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zero-epwing/convert.c

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/*
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* Copyright (C) 2017 Alex Yatskov <alex@foosoft.net>
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* Author: Alex Yatskov <alex@foosoft.net>
*
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* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
#include <iconv.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
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/*
* Local functions
*/
/* https://stackoverflow.com/questions/2162390/iconv-encoding-conversion-problem */
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static char * convert (const char *from_charset, const char *to_charset, const char *input) {
size_t inleft, outleft, converted = 0;
char *output, *outbuf, *tmp;
const char *inbuf;
size_t outlen;
iconv_t cd;
if ((cd = iconv_open (to_charset, from_charset)) == (iconv_t) -1)
return NULL;
inleft = strlen (input);
inbuf = input;
/* we'll start off allocating an output buffer which is the same size
* as our input buffer. */
outlen = inleft;
/* we allocate 4 bytes more than what we need for nul-termination... */
if (!(output = malloc (outlen + 4))) {
iconv_close (cd);
return NULL;
}
do {
errno = 0;
outbuf = output + converted;
outleft = outlen - converted;
converted = iconv (cd, (char **) &inbuf, &inleft, &outbuf, &outleft);
if (converted != (size_t) -1 || errno == EINVAL) {
/*
* EINVAL An incomplete multibyte sequence has been encoun­-
* tered in the input.
*
* We'll just truncate it and ignore it.
*/
break;
}
if (errno != E2BIG) {
/*
* EILSEQ An invalid multibyte sequence has been encountered
* in the input.
*
* Bad input, we can't really recover from this.
*/
iconv_close (cd);
free (output);
return NULL;
}
/*
* E2BIG There is not sufficient room at *outbuf.
*
* We just need to grow our outbuffer and try again.
*/
converted = outbuf - output;
outlen += inleft * 2 + 8;
if (!(tmp = realloc (output, outlen + 4))) {
iconv_close (cd);
free (output);
return NULL;
}
output = tmp;
outbuf = output + converted;
} while (1);
/* flush the iconv conversion */
iconv (cd, NULL, NULL, &outbuf, &outleft);
iconv_close (cd);
/* Note: not all charsets can be nul-terminated with a single
* nul byte. UCS2, for example, needs 2 nul bytes and UCS4
* needs 4. I hope that 4 nul bytes is enough to terminate all
* multibyte charsets? */
/* nul-terminate the string */
memset (outbuf, 0, 4);
return output;
}
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/*
* Exported functions
*/
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char* eucjp_to_utf8(const char src[]) {
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return convert("EUC-JP", "UTF-8", src);
}