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author | Peter Maydell <peter.maydell@linaro.org> | 2013-02-20 15:21:09 +0000 |
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committer | Blue Swirl <blauwirbel@gmail.com> | 2013-02-23 16:11:19 +0000 |
commit | 6ab7e5465a4d6188e29398fb43a30dbab1015b75 (patch) | |
tree | 1e8bc48fc86c89b32a07f9379a40ed907d2a91dd /monitor.c | |
parent | d1c36ba707637173b818652e51181370d51b6c58 (diff) | |
download | qemu-6ab7e5465a4d6188e29398fb43a30dbab1015b75.tar.gz qemu-6ab7e5465a4d6188e29398fb43a30dbab1015b75.tar.bz2 qemu-6ab7e5465a4d6188e29398fb43a30dbab1015b75.zip |
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 <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Tested-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Diffstat (limited to 'monitor.c')
-rw-r--r-- | monitor.c | 6 |
1 files changed, 3 insertions, 3 deletions
@@ -2740,7 +2740,7 @@ static const mon_cmd_t qmp_cmds[] = { /*******************************************************************/ static const char *pch; -static jmp_buf expr_env; +static sigjmp_buf expr_env; #define MD_TLONG 0 #define MD_I32 1 @@ -3135,7 +3135,7 @@ static const MonitorDef monitor_defs[] = { static void expr_error(Monitor *mon, const char *msg) { monitor_printf(mon, "%s\n", msg); - longjmp(expr_env, 1); + siglongjmp(expr_env, 1); } /* return 0 if OK, -1 if not found */ @@ -3345,7 +3345,7 @@ static int64_t expr_sum(Monitor *mon) static int get_expr(Monitor *mon, int64_t *pval, const char **pp) { pch = *pp; - if (setjmp(expr_env)) { + if (sigsetjmp(expr_env, 0)) { *pp = pch; return -1; } |