feat(signal): signal handling and sigset_t

src/signal/kill.c

@@ -0,0 +1,38 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <signal.h>
+
+#include <errno.h>
+
+#include "../internal/syscall.h"
+
+/*
+ * kill/killpg: process- and process-group-directed signals over SYS_kill.
+ *
+ * kill passes its pid straight to the kernel, which interprets it exactly
+ * as POSIX specifies: pid > 0 is a single process, pid == 0 the caller's
+ * process group, pid == -1 every process the caller may signal, and
+ * pid < -1 the process group -pid. killpg(pgrp, sig) is equivalent to
+ * kill(-pgrp, sig): a negative pgrp is not a valid group id and is
+ * rejected with EINVAL here (mirroring musl) rather than inverted into a
+ * positive-pid send by accident.
+ */
+
+int
+kill(pid_t pid, int sig)
+{
+    return syscall_ret(__syscall2(SYS_kill, (long)pid, sig));
+}
+
+int
+killpg(pid_t pgrp, int sig)
+{
+    if (pgrp < 0)
+    {
+        errno = EINVAL;
+        return -1;
+    }
+    return kill(-pgrp, sig);
+}