f15ceeb784
According to runs on /system/lib there using unsigned leb128 does not save us any additional space. In order to keep packing as simple as possible switch to using signed leb128 for everything. Bug: http://b/18051137 Change-Id: I1a47cb9eb2175895b3c3f7c13b4c6b1060de86c0
68 lines
1.9 KiB
C++
68 lines
1.9 KiB
C++
// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "packer.h"
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#include <vector>
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#include "debug.h"
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#include "delta_encoder.h"
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#include "elf_traits.h"
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#include "sleb128.h"
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namespace relocation_packer {
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// Pack relocations into a group encoded packed representation.
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template <typename ELF>
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void RelocationPacker<ELF>::PackRelocations(const std::vector<typename ELF::Rela>& relocations,
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std::vector<uint8_t>* packed) {
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// Run-length encode.
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std::vector<typename ELF::Addr> packed_words;
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RelocationDeltaCodec<ELF> codec;
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codec.Encode(relocations, &packed_words);
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// If insufficient data do nothing.
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if (packed_words.empty())
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return;
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Sleb128Encoder<typename ELF::Addr> sleb128_encoder;
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std::vector<uint8_t> sleb128_packed;
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sleb128_encoder.EnqueueAll(packed_words);
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sleb128_encoder.GetEncoding(&sleb128_packed);
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packed->push_back('A');
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packed->push_back('P');
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packed->push_back('S');
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packed->push_back('2');
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packed->insert(packed->end(), sleb128_packed.begin(), sleb128_packed.end());
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}
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// Unpack relative relocations from a run-length encoded packed
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// representation.
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template <typename ELF>
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void RelocationPacker<ELF>::UnpackRelocations(
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const std::vector<uint8_t>& packed,
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std::vector<typename ELF::Rela>* relocations) {
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std::vector<typename ELF::Addr> packed_words;
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CHECK(packed.size() > 4 &&
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packed[0] == 'A' &&
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packed[1] == 'P' &&
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packed[2] == 'S' &&
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packed[3] == '2');
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Sleb128Decoder<typename ELF::Addr> decoder(packed, 4);
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decoder.DequeueAll(&packed_words);
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RelocationDeltaCodec<ELF> codec;
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codec.Decode(packed_words, relocations);
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}
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template class RelocationPacker<ELF32_traits>;
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template class RelocationPacker<ELF64_traits>;
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} // namespace relocation_packer
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