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netsurf/utils/utf8.c

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/*
* Copyright 2005 John M Bell <jmb202@ecs.soton.ac.uk>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf 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; version 2 of the License.
*
* NetSurf 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, see <http://www.gnu.org/licenses/>.
*/
/** \file
* UTF-8 manipulation functions (implementation).
*/
#define _GNU_SOURCE /* for strndup */
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <iconv.h>
#include "utils/config.h"
#include "utils/log.h"
#include "utils/utf8.h"
static utf8_convert_ret utf8_convert(const char *string, size_t len,
const char *from, const char *to, char **result);
/**
* Convert a UTF-8 multibyte sequence into a single UCS4 character
*
* Encoding of UCS values outside the UTF-16 plane has been removed from
* RFC3629. This function conforms to RFC2279, however.
*
* \param s The sequence to process
* \param l Length of sequence
* \return UCS4 character
*/
size_t utf8_to_ucs4(const char *s_in, size_t l)
{
size_t c = 0;
const unsigned char *s = (const unsigned char *) s_in;
if (!s)
assert(0);
else if (l > 0 && *s < 0x80)
c = *s;
else if (l > 1 && (*s & 0xE0) == 0xC0 && (*(s+1) & 0xC0) == 0x80)
c = ((*s & 0x1F) << 6) | (*(s+1) & 0x3F);
else if (l > 2 && (*s & 0xF0) == 0xE0 && (*(s+1) & 0xC0) == 0x80 &&
(*(s+2) & 0xC0) == 0x80)
c = ((*s & 0x0F) << 12) | ((*(s+1) & 0x3F) << 6) |
(*(s+2) & 0x3F);
else if (l > 3 && (*s & 0xF8) == 0xF0 && (*(s+1) & 0xC0) == 0x80 &&
(*(s+2) & 0xC0) == 0x80 && (*(s+3) & 0xC0) == 0x80)
c = ((*s & 0x0F) << 18) | ((*(s+1) & 0x3F) << 12) |
((*(s+2) & 0x3F) << 6) | (*(s+3) & 0x3F);
else if (l > 4 && (*s & 0xFC) == 0xF8 && (*(s+1) & 0xC0) == 0x80 &&
(*(s+2) & 0xC0) == 0x80 && (*(s+3) & 0xC0) == 0x80 &&
(*(s+4) & 0xC0) == 0x80)
c = ((*s & 0x0F) << 24) | ((*(s+1) & 0x3F) << 18) |
((*(s+2) & 0x3F) << 12) | ((*(s+3) & 0x3F) << 6) |
(*(s+4) & 0x3F);
else if (l > 5 && (*s & 0xFE) == 0xFC && (*(s+1) & 0xC0) == 0x80 &&
(*(s+2) & 0xC0) == 0x80 && (*(s+3) & 0xC0) == 0x80 &&
(*(s+4) & 0xC0) == 0x80 && (*(s+5) & 0xC0) == 0x80)
c = ((*s & 0x0F) << 28) | ((*(s+1) & 0x3F) << 24) |
((*(s+2) & 0x3F) << 18) | ((*(s+3) & 0x3F) << 12) |
((*(s+4) & 0x3F) << 6) | (*(s+5) & 0x3F);
else
assert(0);
return c;
}
/**
* Convert a single UCS4 character into a UTF-8 multibyte sequence
*
* Encoding of UCS values outside the UTF-16 plane has been removed from
* RFC3629. This function conforms to RFC2279, however.
