Update dependencies

vendor/github.com/mdlayher/sdnotify/sdnotify.go

@@ -0,0 +1,96 @@
+// Package sdnotify implements systemd readiness notifications as described in
+// https://www.freedesktop.org/software/systemd/man/sd_notify.html.
+package sdnotify
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"strings"
+)
+
+// Socket is the predefined systemd notification socket environment variable.
+const Socket = "NOTIFY_SOCKET"
+
+// Common notification values. For a description of each, see:
+// https://www.freedesktop.org/software/systemd/man/sd_notify.html#Description.
+const (
+	Ready     = "READY=1"
+	Reloading = "RELOADING=1"
+	Stopping  = "STOPPING=1"
+)
+
+// Statusf creates a formatted STATUS notification with the input format string
+// and values.
+func Statusf(format string, v ...interface{}) string {
+	return fmt.Sprintf("STATUS=%s", fmt.Sprintf(format, v...))
+}
+
+// A Notifier can notify systemd of service status and readiness. Any methods
+// called on a nil Notifier will result in a no-op, allowing graceful
+// functionality degradation when a Go program is not running under systemd
+// supervision.
+type Notifier struct{ wc io.WriteCloser }
+
+// New creates a Notifier which sends notifications to the UNIX socket specified
+// by the NOTIFY_SOCKET environment variable. See Open for more details.
+func New() (*Notifier, error) {
+	s := os.Getenv(Socket)
+	if s == "" {
+		// Don't bother stat'ing an empty socket, just return now.
+		return nil, os.ErrNotExist
+	}
+
+	return Open(s)
+}
+
+// Open creates a Notifier which sends notifications to the UNIX socket
+// specified by sock.
+//
+// If sock does not exist or is unset (meaning the service is not running under
+// systemd supervision, or is not using systemd unit Type=notify), Open will
+// return an error which can be checked with 'errors.Is(err, os.ErrNotExist)'.
+// Calling any of the resulting nil Notifier's methods will result in a no-op.
+func Open(sock string) (*Notifier, error) {
+	// Don't stat Linux abstract namespace sockets, as would be created with a
+	// net.ListenPacket with no path.
+	if !strings.HasPrefix(sock, "@") {
+		if _, err := os.Stat(sock); err != nil {
+			return nil, fmt.Errorf("failed to stat notify socket: %w", err)
+		}
+	}
+
+	c, err := net.Dial("unixgram", sock)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Notifier{wc: c}, nil
+}
+
+// Notify sends zero or more notifications to systemd. See the package constants
+// for a list of common notifications or use the Statusf function to create a
+// STATUS notification.
+//
+// For advanced use cases, see:
+// https://www.freedesktop.org/software/systemd/man/sd_notify.html#Description.
+//
+// If n is nil or no strings are specified, Notify is a no-op.
+func (n *Notifier) Notify(s ...string) error {
+	if n == nil || len(s) == 0 {
+		return nil
+	}
+
+	_, err := io.WriteString(n.wc, strings.Join(s, "\n"))
+	return err
+}
+
+// Close closes the Notifier's socket. If n is nil, Close is a no-op.
+func (n *Notifier) Close() error {
+	if n == nil {
+		return nil
+	}
+
+	return n.wc.Close()
+}