1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "packer.h" 6 7 #include <vector> 8 9 #include "debug.h" 10 #include "delta_encoder.h" 11 #include "elf_traits.h" 12 #include "sleb128.h" 13 14 namespace relocation_packer { 15 16 // Pack relocations into a group encoded packed representation. 17 template <typename ELF> 18 void RelocationPacker<ELF>::PackRelocations(const std::vector<typename ELF::Rela>& relocations, 19 std::vector<uint8_t>* packed) { 20 // Run-length encode. 21 std::vector<typename ELF::Addr> packed_words; 22 RelocationDeltaCodec<ELF> codec; 23 codec.Encode(relocations, &packed_words); 24 25 // If insufficient data do nothing. 26 if (packed_words.empty()) 27 return; 28 29 Sleb128Encoder<typename ELF::Addr> sleb128_encoder; 30 31 std::vector<uint8_t> sleb128_packed; 32 33 sleb128_encoder.EnqueueAll(packed_words); 34 sleb128_encoder.GetEncoding(&sleb128_packed); 35 36 packed->push_back('A'); 37 packed->push_back('P'); 38 packed->push_back('S'); 39 packed->push_back('2'); 40 packed->insert(packed->end(), sleb128_packed.begin(), sleb128_packed.end()); 41 } 42 43 // Unpack relative relocations from a run-length encoded packed 44 // representation. 45 template <typename ELF> 46 void RelocationPacker<ELF>::UnpackRelocations( 47 const std::vector<uint8_t>& packed, 48 std::vector<typename ELF::Rela>* relocations) { 49 50 std::vector<typename ELF::Addr> packed_words; 51 CHECK(packed.size() > 4 && 52 packed[0] == 'A' && 53 packed[1] == 'P' && 54 packed[2] == 'S' && 55 packed[3] == '2'); 56 57 Sleb128Decoder<typename ELF::Addr> decoder(packed, 4); 58 decoder.DequeueAll(&packed_words); 59 60 RelocationDeltaCodec<ELF> codec; 61 codec.Decode(packed_words, relocations); 62 } 63 64 template class RelocationPacker<ELF32_traits>; 65 template class RelocationPacker<ELF64_traits>; 66 67 } // namespace relocation_packer 68
