1 files changed, 13 insertions, 0 deletions
diff --git a/src/signal/sigaddset.c b/src/signal/sigaddset.c
new file mode 100644
index 0000000..23e655d
--- /dev/null
+++ b/src/signal/sigaddset.c
@@ -0,0 +1,13 @@
+#include <signal.h>
+#include <errno.h>
+
+int sigaddset(sigset_t *set, int sig)
+{
+	unsigned s = sig-1;
+	if (s >= 8*sizeof(sigset_t)) {
+		errno = EINVAL;
+		return -1;
+	}
+	set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
+	return 0;
+}