/*
* Copyright (C) 2005 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "unicode"
#include <limits.h>
#include <utils/Unicode.h>
#include <log/log.h>
extern "C" {
static const char32_t kByteMask = 0x000000BF;
static const char32_t kByteMark = 0x00000080;
// Surrogates aren't valid for UTF-32 characters, so define some
// constants that will let us screen them out.
static const char32_t kUnicodeSurrogateHighStart = 0x0000D800;
// Unused, here for completeness:
// static const char32_t kUnicodeSurrogateHighEnd = 0x0000DBFF;
// static const char32_t kUnicodeSurrogateLowStart = 0x0000DC00;
static const char32_t kUnicodeSurrogateLowEnd = 0x0000DFFF;
static const char32_t kUnicodeSurrogateStart = kUnicodeSurrogateHighStart;
static const char32_t kUnicodeSurrogateEnd = kUnicodeSurrogateLowEnd;
static const char32_t kUnicodeMaxCodepoint = 0x0010FFFF;
// Mask used to set appropriate bits in first byte of UTF-8 sequence,
// indexed by number of bytes in the sequence.
// 0xxxxxxx
// -> (00-7f) 7bit. Bit mask for the first byte is 0x00000000
// 110yyyyx 10xxxxxx
// -> (c0-df)(80-bf) 11bit. Bit mask is 0x000000C0
// 1110yyyy 10yxxxxx 10xxxxxx
// -> (e0-ef)(80-bf)(80-bf) 16bit. Bit mask is 0x000000E0
// 11110yyy 10yyxxxx 10xxxxxx 10xxxxxx
// -> (f0-f7)(80-bf)(80-bf)(80-bf) 21bit. Bit mask is 0x000000F0
static const char32_t kFirstByteMark[] = {
0x00000000, 0x00000000, 0x000000C0, 0x000000E0, 0x000000F0
};
// --------------------------------------------------------------------------
// UTF-32
// --------------------------------------------------------------------------
/**
* Return number of UTF-8 bytes required for the character. If the character
* is invalid, return size of 0.
*/
static inline size_t utf32_codepoint_utf8_length(char32_t srcChar)
{
// Figure out how many bytes the result will require.
if (srcChar < 0x00000080) {
return 1;
} else if (srcChar < 0x00000800) {
return 2;
} else if (srcChar < 0x00010000) {
if ((srcChar < kUnicodeSurrogateStart) || (srcChar > kUnicodeSurrogateEnd)) {
return 3;
} else {
// Surrogates are invalid UTF-32 characters.
return 0;
}
}
// Max code point for Unicode is 0x0010FFFF.
else if (srcChar <= kUnicodeMaxCodepoint) {
return 4;
} else {
// Invalid UTF-32 character.
return 0;
}
}
// Write out the source character to <dstP>.
static inline void utf32_codepoint_to_utf8(uint8_t* dstP, char32_t srcChar, size_t bytes)
{
dstP += bytes;
switch (bytes)
{ /* note: everything falls through. */
case 4: *--dstP = (uint8_t)((srcChar | kByteMark) & kByteMask); srcChar >>= 6;
[[fallthrough]];
case 3: *--dstP = (uint8_t)((srcChar | kByteMark) & kByteMask); srcChar >>= 6;
[[fallthrough]];
case 2: *--dstP = (uint8_t)((srcChar | kByteMark) & kByteMask); srcChar >>= 6;
[[fallthrough]];
case 1: *--dstP = (uint8_t)(srcChar | kFirstByteMark[bytes]);
}
}
static inline int32_t utf32_at_internal(const char* cur, size_t *num_read)
{
const char first_char = *cur;
if ((first_char & 0x80) == 0) { // ASCII
*num_read = 1;
return *cur;
}
cur++;
char32_t mask, to_ignore_mask;
size_t num_to_read = 0;
char32_t utf32 = first_char;
for (num_to_read = 1, mask = 0x40, to_ignore_mask = 0xFFFFFF80;
(first_char & mask);
num_to_read++, to_ignore_mask |= mask, mask >>= 1) {
// 0x3F == 00111111
utf32 = (utf32 << 6) + (*cur++ & 0x3F);
}
to_ignore_mask |= mask;
utf32 &= ~(to_ignore_mask << (6 * (num_to_read - 1)));
*num_read = num_to_read;
return static_cast<int32_t>(utf32);
}
int32_t utf32_from_utf8_at(const char *src, size_t src_len, size_t index, size_t *next_index)
{
if (index >= src_len) {
return -1;
}
size_t unused_index;
if (next_index == nullptr) {
next_index = &unused_index;
}
size_t num_read;
int32_t ret = utf32_at_internal(src + index, &num_read);
if (ret >= 0) {
*next_index = index + num_read;
}
return ret;
}
ssize_t utf32_to_utf8_length(const char32_t *src, size_t src_len)
{
if (src == nullptr || src_len == 0) {
return -1;
}
size_t ret = 0;
const char32_t *end = src + src_len;
while (src < end) {
size_t char_len = utf32_codepoint_utf8_length(*src++);
if (SSIZE_MAX - char_len < ret) {
// If this happens, we would overflow the ssize_t type when
// returning from this function, so we cannot express how
// long this string is in an ssize_t.
