add new masked cancellation mode

[musl] / src / thread / pthread_cancel.c

diff --git a/src/thread/pthread_cancel.c b/src/thread/pthread_cancel.c
index c497dbe..1b71aa4 100644 (file)
--- a/src/thread/pthread_cancel.c
+++ b/src/thread/pthread_cancel.c
@@ -1,7 +1,96 @@
 #include "pthread_impl.h"
+#include "syscall.h"
+#include "libc.h"
+
+long __cancel()
+{
+       pthread_t self = __pthread_self();
+       if (self->canceldisable == PTHREAD_CANCEL_ENABLE || self->cancelasync)
+               pthread_exit(PTHREAD_CANCELED);
+       self->canceldisable = PTHREAD_CANCEL_DISABLE;
+       return -ECANCELED;
+}
+
+/* If __syscall_cp_asm has adjusted the stack pointer, it must provide a
+ * definition of __cp_cancel to undo those adjustments and call __cancel.
+ * Otherwise, __cancel provides a definition for __cp_cancel. */
+
+weak_alias(__cancel, __cp_cancel);
+
+long __syscall_cp_asm(volatile void *, syscall_arg_t,
+                      syscall_arg_t, syscall_arg_t, syscall_arg_t,
+                      syscall_arg_t, syscall_arg_t, syscall_arg_t);
+
+long __syscall_cp_c(syscall_arg_t nr,
+                    syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
+                    syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
+{
+       pthread_t self;
+       long r;
+       int st;
+
+       if (!libc.has_thread_pointer || (st=(self=__pthread_self())->canceldisable)
+           && (st==PTHREAD_CANCEL_DISABLE || nr==SYS_close))
+               return __syscall(nr, u, v, w, x, y, z);
+
+       r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
+       if (r==-EINTR && nr!=SYS_close && self->cancel &&
+           self->canceldisable != PTHREAD_CANCEL_DISABLE)
+               r = __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();
+       ucontext_t *uc = ctx;
+       const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
+       extern const char __cp_begin[1], __cp_end[1];
+
+       a_barrier();
+       if (!self->cancel || self->canceldisable == PTHREAD_CANCEL_DISABLE) return;
+
+       _sigaddset(&uc->uc_sigmask, SIGCANCEL);
+
+       if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) {
+               ((char **)&uc->uc_mcontext)[CANCEL_REG_IP] = (char *)__cp_cancel;
+               return;
+       }
+
+       __syscall(SYS_tkill, self->tid, SIGCANCEL);
+}
+
+void __testcancel()
+{
+       if (!libc.has_thread_pointer) return;
+       pthread_t self = __pthread_self();
+       if (self->cancel && !self->canceldisable)
+               __cancel();
+}
+
+static void init_cancellation()
+{
+       struct sigaction sa = {
+               .sa_flags = SA_SIGINFO | SA_RESTART,
+               .sa_sigaction = cancel_handler
+       };
+       sigfillset(&sa.sa_mask);
+       __libc_sigaction(SIGCANCEL, &sa, 0);
+}
 
 int pthread_cancel(pthread_t t)
 {
+       static int init;
+       if (!init) {
+               init_cancellation();
+               init = 1;
+       }
        a_store(&t->cancel, 1);
        return pthread_kill(t, SIGCANCEL);
 }