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/*
* Copyright (C) by Marco d'Itri <md@linux.it>.
*
* simple_recode was inspired by a similar function found in Simon
* Josefsson's libidn.
*
* 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 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <iconv.h>
#include <langinfo.h>
#include "utils.h"
#include "simple_recode.h"
/* Global variables */
iconv_t simple_recode_iconv_handle;
const char *simple_recode_input_charset;
/*
* These value should be tuned to an acceptable compromise between memory
* usage and calling iconv(3) as few times as possible.
*/
#define SIMPLE_RECODE_BUFFER_SIZE_1 256
#define SIMPLE_RECODE_BUFFER_SIZE_2 1024
#define SIMPLE_RECODE_BUFFER_INCREMENT 1
/*
* Convert a NULL-terminated string accordingly to the provided iconv(3)
* handle. The returned string is allocated using malloc(3) and needs to be
* deallocated by the caller.
* Incomplete, invalid and impossible to recode sequences are copied as-is.
* On failure, NULL is returned and errno is set.
*/
char *simple_recode(const iconv_t handle, const char *str)
{
char *inp = (char *) str;
char *outp, *result;
size_t inbytes_remaining, outbytes_remaining, outbuf_size;
inbytes_remaining = strlen(inp);
if (inbytes_remaining + 1 <= SIMPLE_RECODE_BUFFER_SIZE_1
- (SIMPLE_RECODE_BUFFER_SIZE_1 >> SIMPLE_RECODE_BUFFER_INCREMENT))
outbuf_size = SIMPLE_RECODE_BUFFER_SIZE_1;
else
outbuf_size = inbytes_remaining + 1
+ (inbytes_remaining >> SIMPLE_RECODE_BUFFER_INCREMENT);
outp = result = malloc(outbuf_size);
if (!result)
return NULL;
outbytes_remaining = outbuf_size - 1;
do {
size_t err = iconv(handle, &inp, &inbytes_remaining, &outp,
&outbytes_remaining);
if (err != (size_t) -1)
break; /* success */
switch (errno) {
case EINVAL: /* incomplete multibyte sequence */
case EILSEQ: /* invalid multibyte sequence */
#ifdef SIMPLE_RECODE_SKIP_INVALID_SEQUENCES
/* recover from invalid input by replacing it with a '?' */
inp++;
*outp++ = '?'; /* use U+FFFD for unicode output? how? */
#else
/* garbage in, garbage out */
*outp++ = *inp++;
#endif
inbytes_remaining--;
outbytes_remaining--;
continue;
case E2BIG:
{
size_t used = outp - result;
size_t newsize;
char *new_result;
if (outbuf_size < SIMPLE_RECODE_BUFFER_SIZE_2)
newsize = SIMPLE_RECODE_BUFFER_SIZE_2;
else
newsize = outbuf_size
+ (outbuf_size >> SIMPLE_RECODE_BUFFER_INCREMENT);
/* check if the newsize variable has overflowed */
if (newsize <= outbuf_size) {
free(result);
errno = ENOMEM;
return NULL;
}
outbuf_size = newsize;
new_result = realloc(result, outbuf_size);
if (!new_result) {
free(result);
return NULL;
}
result = new_result;
/* update the position in the new output stream */
outp = result + used;
outbytes_remaining = outbuf_size - used - 1;
continue;
}
default:
free(result);
return NULL;
}
} while (inbytes_remaining > 0);
*outp = '\0';
return result;
}
/*
* Like fputs(3), but transparently recodes s using the global variable
* simple_recode_input_charset as the input charset and the current locale
* as the output charset.
* If simple_recode_input_charset is NULL it just calls fputs(3).
* Exits with an error if iconv(3) or iconv_open(3) fail.
*
* Assumes that setlocale(3) has already been called.
*
* If appropriate, the iconv object referenced by the global variable
* simple_recode_iconv_handle should be deallocated with iconv_close(3).
*/
int recode_fputs(const char *s, FILE *stream)
{
char *out;
int result;
if (simple_recode_input_charset == NULL) /* no conversion is needed */
return fputs(s, stream);
if (simple_recode_iconv_handle == NULL) {
simple_recode_iconv_handle = iconv_open(nl_langinfo(CODESET),
simple_recode_input_charset);
if (simple_recode_iconv_handle == (iconv_t) - 1)
err_sys("iconv_open");
}
out = simple_recode(simple_recode_iconv_handle, s);
if (!out)
err_sys("iconv");
result = fputs(out, stream);
free(out);
return result;
}
void simple_recode_iconv_close(void)
{
if (simple_recode_iconv_handle == NULL)
return;
iconv_close(simple_recode_iconv_handle);
simple_recode_iconv_handle = NULL;
simple_recode_input_charset = NULL;
}
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