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Support mb sequences across calls to mb*to*wcs* functions

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Bug: 13077905
Change-Id: I5abdc7cc3c27c109b7900c94b112f18a95c35763
This commit is contained in:
Calin Juravle
2014-05-08 14:38:35 +01:00
parent 8b307e0e98
commit 15a6310e4b
3 changed files with 253 additions and 54 deletions
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191
libc/bionic/wchar.cpp
View File

@@ -32,23 +32,69 @@
#include <wchar.h>
//
// This file is basically OpenBSD's citrus_utf8.c but rewritten to not require a 12-byte mbstate_t
// so we're backwards-compatible with our LP32 ABI where mbstate_t was only 4 bytes. An additional
// advantage of this is that callers who don't supply their own mbstate_t won't be accessing shared
// state.
// This file is basically OpenBSD's citrus_utf8.c but rewritten to not require a
// 12-byte mbstate_t so we're backwards-compatible with our LP32 ABI where
// mbstate_t was only 4 bytes.
//
// We also implement the POSIX interface directly rather than being accessed via function pointers.
// The state is the UTF-8 sequence. We only support <= 4-bytes sequences so LP32
// mbstate_t already has enough space (out of the 4 available bytes we only
// need 3 since we should never need to store the entire sequence in the
// intermediary state).
//
// The C standard leaves the conversion state undefined after a bad conversion.
// To avoid unexpected failures due to the possible use of the internal private
// state we always reset the conversion state when encountering illegal
// sequences.
//
// We also implement the POSIX interface directly rather than being accessed via
// function pointers.
//
#define ERR_ILLEGAL_SEQUENCE static_cast<size_t>(-1)
#define ERR_INCOMPLETE_SEQUENCE static_cast<size_t>(-2)
int mbsinit(const mbstate_t*) {
// We have no state, so we're always in the initial state.
return 1;
static size_t mbstate_bytes_so_far(const mbstate_t* ps) {
return
(ps->__seq[2] != 0) ? 3 :
(ps->__seq[1] != 0) ? 2 :
(ps->__seq[0] != 0) ? 1 : 0;
}
size_t mbrtowc(wchar_t* pwc, const char* s, size_t n, mbstate_t*) {
static void mbstate_set_byte(mbstate_t* ps, int i, char byte) {
ps->__seq[i] = static_cast<uint8_t>(byte);
}
static uint8_t mbstate_get_byte(const mbstate_t* ps, int n) {
return ps->__seq[n];
}
static size_t reset_and_return_illegal(int _errno, mbstate_t* ps) {
errno = _errno;
*(reinterpret_cast<uint32_t*>(ps->__seq)) = 0;
return ERR_ILLEGAL_SEQUENCE;
}
static size_t reset_and_return(int _return, mbstate_t* ps) {
*(reinterpret_cast<uint32_t*>(ps->__seq)) = 0;
return _return;
}
int mbsinit(const mbstate_t* ps) {
return (ps == NULL || (*(reinterpret_cast<const uint32_t*>(ps->__seq)) == 0));
}
size_t mbrtowc(wchar_t* pwc, const char* s, size_t n, mbstate_t* ps) {
static mbstate_t __private_state;
mbstate_t* state = (ps == NULL) ? &__private_state : ps;
// We should never get to a state which has all 4 bytes of the sequence set.
// Full state verification is done when decoding the sequence (after we have
// all the bytes).
if (mbstate_get_byte(state, 3) != 0) {
return reset_and_return_illegal(EINVAL, state);
}
if (s == NULL) {
s = "";
n = 1;
@@ -59,8 +105,8 @@ size_t mbrtowc(wchar_t* pwc, const char* s, size_t n, mbstate_t*) {
return 0;
}
int ch;
if (((ch = static_cast<uint8_t>(*s)) & ~0x7f) == 0) {
uint8_t ch;
if (mbsinit(state) && (((ch = static_cast<uint8_t>(*s)) & ~0x7f) == 0)) {
// Fast path for plain ASCII characters.
if (pwc != NULL) {
*pwc = ch;
@@ -82,7 +128,9 @@ size_t mbrtowc(wchar_t* pwc, const char* s, size_t n, mbstate_t*) {
// between character codes and their multibyte representations.
wchar_t lower_bound;
ch = static_cast<uint8_t>(*s);
// The first byte in the state (if any) tells the length.
