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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/zucchini/zucchini_apply.h"
#include <algorithm>
#include <map>
#include <memory>
#include <utility>
#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
#include "components/zucchini/disassembler.h"
#include "components/zucchini/element_detection.h"
#include "components/zucchini/equivalence_map.h"
#include "components/zucchini/image_index.h"
namespace zucchini {
bool ApplyEquivalenceAndExtraData(ConstBufferView old_image,
const PatchElementReader& patch_reader,
MutableBufferView new_image) {
EquivalenceSource equiv_source = patch_reader.GetEquivalenceSource();
ExtraDataSource extra_data_source = patch_reader.GetExtraDataSource();
MutableBufferView::iterator dst_it = new_image.begin();
for (auto equivalence = equiv_source.GetNext(); equivalence.has_value();
equivalence = equiv_source.GetNext()) {
MutableBufferView::iterator next_dst_it =
new_image.begin() + equivalence->dst_offset;
CHECK(next_dst_it >= dst_it);
offset_t gap = static_cast<offset_t>(next_dst_it - dst_it);
absl::optional<ConstBufferView> extra_data = extra_data_source.GetNext(gap);
if (!extra_data) {
LOG(ERROR) << "Error reading extra_data";
return false;
}
// |extra_data| length is based on what was parsed from the patch so this
// copy should be valid.
dst_it = std::copy(extra_data->begin(), extra_data->end(), dst_it);
CHECK_EQ(dst_it, next_dst_it);
dst_it = std::copy_n(old_image.begin() + equivalence->src_offset,
equivalence->length, dst_it);
CHECK_EQ(dst_it, next_dst_it + equivalence->length);
}
offset_t gap = static_cast<offset_t>(new_image.end() - dst_it);
absl::optional<ConstBufferView> extra_data = extra_data_source.GetNext(gap);
if (!extra_data) {
LOG(ERROR) << "Error reading extra_data";
return false;
}
std::copy(extra_data->begin(), extra_data->end(), dst_it);
if (!equiv_source.Done() || !extra_data_source.Done()) {
LOG(ERROR) << "Found trailing equivalence and extra_data";
return false;
}
return true;
}
bool ApplyRawDelta(const PatchElementReader& patch_reader,
MutableBufferView new_image) {
EquivalenceSource equiv_source = patch_reader.GetEquivalenceSource();
RawDeltaSource raw_delta_source = patch_reader.GetRawDeltaSource();
// Traverse |equiv_source| and |raw_delta_source| in lockstep.
auto equivalence = equiv_source.GetNext();
offset_t base_copy_offset = 0;
for (auto delta = raw_delta_source.GetNext(); delta.has_value();
delta = raw_delta_source.GetNext()) {
while (equivalence.has_value() &&
base_copy_offset + equivalence->length <= delta->copy_offset) {
base_copy_offset += equivalence->length;
equivalence = equiv_source.GetNext();
}
if (!equivalence.has_value()) {
LOG(ERROR) << "Error reading equivalences";
return false;
}
CHECK_GE(delta->copy_offset, base_copy_offset);
CHECK_LT(delta->copy_offset, base_copy_offset + equivalence->length);
// Invert byte diff.
new_image[equivalence->dst_offset - base_copy_offset +
delta->copy_offset] += delta->diff;
}
if (!raw_delta_source.Done()) {
LOG(ERROR) << "Found trailing raw_delta";
return false;
}
return true;
}
bool ApplyReferencesCorrection(ExecutableType exe_type,
ConstBufferView old_image,
const PatchElementReader& patch,
MutableBufferView new_image) {
auto old_disasm = MakeDisassemblerOfType(old_image, exe_type);
auto new_disasm =
MakeDisassemblerOfType(ConstBufferView(new_image), exe_type);
if (!old_disasm || !new_disasm) {
LOG(ERROR) << "Failed to create Disassembler";
return false;
}
if (old_disasm->size() != old_image.size() ||
new_disasm->size() != new_image.size()) {
LOG(ERROR) << "Disassembler and element size mismatch";
return false;
}
ReferenceDeltaSource ref_delta_source = patch.GetReferenceDeltaSource();
std::map<PoolTag, std::vector<ReferenceGroup>> pool_groups;
for (const auto& ref_group : old_disasm->MakeReferenceGroups())
pool_groups[ref_group.pool_tag()].push_back(ref_group);
OffsetMapper offset_mapper(patch.GetEquivalenceSource(),
base::checked_cast<offset_t>(old_image.size()),
base::checked_cast<offset_t>(new_image.size()));
std::vector<ReferenceGroup> new_groups = new_disasm->MakeReferenceGroups();
for (const auto& pool_and_sub_groups : pool_groups) {
PoolTag pool_tag = pool_and_sub_groups.first;
const std::vector<ReferenceGroup>& sub_groups = pool_and_sub_groups.second;
TargetPool targets;
// Load "old" targets, then filter and map them to "new" targets.
