1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #ifndef _LINKER_SLEB128_H 30 #define _LINKER_SLEB128_H 31 32 #include <stdint.h> 33 34 #include <async_safe/log.h> 35 36 #include "linker_debug.h" 37 38 // Helper classes for decoding LEB128, used in packed relocation data. 39 // http://en.wikipedia.org/wiki/LEB128 40 41 class sleb128_decoder { 42 public: sleb128_decoder(const uint8_t * buffer,size_t count)43 sleb128_decoder(const uint8_t* buffer, size_t count) 44 : current_(buffer), end_(buffer+count) { } 45 pop_front()46 size_t pop_front() { 47 size_t value = 0; 48 static const size_t size = CHAR_BIT * sizeof(value); 49 50 size_t shift = 0; 51 uint8_t byte; 52 53 do { 54 if (current_ >= end_) { 55 async_safe_fatal("sleb128_decoder ran out of bounds"); 56 } 57 byte = *current_++; 58 value |= (static_cast<size_t>(byte & 127) << shift); 59 shift += 7; 60 } while (byte & 128); 61 62 if (shift < size && (byte & 64)) { 63 value |= -(static_cast<size_t>(1) << shift); 64 } 65 66 return value; 67 } 68 69 private: 70 const uint8_t* current_; 71 const uint8_t* const end_; 72 }; 73 74 #endif // __LINKER_SLEB128_H 75