new framework to inhibit thread cancellation when needed

[musl] / src / thread / pthread_create.c

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 344b39f..5248700 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -57,9 +57,19 @@ static void cancel_handler(int sig, siginfo_t *si, void *ctx)
 static void cancelpt(int x)
 {
        struct pthread *self = __pthread_self();
-       if (self->canceldisable) return;
-       if ((self->cancelpoint+=x)==1 && x>=0 && self->cancel)
-               docancel(self);
+       switch (x) {
+       case 1:
+               self->cancelpoint++;
+       case 0:
+               if (self->cancel && self->cancelpoint==1 && !self->canceldisable)
+                       docancel(self);
+               break;
+       case -1:
+               self->cancelpoint--;
+               break;
+       default:
+               self->canceldisable += x;
+       }
 }
 
 /* "rsyscall" is a mechanism by which a thread can synchronously force all
@@ -85,7 +95,7 @@ static void rsyscall_handler(int sig, siginfo_t *si, void *ctx)
        /* Threads which have already decremented themselves from the
         * thread count must not increment rs.cnt or otherwise act. */
        if (self->dead) {
-               sigaddset(&((ucontext_t *)ctx)->uc_sigmask, SIGSYSCALL);
+               sigfillset(&((ucontext_t *)ctx)->uc_sigmask);
                return;
        }
 
@@ -151,13 +161,18 @@ static void init_threads()
        libc.lockfile = __lockfile;
        libc.cancelpt = cancelpt;
        libc.rsyscall = rsyscall;
+
+       sigfillset(&sa.sa_mask);
+       sa.sa_sigaction = rsyscall_handler;
+       __libc_sigaction(SIGSYSCALL, &sa, 0);
+
+       sigemptyset(&sa.sa_mask);
        sa.sa_sigaction = cancel_handler;
        __libc_sigaction(SIGCANCEL, &sa, 0);
+
        sigaddset(&sa.sa_mask, SIGSYSCALL);
        sigaddset(&sa.sa_mask, SIGCANCEL);
-       sa.sa_sigaction = rsyscall_handler;
-       __libc_sigaction(SIGSYSCALL, &sa, 0);
-       sigprocmask(SIG_UNBLOCK, &sa.sa_mask, 0);
+       __libc_sigprocmask(SIG_UNBLOCK, &sa.sa_mask, 0);
 }
 
 static int start(void *p)
@@ -190,7 +205,7 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        unsigned char *map, *stack, *tsd;
        static const pthread_attr_t default_attr;
 
-       if (!self) return errno = ENOSYS;
+       if (!self) return ENOSYS;
        if (!init && ++init) init_threads();
 
        if (!attr) attr = &default_attr;