| // Copyright (c) 2011 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. |
| |
| // The main idea in Courgette is to do patching *under a tranformation*. The |
| // input is transformed into a new representation, patching occurs in the new |
| // repesentation, and then the tranform is reversed to get the patched data. |
| // |
| // The idea is applied to pieces (or 'elements') of the whole (or 'ensemble'). |
| // Each of the elements has to go through the same set of steps in lock-step. |
| |
| // This file contains the code to create the patch. |
| |
| |
| #include "courgette/ensemble.h" |
| |
| #include <stddef.h> |
| |
| #include <limits> |
| #include <vector> |
| |
| #include "base/logging.h" |
| #include "base/time/time.h" |
| |
| #include "courgette/crc.h" |
| #include "courgette/difference_estimator.h" |
| #include "courgette/patch_generator_x86_32.h" |
| #include "courgette/patcher_x86_32.h" |
| #include "courgette/region.h" |
| #include "courgette/simple_delta.h" |
| #include "courgette/streams.h" |
| #include "courgette/third_party/bsdiff/bsdiff.h" |
| |
| namespace courgette { |
| |
| TransformationPatchGenerator::TransformationPatchGenerator( |
| Element* old_element, |
| Element* new_element, |
| TransformationPatcher* patcher) |
| : old_element_(old_element), |
| new_element_(new_element), |
| patcher_(patcher) { |
| } |
| |
| TransformationPatchGenerator::~TransformationPatchGenerator() { |
| delete patcher_; |
| } |
| |
| // The default implementation of PredictTransformParameters delegates to the |
| // patcher. |
| Status TransformationPatchGenerator::PredictTransformParameters( |
| SinkStreamSet* prediction) { |
| return patcher_->PredictTransformParameters(prediction); |
| } |
| |
| // The default implementation of Reform delegates to the patcher. |
| Status TransformationPatchGenerator::Reform( |
| SourceStreamSet* transformed_element, |
| SinkStream* reformed_element) { |
| return patcher_->Reform(transformed_element, reformed_element); |
| } |
| |
| // Makes a TransformationPatchGenerator of the appropriate variety for the |
| // Element kind. |
| TransformationPatchGenerator* MakeGenerator(Element* old_element, |
| Element* new_element) { |
| switch (new_element->kind()) { |
| case EXE_UNKNOWN: |
| break; |
| case EXE_WIN_32_X86: { |
| TransformationPatchGenerator* generator = |
| new PatchGeneratorX86_32( |
| old_element, |
| new_element, |
| new PatcherX86_32(old_element->region()), |
| EXE_WIN_32_X86); |
| return generator; |
| } |
| case EXE_ELF_32_X86: { |
| TransformationPatchGenerator* generator = |
| new PatchGeneratorX86_32( |
| old_element, |
| new_element, |
| new PatcherX86_32(old_element->region()), |
| EXE_ELF_32_X86); |
| return generator; |
| } |
| case EXE_ELF_32_ARM: { |
| TransformationPatchGenerator* generator = |
| new PatchGeneratorX86_32( |
| old_element, |
| new_element, |
| new PatcherX86_32(old_element->region()), |
| EXE_ELF_32_ARM); |
| return generator; |
| } |
| case EXE_WIN_32_X64: { |
| TransformationPatchGenerator* generator = |
| new PatchGeneratorX86_32( |
| old_element, |
| new_element, |
| new PatcherX86_32(old_element->region()), |
| EXE_WIN_32_X64); |
| return generator; |
| } |
| } |
| |
| LOG(WARNING) << "Unexpected Element::Kind " << old_element->kind(); |
| return nullptr; |
| } |
| |
| // Checks to see if the proposed comparison is 'unsafe'. Sometimes one element |
| // from 'old' is matched as the closest element to multiple elements from 'new'. |
| // Each time this happens, the old element is transformed and serialized. This |
| // is a problem when the old element is huge compared with the new element |
| // because the mutliple serialized copies can be much bigger than the size of |
| // either ensemble. |
| // |
| // The right way to avoid this is to ensure any one element from 'old' is |
| // serialized once, which requires matching code in the patch application. |
| // |
| // This is a quick hack to avoid the problem by prohibiting a big difference in |
| // size between matching elements. |
| bool UnsafeDifference(Element* old_element, Element* new_element) { |