android_errorWriteLog(0x534e4554, "37723026");
return -1;
}
ret += char_len;
}
return ret;
}
void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst, size_t dst_len)
{
if (src == nullptr || src_len == 0 || dst == nullptr) {
return;
}
const char32_t *cur_utf32 = src;
const char32_t *end_utf32 = src + src_len;
char *cur = dst;
while (cur_utf32 < end_utf32) {
size_t len = utf32_codepoint_utf8_length(*cur_utf32);
LOG_ALWAYS_FATAL_IF(dst_len < len, "%zu < %zu", dst_len, len);
utf32_codepoint_to_utf8((uint8_t *)cur, *cur_utf32++, len);
cur += len;
dst_len -= len;
}
LOG_ALWAYS_FATAL_IF(dst_len < 1, "dst_len < 1: %zu < 1", dst_len);
*cur = '\0';
}
// --------------------------------------------------------------------------
// UTF-16
// --------------------------------------------------------------------------
int strcmp16(const char16_t *s1, const char16_t *s2)
{
char16_t ch;
int d = 0;
while ( 1 ) {
d = (int)(ch = *s1++) - (int)*s2++;
if ( d || !ch )
break;
}
return d;
}
int strncmp16(const char16_t *s1, const char16_t *s2, size_t n)
{
char16_t ch;
int d = 0;
if (n == 0) {
return 0;
}
do {
d = (int)(ch = *s1++) - (int)*s2++;
if ( d || !ch ) {
break;
}
} while (--n);
return d;
}
size_t strlen16(const char16_t *s)
{
const char16_t *ss = s;
while ( *ss )
ss++;
return ss-s;
}
size_t strnlen16(const char16_t *s, size_t maxlen)
{
const char16_t *ss = s;
/* Important: the maxlen test must precede the reference through ss;
since the byte beyond the maximum may segfault */
while ((maxlen > 0) && *ss) {
ss++;
maxlen--;
}
return ss-s;
}
char16_t* strstr16(const char16_t* src, const char16_t* target)
{
const char16_t needle = *target;
if (needle == '\0') return (char16_t*)src;
const size_t target_len = strlen16(++target);
do {
do {
if (*src == '\0') {
return nullptr;
}
} while (*src++ != needle);
} while (strncmp16(src, target, target_len) != 0);
src--;
return (char16_t*)src;
}
int strzcmp16(const char16_t *s1, size_t n1, const char16_t *s2, size_t n2)
{
const char16_t* e1 = s1+n1;
const char16_t* e2 = s2+n2;
while (s1 < e1 && s2 < e2) {
const int d = (int)*s1++ - (int)*s2++;
if (d) {
return d;
}
}
return n1 < n2
? (0 - (int)*s2)
: (n1 > n2
? ((int)*s1 - 0)
: 0);
}
// is_any_surrogate() returns true if w is either a high or low surrogate
static constexpr bool is_any_surrogate(char16_t w) {
return (w & 0xf800) == 0xd800;
}
// is_surrogate_pair() returns true if w1 and w2 form a valid surrogate pair
static constexpr bool is_surrogate_pair(char16_t w1, char16_t w2) {
return ((w1 & 0xfc00) == 0xd800) && ((w2 & 0xfc00) == 0xdc00);
}
// TODO: currently utf16_to_utf8_length() returns -1 if src_len == 0,
// which is inconsistent with utf8_to_utf16_length(), here we keep the
// current behavior as intended not to break compatibility
ssize_t utf16_to_utf8_length(const char16_t *src, size_t src_len)
{
if (src == nullptr || src_len == 0)
return -1;
const char16_t* const end = src + src_len;
const char16_t* in = src;
size_t utf8_len = 0;
while (in < end) {
char16_t w = *in++;
