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Diffstat (limited to 'xpcom/build/mach_override.h')
| -rw-r--r-- | xpcom/build/mach_override.h | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/xpcom/build/mach_override.h b/xpcom/build/mach_override.h new file mode 100644 index 0000000000..d9be988a34 --- /dev/null +++ b/xpcom/build/mach_override.h @@ -0,0 +1,121 @@ +/******************************************************************************* + mach_override.h + Copyright (c) 2003-2009 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com> + Some rights reserved: <http://opensource.org/licenses/mit-license.php> + + ***************************************************************************/ + +/***************************************************************************//** + @mainpage mach_override + @author Jonathan 'Wolf' Rentzsch: <http://rentzsch.com> + + This package, coded in C to the Mach API, allows you to override ("patch") + program- and system-supplied functions at runtime. You can fully replace + functions with your implementations, or merely head- or tail-patch the + original implementations. + + Use it by #include'ing mach_override.h from your .c, .m or .mm file(s). + + @todo Discontinue use of Carbon's MakeDataExecutable() and + CompareAndSwap() calls and start using the Mach equivalents, if they + exist. If they don't, write them and roll them in. That way, this + code will be pure Mach, which will make it easier to use everywhere. + Update: MakeDataExecutable() has been replaced by + msync(MS_INVALIDATE). There is an OSCompareAndSwap in libkern, but + I'm currently unsure if I can link against it. May have to roll in + my own version... + @todo Stop using an entire 4K high-allocated VM page per 28-byte escape + branch island. Done right, this will dramatically speed up escape + island allocations when they number over 250. Then again, if you're + overriding more than 250 functions, maybe speed isn't your main + concern... + @todo Add detection of: b, bl, bla, bc, bcl, bcla, bcctrl, bclrl + first-instructions. Initially, we should refuse to override + functions beginning with these instructions. Eventually, we should + dynamically rewrite them to make them position-independent. + @todo Write mach_unoverride(), which would remove an override placed on a + function. Must be multiple-override aware, which means an almost + complete rewrite under the covers, because the target address can't + be spread across two load instructions like it is now since it will + need to be atomically updatable. + @todo Add non-rentry variants of overrides to test_mach_override. + + ***************************************************************************/ + +#ifndef _mach_override_ +#define _mach_override_ + +#include <sys/types.h> +#include <mach/error.h> + +#ifdef __cplusplus + extern "C" { +#endif + +/** + Returned if the function to be overrided begins with a 'mfctr' instruction. +*/ +#define err_cannot_override (err_local|1) + +/************************************************************************************//** + Dynamically overrides the function implementation referenced by + originalFunctionAddress with the implentation pointed to by overrideFunctionAddress. + Optionally returns a pointer to a "reentry island" which, if jumped to, will resume + the original implementation. + + @param originalFunctionAddress -> Required address of the function to + override (with overrideFunctionAddress). + @param overrideFunctionAddress -> Required address to the overriding + function. + @param originalFunctionReentryIsland <- Optional pointer to pointer to the + reentry island. Can be nullptr. + @result <- err_cannot_override if the original + function's implementation begins with + the 'mfctr' instruction. + + ************************************************************************************/ + + mach_error_t +mach_override_ptr( + void *originalFunctionAddress, + const void *overrideFunctionAddress, + void **originalFunctionReentryIsland ); + +/************************************************************************************//** + + + ************************************************************************************/ + +#ifdef __cplusplus + +#define MACH_OVERRIDE( ORIGINAL_FUNCTION_RETURN_TYPE, ORIGINAL_FUNCTION_NAME, ORIGINAL_FUNCTION_ARGS, ERR ) \ + { \ + static ORIGINAL_FUNCTION_RETURN_TYPE (*ORIGINAL_FUNCTION_NAME##_reenter)ORIGINAL_FUNCTION_ARGS; \ + static bool ORIGINAL_FUNCTION_NAME##_overriden = false; \ + class mach_override_class__##ORIGINAL_FUNCTION_NAME { \ + public: \ + static kern_return_t override(void *originalFunctionPtr) { \ + kern_return_t result = err_none; \ + if (!ORIGINAL_FUNCTION_NAME##_overriden) { \ + ORIGINAL_FUNCTION_NAME##_overriden = true; \ + result = mach_override_ptr( (void*)originalFunctionPtr, \ + (void*)mach_override_class__##ORIGINAL_FUNCTION_NAME::replacement, \ + (void**)&ORIGINAL_FUNCTION_NAME##_reenter ); \ + } \ + return result; \ + } \ + static ORIGINAL_FUNCTION_RETURN_TYPE replacement ORIGINAL_FUNCTION_ARGS { + +#define END_MACH_OVERRIDE( ORIGINAL_FUNCTION_NAME ) \ + } \ + }; \ + \ + err = mach_override_class__##ORIGINAL_FUNCTION_NAME::override((void*)ORIGINAL_FUNCTION_NAME); \ + } + +#endif + +#ifdef __cplusplus + } +#endif +#endif // _mach_override_ |