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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 <stddef.h>
#include <memory>
#include <string>
#include <vector>
#include "base/macros.h"
#include "components/zucchini/buffer_view.h"
#include "components/zucchini/image_utils.h"
namespace zucchini {
// A vacuous ReferenceReader that produces no references.
class EmptyReferenceReader : public ReferenceReader {
base::Optional<Reference> GetNext() override;
// A vacuous EmptyReferenceWriter that does not write.
class EmptyReferenceWriter : public ReferenceWriter {
void PutNext(Reference reference) override;
// Disassembler needs to be declared before ReferenceGroup because the latter
// contains member pointers based on the former, and we use a compiler flag,
// -fcomplete-member-pointers, which enforces that member pointer base types are
// complete. This flag helps prevent us from running into problems in the
// Microsoft C++ ABI (see
class ReferenceGroup;
// A Disassembler is used to encapsulate architecture specific operations, to:
// - Describe types of references found in the architecture using traits.
// - Extract references contained in an image file.
// - Correct target for some references.
class Disassembler {
// Attempts to parse |image| and create an architecture-specifc Disassembler,
// as determined by DIS, which is inherited from Disassembler. Returns an
// instance of DIS if successful, and null otherwise.
template <class DIS>
static std::unique_ptr<DIS> Make(ConstBufferView image) {
auto disasm = std::make_unique<DIS>();
if (!disasm->Parse(image))
return nullptr;
return disasm;
virtual ~Disassembler();
// Returns the type of executable handled by the Disassembler.
virtual ExecutableType GetExeType() const = 0;
// Returns a more detailed description of the executable type.
virtual std::string GetExeTypeString() const = 0;
// Creates and returns a vector that contains all groups of references.
// Groups must be aggregated by pool.
virtual std::vector<ReferenceGroup> MakeReferenceGroups() const = 0;
ConstBufferView image() const { return image_; }
size_t size() const { return image_.size(); }
int num_equivalence_iterations() const { return num_equivalence_iterations_; }
explicit Disassembler(int num_equivalence_iterations);
// Parses |image| and initializes internal states. Returns true on success.
// This must be called once and before any other operation.
virtual bool Parse(ConstBufferView image) = 0;
// Raw image data. After Parse(), a Disassembler should shrink this to contain
// only the portion containing the executable file it recognizes.
ConstBufferView image_;
// The number of iterations to run for equivalence map generation. This should
// roughly be the max length of reference indirection chains.
int num_equivalence_iterations_;
// A ReferenceGroup is associated with a specific |type| and has convenience
// methods to obtain readers and writers for that type. A ReferenceGroup does
// not store references; it is a lightweight class that communicates with the
// disassembler to operate on them.
class ReferenceGroup {
// Member function pointer used to obtain a ReferenceReader.
using ReaderFactory = std::unique_ptr<ReferenceReader> (
Disassembler::*)(offset_t lower, offset_t upper);
// Member function pointer used to obtain a ReferenceWriter.
using WriterFactory = std::unique_ptr<ReferenceWriter> (Disassembler::*)(
MutableBufferView image);
// RefinedGeneratorFactory and RefinedReceptorFactory don't have to be
// identical to GeneratorFactory and ReceptorFactory, but they must be
// convertible. As a result, they can be pointer to member function of a
// derived Disassembler.
template <class RefinedReaderFactory, class RefinedWriterFactory>
ReferenceGroup(ReferenceTypeTraits traits,
RefinedReaderFactory reader_factory,
RefinedWriterFactory writer_factory)
: traits_(traits),
writer_factory_(static_cast<WriterFactory>(writer_factory)) {}
// Returns a reader for all references in the binary.
// Invalidates any other writer or reader previously obtained for |disasm|.
std::unique_ptr<ReferenceReader> GetReader(Disassembler* disasm) const;
// Returns a reader for references whose bytes are entirely contained in
// |[lower, upper)|.
// Invalidates any other writer or reader previously obtained for |disasm|.
std::unique_ptr<ReferenceReader> GetReader(offset_t lower,
offset_t upper,
Disassembler* disasm) const;
// Returns a writer for references in |image|, assuming that |image| was the
// same one initially parsed by |disasm|.
// Invalidates any other writer or reader previously obtained for |disasm|.
std::unique_ptr<ReferenceWriter> GetWriter(MutableBufferView image,
Disassembler* disasm) const;
// Returns traits describing the reference type.
const ReferenceTypeTraits& traits() const { return traits_; }
// Shorthand for traits().width.
offset_t width() const { return traits().width; }
// Shorthand for traits().type_tag.
TypeTag type_tag() const { return traits().type_tag; }
// Shorthand for traits().pool_tag.
PoolTag pool_tag() const { return traits().pool_tag; }
ReferenceTypeTraits traits_;
ReaderFactory reader_factory_ = nullptr;
WriterFactory writer_factory_ = nullptr;
} // namespace zucchini