The Tor Browser / file comparison
comparison: xpcom/build/mach_override.h
xpcom/build/mach_override.h
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
equal
deleted
inserted
replaced
| -1:000000000000 | 0:8eadf0b1f5b2 |
|---|---|
| 1 /******************************************************************************* | |
| 2 mach_override.h | |
| 3 Copyright (c) 2003-2009 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com> | |
| 4 Some rights reserved: <http://opensource.org/licenses/mit-license.php> | |
| 5 | |
| 6 ***************************************************************************/ | |
| 7 | |
| 8 /***************************************************************************//** | |
| 9 @mainpage mach_override | |
| 10 @author Jonathan 'Wolf' Rentzsch: <http://rentzsch.com> | |
| 11 | |
| 12 This package, coded in C to the Mach API, allows you to override ("patch") | |
| 13 program- and system-supplied functions at runtime. You can fully replace | |
| 14 functions with your implementations, or merely head- or tail-patch the | |
| 15 original implementations. | |
| 16 | |
| 17 Use it by #include'ing mach_override.h from your .c, .m or .mm file(s). | |
| 18 | |
| 19 @todo Discontinue use of Carbon's MakeDataExecutable() and | |
| 20 CompareAndSwap() calls and start using the Mach equivalents, if they | |
| 21 exist. If they don't, write them and roll them in. That way, this | |
| 22 code will be pure Mach, which will make it easier to use everywhere. | |
| 23 Update: MakeDataExecutable() has been replaced by | |
| 24 msync(MS_INVALIDATE). There is an OSCompareAndSwap in libkern, but | |
| 25 I'm currently unsure if I can link against it. May have to roll in | |
| 26 my own version... | |
| 27 @todo Stop using an entire 4K high-allocated VM page per 28-byte escape | |
| 28 branch island. Done right, this will dramatically speed up escape | |
| 29 island allocations when they number over 250. Then again, if you're | |
| 30 overriding more than 250 functions, maybe speed isn't your main | |
| 31 concern... | |
| 32 @todo Add detection of: b, bl, bla, bc, bcl, bcla, bcctrl, bclrl | |
| 33 first-instructions. Initially, we should refuse to override | |
| 34 functions beginning with these instructions. Eventually, we should | |
| 35 dynamically rewrite them to make them position-independent. | |
| 36 @todo Write mach_unoverride(), which would remove an override placed on a | |
| 37 function. Must be multiple-override aware, which means an almost | |
| 38 complete rewrite under the covers, because the target address can't | |
| 39 be spread across two load instructions like it is now since it will | |
| 40 need to be atomically updatable. | |
| 41 @todo Add non-rentry variants of overrides to test_mach_override. | |
| 42 | |
| 43 ***************************************************************************/ | |
| 44 | |
| 45 #ifndef _mach_override_ | |
| 46 #define _mach_override_ | |
| 47 | |
| 48 #include <sys/types.h> | |
| 49 #include <mach/error.h> | |
| 50 | |
| 51 #ifdef __cplusplus | |
| 52 extern "C" { | |
| 53 #endif | |
| 54 | |
| 55 /** | |
| 56 Returned if the function to be overrided begins with a 'mfctr' instruction. | |
| 57 */ | |
| 58 #define err_cannot_override (err_local|1) | |
| 59 | |
| 60 /************************************************************************************//** | |
| 61 Dynamically overrides the function implementation referenced by | |
| 62 originalFunctionAddress with the implentation pointed to by overrideFunctionAddress. | |
| 63 Optionally returns a pointer to a "reentry island" which, if jumped to, will resume | |
| 64 the original implementation. | |
| 65 | |
| 66 @param originalFunctionAddress -> Required address of the function to | |
| 67 override (with overrideFunctionAddress). | |
| 68 @param overrideFunctionAddress -> Required address to the overriding | |
| 69 function. | |
| 70 @param originalFunctionReentryIsland <- Optional pointer to pointer to the | |
| 71 reentry island. Can be nullptr. | |
| 72 @result <- err_cannot_override if the original | |
| 73 function's implementation begins with | |
| 74 the 'mfctr' instruction. | |
| 75 | |
| 76 ************************************************************************************/ | |
| 77 | |
| 78 mach_error_t | |
| 79 mach_override_ptr( | |
| 80 void *originalFunctionAddress, | |
| 81 const void *overrideFunctionAddress, | |
| 82 void **originalFunctionReentryIsland ); | |
| 83 | |
| 84 /************************************************************************************//** | |
| 85 | |
| 86 | |
| 87 ************************************************************************************/ | |
| 88 | |
| 89 #ifdef __cplusplus | |
| 90 | |
| 91 #define MACH_OVERRIDE( ORIGINAL_FUNCTION_RETURN_TYPE, ORIGINAL_FUNCTION_NAME, ORIGINAL_FUNCTION_ARGS, ERR ) \ | |
| 92 { \ | |
| 93 static ORIGINAL_FUNCTION_RETURN_TYPE (*ORIGINAL_FUNCTION_NAME##_reenter)ORIGINAL_FUNCTION_ARGS; \ | |
| 94 static bool ORIGINAL_FUNCTION_NAME##_overriden = false; \ | |
| 95 class mach_override_class__##ORIGINAL_FUNCTION_NAME { \ | |
| 96 public: \ | |
| 97 static kern_return_t override(void *originalFunctionPtr) { \ | |
| 98 kern_return_t result = err_none; \ | |
| 99 if (!ORIGINAL_FUNCTION_NAME##_overriden) { \ | |
| 100 ORIGINAL_FUNCTION_NAME##_overriden = true; \ | |
| 101 result = mach_override_ptr( (void*)originalFunctionPtr, \ | |
| 102 (void*)mach_override_class__##ORIGINAL_FUNCTION_NAME::replacement, \ | |
| 103 (void**)&ORIGINAL_FUNCTION_NAME##_reenter ); \ | |
| 104 } \ | |
| 105 return result; \ | |
| 106 } \ | |
| 107 static ORIGINAL_FUNCTION_RETURN_TYPE replacement ORIGINAL_FUNCTION_ARGS { | |
| 108 | |
| 109 #define END_MACH_OVERRIDE( ORIGINAL_FUNCTION_NAME ) \ | |
| 110 } \ | |
| 111 }; \ | |
| 112 \ | |
| 113 err = mach_override_class__##ORIGINAL_FUNCTION_NAME::override((void*)ORIGINAL_FUNCTION_NAME); \ | |
| 114 } | |
| 115 | |
| 116 #endif | |
| 117 | |
| 118 #ifdef __cplusplus | |
| 119 } | |
| 120 #endif | |
| 121 #endif // _mach_override_ |