if (w < 0x0080) [[likely]] {
utf8_len += 1;
continue;
}
if (w < 0x0800) [[likely]] {
utf8_len += 2;
continue;
}
if (!is_any_surrogate(w)) [[likely]] {
utf8_len += 3;
continue;
}
if (in < end && is_surrogate_pair(w, *in)) {
utf8_len += 4;
in++;
continue;
}
/* skip if at the end of the string or invalid surrogate pair */
}
return (in == end && utf8_len < SSIZE_MAX) ? utf8_len : -1;
}
void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst, size_t dst_len)
{
if (src == nullptr || src_len == 0 || dst == nullptr) {
return;
}
const char16_t* in = src;
const char16_t* const in_end = src + src_len;
char* out = dst;
const char* const out_end = dst + dst_len;
char16_t w2;
auto err_out = [&out, &out_end, &dst_len]() {
LOG_ALWAYS_FATAL_IF(out >= out_end,
"target utf8 string size %zu too short", dst_len);
};
while (in < in_end) {
char16_t w = *in++;
if (w < 0x0080) [[likely]] {
if (out + 1 > out_end)
return err_out();
*out++ = (char)(w & 0xff);
continue;
}
if (w < 0x0800) [[likely]] {
if (out + 2 > out_end)
return err_out();
*out++ = (char)(0xc0 | ((w >> 6) & 0x1f));
*out++ = (char)(0x80 | ((w >> 0) & 0x3f));
continue;
}
if (!is_any_surrogate(w)) [[likely]] {
if (out + 3 > out_end)
return err_out();
*out++ = (char)(0xe0 | ((w >> 12) & 0xf));
*out++ = (char)(0x80 | ((w >> 6) & 0x3f));
*out++ = (char)(0x80 | ((w >> 0) & 0x3f));
continue;
}
/* surrogate pair */
if (in < in_end && (w2 = *in, is_surrogate_pair(w, w2))) {
if (out + 4 > out_end)
return err_out();
char32_t dw = (char32_t)(0x10000 + ((w - 0xd800) << 10) + (w2 - 0xdc00));
*out++ = (char)(0xf0 | ((dw >> 18) & 0x07));
*out++ = (char)(0x80 | ((dw >> 12) & 0x3f));
*out++ = (char)(0x80 | ((dw >> 6) & 0x3f));
*out++ = (char)(0x80 | ((dw >> 0) & 0x3f));
in++;
}
/* We reach here in two cases:
* 1) (in == in_end), which means end of the input string
* 2) (w2 & 0xfc00) != 0xdc00, which means invalid surrogate pair
* In either case, we intentionally do nothing and skip
*/
}
*out = '\0';
return;
}
// --------------------------------------------------------------------------
// UTF-8
// --------------------------------------------------------------------------
static char32_t utf8_4b_to_utf32(uint8_t c1, uint8_t c2, uint8_t c3, uint8_t c4) {
return ((c1 & 0x07) << 18) | ((c2 & 0x3f) << 12) | ((c3 & 0x3f) << 6) | (c4 & 0x3f);
}
// TODO: current behavior of converting UTF8 to UTF-16 has a few issues below
//
// 1. invalid trailing bytes (i.e. not b'10xxxxxx) are treated as valid trailing
// bytes and follows normal conversion rules
// 2. invalid leading byte (b'10xxxxxx) is treated as a valid single UTF-8 byte
// 3. invalid leading byte (b'11111xxx) is treated as a valid leading byte
// (same as b'11110xxx) for a 4-byte UTF-8 sequence
// 4. an invalid 4-byte UTF-8 sequence that translates to a codepoint < U+10000
// will be converted as a valid UTF-16 character
//
// We keep the current behavior as is but with warnings logged, so as not to
// break compatibility. However, this needs to be addressed later.
