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 } 66
