freebsd-dev/lib/libc/locale/utf8.c
Tim J. Robbins 972baa3747 Add a UTF-8 encoding method, which will eventually replace the antique
"UTF2" method. Although UTF-8 and the old UTF2 encoding are compatible
for 16-bit characters, the new UTF-8 implementation is much more strict
about rejecting malformed input and also handles the full 31 bit range
of characters.
2002-10-10 22:56:18 +00:00

205 lines
5.0 KiB
C

/*-
* Copyright (c) 2002 Tim J. Robbins
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <rune.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
rune_t _UTF8_sgetrune(const char *, size_t, char const **);
int _UTF8_sputrune(rune_t, char *, size_t, char **);
int
_UTF8_init(_RuneLocale *rl)
{
rl->sgetrune = _UTF8_sgetrune;
rl->sputrune = _UTF8_sputrune;
_CurrentRuneLocale = rl;
__mb_cur_max = 6;
return (0);
}
rune_t
_UTF8_sgetrune(const char *string, size_t n, const char **result)
{
int ch, len, mask, siglen;
rune_t lbound, wch;
if (n < 1) {
if (result != NULL)
*result = string;
return (_INVALID_RUNE);
}
/*
* Determine the number of octets that make up this character from
* the first octet, and a mask that extracts the interesting bits of
* the first octet.
*
* We also specify a lower bound for the character code to detect
* redundant, non-"shortest form" encodings. For example, the
* sequence C0 80 is _not_ a legal representation of the null
* character. This enforces a 1-to-1 mapping between character
* codes and their multibyte representations.
*/
ch = (unsigned char)*string;
if ((ch & 0x80) == 0) {
mask = 0x7f;
len = 1;
lbound = 0;
} else if ((ch & 0xe0) == 0xc0) {
mask = 0x1f;
len = 2;
lbound = 0x80;
} else if ((ch & 0xf0) == 0xe0) {
mask = 0x0f;
len = 3;
lbound = 0x800;
} else if ((ch & 0xf8) == 0xf0) {
mask = 0x07;
len = 4;
lbound = 0x10000;
} else if ((ch & 0xfc) == 0xf8) {
mask = 0x03;
len = 5;
lbound = 0x200000;
} else if ((ch & 0xfc) == 0xfc) {
mask = 0x01;
len = 6;
lbound = 0x4000000;
} else {
/*
* Malformed input; input is not UTF-8.
*/
if (result != NULL)
*result = string + 1;
return (_INVALID_RUNE);
}
if (n < len) {
/*
* Truncated or partial input.
*/
if (result != NULL)
*result = string;
return (_INVALID_RUNE);
}
/*
* Decode the octet sequence representing the character in chunks
* of 6 bits, most significant first.
*/
wch = (unsigned char)*string++ & mask;
while (--len != 0) {
if ((*string & 0xc0) != 0x80) {
/*
* Malformed input; bad characters in the middle
* of a character.
*/
wch = _INVALID_RUNE;
if (result != NULL)
*result = string + 1;
return (_INVALID_RUNE);
}
wch <<= 6;
wch |= *string++ & 0x3f;
}
if (wch != _INVALID_RUNE && wch < lbound)
/*
* Malformed input; redundant encoding.
*/
wch = _INVALID_RUNE;
if (result != NULL)
*result = string;
return (wch);
}
int
_UTF8_sputrune(rune_t c, char *string, size_t n, char **result)
{
unsigned char lead;
int i, len;
/*
* Determine the number of octets needed to represent this character.
* We always output the shortest sequence possible. Also specify the
* first few bits of the first octet, which contains the information
* about the sequence length.
*/
if ((c & ~0x7f) == 0) {
lead = 0;
len = 1;
} else if ((c & ~0x7ff) == 0) {
lead = 0xc0;
len = 2;
} else if ((c & ~0xffff) == 0) {
lead = 0xe0;
len = 3;
} else if ((c & ~0x1fffff) == 0) {
lead = 0xf0;
len = 4;
} else if ((c & ~0x3ffffff) == 0) {
lead = 0xf8;
len = 5;
} else if ((c & ~0x7fffffff) == 0) {
lead = 0xfc;
len = 6;
} else {
/*
* Wide character code is out of range.
*/
if (result != NULL)
*result = NULL;
return (0);
}
if (n < len) {
if (result != NULL)
*result = NULL;
} else {
/*
* Output the octets representing the character in chunks
* of 6 bits, least significant last. The first octet is
* a special case because it contains the sequence length
* information.
*/
for (i = len - 1; i > 0; i--) {
string[i] = (c & 0x3f) | 0x80;
c >>= 6;
}
*string = (c & 0xff) | lead;
if (result != NULL)
*result = string + len;
}
return (len);
}