// Copyright 2017 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "src/utf8_fix.h"
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#include <algorithm>
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#include <cassert>
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namespace protobuf_mutator {
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namespace {
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void StoreCode(char* e, char32_t code, uint8_t size, uint8_t prefix) {
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while (--size) {
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*(--e) = 0x80 | (code & 0x3F);
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code >>= 6;
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}
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*(--e) = prefix | code;
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}
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char* FixCode(char* b, const char* e, RandomEngine* random) {
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const char* start = b;
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assert(b < e);
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e = std::min<const char*>(e, b + 4);
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char32_t c = *b++;
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for (; b < e && (*b & 0xC0) == 0x80; ++b) {
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c = (c << 6) + (*b & 0x3F);
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}
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uint8_t size = b - start;
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switch (size) {
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case 1:
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c &= 0x7F;
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StoreCode(b, c, size, 0);
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break;
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case 2:
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c &= 0x7FF;
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if (c < 0x80) {
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c = std::uniform_int_distribution<char32_t>(0x80, 0x7FF)(*random);
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}
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StoreCode(b, c, size, 0xC0);
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break;
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case 3:
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c &= 0xFFFF;
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// [0xD800, 0xE000) are reserved for UTF-16 surrogate halves.
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if (c < 0x800 || (c >= 0xD800 && c < 0xE000)) {
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uint32_t halves = 0xE000 - 0xD800;
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c = std::uniform_int_distribution<char32_t>(0x800,
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0xFFFF - halves)(*random);
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if (c >= 0xD800) c += halves;
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}
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StoreCode(b, c, size, 0xE0);
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break;
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case 4:
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c &= 0x1FFFFF;
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if (c < 0x10000 || c > 0x10FFFF) {
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c = std::uniform_int_distribution<char32_t>(0x10000, 0x10FFFF)(*random);
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}
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StoreCode(b, c, size, 0xF0);
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break;
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default:
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assert(false && "Unexpected size of UTF-8 sequence");
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}
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return b;
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}
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} // namespace
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void FixUtf8String(std::string* str, RandomEngine* random) {
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if (str->empty()) return;
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char* b = &(*str)[0];
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const char* e = b + str->size();
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while (b < e) {
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b = FixCode(b, e, random);
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}
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}
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} // namespace protobuf_mutator
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