libc: implement signal(3)

Fixes #4824
genodelabs · May 30, 2023 · 2923849 · 2923849
1 parent 7064418
commit 2923849
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/repos/libports/src/lib/libc/dummies.cc b/repos/libports/src/lib/libc/dummies.cc
@@ -129,7 +129,6 @@ DUMMY(int   , -1, sched_setparam, (pid_t, const sched_param *))
 DUMMY(int   , -1, sched_setscheduler, (pid_t, int, const sched_param *))
 DUMMY(int   , -1, sched_yield, (void))
 DUMMY(int   , -1, __semctl, (void))
-DUMMY_SILENT(sig_t, SIG_ERR, signal, (int, sig_t));
 DUMMY_SILENT(int   , -1, sigaltstack, (const stack_t *, stack_t *))
 DUMMY(int   , -1, setegid, (uid_t))
 DUMMY(int   , -1, seteuid, (uid_t))

diff --git a/repos/libports/src/lib/libc/signal.cc b/repos/libports/src/lib/libc/signal.cc
@@ -131,6 +131,19 @@ extern "C" int sigaction(int signum, const struct sigaction *act, struct sigacti
 }
 
 
+extern "C" __sighandler_t * signal(int sig, __sighandler_t * func)
+{
+	struct sigaction oact { }, act { };
+	act.sa_handler = func;
+
+	if (sigaction(sig, &act, &oact) == 0)
+		return oact.sa_handler;
+
+	errno = EINVAL;
+	return SIG_ERR;
+}
+
+
 extern "C" int       _sigaction(int, const struct sigaction *, struct sigaction *) __attribute__((weak, alias("sigaction")));
 extern "C" int  __sys_sigaction(int, const struct sigaction *, struct sigaction *) __attribute__((weak, alias("sigaction")));
 extern "C" int __libc_sigaction(int, const struct sigaction *, struct sigaction *) __attribute__((weak, alias("sigaction")));