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ntdll: Implement RtlDecodePointer and RtlEncodePointer.

This commit is contained in:
Mike McCormack 2007-01-22 19:24:14 +09:00 committed by Alexandre Julliard
parent 4dc61069a6
commit bcc717174c
2 changed files with 38 additions and 2 deletions
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4
dlls/ntdll/ntdll.spec
View File

@ -501,7 +501,7 @@
@ stub RtlDeactivateActivationContext
@ stub RtlDeactivateActivationContextUnsafeFast
@ stub RtlDebugPrintTimes
# @ stub RtlDecodePointer
@ stdcall RtlDecodePointer(ptr)
# @ stub RtlDecodeSystemPointer
@ stub RtlDecompressBuffer
@ stub RtlDecompressFragment
@ -543,7 +543,7 @@
@ stdcall RtlDuplicateUnicodeString(long ptr ptr)
@ stdcall RtlEmptyAtomTable(ptr long)
# @ stub RtlEnableEarlyCriticalSectionEventCreation
# @ stub RtlEncodePointer
@ stdcall RtlEncodePointer(ptr)
# @ stub RtlEncodeSystemPointer
@ stdcall -ret64 RtlEnlargedIntegerMultiply(long long)
@ stdcall RtlEnlargedUnsignedDivide(double long ptr)

36
dlls/ntdll/rtl.c
View File

@ -886,3 +886,39 @@ NTSTATUS WINAPI RtlIpv4AddressToStringExW (PULONG IP, PULONG Port,
return STATUS_SUCCESS;
}
static DWORD_PTR get_pointer_obfuscator( void )
{
static DWORD_PTR pointer_obfuscator;
if (!pointer_obfuscator)
{
ULONG seed = NtGetTickCount();
ULONG_PTR rand;
/* generate a random value for the obfuscator */
rand = RtlUniform( &seed );
/* handle 64bit pointers */
rand ^= RtlUniform( &seed ) << ((sizeof (DWORD_PTR) - sizeof (ULONG))*8);
/* set the high bits so dereferencing obfuscated pointers will (usually) crash */
rand |= 0xc0000000 << ((sizeof (DWORD_PTR) - sizeof (ULONG))*8);
interlocked_cmpxchg_ptr( (void**) &pointer_obfuscator, (void*) rand, NULL );
}
return pointer_obfuscator;
}
PVOID WINAPI RtlEncodePointer( PVOID ptr )
{
DWORD_PTR ptrval = (DWORD_PTR) ptr;
return (PVOID)(ptrval ^ get_pointer_obfuscator());
}
PVOID WINAPI RtlDecodePointer( PVOID ptr )
{
DWORD_PTR ptrval = (DWORD_PTR) ptr;
return (PVOID)(ptrval ^ get_pointer_obfuscator());
}