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authorRich Felker <dalias@aerifal.cx>2023-02-11 19:13:10 -0500
committerRich Felker <dalias@aerifal.cx>2023-02-12 15:05:39 -0500
commit0ab97350f01b42de0f9fd811ee08653169661859 (patch)
tree30c9b583f4e9ce595dcf0070b20b1981a18fa474 /src
parent711673ee772e20a74aaf301c2d7745c20c4f4d47 (diff)
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mq_notify: block all (application) signals in the worker thread
until the mq notification event arrives, it is mandatory that signals be blocked. otherwise, a signal can be received, and its handler executed, in a thread which does not yet exist on the abstract machine. after the point of the event arriving, having signals blocked is not a conformance requirement but a QoI requirement. while the application can unblock any signals it wants unblocked in the event handler thread, if they did not start out blocked, it could not block them without a race window where they are momentarily unblocked, and this would preclude controlled delivery or other forms of acceptance (sigwait, etc.) anywhere in the application.
Diffstat (limited to 'src')
-rw-r--r--src/mq/mq_notify.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/src/mq/mq_notify.c b/src/mq/mq_notify.c
index 8109dfb2..0e1e6c7a 100644
--- a/src/mq/mq_notify.c
+++ b/src/mq/mq_notify.c
@@ -50,6 +50,7 @@ int mq_notify(mqd_t mqd, const struct sigevent *sev)
pthread_t td;
int s;
int cs;
+ sigset_t allmask, origmask;
if (!sev || sev->sigev_notify != SIGEV_THREAD)
return syscall(SYS_mq_notify, mqd, sev);
@@ -64,11 +65,15 @@ int mq_notify(mqd_t mqd, const struct sigevent *sev)
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
sem_init(&args.sem, 0, 0);
+ sigfillset(&allmask);
+ pthread_sigmask(SIG_BLOCK, &allmask, &origmask);
if (pthread_create(&td, &attr, start, &args)) {
__syscall(SYS_close, s);
+ pthread_sigmask(SIG_SETMASK, &origmask, 0);
errno = EAGAIN;
return -1;
}
+ pthread_sigmask(SIG_SETMASK, &origmask, 0);
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
sem_wait(&args.sem);