1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/build/mach_override.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,121 @@
1.4 +/*******************************************************************************
1.5 + mach_override.h
1.6 + Copyright (c) 2003-2009 Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
1.7 + Some rights reserved: <http://opensource.org/licenses/mit-license.php>
1.8 +
1.9 + ***************************************************************************/
1.10 +
1.11 +/***************************************************************************//**
1.12 + @mainpage mach_override
1.13 + @author Jonathan 'Wolf' Rentzsch: <http://rentzsch.com>
1.14 +
1.15 + This package, coded in C to the Mach API, allows you to override ("patch")
1.16 + program- and system-supplied functions at runtime. You can fully replace
1.17 + functions with your implementations, or merely head- or tail-patch the
1.18 + original implementations.
1.19 +
1.20 + Use it by #include'ing mach_override.h from your .c, .m or .mm file(s).
1.21 +
1.22 + @todo Discontinue use of Carbon's MakeDataExecutable() and
1.23 + CompareAndSwap() calls and start using the Mach equivalents, if they
1.24 + exist. If they don't, write them and roll them in. That way, this
1.25 + code will be pure Mach, which will make it easier to use everywhere.
1.26 + Update: MakeDataExecutable() has been replaced by
1.27 + msync(MS_INVALIDATE). There is an OSCompareAndSwap in libkern, but
1.28 + I'm currently unsure if I can link against it. May have to roll in
1.29 + my own version...
1.30 + @todo Stop using an entire 4K high-allocated VM page per 28-byte escape
1.31 + branch island. Done right, this will dramatically speed up escape
1.32 + island allocations when they number over 250. Then again, if you're
1.33 + overriding more than 250 functions, maybe speed isn't your main
1.34 + concern...
1.35 + @todo Add detection of: b, bl, bla, bc, bcl, bcla, bcctrl, bclrl
1.36 + first-instructions. Initially, we should refuse to override
1.37 + functions beginning with these instructions. Eventually, we should
1.38 + dynamically rewrite them to make them position-independent.
1.39 + @todo Write mach_unoverride(), which would remove an override placed on a
1.40 + function. Must be multiple-override aware, which means an almost
1.41 + complete rewrite under the covers, because the target address can't
1.42 + be spread across two load instructions like it is now since it will
1.43 + need to be atomically updatable.
1.44 + @todo Add non-rentry variants of overrides to test_mach_override.
1.45 +
1.46 + ***************************************************************************/
1.47 +
1.48 +#ifndef _mach_override_
1.49 +#define _mach_override_
1.50 +
1.51 +#include <sys/types.h>
1.52 +#include <mach/error.h>
1.53 +
1.54 +#ifdef __cplusplus
1.55 + extern "C" {
1.56 +#endif
1.57 +
1.58 +/**
1.59 + Returned if the function to be overrided begins with a 'mfctr' instruction.
1.60 +*/
1.61 +#define err_cannot_override (err_local|1)
1.62 +
1.63 +/************************************************************************************//**
1.64 + Dynamically overrides the function implementation referenced by
1.65 + originalFunctionAddress with the implentation pointed to by overrideFunctionAddress.
1.66 + Optionally returns a pointer to a "reentry island" which, if jumped to, will resume
1.67 + the original implementation.
1.68 +
1.69 + @param originalFunctionAddress -> Required address of the function to
1.70 + override (with overrideFunctionAddress).
1.71 + @param overrideFunctionAddress -> Required address to the overriding
1.72 + function.
1.73 + @param originalFunctionReentryIsland <- Optional pointer to pointer to the
1.74 + reentry island. Can be nullptr.
1.75 + @result <- err_cannot_override if the original
1.76 + function's implementation begins with
1.77 + the 'mfctr' instruction.
1.78 +
1.79 + ************************************************************************************/
1.80 +
1.81 + mach_error_t
1.82 +mach_override_ptr(
1.83 + void *originalFunctionAddress,
1.84 + const void *overrideFunctionAddress,
1.85 + void **originalFunctionReentryIsland );
1.86 +
1.87 +/************************************************************************************//**
1.88 +
1.89 +
1.90 + ************************************************************************************/
1.91 +
1.92 +#ifdef __cplusplus
1.93 +
1.94 +#define MACH_OVERRIDE( ORIGINAL_FUNCTION_RETURN_TYPE, ORIGINAL_FUNCTION_NAME, ORIGINAL_FUNCTION_ARGS, ERR ) \
1.95 + { \
1.96 + static ORIGINAL_FUNCTION_RETURN_TYPE (*ORIGINAL_FUNCTION_NAME##_reenter)ORIGINAL_FUNCTION_ARGS; \
1.97 + static bool ORIGINAL_FUNCTION_NAME##_overriden = false; \
1.98 + class mach_override_class__##ORIGINAL_FUNCTION_NAME { \
1.99 + public: \
1.100 + static kern_return_t override(void *originalFunctionPtr) { \
1.101 + kern_return_t result = err_none; \
1.102 + if (!ORIGINAL_FUNCTION_NAME##_overriden) { \
1.103 + ORIGINAL_FUNCTION_NAME##_overriden = true; \
1.104 + result = mach_override_ptr( (void*)originalFunctionPtr, \
1.105 + (void*)mach_override_class__##ORIGINAL_FUNCTION_NAME::replacement, \
1.106 + (void**)&ORIGINAL_FUNCTION_NAME##_reenter ); \
1.107 + } \
1.108 + return result; \
1.109 + } \
1.110 + static ORIGINAL_FUNCTION_RETURN_TYPE replacement ORIGINAL_FUNCTION_ARGS {
1.111 +
1.112 +#define END_MACH_OVERRIDE( ORIGINAL_FUNCTION_NAME ) \
1.113 + } \
1.114 + }; \
1.115 + \
1.116 + err = mach_override_class__##ORIGINAL_FUNCTION_NAME::override((void*)ORIGINAL_FUNCTION_NAME); \
1.117 + }
1.118 +
1.119 +#endif
1.120 +
1.121 +#ifdef __cplusplus
1.122 + }
1.123 +#endif
1.124 +#endif // _mach_override_
