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29
30// macho_walker.h: Iterate over the load commands in a mach-o file
31//
32// Author: Dan Waylonis
33
34#ifndef COMMON_MAC_MACHO_WALKER_H__
35#define COMMON_MAC_MACHO_WALKER_H__
36
37#include <mach/machine.h>
38#include <mach-o/loader.h>
39#include <sys/types.h>
40
41namespace MacFileUtilities {
42
43class MachoWalker {
44 public:
45  // A callback function executed when a new load command is read.  If no
46  // further processing of load commands is desired, return false.  Otherwise,
47  // return true.
48  // |cmd| is the current command, and |offset| is the location relative to the
49  // beginning of the file (not header) where the command was read.  If |swap|
50  // is set, then any command data (other than the returned load_command) should
51  // be swapped when read
52  typedef bool (*LoadCommandCallback)(MachoWalker *walker, load_command *cmd,
53                                      off_t offset, bool swap, void *context);
54
55  MachoWalker(const char *path, LoadCommandCallback callback, void *context);
56  MachoWalker(void *memory, size_t size, LoadCommandCallback callback,
57              void *context);
58  ~MachoWalker();
59
60  // Begin walking the header for |cpu_type| and |cpu_subtype|.  If |cpu_type|
61  // is 0, then the native cpu type is used. Otherwise, accepted values are
62  // listed in /usr/include/mach/machine.h (e.g., CPU_TYPE_X86 or
63  // CPU_TYPE_POWERPC). If |cpu_subtype| is CPU_SUBTYPE_MULTIPLE, the match is
64  // only done on |cpu_type|.
65  // Returns false if opening the file failed or if the |cpu_type|/|cpu_subtype|
66  // is not present in the file.
67  bool WalkHeader(cpu_type_t cpu_type, cpu_subtype_t cpu_subtype);
68
69  // Read |size| bytes from the opened file at |offset| into |buffer|
70  bool ReadBytes(void *buffer, size_t size, off_t offset);
71
72  // Return the current header and header offset
73  bool CurrentHeader(struct mach_header_64 *header, off_t *offset);
74
75 private:
76  // Locate (if any) the header offset for |cpu_type| and return in |offset|.
77  // Return true if found, false otherwise.
78  bool FindHeader(cpu_type_t cpu_type,
79                  cpu_subtype_t cpu_subtype,
80                  off_t &offset);
81
82  // Process an individual header starting at |offset| from the start of the
83  // file.  Return true if successful, false otherwise.
84  bool WalkHeaderAtOffset(off_t offset);
85  bool WalkHeader64AtOffset(off_t offset);
86
87  // Bottleneck for walking the load commands
88  bool WalkHeaderCore(off_t offset, uint32_t number_of_commands, bool swap);
89
90  // File descriptor to the opened file
91  int file_;
92
93  // Memory location to read from.
94  void *memory_;
95
96  // Size of the memory segment we can read from.
97  size_t memory_size_;
98
99  // User specified callback & context
100  LoadCommandCallback callback_;
101  void *callback_context_;
102
103  // Current header, size, and offset.  The mach_header_64 is used for both
104  // 32-bit and 64-bit headers because they only differ in their last field
105  // (reserved).  By adding the |current_header_size_| and the
106  // |current_header_offset_|, you can determine the offset in the file just
107  // after the header.
108  struct mach_header_64 *current_header_;
109  unsigned long current_header_size_;
110  off_t current_header_offset_;
111
112 private:
113  MachoWalker(const MachoWalker &);
114  MachoWalker &operator=(const MachoWalker &);
115};
116
117}  // namespace MacFileUtilities
118
119#endif  // COMMON_MAC_MACHO_WALKER_H__
120