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/*
* Copyright 2017 WebAssembly Community Group participants
*
* 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.
*/
#include "wabt/utf8.h"
#include <cstdint>
namespace wabt {
namespace {
// clang-format off
const int s_utf8_length[256] = {
// 0 1 2 3 4 5 6 7 8 9 a b c d e f
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x00
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x10
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x20
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x30
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x40
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x50
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x60
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x70
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0x80
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0x90
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0xa0
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0xb0
0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0xc0
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // 0xd0
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, // 0xe0
4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0xf0
};
// clang-format on
// Returns true if this is a valid continuation byte.
bool IsCont(uint8_t c) {
return (c & 0xc0) == 0x80;
}
} // end anonymous namespace
bool IsValidUtf8(const char* s, size_t s_length) {
const uint8_t* p = reinterpret_cast<const uint8_t*>(s);
const uint8_t* end = p + s_length;
while (p < end) {
uint8_t cu0 = *p;
int length = s_utf8_length[cu0];
if (p + length > end) {
return false;
}
switch (length) {
case 0:
return false;
case 1:
p++;
break;
case 2:
p++;
if (!IsCont(*p++)) {
return false;
}
break;
case 3: {
p++;
uint8_t cu1 = *p++;
uint8_t cu2 = *p++;
if (!(IsCont(cu1) && IsCont(cu2)) ||
(cu0 == 0xe0 && cu1 < 0xa0) || // Overlong encoding.
(cu0 == 0xed && cu1 >= 0xa0)) // UTF-16 surrogate halves.
return false;
break;
}
case 4: {
p++;
uint8_t cu1 = *p++;
uint8_t cu2 = *p++;
uint8_t cu3 = *p++;
if (!(IsCont(cu1) && IsCont(cu2) && IsCont(cu3)) ||
(cu0 == 0xf0 && cu1 < 0x90) || // Overlong encoding.
(cu0 == 0xf4 && cu1 >= 0x90)) // Code point >= 0x11000.
return false;
break;
}
}
}
return true;
}
} // namespace wabt
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