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Bug 677247 - Unregister Dll hooks when WindowsDllInterceptor is destructed. r=ehsan

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This commit is contained in:
Mike Hommey 2011-08-11 07:54:57 +02:00
parent 89a381ae19
commit 2b57c3eacd
1 changed files with 42 additions and 0 deletions
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42
toolkit/xre/nsWindowsDllInterceptor.h
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@ -56,6 +56,10 @@
* to invoke the original function (so address of trampoline is
* returned).
*
* When the WindowsDllInterceptor class is destructed, OrigFunction is
* patched again to jump directly to the trampoline instead of going
* through the hook function. As such, re-intercepting the same function
* won't work, as jump instructions are not supported.
*/
class WindowsDllInterceptor
@ -71,6 +75,39 @@ public:
Init(modulename, nhooks);
}
~WindowsDllInterceptor() {
int i;
byteptr_t p;
for (i = 0, p = mHookPage; i < mCurHooks; i++, p += kHookSize) {
#if defined(_M_IX86)
size_t nBytes = 1 + sizeof(intptr_t);
#elif defined(_M_X64)
size_t nBytes = 2 + sizeof(intptr_t);
#else
#error "Unknown processor type"
#endif
byteptr_t origBytes = *((byteptr_t *)p);
// ensure we can modify the original code
DWORD op;
if (!VirtualProtectEx(GetCurrentProcess(), origBytes, nBytes, PAGE_EXECUTE_READWRITE, &op)) {
//printf ("VirtualProtectEx failed! %d\n", GetLastError());
continue;
}
// Remove the hook by making the original function jump directly
// in the trampoline.
intptr_t dest = (intptr_t)(p + sizeof(void *));
#if defined(_M_IX86)
*((intptr_t*)(origBytes+1)) = dest - (intptr_t)(origBytes+5); // target displacement
#elif defined(_M_X64)
*((intptr_t*)(origBytes+2)) = dest;
#else
#error "Unknown processor type"
#endif
// restore protection; if this fails we can't really do anything about it
VirtualProtectEx(GetCurrentProcess(), origBytes, nBytes, op, &op);
}
}
void Init(const char *modulename, int nhooks = 0) {
if (mModule)
return;
@ -301,6 +338,11 @@ protected:
return 0;
}
// We keep the address of the original function in the first bytes of
// the trampoline buffer
*((void **)tramp) = origFunction;
tramp += sizeof(void *);
memcpy(tramp, origFunction, nBytes);
// OrigFunction+N, the target of the trampoline