initial signal implementation

kernel-src/sys/syscalls/sigaction.c

@@ -0,0 +1,29 @@
+#include <kernel/syscalls.h>
+#include <arch/cpu.h>
+#include <logging.h>
+
+syscallret_t syscall_sigaction(context_t *, int sig, sigaction_t *new, sigaction_t *old) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	if (sig > NSIG || sig == SIGKILL || sig == SIGSTOP) {
+		ret.errno = EINVAL;
+		return ret;
+	}
+
+	sigaction_t newtmp, oldtmp;
+	if (new) {
+		newtmp = *new;
+		__assert(newtmp.flags & SA_RESTORER);
+	}
+
+	signal_action(_cpu()->thread->proc, sig, new ? &newtmp : NULL, old ? &oldtmp : NULL);
+
+	if (old)
+		*old = oldtmp;
+
+	ret.errno = 0;
+	ret.ret = 0;
+	return ret;
+}