Initial commit

vendor/go.i3wm.org/i3/validpid.go

@@ -0,0 +1,16 @@
+package i3
+
+import "syscall"
+
+func pidValid(pid int) bool {
+	// As per kill(2) from POSIX.1-2008, sending signal 0 validates a pid.
+	if err := syscall.Kill(pid, 0); err != nil {
+		if err == syscall.EPERM {
+			// Process still alive (but no permission to signal):
+			return true
+		}
+		// errno is likely ESRCH (process not found).
+		return false // Process not alive.
+	}
+	return true // Process still alive.
+}