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71 lines
2.0 KiB
71 lines
2.0 KiB
/*
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* Copyright (C) 2017 The Android Open Source Project
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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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*/
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#include "slicer/dex_format.h"
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namespace dex {
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// Retrieve the next UTF-16 character from a UTF-8 string.
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// Advances "*pUtf8Ptr" to the start of the next character.
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//
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// NOTE: If a string is corrupted by dropping a '\0' in the middle
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// of a 3-byte sequence, you can end up overrunning the buffer with
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// reads (and possibly with the writes if the length was computed and
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// cached before the damage). For performance reasons, this function
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// assumes that the string being parsed is known to be valid (e.g., by
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// already being verified).
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static u2 GetUtf16FromUtf8(const char** pUtf8Ptr) {
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u4 one = *(*pUtf8Ptr)++;
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if ((one & 0x80) != 0) {
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// two- or three-byte encoding
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u4 two = *(*pUtf8Ptr)++;
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if ((one & 0x20) != 0) {
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// three-byte encoding
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u4 three = *(*pUtf8Ptr)++;
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return ((one & 0x0f) << 12) | ((two & 0x3f) << 6) | (three & 0x3f);
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} else {
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// two-byte encoding
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return ((one & 0x1f) << 6) | (two & 0x3f);
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}
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} else {
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// one-byte encoding
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return one;
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}
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}
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int Utf8Cmp(const char* s1, const char* s2) {
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for (;;) {
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if (*s1 == '\0') {
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if (*s2 == '\0') {
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return 0;
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}
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return -1;
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} else if (*s2 == '\0') {
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return 1;
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}
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int utf1 = GetUtf16FromUtf8(&s1);
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int utf2 = GetUtf16FromUtf8(&s2);
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int diff = utf1 - utf2;
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if (diff != 0) {
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return diff;
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}
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}
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}
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} // namespace dex
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