diff options
Diffstat (limited to 'simple_recode.c')
| -rw-r--r-- | simple_recode.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/simple_recode.c b/simple_recode.c new file mode 100644 index 0000000..d4b0072 --- /dev/null +++ b/simple_recode.c @@ -0,0 +1,182 @@ +/* + * 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. + */ + +#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; +} + |