fix broken thread list unlocking after fork

[musl] / src / signal / sigaction.c

diff --git a/src/signal/sigaction.c b/src/signal/sigaction.c
index 5499bd1..e45308f 100644 (file)
--- a/src/signal/sigaction.c
+++ b/src/signal/sigaction.c
@@ -1,17 +1,13 @@
-#include <stdlib.h>
 #include <signal.h>
 #include <errno.h>
 #include <string.h>
 #include "syscall.h"
 #include "pthread_impl.h"
 #include "libc.h"
+#include "lock.h"
 #include "ksigaction.h"
 
-void __restore(), __restore_rt();
-
-static pthread_t dummy(void) { return 0; }
-weak_alias(dummy, __pthread_self_def);
-
+static int unmask_done;
 static unsigned long handler_set[_NSIG/(8*sizeof(long))];
 
 void __get_handler_set(sigset_t *set)
@@ -19,41 +15,73 @@ void __get_handler_set(sigset_t *set)
        memcpy(set, handler_set, sizeof handler_set);
 }
 
+volatile int __eintr_valid_flag;
+
 int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)
 {
        struct k_sigaction ksa, ksa_old;
-       if (sig >= (unsigned)_NSIG) {
-               errno = EINVAL;
-               return -1;
-       }
        if (sa) {
                if ((uintptr_t)sa->sa_handler > 1UL) {
                        a_or_l(handler_set+(sig-1)/(8*sizeof(long)),
                                1UL<<(sig-1)%(8*sizeof(long)));
-                       __pthread_self_def();
+
+                       /* If pthread_create has not yet been called,
+                        * implementation-internal signals might not
+                        * yet have been unblocked. They must be
+                        * unblocked before any signal handler is
+                        * installed, so that an application cannot
+                        * receive an illegal sigset_t (with them
+                        * blocked) as part of the ucontext_t passed
+                        * to the signal handler. */
+                       if (!libc.threaded && !unmask_done) {
+                               __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
+                                       SIGPT_SET, 0, _NSIG/8);
+                               unmask_done = 1;
+                       }
+
+                       if (!(sa->sa_flags & SA_RESTART)) {
+                               a_store(&__eintr_valid_flag, 1);
+                       }
                }
                ksa.handler = sa->sa_handler;
-               ksa.flags = sa->sa_flags | SA_RESTORER;
+               ksa.flags = sa->sa_flags;
+#ifdef SA_RESTORER
+               ksa.flags |= SA_RESTORER;
                ksa.restorer = (sa->sa_flags & SA_SIGINFO) ? __restore_rt : __restore;
-               memcpy(&ksa.mask, &sa->sa_mask, sizeof ksa.mask);
+#endif
+               memcpy(&ksa.mask, &sa->sa_mask, _NSIG/8);
        }
-       if (syscall(SYS_rt_sigaction, sig, sa?&ksa:0, old?&ksa_old:0, sizeof ksa.mask))
-               return -1;
-       if (old) {
+       int r = __syscall(SYS_rt_sigaction, sig, sa?&ksa:0, old?&ksa_old:0, _NSIG/8);
+       if (old && !r) {
                old->sa_handler = ksa_old.handler;
                old->sa_flags = ksa_old.flags;
-               memcpy(&old->sa_mask, &ksa_old.mask, sizeof ksa_old.mask);
+               memcpy(&old->sa_mask, &ksa_old.mask, _NSIG/8);
        }
-       return 0;
+       return __syscall_ret(r);
 }
 
 int __sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)
 {
-       if (sig-32U < 3) {
+       unsigned long set[_NSIG/(8*sizeof(long))];
+
+       if (sig-32U < 3 || sig-1U >= _NSIG-1) {
                errno = EINVAL;
                return -1;
        }
-       return __libc_sigaction(sig, sa, old);
+
+       /* Doing anything with the disposition of SIGABRT requires a lock,
+        * so that it cannot be changed while abort is terminating the
+        * process and so any change made by abort can't be observed. */
+       if (sig == SIGABRT) {
+               __block_all_sigs(&set);
+               LOCK(__abort_lock);
+       }
+       int r = __libc_sigaction(sig, sa, old);
+       if (sig == SIGABRT) {
+               UNLOCK(__abort_lock);
+               __restore_sigs(&set);
+       }
+       return r;
 }
 
 weak_alias(__sigaction, sigaction);