The Android Open Source Project | f6c3871 | 2009-03-03 19:28:47 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2008 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | /* |
| 18 | * Functions for interpreting LEB128 (little endian base 128) values |
| 19 | */ |
| 20 | |
| 21 | #include "Leb128.h" |
| 22 | |
| 23 | /* |
| 24 | * Reads an unsigned LEB128 value, updating the given pointer to point |
| 25 | * just past the end of the read value and also indicating whether the |
| 26 | * value was syntactically valid. The only syntactically *invalid* |
| 27 | * values are ones that are five bytes long where the final byte has |
| 28 | * any but the low-order four bits set. Additionally, if the limit is |
| 29 | * passed as non-NULL and bytes would need to be read past the limit, |
| 30 | * then the read is considered invalid. |
| 31 | */ |
| 32 | int readAndVerifyUnsignedLeb128(const u1** pStream, const u1* limit, |
| 33 | bool* okay) { |
| 34 | const u1* ptr = *pStream; |
| 35 | int result = readUnsignedLeb128(pStream); |
| 36 | |
| 37 | if (((limit != NULL) && (*pStream > limit)) |
| 38 | || (((*pStream - ptr) == 5) && (ptr[4] > 0x0f))) { |
| 39 | *okay = false; |
| 40 | } |
| 41 | |
| 42 | return result; |
| 43 | } |
| 44 | |
| 45 | /* |
| 46 | * Reads a signed LEB128 value, updating the given pointer to point |
| 47 | * just past the end of the read value and also indicating whether the |
| 48 | * value was syntactically valid. The only syntactically *invalid* |
| 49 | * values are ones that are five bytes long where the final byte has |
| 50 | * any but the low-order four bits set. Additionally, if the limit is |
| 51 | * passed as non-NULL and bytes would need to be read past the limit, |
| 52 | * then the read is considered invalid. |
| 53 | */ |
| 54 | int readAndVerifySignedLeb128(const u1** pStream, const u1* limit, |
| 55 | bool* okay) { |
| 56 | const u1* ptr = *pStream; |
| 57 | int result = readSignedLeb128(pStream); |
| 58 | |
| 59 | if (((limit != NULL) && (*pStream > limit)) |
| 60 | || (((*pStream - ptr) == 5) && (ptr[4] > 0x0f))) { |
| 61 | *okay = false; |
| 62 | } |
| 63 | |
| 64 | return result; |
| 65 | } |