*
* \param c The character to process (0 <= c <= 0x7FFFFFFF)
* \param s Pointer to 6 byte long output buffer
* \return Length of multibyte sequence
*/
size_t utf8_from_ucs4(size_t c, char *s)
{
size_t l = 0;
if (c > 0x7FFFFFFF || s == NULL)
assert(0);
else if (c < 0x80) {
*s = (char)c;
l = 1;
}
else if (c < 0x800) {
*s = 0xC0 | ((c >> 6) & 0x1F);
*(s+1) = 0x80 | (c & 0x3F);
l = 2;
}
else if (c < 0x10000) {
*s = 0xE0 | ((c >> 12) & 0xF);
*(s+1) = 0x80 | ((c >> 6) & 0x3F);
*(s+2) = 0x80 | (c & 0x3F);
l = 3;
}
else if (c < 0x200000) {
*s = 0xF0 | ((c >> 18) & 0x7);
*(s+1) = 0x80 | ((c >> 12) & 0x3F);
*(s+2) = 0x80 | ((c >> 6) & 0x3F);
*(s+3) = 0x80 | (c & 0x3F);
l = 4;
}
else if (c < 0x4000000) {
*s = 0xF8 | ((c >> 24) & 0x3);
*(s+1) = 0x80 | ((c >> 18) & 0x3F);
*(s+2) = 0x80 | ((c >> 12) & 0x3F);
*(s+3) = 0x80 | ((c >> 6) & 0x3F);
*(s+4) = 0x80 | (c & 0x3F);
l = 5;
}
else if (c <= 0x7FFFFFFF) {
*s = 0xFC | ((c >> 30) & 0x1);
*(s+1) = 0x80 | ((c >> 24) & 0x3F);
*(s+2) = 0x80 | ((c >> 18) & 0x3F);
*(s+3) = 0x80 | ((c >> 12) & 0x3F);
*(s+4) = 0x80 | ((c >> 6) & 0x3F);
*(s+5) = 0x80 | (c & 0x3F);
l = 6;
}
return l;
}
/**
* Calculate the length (in characters) of a NULL-terminated UTF-8 string
*
* \param s The string
* \return Length of string
*/
size_t utf8_length(const char *s)
{
const char *__s = s;
int l = 0;
assert(__s != NULL);
while (*__s != '\0') {
if ((*__s & 0x80) == 0x00)
__s += 1;
else if ((*__s & 0xE0) == 0xC0)
__s += 2;
else if ((*__s & 0xF0) == 0xE0)
__s += 3;
else if ((*__s & 0xF8) == 0xF0)
__s += 4;
else if ((*__s & 0xFC) == 0xF8)
__s += 5;
else if ((*__s & 0xFE) == 0xFC)
__s += 6;
else
assert(0);
l++;
}
return l;
}
/**
* Find previous legal UTF-8 char in string
*
* \param s The string
* \param o Offset in the string to start at
* \return Offset of first byte of previous legal character
*/
size_t utf8_prev(const char *s, size_t o)
{
assert(s != NULL);
while (o != 0 && (s[--o] & 0xC0) == 0x80)
/* do nothing */;
return o;
}
/**
* Find next legal UTF-8 char in string
*
* \param s The string
* \param l Maximum offset in string
* \param o Offset in the string to start at
* \return Offset of first byte of next legal character
*/
size_t utf8_next(const char *s, size_t l, size_t o)
{
assert(s != NULL);
while (o != l && (s[++o] & 0xC0) == 0x80)
/* do nothing */;
return o;
}
/* Cache of previous iconv conversion descriptor used by utf8_convert */
static struct {
char from[32]; /**< Encoding name to convert from */
char to[32]; /**< Encoding name to convert to */
iconv_t cd; /**< Iconv conversion descriptor */
} last_cd;
/**
* Finalise the UTF-8 library
*/
void utf8_finalise(void)
{
if (last_cd.cd != 0)
iconv_close(last_cd.cd);
/* paranoia follows */
last_cd.from[0] = '\0';
last_cd.to[0] = '\0';
last_cd.cd = 0;
}
/**
* Convert a UTF8 string into the named encoding
*
* \param string The NULL-terminated string to convert
* \param encname The encoding name (suitable for passing to iconv)
* \param len Length of input string to consider (in bytes), or 0
* \param result Pointer to location to store result (allocated on heap)
* \return Appropriate utf8_convert_ret value
*/
utf8_convert_ret utf8_to_enc(const char *string, const char *encname,
size_t len, char **result)
{
return utf8_convert(string, len, "UTF-8", encname, result);
}
/**
* Convert a string in the named encoding into a UTF-8 string
*
