always terminate by SIGABRT when abort is called

[musl] / src / signal / sigaction.c

diff --git a/src/signal/sigaction.c b/src/signal/sigaction.c
index 6eca06f..7998950 100644 (file)
--- a/src/signal/sigaction.c
+++ b/src/signal/sigaction.c
@@ -6,6 +6,11 @@
 #include "libc.h"
 #include "ksigaction.h"
 
+volatile int dummy_lock[1] = { 0 };
+
+__attribute__((__visibility__("hidden")))
+weak_alias(dummy_lock, __abort_lock);
+
 static int unmask_done;
 static unsigned long handler_set[_NSIG/(8*sizeof(long))];
 
@@ -17,6 +22,7 @@ void __get_handler_set(sigset_t *set)
 int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)
 {
        struct k_sigaction ksa, ksa_old;
+       unsigned long set[_NSIG/(8*sizeof(long))];
        if (sa) {
                if ((uintptr_t)sa->sa_handler > 1UL) {
                        a_or_l(handler_set+(sig-1)/(8*sizeof(long)),
@@ -36,19 +42,30 @@ int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigact
                                unmask_done = 1;
                        }
                }
+               /* Changing the disposition of SIGABRT to anything but
+                * SIG_DFL requires a lock, so that it cannot be changed
+                * while abort is terminating the process after simply
+                * calling raise(SIGABRT) failed to do so. */
+               if (sa->sa_handler != SIG_DFL && sig == SIGABRT) {
+                       __block_all_sigs(&set);
+                       LOCK(__abort_lock);
+               }
                ksa.handler = sa->sa_handler;
                ksa.flags = sa->sa_flags | SA_RESTORER;
                ksa.restorer = (sa->sa_flags & SA_SIGINFO) ? __restore_rt : __restore;
                memcpy(&ksa.mask, &sa->sa_mask, sizeof ksa.mask);
        }
-       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, sizeof ksa.mask);
+       if (sig == SIGABRT && sa && sa->sa_handler != SIG_DFL) {
+               UNLOCK(__abort_lock);
+               __restore_sigs(&set);
+       }
+       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);
        }
-       return 0;
+       return __syscall_ret(r);
 }
 
 int __sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)