size_t bytes_so_far = mbstate_bytes_so_far(state);
ch = bytes_so_far > 0 ? mbstate_get_byte(state, 0) : static_cast<uint8_t>(*s);
if ((ch & 0x80) == 0) {
mask = 0x7f;
length = 1;
@@ -101,106 +149,144 @@ size_t mbrtowc(wchar_t* pwc, const char* s, size_t n, mbstate_t*) {
lower_bound = 0x10000;
} else {
// Malformed input; input is not UTF-8. See RFC 3629.
errno = EILSEQ;
return ERR_ILLEGAL_SEQUENCE;
return reset_and_return_illegal(EILSEQ, state);
}
// Fill in the state.
size_t bytes_wanted = length - bytes_so_far;
size_t i;
for (i = 0; i < MIN(bytes_wanted, n); i++) {
if (!mbsinit(state) && ((*s & 0xc0) != 0x80)) {
// Malformed input; bad characters in the middle of a character.
return reset_and_return_illegal(EILSEQ, state);
}
mbstate_set_byte(state, bytes_so_far + i, *s++);
}
if (i < bytes_wanted) {
return ERR_INCOMPLETE_SEQUENCE;
}
// Decode the octet sequence representing the character in chunks
// of 6 bits, most significant first.
wchar_t wch = static_cast<uint8_t>(*s++) & mask;
size_t i;
for (i = 1; i < MIN(length, n); i++) {
if ((*s & 0xc0) != 0x80) {
// Malformed input; bad characters in the middle of a character.
errno = EILSEQ;
return ERR_ILLEGAL_SEQUENCE;
}
wchar_t wch = mbstate_get_byte(state, 0) & mask;
for (i = 1; i < length; i++) {
wch <<= 6;
wch |= *s++ & 0x3f;
}
if (i < length) {
return ERR_INCOMPLETE_SEQUENCE;
wch |= mbstate_get_byte(state, i) & 0x3f;
}
if (wch < lower_bound) {
// Malformed input; redundant encoding.
errno = EILSEQ;
return ERR_ILLEGAL_SEQUENCE;
return reset_and_return_illegal(EILSEQ, state);
}
if ((wch >= 0xd800 && wch <= 0xdfff) || wch == 0xfffe || wch == 0xffff) {
// Malformed input; invalid code points.
errno = EILSEQ;
return ERR_ILLEGAL_SEQUENCE;
return reset_and_return_illegal(EILSEQ, state);
}
if (pwc != NULL) {
*pwc = wch;
}
return (wch == L'\0' ? 0 : length);
return reset_and_return(wch == L'\0' ? 0 : bytes_wanted, state);
}
size_t mbsnrtowcs(wchar_t* dst, const char** src, size_t nmc, size_t len, mbstate_t* ps) {
static mbstate_t __private_state;
mbstate_t* state = (ps == NULL) ? &__private_state : ps;
size_t i, o, r;
if (dst == NULL) {
/*
* The fast path in the loop below is not safe if an ASCII
* character appears as anything but the first byte of a
* multibyte sequence. Check now to avoid doing it in the loop.
*/
if ((nmc > 0) && (mbstate_bytes_so_far(state) > 0)
&& (static_cast<uint8_t>((*src)[0]) < 0x80)) {
return reset_and_return_illegal(EILSEQ, state);
}
for (i = o = 0; i < nmc; i += r, o++) {
if (static_cast<uint8_t>((*src)[i]) < 0x80) {
// Fast path for plain ASCII characters.
if ((*src)[i] == '\0') {
return o;
return reset_and_return(o, state);
}
r = 1;
} else {
r = mbrtowc(NULL, *src + i, nmc - i, ps);
r = mbrtowc(NULL, *src + i, nmc - i, state);
if (r == ERR_ILLEGAL_SEQUENCE) {
return r;
return reset_and_return_illegal(EILSEQ, state);
}
if (r == ERR_INCOMPLETE_SEQUENCE) {
return o;
return reset_and_return_illegal(EILSEQ, state);
}
if (r == 0) {
return o;
return reset_and_return(o, state);
}
}
}
return o;
return reset_and_return(o, state);
}
/*
* The fast path in the loop below is not safe if an ASCII
* character appears as anything but the first byte of a
* multibyte sequence. Check now to avoid doing it in the loop.
