lib/unicodeio.c

   1 /* Unicode character output to streams with locale dependent encoding.
   2
   3    Copyright (C) 2000-2003 Free Software Foundation, Inc.
   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, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License along
  16    with this program; if not, write to the Free Software Foundation,
  17    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  18
  19 /* Written by Bruno Haible <haible@clisp.cons.org>.  */
  20
  21 /* Note: This file requires the locale_charset() function.  See in
  22    libiconv-1.8/libcharset/INTEGRATE for how to obtain it.  */
  23
  24 #ifdef HAVE_CONFIG_H
  25 # include <config.h>
  26 #endif
  27
  28 /* Specification.  */
  29 #include "unicodeio.h"
  30
  31 #include <stdio.h>
  32 #include <string.h>
  33
  34 #include <errno.h>
  35 #ifndef errno
  36 extern int errno;
  37 #endif
  38
  39 #if HAVE_ICONV
  40 # include <iconv.h>
  41 #endif
  42
  43 #include <error.h>
  44
  45 #include "gettext.h"
  46 #define _(msgid) gettext (msgid)
  47 #define N_(msgid) msgid
  48
  49 #include "localcharset.h"
  50
  51 /* When we pass a Unicode character to iconv(), we must pass it in a
  52    suitable encoding. The standardized Unicode encodings are
  53    UTF-8, UCS-2, UCS-4, UTF-16, UTF-16BE, UTF-16LE, UTF-7.
  54    UCS-2 supports only characters up to \U0000FFFF.
  55    UTF-16 and variants support only characters up to \U0010FFFF.
  56    UTF-7 is way too complex and not supported by glibc-2.1.
  57    UCS-4 specification leaves doubts about endianness and byte order
  58    mark. glibc currently interprets it as big endian without byte order
  59    mark, but this is not backed by an RFC.
  60    So we use UTF-8. It supports characters up to \U7FFFFFFF and is
  61    unambiguously defined.  */
  62
  63 /* Stores the UTF-8 representation of the Unicode character wc in r[0..5].
  64    Returns the number of bytes stored, or -1 if wc is out of range.  */
  65 static int
  66 utf8_wctomb (unsigned char *r, unsigned int wc)
  67 {
  68   int count;
  69
  70   if (wc < 0x80)
  71     count = 1;
  72   else if (wc < 0x800)
  73     count = 2;
  74   else if (wc < 0x10000)
  75     count = 3;
  76   else if (wc < 0x200000)
  77     count = 4;
  78   else if (wc < 0x4000000)
  79     count = 5;
  80   else if (wc <= 0x7fffffff)
  81     count = 6;
  82   else
  83     return -1;
  84
  85   switch (count)
  86     {
  87       /* Note: code falls through cases! */
  88       case 6: r[5] = 0x80 | (wc & 0x3f); wc = wc >> 6; wc |= 0x4000000;
  89       case 5: r[4] = 0x80 | (wc & 0x3f); wc = wc >> 6; wc |= 0x200000;
  90       case 4: r[3] = 0x80 | (wc & 0x3f); wc = wc >> 6; wc |= 0x10000;
  91       case 3: r[2] = 0x80 | (wc & 0x3f); wc = wc >> 6; wc |= 0x800;
  92       case 2: r[1] = 0x80 | (wc & 0x3f); wc = wc >> 6; wc |= 0xc0;
  93       case 1: r[0] = wc;
  94     }
  95
  96   return count;
  97 }
  98
  99 /* Luckily, the encoding's name is platform independent.  */
 100 #define UTF8_NAME "UTF-8"
 101
 102 /* Converts the Unicode character CODE to its multibyte representation
 103    in the current locale and calls the SUCCESS callback on the resulting
 104    byte sequence.  If an error occurs, invokes the FAILURE callback instead,
 105    passing it CODE and an English error string.