| double kMaxBloat = 2.0; |
| size_t kMinWorrysomeDifference = 2 << 20; // 2MB |
| size_t old_size = old_element->region().length(); |
| size_t new_size = new_element->region().length(); |
| size_t low_size = std::min(old_size, new_size); |
| size_t high_size = std::max(old_size, new_size); |
| if (high_size - low_size < kMinWorrysomeDifference) return false; |
| if (high_size < low_size * kMaxBloat) return false; |
| return true; |
| } |
| |
| // FindGenerators finds TransformationPatchGenerators for the elements of |
| // |new_ensemble|. For each element of |new_ensemble| we find the closest |
| // matching element from |old_ensemble| and use that as the basis for |
| // differential compression. The elements have to be the same kind so as to |
| // support transformation into the same kind of 'new representation'. |
| // |
| Status FindGenerators(Ensemble* old_ensemble, Ensemble* new_ensemble, |
| std::vector<TransformationPatchGenerator*>* generators) { |
| base::Time start_find_time = base::Time::Now(); |
| old_ensemble->FindEmbeddedElements(); |
| new_ensemble->FindEmbeddedElements(); |
| VLOG(1) << "done FindEmbeddedElements " |
| << (base::Time::Now() - start_find_time).InSecondsF(); |
| |
| std::vector<Element*> old_elements(old_ensemble->elements()); |
| std::vector<Element*> new_elements(new_ensemble->elements()); |
| |
| VLOG(1) << "old has " << old_elements.size() << " elements"; |
| VLOG(1) << "new has " << new_elements.size() << " elements"; |
| |
| DifferenceEstimator difference_estimator; |
| std::vector<DifferenceEstimator::Base*> bases; |
| |
| base::Time start_bases_time = base::Time::Now(); |
| for (size_t i = 0; i < old_elements.size(); ++i) { |
| bases.push_back( |
| difference_estimator.MakeBase(old_elements[i]->region())); |
| } |
| VLOG(1) << "done make bases " |
| << (base::Time::Now() - start_bases_time).InSecondsF() << "s"; |
| |
| for (size_t new_index = 0; new_index < new_elements.size(); ++new_index) { |
| Element* new_element = new_elements[new_index]; |
| DifferenceEstimator::Subject* new_subject = |
| difference_estimator.MakeSubject(new_element->region()); |
| |
| // Search through old elements to find the best match. |
| // |
| // TODO(sra): This is O(N x M), i.e. O(N^2) since old_ensemble and |
| // new_ensemble probably have a very similar structure. We can make the |
| // search faster by making the comparison provided by DifferenceEstimator |
| // more nuanced, returning early if the measured difference is greater than |
| // the current best. This will be most effective if we can arrange that the |
| // first elements we try to match are likely the 'right' ones. We could |
| // prioritize elements that are of a similar size or similar position in the |
| // sequence of elements. |
| // |
| Element* best_old_element = nullptr; |
| size_t best_difference = std::numeric_limits<size_t>::max(); |
| for (size_t old_index = 0; old_index < old_elements.size(); ++old_index) { |
| Element* old_element = old_elements[old_index]; |
| // Elements of different kinds are incompatible. |
| if (old_element->kind() != new_element->kind()) |
| continue; |
| |
| if (UnsafeDifference(old_element, new_element)) |
| continue; |
| |
| base::Time start_compare = base::Time::Now(); |
| DifferenceEstimator::Base* old_base = bases[old_index]; |
| size_t difference = difference_estimator.Measure(old_base, new_subject); |
| |
| VLOG(1) << "Compare " << old_element->Name() |
| << " to " << new_element->Name() |
| << " --> " << difference |
| << " in " << (base::Time::Now() - start_compare).InSecondsF() |
| << "s"; |
| if (difference == 0) { |
| VLOG(1) << "Skip " << new_element->Name() |
| << " - identical to " << old_element->Name(); |
| best_difference = 0; |
| best_old_element = nullptr; |
| break; |
| } |
| if (difference < best_difference) { |
| best_difference = difference; |
| best_old_element = old_element; |
| } |
| } |
| |
| if (best_old_element) { |
| VLOG(1) << "Matched " << best_old_element->Name() |
| << " to " << new_element->Name() |
| << " --> " << best_difference; |
| TransformationPatchGenerator* generator = |
