From 6ab7e5465a4d6188e29398fb43a30dbab1015b75 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Wed, 20 Feb 2013 15:21:09 +0000 Subject: Replace all setjmp()/longjmp() with sigsetjmp()/siglongjmp() The setjmp() function doesn't specify whether signal masks are saved and restored; on Linux they are not, but on BSD (including MacOSX) they are. We want to have consistent behaviour across platforms, so we should always use "don't save/restore signal mask" (this is also generally going to be faster). This also works around a bug in MacOSX where the signal-restoration on longjmp() affects the signal mask for a completely different thread, not just the mask for the thread which did the longjmp. The most visible effect of this was that ctrl-C was ignored on MacOSX because the CPU thread did a longjmp which resulted in its signal mask being applied to every thread, so that all threads had SIGINT and SIGTERM blocked. The POSIX-sanctioned portable way to do a jump without affecting signal masks is to siglongjmp() to a sigjmp_buf which was created by calling sigsetjmp() with a zero savemask parameter, so change all uses of setjmp()/longjmp() accordingly. [Technically POSIX allows sigsetjmp(buf, 0) to save the signal mask; however the following siglongjmp() must not restore the signal mask, so the pair can be effectively considered as "sigjmp/longjmp which don't touch the mask".] For Windows we provide a trivial sigsetjmp/siglongjmp in terms of setjmp/longjmp -- this is OK because no user will ever pass a non-zero savemask. The setjmp() uses in tests/tcg/test-i386.c and tests/tcg/linux-test.c are left untouched because these are self-contained singlethreaded test programs intended to be run under QEMU's Linux emulation, so they have neither the portability nor the multithreading issues to deal with. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Tested-by: Stefan Weil Reviewed-by: Laszlo Ersek Signed-off-by: Blue Swirl --- include/sysemu/os-win32.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/sysemu/os-win32.h') diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h index bf9edeb..71f5fa0 100644 --- a/include/sysemu/os-win32.h +++ b/include/sysemu/os-win32.h @@ -63,6 +63,14 @@ # undef setjmp # define setjmp(env) _setjmp(env, NULL) #endif +/* QEMU uses sigsetjmp()/siglongjmp() as the portable way to specify + * "longjmp and don't touch the signal masks". Since we know that the + * savemask parameter will always be zero we can safely define these + * in terms of setjmp/longjmp on Win32. + */ +#define sigjmp_buf jmp_buf +#define sigsetjmp(env, savemask) setjmp(env) +#define siglongjmp(env, val) longjmp(env, val) /* Declaration of ffs() is missing in MinGW's strings.h. */ int ffs(int i); -- cgit v1.1