1  // Copyright 2006 Google LLC
  2  //
  3  // Redistribution and use in source and binary forms, with or without
  4  // modification, are permitted provided that the following conditions are
  5  // met:
  6  //
  7  //     * Redistributions of source code must retain the above copyright
  8  // notice, this list of conditions and the following disclaimer.
  9  //     * Redistributions in binary form must reproduce the above
 10  // copyright notice, this list of conditions and the following disclaimer
 11  // in the documentation and/or other materials provided with the
 12  // distribution.
 13  //     * Neither the name of Google LLC nor the names of its
 14  // contributors may be used to endorse or promote products derived from
 15  // this software without specific prior written permission.
 16  //
 17  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 18  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 19  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 20  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 21  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 22  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 23  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 24  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 25  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 26  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 27  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 28  
 29  // macho_walker.h: Iterate over the load commands in a mach-o file
 30  //
 31  // Author: Dan Waylonis
 32  
 33  #ifndef COMMON_MAC_MACHO_WALKER_H__
 34  #define COMMON_MAC_MACHO_WALKER_H__
 35  
 36  #include <mach/machine.h>
 37  #include <mach-o/loader.h>
 38  #include <sys/types.h>
 39  
 40  namespace MacFileUtilities {
 41  
 42  class MachoWalker {
 43   public:
 44    // A callback function executed when a new load command is read.  If no
 45    // further processing of load commands is desired, return false.  Otherwise,
 46    // return true.
 47    // |cmd| is the current command, and |offset| is the location relative to the
 48    // beginning of the file (not header) where the command was read.  If |swap|
 49    // is set, then any command data (other than the returned load_command) should
 50    // be swapped when read
 51    typedef bool (*LoadCommandCallback)(MachoWalker* walker, load_command* cmd,
 52                                        off_t offset, bool swap, void* context);
 53  
 54    MachoWalker(const char* path, LoadCommandCallback callback, void* context);
 55    MachoWalker(void* memory, size_t size, LoadCommandCallback callback,
 56                void* context);
 57    ~MachoWalker();
 58  
 59    // Begin walking the header for |cpu_type| and |cpu_subtype|.  If |cpu_type|
 60    // is 0, then the native cpu type is used. Otherwise, accepted values are
 61    // listed in /usr/include/mach/machine.h (e.g., CPU_TYPE_X86 or
 62    // CPU_TYPE_POWERPC). If |cpu_subtype| is CPU_SUBTYPE_MULTIPLE, the match is
 63    // only done on |cpu_type|.
 64    // Returns false if opening the file failed or if the |cpu_type|/|cpu_subtype|
 65    // is not present in the file.
 66    bool WalkHeader(cpu_type_t cpu_type, cpu_subtype_t cpu_subtype);
 67  
 68    // Read |size| bytes from the opened file at |offset| into |buffer|
 69    bool ReadBytes(void* buffer, size_t size, off_t offset);
 70  
 71    // Return the current header and header offset
 72    bool CurrentHeader(struct mach_header_64* header, off_t* offset);
 73  
 74   private:
 75    // Locate (if any) the header offset for |cpu_type| and return in |offset|.
 76    // Return true if found, false otherwise.
 77    bool FindHeader(cpu_type_t cpu_type,
 78                    cpu_subtype_t cpu_subtype,
 79                    off_t& offset);
 80  
 81    // Process an individual header starting at |offset| from the start of the
 82    // file.  Return true if successful, false otherwise.
 83    bool WalkHeaderAtOffset(off_t offset);
 84    bool WalkHeader64AtOffset(off_t offset);
 85  
 86    // Bottleneck for walking the load commands
 87    bool WalkHeaderCore(off_t offset, uint32_t number_of_commands, bool swap);
 88  
 89    // File descriptor to the opened file
 90    int file_;
 91  
 92    // Memory location to read from.
 93    void* memory_;
 94  
 95    // Size of the memory segment we can read from.
 96    size_t memory_size_;
 97  
 98    // User specified callback & context
 99    LoadCommandCallback callback_;
100    void* callback_context_;
101  
102    // Current header, size, and offset.  The mach_header_64 is used for both
103    // 32-bit and 64-bit headers because they only differ in their last field
104    // (reserved).  By adding the |current_header_size_| and the
105    // |current_header_offset_|, you can determine the offset in the file just
106    // after the header.
107    struct mach_header_64* current_header_;
108    unsigned long current_header_size_;
109    off_t current_header_offset_;
110  
111   private:
112    MachoWalker(const MachoWalker&);
113    MachoWalker& operator=(const MachoWalker&);
114  };
115  
116  }  // namespace MacFileUtilities
117  
118  #endif  // COMMON_MAC_MACHO_WALKER_H__