| MakeGenerator(best_old_element, new_element); |
| if (generator) |
| generators->push_back(generator); |
| } |
| } |
| |
| VLOG(1) << "done FindGenerators found " << generators->size() |
| << " in " << (base::Time::Now() - start_find_time).InSecondsF() |
| << "s"; |
| |
| return C_OK; |
| } |
| |
| void FreeGenerators(std::vector<TransformationPatchGenerator*>* generators) { |
| for (size_t i = 0; i < generators->size(); ++i) { |
| delete (*generators)[i]; |
| } |
| generators->clear(); |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| Status GenerateEnsemblePatch(SourceStream* base, |
| SourceStream* update, |
| SinkStream* final_patch) { |
| VLOG(1) << "start GenerateEnsemblePatch"; |
| base::Time start_time = base::Time::Now(); |
| |
| Region old_region(base->Buffer(), base->Remaining()); |
| Region new_region(update->Buffer(), update->Remaining()); |
| Ensemble old_ensemble(old_region, "old"); |
| Ensemble new_ensemble(new_region, "new"); |
| std::vector<TransformationPatchGenerator*> generators; |
| Status generators_status = FindGenerators(&old_ensemble, &new_ensemble, |
| &generators); |
| if (generators_status != C_OK) |
| return generators_status; |
| |
| SinkStreamSet patch_streams; |
| |
| SinkStream* tranformation_descriptions = patch_streams.stream(0); |
| SinkStream* parameter_correction = patch_streams.stream(1); |
| SinkStream* transformed_elements_correction = patch_streams.stream(2); |
| SinkStream* ensemble_correction = patch_streams.stream(3); |
| |
| size_t number_of_transformations = generators.size(); |
| if (!tranformation_descriptions->WriteSizeVarint32(number_of_transformations)) |
| return C_STREAM_ERROR; |
| |
| for (size_t i = 0; i < number_of_transformations; ++i) { |
| ExecutableType kind = generators[i]->Kind(); |
| if (!tranformation_descriptions->WriteVarint32(kind)) |
| return C_STREAM_ERROR; |
| } |
| |
| for (size_t i = 0; i < number_of_transformations; ++i) { |
| Status status = |
| generators[i]->WriteInitialParameters(tranformation_descriptions); |
| if (status != C_OK) |
| return status; |
| } |
| |
| // |
| // Generate sub-patch for parameters. |
| // |
| SinkStreamSet predicted_parameters_sink; |
| SinkStreamSet corrected_parameters_sink; |
| |
| for (size_t i = 0; i < number_of_transformations; ++i) { |
| SinkStreamSet single_predicted_parameters; |
| Status status; |
| status = generators[i]->PredictTransformParameters( |
| &single_predicted_parameters); |
| if (status != C_OK) |
| return status; |
| if (!predicted_parameters_sink.WriteSet(&single_predicted_parameters)) |
| return C_STREAM_ERROR; |
| |
| SinkStreamSet single_corrected_parameters; |
| status = generators[i]->CorrectedTransformParameters( |
| &single_corrected_parameters); |
| if (status != C_OK) |
| return status; |
| if (!corrected_parameters_sink.WriteSet(&single_corrected_parameters)) |
| return C_STREAM_ERROR; |
| } |
| |
| SinkStream linearized_predicted_parameters; |
| SinkStream linearized_corrected_parameters; |
| |
| if (!predicted_parameters_sink.CopyTo(&linearized_predicted_parameters)) |
| return C_STREAM_ERROR; |
| if (!corrected_parameters_sink.CopyTo(&linearized_corrected_parameters)) |
| return C_STREAM_ERROR; |
| |
| SourceStream predicted_parameters_source; |
| SourceStream corrected_parameters_source; |
| predicted_parameters_source.Init(linearized_predicted_parameters); |
| corrected_parameters_source.Init(linearized_corrected_parameters); |
| |
| Status delta1_status = GenerateSimpleDelta(&predicted_parameters_source, |
| &corrected_parameters_source, |
| parameter_correction); |
| if (delta1_status != C_OK) |
| return delta1_status; |
| |
| // |
| // Generate sub-patch for elements. |
| // |
| corrected_parameters_source.Init(linearized_corrected_parameters); |
| SourceStreamSet corrected_parameters_source_set; |
| if (!corrected_parameters_source_set.Init(&corrected_parameters_source)) |
| return C_STREAM_ERROR; |
| |
| SinkStreamSet predicted_transformed_elements; |
| SinkStreamSet corrected_transformed_elements; |
| |
| for (size_t i = 0; i < number_of_transformations; ++i) { |
| SourceStreamSet single_parameters; |