 106    Returns whatever the callback returned.
 107    Assumes that the locale doesn't change between two calls.  */
 108 long
 109 unicode_to_mb (unsigned int code,
 110                long (*success) (const char *buf, size_t buflen,
 111                                 void *callback_arg),
 112                long (*failure) (unsigned int code, const char *msg,
 113                                 void *callback_arg),
 114                void *callback_arg)
 115 {
 116   static int initialized;
 117   static int is_utf8;
 118 #if HAVE_ICONV
 119   static iconv_t utf8_to_local;
 120 #endif
 121
 122   char inbuf[6];
 123   int count;
 124
 125   if (!initialized)
 126     {
 127       const char *charset = locale_charset ();
 128
 129       is_utf8 = !strcmp (charset, UTF8_NAME);
 130 #if HAVE_ICONV
 131       if (!is_utf8)
 132         {
 133           utf8_to_local = iconv_open (charset, UTF8_NAME);
 134           if (utf8_to_local == (iconv_t)(-1))
 135             /* For an unknown encoding, assume ASCII.  */
 136             utf8_to_local = iconv_open ("ASCII", UTF8_NAME);
 137         }
 138 #endif
 139       initialized = 1;
 140     }
 141
 142   /* Test whether the utf8_to_local converter is available at all.  */
 143   if (!is_utf8)
 144     {
 145 #if HAVE_ICONV
 146       if (utf8_to_local == (iconv_t)(-1))
 147         return failure (code, N_("iconv function not usable"), callback_arg);
 148 #else
 149       return failure (code, N_("iconv function not available"), callback_arg);
 150 #endif
 151     }
 152
 153   /* Convert the character to UTF-8.  */
 154   count = utf8_wctomb ((unsigned char *) inbuf, code);
 155   if (count < 0)
 156     return failure (code, N_("character out of range"), callback_arg);
 157
 158 #if HAVE_ICONV
 159   if (!is_utf8)
 160     {
 161       char outbuf[25];
 162       const char *inptr;
 163       size_t inbytesleft;
 164       char *outptr;
 165       size_t outbytesleft;
 166       size_t res;
 167
 168       inptr = inbuf;
 169       inbytesleft = count;
 170       outptr = outbuf;
 171       outbytesleft = sizeof (outbuf);
 172
 173       /* Convert the character from UTF-8 to the locale's charset.  */
 174       res = iconv (utf8_to_local,
 175                    (ICONV_CONST char **)&inptr, &inbytesleft,
 176                    &outptr, &outbytesleft);
 177       if (inbytesleft > 0 || res == (size_t)(-1)
 178           /* Irix iconv() inserts a NUL byte if it cannot convert. */
 179 # if !defined _LIBICONV_VERSION && (defined sgi || defined __sgi)
 180           || (res > 0 && code != 0 && outptr - outbuf == 1 && *outbuf == '\0')
 181 # endif
 182          )
 183         return failure (code, NULL, callback_arg);
 184
 185       /* Avoid glibc-2.1 bug and Solaris 7 bug.  */
 186 # if defined _LIBICONV_VERSION \
 187     || !((__GLIBC__ - 0 == 2 && __GLIBC_MINOR__ - 0 <= 1) || defined __sun)
 188
 189       /* Get back to the initial shift state.  */
 190       res = iconv (utf8_to_local, NULL, NULL, &outptr, &outbytesleft);
 191       if (res == (size_t)(-1))
 192         return failure (code, NULL, callback_arg);
 193 # endif
 194
 195       return success (outbuf, outptr - outbuf, callback_arg);
 196     }
 197 #endif
 198
 199   /* At this point, is_utf8 is true, so no conversion is needed.  */
 200   return success (inbuf, count, callback_arg);
 201 }
 202
 203 /* Simple success callback that outputs the converted string.
 204    The STREAM is passed as callback_arg.  */
 205 long
 206 fwrite_success_callback (const char *buf, size_t buflen, void *callback_arg)
 207 {
 208   FILE *stream = (FILE *) callback_arg;
 209
 210   fwrite (buf, 1, buflen, stream);
 211   return 0;
 212 }
 213
 214 /* Simple failure callback that displays an error and exits.  */
 215 static long
 216 exit_failure_callback (unsigned int code, const char *msg, void *callback_arg)
 217 {
 218   if (msg == NULL)
 219     error (1, 0, _("cannot convert U+%04X to local character set"), code);
 220   else
 221     error (1, 0, _("cannot convert U+%04X to local character set: %s"), code,
 222            gettext (msg));
 223   return -1;
 224 }
 225
 226 /* Simple failure callback that displays a fallback representation in plain
 227    ASCII, using the same notation as ISO C99 strings.  */
 228 static long
 229 fallback_failure_callback (unsigned int code, const char *msg, void *callback_arg)
 230 {
 231   FILE *stream = (FILE *) callback_arg;
 232
 233   if (code < 0x10000)
 234     fprintf (stream, "\\u%04X", code);
 235   else
 236     fprintf (stream, "\\U%08X", code);
 237   return -1;
 238 }
 239
 240 /* Outputs the Unicode character CODE to the output stream STREAM.
 241    Upon failure, exit if exit_on_error is true, otherwise output a fallback
 242    notation.  */
 243 void
 244 print_unicode_char (FILE *stream, unsigned int code, int exit_on_error)
 245 {
 246   unicode_to_mb (code, fwrite_success_callback,
 247                  exit_on_error
 248                  ? exit_failure_callback
 249                  : fallback_failure_callback,
 250                  stream);
 251 }