 * of code, so we can save space by not having a table for this one.
224 static int mbtowc_ascii(void *map, int *pwc, const char *s, size_t n)
230 wc = (unsigned char)*s;
238 static int wctomb_ascii(void *map, char *s, int wc)
249 * Implementation of ISO-8859-1.
250 * Probably on most architectures this compiles to less than 256 bytes
251 * of code, so we can save space by not having a table for this one.
254 static int mbtowc_iso1(void *map, int *pwc, const char *s, size_t n)
260 wc = (unsigned char)*s;
268 static int wctomb_iso1(void *map, char *s, int wc)
279 * Implementation of any 8-bit charset.
283 const unsigned short *from;
284 struct inverse_map *to;
287 static int mbtowc_8bit(void *map1, int *pwc, const char *s, size_t n)
289 struct map *map = map1;
294 wc = map->from[(unsigned char)*s];
303 * For the inverse map we use a hash table, which has the advantages
304 * of small constant memory requirement and simple memory allocation,
305 * but the disadvantage of slow conversion in the worst case.
306 * If you need real-time performance while letting a potentially
307 * malicious user define their own map, then the method used in
308 * linux/drivers/char/consolemap.c would be more appropriate.
312 unsigned char first[256];
313 unsigned char next[256];
317 * The simple hash is good enough for this application.
318 * Use the alternative trivial hashes for testing.
320 #define HASH(i) ((i) & 0xff)
321 /* #define HASH(i) 0 */
322 /* #define HASH(i) 99 */
324 static struct inverse_map *make_inverse_map(const unsigned short *from)
326 struct inverse_map *to;
330 to = (struct inverse_map *)malloc(sizeof(struct inverse_map));
333 for (i = 0; i < 256; i++)
334 to->first[i] = to->next[i] = used[i] = 0;
335 for (i = 255; i >= 0; i--)
336 if (from[i] != 0xffff) {
338 to->next[i] = to->first[k];
343 /* Point the empty buckets at an empty list. */
344 for (i = 0; i < 256; i++)
348 for (j = 0; j < 256; j++)
355 int wctomb_8bit(void *map1, char *s, int wc1)
357 struct map *map = map1;
358 unsigned short wc = wc1;
367 if (1) /* Change 1 to 0 to test the case where malloc fails. */
369 map->to = make_inverse_map(map->from);
372 /* Use the inverse map. */
373 i = map->to->first[HASH(wc)];
375 if (map->from[i] == wc) {
379 if (!(i = map->to->next[i]))
384 /* We don't have an inverse map, so do a linear search. */
385 for (i = 0; i < 256; i++)
386 if (map->from[i] == wc) {
396 * The "constructor" charset_find().
399 struct charset charset_utf8 = {
406 struct charset charset_iso1 = {
413 struct charset charset_ascii = {
420 struct charset *charset_find(const char *code)
424 /* Find good (MIME) name. */
425 for (i = 0; names[i].bad; i++)
426 if (!ascii_strcasecmp(code, names[i].bad)) {
427 code = names[i].good;
431 /* Recognise some charsets for which we avoid using a table. */
432 if (!ascii_strcasecmp(code, "UTF-8"))
433 return &charset_utf8;
434 if (!ascii_strcasecmp(code, "US-ASCII"))
435 return &charset_ascii;
436 if (!ascii_strcasecmp(code, "ISO-8859-1"))
437 return &charset_iso1;
439 /* Look for a mapping for a simple 8-bit encoding. */
440 for (i = 0; maps[i].name; i++)
441 if (!ascii_strcasecmp(code, maps[i].name)) {
442 if (!maps[i].charset) {
443 maps[i].charset = (struct charset *)malloc(sizeof(struct charset));
444 if (maps[i].charset) {
445 struct map *map = (struct map *)malloc(sizeof(struct map));
447 free(maps[i].charset);
451 maps[i].charset->max = 1;
452 maps[i].charset->mbtowc = &mbtowc_8bit;
453 maps[i].charset->wctomb = &wctomb_8bit;
454 maps[i].charset->map = map;
455 map->from = maps[i].map;
456 map->to = 0; /* inverse mapping is created when required */
460 return maps[i].charset;
467 * Function to convert a buffer from one encoding to another.
468 * Invalid bytes are replaced by '#', and characters that are
469 * not available in the target encoding are replaced by '?'.
470 * Each of TO and TOLEN may be zero, if the result is not needed.
471 * The output buffer is null-terminated, so it is all right to
472 * use charset_convert(fromcode, tocode, s, strlen(s), &t, 0).
475 int charset_convert(const char *fromcode, const char *tocode,
476 const char *from, size_t fromlen,
477 char **to, size_t *tolen)
480 struct charset *charset1, *charset2;
481 char *tobuf, *p, *newbuf;
484 charset1 = charset_find(fromcode);
485 charset2 = charset_find(tocode);
486 if (!charset1 || !charset2 )
489 tobuf = (char *)malloc(fromlen * charset2->max + 1);
493 for (p = tobuf; fromlen; from += i, fromlen -= i, p += j) {
494 i = charset_mbtowc(charset1, &wc, from, fromlen);
502 j = charset_wctomb(charset2, p, wc);
506 j = charset_wctomb(charset2, p, '?');
516 newbuf = realloc(tobuf, p - tobuf);
517 *to = newbuf ? newbuf : tobuf;
525 #endif /* USE_CHARSET_ICONV */