1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef COURGETTE_DISASSEMBLER_H_ 6 #define COURGETTE_DISASSEMBLER_H_ 7 8 #include "base/basictypes.h" 9 10 #include "courgette/courgette.h" 11 12 namespace courgette { 13 14 class AssemblyProgram; 15 16 // A Relative Virtual Address is the address in the image file after it is 17 // loaded into memory relative to the image load address. 18 typedef uint32 RVA; 19 20 class Disassembler { 21 public: 22 virtual ~Disassembler(); 23 24 virtual ExecutableType kind() { return EXE_UNKNOWN; } 25 26 // ok() may always be called but returns 'true' only after ParseHeader 27 // succeeds. 28 bool ok() const { return failure_reason_ == NULL; } 29 30 // Returns 'true' if the buffer appears to be a valid executable of the 31 // expected type. It is not required that this be called before Disassemble. 32 virtual bool ParseHeader() = 0; 33 34 // Disassembles the item passed to the factory method into the output 35 // parameter 'program'. 36 virtual bool Disassemble(AssemblyProgram* program) = 0; 37 38 // Returns the length of the source executable. May reduce after ParseHeader. 39 size_t length() const { return length_; } 40 const uint8* start() const { return start_; } 41 const uint8* end() const { return end_; } 42 43 // Returns a pointer into the memory copy of the file format. 44 // FileOffsetToPointer(0) returns a pointer to the start of the file format. 45 const uint8* OffsetToPointer(size_t offset) const; 46 47 protected: 48 Disassembler(const void* start, size_t length); 49 50 bool Good(); 51 bool Bad(const char *reason); 52 53 // These helper functions avoid the need for casts in the main code. 54 uint16 ReadU16(const uint8* address, size_t offset) { 55 return *reinterpret_cast<const uint16*>(address + offset); 56 } 57 58 uint32 ReadU32(const uint8* address, size_t offset) { 59 return *reinterpret_cast<const uint32*>(address + offset); 60 } 61 62 uint64 ReadU64(const uint8* address, size_t offset) { 63 return *reinterpret_cast<const uint64*>(address + offset); 64 } 65 66 static uint32 Read32LittleEndian(const void* address) { 67 return *reinterpret_cast<const uint32*>(address); 68 } 69 70 static uint16 Read16LittleEndian(const void* address) { 71 return *reinterpret_cast<const uint16*>(address); 72 } 73 74 // Reduce the length of the image in memory. Does not actually free 75 // (or realloc) any memory. Usually only called via ParseHeader() 76 void ReduceLength(size_t reduced_length); 77 78 private: 79 const char* failure_reason_; 80 81 // 82 // Basic information that is always valid after Construction, though 83 // ParseHeader may shorten the length if the executable is shorter than 84 // the total data. 85 // 86 size_t length_; // In current memory. 87 const uint8* start_; // In current memory, base for 'file offsets'. 88 const uint8* end_; // In current memory. 89 90 DISALLOW_COPY_AND_ASSIGN(Disassembler); 91 }; 92 93 } // namespace courgette 94 #endif // COURGETTE_DISASSEMBLER_H_ 95
