third_party/mach_override/mach_override.h

   1 // mach_override.h semver:1.2.0
   2 //   Copyright (c) 2003-2012 Jonathan 'Wolf' Rentzsch: http://rentzsch.com
   3 //   Some rights reserved: http://opensource.org/licenses/mit
   4 //   https://github.com/rentzsch/mach_override
   5
   6 #ifndef         _mach_override_
   7 #define         _mach_override_
   8
   9 #include <sys/types.h>
  10 #include <mach/error.h>
  11
  12 #define err_cannot_override     (err_local|1)
  13
  14 __BEGIN_DECLS
  15
  16 /****************************************************************************************
  17         Dynamically overrides the function implementation referenced by
  18         originalFunctionAddress with the implentation pointed to by overrideFunctionAddress.
  19         Optionally returns a pointer to a "reentry island" which, if jumped to, will resume
  20         the original implementation.
  21
  22         @param  originalFunctionAddress                 ->      Required address of the function to
  23                                                                                                 override (with overrideFunctionAddress).
  24         @param  overrideFunctionAddress                 ->      Required address to the overriding
  25                                                                                                 function.
  26         @param  originalFunctionReentryIsland   <-      Optional pointer to pointer to the
  27                                                                                                 reentry island. Can be NULL.
  28         @result                                                                 <-      err_cannot_override if the original
  29                                                                                                 function's implementation begins with
  30                                                                                                 the 'mfctr' instruction.
  31
  32         ************************************************************************************/
  33
  34     mach_error_t
  35 mach_override_ptr(
  36         void *originalFunctionAddress,
  37     const void *overrideFunctionAddress,
  38     void **originalFunctionReentryIsland );
  39
  40 __END_DECLS
  41
  42 /****************************************************************************************
  43         If you're using C++ this macro will ease the tedium of typedef'ing, naming, keeping
  44         track of reentry islands and defining your override code. See test_mach_override.cp
  45         for example usage.
  46
  47         ************************************************************************************/
  48
  49 #ifdef  __cplusplus
  50 #define MACH_OVERRIDE( ORIGINAL_FUNCTION_RETURN_TYPE, ORIGINAL_FUNCTION_NAME, ORIGINAL_FUNCTION_ARGS, ERR )             \
  51 {                                                                                                                                                                                                                               \
  52         static ORIGINAL_FUNCTION_RETURN_TYPE (*ORIGINAL_FUNCTION_NAME##_reenter)ORIGINAL_FUNCTION_ARGS;                         \
  53         static bool ORIGINAL_FUNCTION_NAME##_overriden = false;                                                                                                         \
  54         class mach_override_class__##ORIGINAL_FUNCTION_NAME {                                                                                                           \
  55         public:                                                                                                                                                                                                         \
  56                 static kern_return_t override(void *originalFunctionPtr) {                                                                                              \
  57                         kern_return_t result = err_none;                                                                                                                                        \
  58                         if (!ORIGINAL_FUNCTION_NAME##_overriden) {                                                                                                                      \
  59                                 ORIGINAL_FUNCTION_NAME##_overriden = true;                                                                                                              \
  60                                 result = mach_override_ptr( (void*)originalFunctionPtr,                                                                                 \
  61                                                                                         (void*)mach_override_class__##ORIGINAL_FUNCTION_NAME::replacement,      \
  62                                                                                         (void**)&ORIGINAL_FUNCTION_NAME##_reenter );                                            \
  63                         }                                                                                                                                                                                                       \
  64                         return result;                                                                                                                                                                          \
  65                 }                                                                                                                                                                                                               \
  66                 static ORIGINAL_FUNCTION_RETURN_TYPE replacement ORIGINAL_FUNCTION_ARGS {
  67
  68 #define END_MACH_OVERRIDE( ORIGINAL_FUNCTION_NAME )                                                                                                                             \
  69                 }                                                                                                                                                                                                               \
  70         };                                                                                                                                                                                                                      \
  71                                                                                                                                                                                                                                 \
  72         err = mach_override_class__##ORIGINAL_FUNCTION_NAME::override((void*)ORIGINAL_FUNCTION_NAME);                           \
  73 }
  74 #endif
  75
  76 #endif  //      _mach_override_