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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