*/
if ((nmc > 0) && (mbstate_bytes_so_far(state) > 0)
&& (static_cast<uint8_t>((*src)[0]) < 0x80)) {
return reset_and_return_illegal(EILSEQ, state);
}
for (i = o = 0; i < nmc && o < len; i += r, o++) {
if (static_cast<uint8_t>((*src)[i]) < 0x80) {
// Fast path for plain ASCII characters.
dst[o] = (*src)[i];
if ((*src)[i] == '\0') {
*src = NULL;
return o;
return reset_and_return_illegal(EILSEQ, state);
}
r = 1;
} else {
r = mbrtowc(dst + o, *src + i, nmc - i, ps);
r = mbrtowc(dst + o, *src + i, nmc - i, state);
if (r == ERR_ILLEGAL_SEQUENCE) {
*src += i;
return r;
return reset_and_return_illegal(EILSEQ, state);
}
if (r == ERR_INCOMPLETE_SEQUENCE) {
*src += nmc;
return o;
return reset_and_return(EILSEQ, state);
}
if (r == 0) {
*src = NULL;
return o;
return reset_and_return(o, state);
}
}
}
*src += i;
return o;
return reset_and_return(o, state);
}
size_t mbsrtowcs(wchar_t* dst, const char** src, size_t len, mbstate_t* ps) {
return mbsnrtowcs(dst, src, SIZE_MAX, len, ps);
}
size_t wcrtomb(char* s, wchar_t wc, mbstate_t*) {
size_t wcrtomb(char* s, wchar_t wc, mbstate_t* ps) {
static mbstate_t __private_state;
mbstate_t* state = (ps == NULL) ? &__private_state : ps;
if (s == NULL) {
// Reset to initial shift state (no-op).
return 1;
// Equivalent to wcrtomb(buf, L'\0', ps).
return reset_and_return(1, state);
}
// POSIX states that if wc is a null wide character, a null byte shall be
// stored, preceded by any shift sequence needed to restore the initial shift
// state. Since shift states are not supported, only the null byte is stored.
if (wc == L'\0') {
*s = '\0';
reset_and_return(1, state);
}
if (!mbsinit(state)) {
return reset_and_return_illegal(EILSEQ, state);
}
if ((wc & ~0x7f) == 0) {
@@ -246,6 +332,13 @@ size_t wcrtomb(char* s, wchar_t wc, mbstate_t*) {
}
size_t wcsnrtombs(char* dst, const wchar_t** src, size_t nwc, size_t len, mbstate_t* ps) {
static mbstate_t __private_state;
mbstate_t* state = (ps == NULL) ? &__private_state : ps;
if (!mbsinit(state)) {
return reset_and_return_illegal(EILSEQ, state);
}
char buf[MB_LEN_MAX];
size_t i, o, r;
if (dst == NULL) {
@@ -258,7 +351,7 @@ size_t wcsnrtombs(char* dst, const wchar_t** src, size_t nwc, size_t len, mbstat
}
r = 1;
} else {
r = wcrtomb(buf, wc, ps);
r = wcrtomb(buf, wc, state);
if (r == ERR_ILLEGAL_SEQUENCE) {
return r;
}
@@ -279,14 +372,14 @@ size_t wcsnrtombs(char* dst, const wchar_t** src, size_t nwc, size_t len, mbstat
r = 1;
} else if (len - o >= sizeof(buf)) {
// Enough space to translate in-place.
r = wcrtomb(dst + o, wc, ps);
r = wcrtomb(dst + o, wc, state);
if (r == ERR_ILLEGAL_SEQUENCE) {
*src += i;
return r;
}
} else {
// May not be enough space; use temp buffer.
r = wcrtomb(buf, wc, ps);
r = wcrtomb(buf, wc, state);
if (r == ERR_ILLEGAL_SEQUENCE) {
*src += i;
return r;

8
libc/include/wchar.h
View File

@@ -41,11 +41,9 @@ __BEGIN_DECLS
typedef __WINT_TYPE__ wint_t;
typedef struct {
#ifdef __LP32__
int dummy;
#else
// 8 bytes should be enough to support at least UTF-8
char __reserved[8];
uint8_t __seq[4];
#ifdef __LP64__
char __reserved[4];
#endif
} mbstate_t;