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_ 77