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 #pragma once 30 31 #include <stdint.h> 32 33 #include <async_safe/log.h> 34 35 #include "linker_debug.h" 36 37 // Helper classes for decoding LEB128, used in packed relocation data. 38 // http://en.wikipedia.org/wiki/LEB128 39 40 class sleb128_decoder { 41 public: sleb128_decoder(const uint8_t * buffer,size_t count)42 sleb128_decoder(const uint8_t* buffer, size_t count) 43 : current_(buffer), end_(buffer+count) { } 44 pop_front()45 size_t pop_front() { 46 size_t value = 0; 47 static const size_t size = CHAR_BIT * sizeof(value); 48 49 size_t shift = 0; 50 uint8_t byte; 51 52 do { 53 if (current_ >= end_) { 54 async_safe_fatal("sleb128_decoder ran out of bounds"); 55 } 56 byte = *current_++; 57 value |= (static_cast<size_t>(byte & 127) << shift); 58 shift += 7; 59 } while (byte & 128); 60 61 if (shift < size && (byte & 64)) { 62 value |= -(static_cast<size_t>(1) << shift); 63 } 64 65 return value; 66 } 67 68 private: 69 const uint8_t* current_; 70 const uint8_t* const end_; 71 }; 72