for (ReferenceGroup group : sub_groups)
targets.InsertTargets(std::move(*group.GetReader(old_disasm.get())));
targets.FilterAndProject(offset_mapper);
// Load extra targets from patch.
TargetSource target_source = patch.GetExtraTargetSource(pool_tag);
targets.InsertTargets(&target_source);
if (!target_source.Done()) {
LOG(ERROR) << "Found trailing extra_targets";
return false;
}
// Correct all new references, and write results to |new_disasm|.
for (ReferenceGroup group : sub_groups) {
std::unique_ptr<ReferenceWriter> ref_writer =
new_groups[group.type_tag().value()].GetWriter(new_image,
new_disasm.get());
EquivalenceSource equiv_source = patch.GetEquivalenceSource();
for (auto equivalence = equiv_source.GetNext(); equivalence.has_value();
equivalence = equiv_source.GetNext()) {
std::unique_ptr<ReferenceReader> ref_gen = group.GetReader(
equivalence->src_offset, equivalence->src_end(), old_disasm.get());
for (auto ref = ref_gen->GetNext(); ref.has_value();
ref = ref_gen->GetNext()) {
DCHECK_GE(ref->location, equivalence->src_offset);
DCHECK_LT(ref->location, equivalence->src_end());
offset_t projected_target =
offset_mapper.ExtendedForwardProject(ref->target);
offset_t expected_key = targets.KeyForNearestOffset(projected_target);
auto delta = ref_delta_source.GetNext();
if (!delta.has_value()) {
LOG(ERROR) << "Error reading reference_delta";
return false;
}
const key_t key = expected_key + delta.value();
if (!targets.KeyIsValid(key)) {
LOG(ERROR) << "Invalid reference_delta";
return false;
}
ref->target = targets.OffsetForKey(expected_key + delta.value());
ref->location =
ref->location - equivalence->src_offset + equivalence->dst_offset;
ref_writer->PutNext(*ref);
}
}
}
}
if (!ref_delta_source.Done()) {
LOG(ERROR) << "Found trailing ref_delta_source";
return false;
}
return true;
}
bool ApplyElement(ExecutableType exe_type,
ConstBufferView old_image,
const PatchElementReader& patch_reader,
MutableBufferView new_image) {
return ApplyEquivalenceAndExtraData(old_image, patch_reader, new_image) &&
ApplyRawDelta(patch_reader, new_image) &&
ApplyReferencesCorrection(exe_type, old_image, patch_reader,
new_image);
}
/******** Exported Functions ********/
status::Code ApplyBuffer(ConstBufferView old_image,
const EnsemblePatchReader& patch_reader,
MutableBufferView new_image) {
if (!patch_reader.CheckOldFile(old_image)) {
LOG(ERROR) << "Invalid old_image.";
return status::kStatusInvalidOldImage;
}
for (const auto& element_patch : patch_reader.elements()) {
ElementMatch match = element_patch.element_match();
if (!ApplyElement(match.exe_type(), old_image[match.old_element.region()],
element_patch, new_image[match.new_element.region()]))
return status::kStatusFatal;
}
if (!patch_reader.CheckNewFile(ConstBufferView(new_image))) {
LOG(ERROR) << "Invalid new_image.";
return status::kStatusInvalidNewImage;
}
return status::kStatusSuccess;
}
} // namespace zucchini
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