From: Yuxuan Shui yshui@codeweavers.com
ntlea for some reason expects GetWindowLongA to start with a "push $-2", and will try to skip over this instruction. If we don't anticipate this, it will ended up either skipping over critical instructions, or on a desync address. Either way, it would be bad. --- dlls/user32/win.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-)
diff --git a/dlls/user32/win.c b/dlls/user32/win.c index 28cf40441d9..895b222cceb 100644 --- a/dlls/user32/win.c +++ b/dlls/user32/win.c @@ -884,11 +884,33 @@ WORD WINAPI GetWindowWord( HWND hwnd, INT offset ) return NtUserGetWindowWord( hwnd, offset ); }
- /********************************************************************** * GetWindowLongA (USER32.@) */ -LONG WINAPI GetWindowLongA( HWND hwnd, INT offset ) + +#ifdef __i386__ + +/* This wrapper is here to workaround a ntlea quirk. First of all, ntlea + * checks whether GetWindowLongA starts with the Win32 hotpatchable prologue, + * if it can find that, it will use a hooking strategy more difficult for us + * to deal with. Secondly, it assumes what follows the prologue is a `pushl $-2`, + * and will try to skip over this instruction when calling `GetWindowLongA`, + * (i.e. it tries to jump to `GetWindowLongA + 7`, 5 bytes for the prologue, 2 + * bytes for the `pushl`.). We have to anticipate that and make sure the result + * of doing this won't be a messed up stack, or a desynced PC. + */ +__ASM_STDCALL_FUNC(GetWindowLongA, 8, + "movl.s %edi, %edi\n" + "pushl %ebp\n" + "movl.s %esp, %ebp\n" + "pushl $-2\n" + "addl $4, %esp\n" + "popl %ebp\n" + "jmp " __ASM_STDCALL("get_window_longA", 8) "\n") +LONG WINAPI get_window_longA( HWND hwnd, INT offset ) +#else +LONG WINAPI DECLSPEC_HOTPATCH GetWindowLongA(HWND hwnd, INT offset) +#endif { switch (offset) { @@ -910,7 +932,6 @@ LONG WINAPI GetWindowLongA( HWND hwnd, INT offset ) } }
- /********************************************************************** * GetWindowLongW (USER32.@) */