bastion 0.53.2

client-go/filelock_unix.go

@@ -0,0 +1,23 @@
+//go:build !windows
+
+package main
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// flockFile takes an exclusive advisory lock on f (blocking). Released by
+// closing f. Advisory is enough: every writer of a pairing file is this
+// binary, and every one of them goes through withPairingsLock.
+func flockFile(f *os.File) error {
+	return unix.Flock(int(f.Fd()), unix.LOCK_EX)
+}
+
+// flockFileNB is flockFile without the wait: it fails immediately when another
+// process holds the lock, so an interactive `run` can say "already running"
+// instead of hanging as an invisible standby (singleton.go).
+func flockFileNB(f *os.File) error {
+	return unix.Flock(int(f.Fd()), unix.LOCK_EX|unix.LOCK_NB)
+}