* \param string The NULL-terminated string to convert
* \param encname The encoding name (suitable for passing to iconv)
* \param len Length of input string to consider (in bytes), or 0
* \param result Pointer to location to store result (allocated on heap)
* \return Appropriate utf8_convert_ret value
*/
utf8_convert_ret utf8_from_enc(const char *string, const char *encname,
size_t len, char **result)
{
return utf8_convert(string, len, encname, "UTF-8", result);
}
/**
* Convert a string from one encoding to another
*
* \param string The NULL-terminated string to convert
* \param len Length of input string to consider (in bytes), or 0
* \param from The encoding name to convert from
* \param to The encoding name to convert to
* \param result Pointer to location in which to store result
* \return Appropriate utf8_convert_ret value
*/
utf8_convert_ret utf8_convert(const char *string, size_t len,
const char *from, const char *to, char **result)
{
iconv_t cd;
char *temp, *out, *in;
size_t slen, rlen;
assert(string && from && to && result);
if (string[0] == '\0') {
/* On AmigaOS, iconv() returns an error if we pass an
* empty string. This prevents iconv() being called as
* there is no conversion necessary anyway. */
*result = strdup("");
if (!(*result)) {
*result = NULL;
return UTF8_CONVERT_NOMEM;
}
return UTF8_CONVERT_OK;
}
if (strcasecmp(from, to) == 0) {
/* conversion from an encoding to itself == strdup */
slen = len ? len : strlen(string);
*(result) = strndup(string, slen);
if (!(*result)) {
*(result) = NULL;
return UTF8_CONVERT_NOMEM;
}
return UTF8_CONVERT_OK;
}
in = (char *)string;
/* we cache the last used conversion descriptor,
* so check if we're trying to use it here */
if (strncasecmp(last_cd.from, from, sizeof(last_cd.from)) == 0 &&
strncasecmp(last_cd.to, to, sizeof(last_cd.to)) == 0) {
cd = last_cd.cd;
}
else {
/* no match, so create a new cd */
cd = iconv_open(to, from);
if (cd == (iconv_t)-1) {
if (errno == EINVAL)
return UTF8_CONVERT_BADENC;
/* default to no memory */
return UTF8_CONVERT_NOMEM;
}
/* close the last cd - we don't care if this fails */
if (last_cd.cd)
iconv_close(last_cd.cd);
/* and copy the to/from/cd data into last_cd */
strncpy(last_cd.from, from, sizeof(last_cd.from));
strncpy(last_cd.to, to, sizeof(last_cd.to));
last_cd.cd = cd;
}
slen = len ? len : strlen(string);
/* Worst case = ACSII -> UCS4, so allocate an output buffer
* 4 times larger than the input buffer, and add 4 bytes at
* the end for the NULL terminator
*/
rlen = slen * 4 + 4;
temp = out = malloc(rlen);
if (!out)
return UTF8_CONVERT_NOMEM;
/* perform conversion */
if (iconv(cd, &in, &slen, &out, &rlen) == (size_t)-1) {
free(temp);
/* clear the cached conversion descriptor as it's invalid */
last_cd.from[0] = '\0';
last_cd.to[0] = '\0';
last_cd.cd = 0;
/** \todo handle the various cases properly
* There are 3 possible error cases:
* a) Insufficiently large output buffer
* b) Invalid input byte sequence
* c) Incomplete input sequence */
return UTF8_CONVERT_NOMEM;
}
*(result) = realloc(temp, out - temp + 4);
if (!(*result)) {
free(temp);
*(result) = NULL; /* for sanity's sake */
return UTF8_CONVERT_NOMEM;
}
/* NULL terminate - needs 4 characters as we may have
* converted to UTF-32 */
memset((*result) + (out - temp), 0, 4);
return UTF8_CONVERT_OK;
}
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