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 "linker_debug.h" 35 36 // Helper classes for decoding LEB128, used in packed relocation data. 37 // http://en.wikipedia.org/wiki/LEB128 38 39 class sleb128_decoder { 40 public: 41 sleb128_decoder(const uint8_t* buffer, size_t count) 42 : current_(buffer), end_(buffer+count) { } 43 44 size_t pop_front() { 45 size_t value = 0; 46 static const size_t size = CHAR_BIT * sizeof(value); 47 48 size_t shift = 0; 49 uint8_t byte; 50 51 do { 52 if (current_ >= end_) { 53 __libc_fatal("sleb128_decoder ran out of bounds"); 54 } 55 byte = *current_++; 56 value |= (static_cast<size_t>(byte & 127) << shift); 57 shift += 7; 58 } while (byte & 128); 59 60 if (shift < size && (byte & 64)) { 61 value |= -(static_cast<size_t>(1) << shift); 62 } 63 64 return value; 65 } 66 67 private: 68 const uint8_t* current_; 69 const uint8_t* const end_; 70 }; 71 72 #endif // __LINKER_SLEB128_H 73
