mdw@git.distorted.org.uk Git - disorder/blob - lib/charset.c

   1 /*
   2  * This file is part of DisOrder.
   3  * Copyright (C) 2004, 2005 Richard Kettlewell
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  18  * USA
  19  */
  20 /** @file lib/charset.c @brief Character set conversion */
  21
  22 #include <config.h>
  23 #include "types.h"
  24
  25 #include <iconv.h>
  26 #include <string.h>
  27 #include <errno.h>
  28 #include <langinfo.h>
  29
  30 #include "mem.h"
  31 #include "log.h"
  32 #include "charset.h"
  33 #include "configuration.h"
  34 #include "vector.h"
  35 #include "unicode.h"
  36
  37 /** @brief Low-level converstion routine
  38  * @param from Source encoding
  39  * @param to Destination encoding
  40  * @param ptr First byte to convert
  41  * @param n Number of bytes to convert
  42  * @return Converted text, 0-terminated; or NULL on error.
  43  */
  44 static void *convert(const char *from, const char *to,
  45                      const void *ptr, size_t n) {
  46   iconv_t i;
  47   size_t len;
  48   char *buf = 0, *s, *d;
  49   size_t bufsize = 0, sl, dl;
  50
  51   if((i = iconv_open(to, from)) == (iconv_t)-1)
  52     fatal(errno, "error calling iconv_open");
  53   do {
  54     bufsize = bufsize ? 2 * bufsize : 32;
  55     buf = xrealloc_noptr(buf, bufsize);
  56     iconv(i, 0, 0, 0, 0);
  57     s = (char *)ptr;
  58     sl = n;
  59     d = buf;
  60     dl = bufsize;
  61     /* (void *) to work around FreeBSD's nonstandard iconv prototype */
  62     len = iconv(i, (void *)&s, &sl, &d, &dl);
  63   } while(len == (size_t)-1 && errno == E2BIG);
  64   iconv_close(i);
  65   if(len == (size_t)-1) {
  66     error(errno, "error converting from %s to %s", from, to);
  67     return 0;
  68   }
  69   return buf;
  70 }
  71
  72 /** @brief Convert from the local multibyte encoding to UTF-8 */
  73 char *mb2utf8(const char *mb) {
  74   return convert(nl_langinfo(CODESET), "UTF-8", mb, strlen(mb) + 1);
  75 }
  76
  77 /** @brief Convert from UTF-8 to the local multibyte encoding */
  78 char *utf82mb(const char *utf8) {
  79   return convert("UTF-8", nl_langinfo(CODESET), utf8, strlen(utf8) + 1);
  80 }
  81
  82 /** @brief Convert from encoding @p from to UTF-8 */
  83 char *any2utf8(const char *from, const char *any) {
  84   return convert(from, "UTF-8", any, strlen(any) + 1);
  85 }
  86
  87 /** @brief Convert from encoding @p from to the local multibyte encoding */
  88 char *any2mb(const char *from, const char *any) {
  89   if(from) return convert(from, nl_langinfo(CODESET), any, strlen(any) + 1);
  90   else return xstrdup(any);
  91 }
  92
  93 /** @brief Convert from encoding @p from to encoding @p to */
  94 char *any2any(const char *from,
  95               const char *to,
  96               const char *any) {
  97   if(from || to) return convert(from, to, any, strlen(any) + 1);
  98   else return xstrdup(any);
  99 }
 100
 101 /** @brief Truncate a string for display purposes
 102  * @param s Pointer to UTF-8 string
 103  * @param max Maximum number of columns
 104  * @return @p or truncated string (never NULL)
 105  *
 106  * Returns a string that is no longer than @p max graphemes long and is either
 107  * (canonically) equal to @p s or is a truncated form of it with an ellipsis
 108  * appended.
 109  *
 110  * We don't take display width into account (tricky for HTML!) and we don't
 111  * attempt to implement the Bidi algorithm.  If you have track names for which
 112  * either of these matter in practice then get in touch.
 113  */
 114 const char *truncate_for_display(const char *s, long max) {
 115   uint32_t *s32;
 116   size_t l32, cut;
 117   utf32_iterator it;
 118
 119   /* Convert to UTF-32 for processing */
 120   if(!(s32 = utf8_to_utf32(s, strlen(s), &l32)))
 121     return 0;
 122   it = utf32_iterator_new(s32, l32);
 123   cut = l32;
 124   while(max && utf32_iterator_where(it) < l32) {
 125     utf32_iterator_advance(it, 1);
 126     if(utf32_iterator_grapheme_boundary(it))
 127       --max;
 128     if(max == 1)
 129       cut = utf32_iterator_where(it);
 130   }
 131   if(max == 0) {                        /* we need to cut */
 132     s32[cut] = 0x2026;                  /* HORIZONTAL ELLIPSIS */
 133     l32 = cut + 1;
 134     s = utf32_to_utf8(s32, l32, 0);
 135   }
 136   xfree(s32);
 137   return s;
 138 }
 139
 140 /*
 141 Local Variables:
 142 c-basic-offset:2
 143 comment-column:40
 144 fill-column:79
 145 indent-tabs-mode:nil
 146 End:
 147 */