| if (!corrected_parameters_source_set.ReadSet(&single_parameters)) |
| return C_STREAM_ERROR; |
| SinkStreamSet single_predicted_transformed_element; |
| SinkStreamSet single_corrected_transformed_element; |
| Status status = generators[i]->Transform( |
| &single_parameters, |
| &single_predicted_transformed_element, |
| &single_corrected_transformed_element); |
| if (status != C_OK) |
| return status; |
| if (!single_parameters.Empty()) |
| return C_STREAM_NOT_CONSUMED; |
| if (!predicted_transformed_elements.WriteSet( |
| &single_predicted_transformed_element)) |
| return C_STREAM_ERROR; |
| if (!corrected_transformed_elements.WriteSet( |
| &single_corrected_transformed_element)) |
| return C_STREAM_ERROR; |
| } |
| |
| if (!corrected_parameters_source_set.Empty()) |
| return C_STREAM_NOT_CONSUMED; |
| |
| SinkStream linearized_predicted_transformed_elements; |
| SinkStream linearized_corrected_transformed_elements; |
| |
| if (!predicted_transformed_elements.CopyTo( |
| &linearized_predicted_transformed_elements)) |
| return C_STREAM_ERROR; |
| if (!corrected_transformed_elements.CopyTo( |
| &linearized_corrected_transformed_elements)) |
| return C_STREAM_ERROR; |
| |
| SourceStream predicted_transformed_elements_source; |
| SourceStream corrected_transformed_elements_source; |
| predicted_transformed_elements_source |
| .Init(linearized_predicted_transformed_elements); |
| corrected_transformed_elements_source |
| .Init(linearized_corrected_transformed_elements); |
| |
| Status delta2_status = |
| GenerateSimpleDelta(&predicted_transformed_elements_source, |
| &corrected_transformed_elements_source, |
| transformed_elements_correction); |
| if (delta2_status != C_OK) |
| return delta2_status; |
| |
| // Last use, free storage. |
| linearized_predicted_transformed_elements.Retire(); |
| |
| // |
| // Generate sub-patch for whole enchilada. |
| // |
| SinkStream predicted_ensemble; |
| |
| if (!predicted_ensemble.Write(base->Buffer(), base->Remaining())) |
| return C_STREAM_ERROR; |
| |
| SourceStreamSet corrected_transformed_elements_source_set; |
| corrected_transformed_elements_source |
| .Init(linearized_corrected_transformed_elements); |
| if (!corrected_transformed_elements_source_set |
| .Init(&corrected_transformed_elements_source)) |
| return C_STREAM_ERROR; |
| |
| for (size_t i = 0; i < number_of_transformations; ++i) { |
| SourceStreamSet single_corrected_transformed_element; |
| if (!corrected_transformed_elements_source_set.ReadSet( |
| &single_corrected_transformed_element)) |
| return C_STREAM_ERROR; |
| Status status = generators[i]->Reform(&single_corrected_transformed_element, |
| &predicted_ensemble); |
| if (status != C_OK) |
| return status; |
| if (!single_corrected_transformed_element.Empty()) |
| return C_STREAM_NOT_CONSUMED; |
| } |
| |
| if (!corrected_transformed_elements_source_set.Empty()) |
| return C_STREAM_NOT_CONSUMED; |
| |
| // No more references to this stream's buffer. |
| linearized_corrected_transformed_elements.Retire(); |
| |
| FreeGenerators(&generators); |
| |
| size_t final_patch_input_size = predicted_ensemble.Length(); |
| SourceStream predicted_ensemble_source; |
| predicted_ensemble_source.Init(predicted_ensemble); |
| Status delta3_status = GenerateSimpleDelta(&predicted_ensemble_source, |
| update, |
| ensemble_correction); |
| if (delta3_status != C_OK) |
| return delta3_status; |
| |
| // |
| // Final output stream has a header followed by a StreamSet. |
| // |
| if (!final_patch->WriteVarint32(CourgettePatchFile::kMagic) || |
| !final_patch->WriteVarint32(CourgettePatchFile::kVersion) || |
| !final_patch->WriteVarint32(CalculateCrc(old_region.start(), |
| old_region.length())) || |
| !final_patch->WriteVarint32(CalculateCrc(new_region.start(), |
| new_region.length())) || |
| !final_patch->WriteSizeVarint32(final_patch_input_size) || |
| !patch_streams.CopyTo(final_patch)) { |
| return C_STREAM_ERROR; |
| } |
| |
| VLOG(1) << "done GenerateEnsemblePatch " |
| << (base::Time::Now() - start_time).InSecondsF() << "s"; |
| |
| return C_OK; |
| } |
| |
| } // namespace |
