fix cancellation failure in single-threaded programs

[musl] / src / thread / cancel_impl.c

diff --git a/src/thread/cancel_impl.c b/src/thread/cancel_impl.c
index 5ce545d..7652a7c 100644 (file)
--- a/src/thread/cancel_impl.c
+++ b/src/thread/cancel_impl.c
@@ -1,5 +1,14 @@
 #include "pthread_impl.h"
 
+void __cancel()
+{
+       pthread_t self = __pthread_self();
+       self->cp_sp = 0;
+       self->canceldisable = 1;
+       self->cancelasync = 0;
+       pthread_exit(PTHREAD_CANCELED);
+}
+
 long __syscall_cp_asm(volatile void *, long, long, long, long, long, long, long);
 
 long (__syscall_cp)(long nr, long u, long v, long w, long x, long y, long z)
@@ -8,7 +17,7 @@ long (__syscall_cp)(long nr, long u, long v, long w, long x, long y, long z)
        uintptr_t old_sp, old_ip;
        long r;
 
-       if (!libc.lock || (self = __pthread_self())->canceldisable)
+       if (!libc.main_thread || (self = __pthread_self())->canceldisable)
                return __syscall(nr, u, v, w, x, y, z);
 
        old_sp = self->cp_sp;
@@ -16,12 +25,19 @@ long (__syscall_cp)(long nr, long u, long v, long w, long x, long y, long z)
        self->cp_sp = 0;
        self->cp_ip = 0;
        r = __syscall_cp_asm(&self->cp_sp, nr, u, v, w, x, y, z);
-       self->cp_sp = old_sp;
        self->cp_ip = old_ip;
-       if (r == -EINTR && self->cancel) pthread_exit(PTHREAD_CANCELED);
+       self->cp_sp = old_sp;
+       if (r==-EINTR && nr!=SYS_close && self->cancel && !self->canceldisable)
+               __cancel();
        return r;
 }
 
+static void _sigaddset(sigset_t *set, int sig)
+{
+       unsigned s = sig-1;
+       set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
+}
+
 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
 {
        pthread_t self = __pthread_self();
@@ -31,23 +47,23 @@ static void cancel_handler(int sig, siginfo_t *si, void *ctx)
 
        if (!self->cancel || self->canceldisable) return;
 
-       if (self->cancelasync) pthread_exit(PTHREAD_CANCELED);
+       _sigaddset(&uc->uc_sigmask, SIGCANCEL);
 
-       if (sp != self->cp_sp) {
-               if (!sp) return;
-               sigaddset(&uc->uc_sigmask, SIGCANCEL);
-               __syscall(SYS_tgkill, self->pid, self->tid, SIGCANCEL);
-               return;
+       if (self->cancelasync || sp == self->cp_sp && ip <= self->cp_ip) {
+               self->canceldisable = 1;
+               pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
+               __cancel();
        }
 
-       if (ip <= self->cp_ip) pthread_exit(PTHREAD_CANCELED);
+       if (self->cp_sp)
+               __syscall(SYS_tgkill, self->pid, self->tid, SIGCANCEL);
 }
 
-static void testcancel()
+void __testcancel()
 {
-       pthread_t self = __pthread_self();
+       pthread_t self = pthread_self();
        if (self->cancel && !self->canceldisable)
-               pthread_exit(PTHREAD_CANCELED);
+               __cancel();
 }
 
 static void init_cancellation()
@@ -58,13 +74,15 @@ static void init_cancellation()
        };
        sigfillset(&sa.sa_mask);
        __libc_sigaction(SIGCANCEL, &sa, 0);
-       libc.testcancel = testcancel;
 }
 
 int pthread_cancel(pthread_t t)
 {
-       static pthread_once_t once;
-       pthread_once(&once, init_cancellation);
+       static int init;
+       if (!init) {
+               init_cancellation();
+               init = 1;
+       }
        a_store(&t->cancel, 1);
        return pthread_kill(t, SIGCANCEL);
 }