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// 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.
#ifndef COURGETTE_DISASSEMBLER_H_
#define COURGETTE_DISASSEMBLER_H_
#include "base/basictypes.h"
#include "courgette/courgette.h"
// COURGETTE_HISTOGRAM_TARGETS prints out a histogram of how frequently
// different target addresses are referenced. Purely for debugging.
#define COURGETTE_HISTOGRAM_TARGETS 0
namespace courgette {
class AssemblyProgram;
// A Relative Virtual Address is the address in the image file after it is
// loaded into memory relative to the image load address.
typedef uint32 RVA;
class Disassembler {
public:
virtual ~Disassembler();
virtual ExecutableType kind() { return EXE_UNKNOWN; }
// ok() may always be called but returns 'true' only after ParseHeader
// succeeds.
bool ok() const { return failure_reason_ == NULL; }
// Returns 'true' if the buffer appears to be a valid executable of the
// expected type. It is not required that this be called before Disassemble.
virtual bool ParseHeader() = 0;
// Disassembles the item passed to the factory method into the output
// parameter 'program'.
virtual bool Disassemble(AssemblyProgram* program) = 0;
// Returns the length of the source executable. May reduce after ParseHeader.
size_t length() const { return length_; }
const uint8* start() const { return start_; }
const uint8* end() const { return end_; }
// Returns a pointer into the memory copy of the file format.
// FileOffsetToPointer(0) returns a pointer to the start of the file format.
const uint8* OffsetToPointer(size_t offset) const;
protected:
Disassembler(const void* start, size_t length);
bool Good();
bool Bad(const char *reason);
// These helper functions avoid the need for casts in the main code.
uint16 ReadU16(const uint8* address, size_t offset) {
return *reinterpret_cast<const uint16*>(address + offset);
}
uint32 ReadU32(const uint8* address, size_t offset) {
return *reinterpret_cast<const uint32*>(address + offset);
}
uint64 ReadU64(const uint8* address, size_t offset) {
return *reinterpret_cast<const uint64*>(address + offset);
}
static uint32 Read32LittleEndian(const void* address) {
return *reinterpret_cast<const uint32*>(address);
}
static uint16 Read16LittleEndian(const void* address) {
return *reinterpret_cast<const uint16*>(address);
}
// Reduce the length of the image in memory. Does not actually free
// (or realloc) any memory. Usually only called via ParseHeader()
void ReduceLength(size_t reduced_length);
private:
const char* failure_reason_;
//
// Basic information that is always valid after Construction, though
// ParseHeader may shorten the length if the executable is shorter than
// the total data.
//
size_t length_; // In current memory.
const uint8* start_; // In current memory, base for 'file offsets'.
const uint8* end_; // In current memory.
DISALLOW_COPY_AND_ASSIGN(Disassembler);
};
} // namespace courgette
#endif // COURGETTE_DISASSEMBLER_H_
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