ssize_t utf8_to_utf16_length(const uint8_t* u8str, size_t u8len, bool overreadIsFatal)
{
if (u8str == nullptr)
return -1;
const uint8_t* const in_end = u8str + u8len;
const uint8_t* in = u8str;
size_t utf16_len = 0;
while (in < in_end) {
uint8_t c = *in;
utf16_len++;
if ((c & 0x80) == 0) [[likely]] {
in++;
continue;
}
if (c < 0xc0) [[unlikely]] {
ALOGW("Invalid UTF-8 leading byte: 0x%02x", c);
in++;
continue;
}
if (c < 0xe0) [[likely]] {
in += 2;
continue;
}
if (c < 0xf0) [[likely]] {
in += 3;
continue;
} else {
uint8_t c2, c3, c4;
if (c >= 0xf8) [[unlikely]] {
ALOGW("Invalid UTF-8 leading byte: 0x%02x", c);
}
c2 = in[1]; c3 = in[2]; c4 = in[3];
if (utf8_4b_to_utf32(c, c2, c3, c4) >= 0x10000) {
utf16_len++;
}
in += 4;
continue;
}
}
if (in == in_end) {
return utf16_len < SSIZE_MAX ? utf16_len : -1;
}
if (overreadIsFatal)
LOG_ALWAYS_FATAL("Attempt to overread computing length of utf8 string");
return -1;
}
char16_t* utf8_to_utf16(const uint8_t* u8str, size_t u8len, char16_t* u16str, size_t u16len) {
// A value > SSIZE_MAX is probably a negative value returned as an error and casted.
LOG_ALWAYS_FATAL_IF(u16len == 0 || u16len > SSIZE_MAX, "u16len is %zu", u16len);
char16_t* end = utf8_to_utf16_no_null_terminator(u8str, u8len, u16str, u16len - 1);
*end = 0;
return end;
}
char16_t* utf8_to_utf16_no_null_terminator(
const uint8_t* src, size_t srcLen, char16_t* dst, size_t dstLen) {
if (src == nullptr || srcLen == 0 || dstLen == 0) {
return dst;
}
// A value > SSIZE_MAX is probably a negative value returned as an error and casted.
LOG_ALWAYS_FATAL_IF(dstLen > SSIZE_MAX, "dstLen is %zu", dstLen);
const uint8_t* const in_end = src + srcLen;
const uint8_t* in = src;
const char16_t* const out_end = dst + dstLen;
char16_t* out = dst;
uint8_t c, c2, c3, c4;
char32_t w;
auto err_in = [&c, &out]() {
ALOGW("Unended UTF-8 byte: 0x%02x", c);
return out;
};
while (in < in_end && out < out_end) {
c = *in++;
if ((c & 0x80) == 0) [[likely]] {
*out++ = (char16_t)(c);
continue;
}
if (c < 0xc0) [[unlikely]] {
ALOGW("Invalid UTF-8 leading byte: 0x%02x", c);
*out++ = (char16_t)(c);
continue;
}
if (c < 0xe0) [[likely]] {
if (in + 1 > in_end) [[unlikely]] {
return err_in();
}
c2 = *in++;
*out++ = (char16_t)(((c & 0x1f) << 6) | (c2 & 0x3f));
continue;
}
if (c < 0xf0) [[likely]] {
if (in + 2 > in_end) [[unlikely]] {
return err_in();
}
c2 = *in++; c3 = *in++;
*out++ = (char16_t)(((c & 0x0f) << 12) |
((c2 & 0x3f) << 6) | (c3 & 0x3f));
continue;
} else {
if (in + 3 > in_end) [[unlikely]] {
return err_in();
}
if (c >= 0xf8) [[unlikely]] {
ALOGW("Invalid UTF-8 leading byte: 0x%02x", c);
}
// Multiple UTF16 characters with surrogates
c2 = *in++; c3 = *in++; c4 = *in++;
w = utf8_4b_to_utf32(c, c2, c3, c4);
if (w < 0x10000) [[unlikely]] {
*out++ = (char16_t)(w);
} else {
if (out + 2 > out_end) [[unlikely]] {
// Ooops.... not enough room for this surrogate pair.
return out;
}
*out++ = (char16_t)(((w - 0x10000) >> 10) + 0xd800);
*out++ = (char16_t)(((w - 0x10000) & 0x3ff) + 0xdc00);
}
continue;
}
}
return out;
}
}