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