Mac: Let chrome coexist with the Chinese Handwriting IME.

The renderer sandbox breaks the Chinese Handwriting shortcut while Chrome
is running, even when Chrome is not active: In a nutshell, Carbon tries to load
the IME in every process, and if that fails, it uninstalls the toggle shorcut. It
fails in the renderer process due to the sandbox. See the bug for details.

Prewarming (patch set 1) doesn't work because that opens up clipboard
access to the renderer – the IME doesn't load correctly if it doesn't have
clipboard access.

dyld __interpose based interposing (patch set 2) doesn't work because
TISCreateInputSourceList and its broken caller are in the same
framework (HIToolbox).

Hence, use binary rewriting to return an arbitrary array with size > 0 to make
HIToolbox believe that the IME loads correctly, so that it doesn't uninstall the
global handwriting keyboard shortcut (only on >= 10.6).

BUG=31225
TEST=Enable Chinese in the input menu. Make sure Chrome's not running.
Note that ctrl-shift-space opens and dismisses the Handwriting IME
(you need a multitouch trackpad for that). Open Chrome, note that the
IME still works.
(If you run Chrome without this patch, the IME will be broken until you do
  ps aux | grep Chinese
and then
  kill $CHINESE_HANDWRITING_PID
and then toggle the IME once through the Menu Extra menu.)
It is a good idea to have a Terminal open during testing, because killing
the task is the only way to dismiss the IME with the keyboard without this
CL.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=81308

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=81332

Review URL: http://codereview.chromium.org/6801056

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@81500 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 121 insertions, 0 deletions

diff --git a/third_party/mach_override/mach_override.h b/third_party/mach_override/mach_override.h
new file mode 100644
index 0000000..76fdb1b
--- /dev/null
+++ b/third_party/mach_override/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 NULL.
+	@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_