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Update: MakeDataExecutable() has been replaced by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