sd_daemon/notify_*.go:socketUnixgram(): Cross-reference with net

2 files changed, 13 insertions, 3 deletions

diff --git a/sd_daemon/notify_linux.go b/sd_daemon/notify_linux.go
index 903f1ad..085b25c 100644
--- a/sd_daemon/notify_linux.go
+++ b/sd_daemon/notify_linux.go
@@ -99,7 +99,16 @@ func (msg Notification) send(unsetEnv bool) error {
 // the high-level interface of "net", and messing around with FileConn
 // and UnixConn.  Maybe we just drop to using unix.Socket and
 // unix.SendmsgN directly.
+//
+// See: net/sock_cloexec.go:sysSocket()
 func socketUnixgram(name string) (*net.UnixConn, error) {
+	// Don't bother with SOCK_NONBLOCK, net.FileConn() will call
+	// syscall.SetNonblock().
+	//
+	// BUG(lukeshu): On Linux, Notification.Send() depends on
+	// SOCK_CLOEXEC in Linux 2.6.27 (2008-10-09), which is
+	// slightly newer than Go itself depends on, 2.6.23
+	// (2007-10-09).
 	fd, err := unix.Socket(unix.AF_UNIX, unix.SOCK_DGRAM|unix.SOCK_CLOEXEC, 0)
 	if err != nil {
 		return nil, os.NewSyscallError("socket", err)
diff --git a/sd_daemon/notify_nonlinux.go b/sd_daemon/notify_nonlinux.go
index d09cef0..dc268d3 100644
--- a/sd_daemon/notify_nonlinux.go
+++ b/sd_daemon/notify_nonlinux.go
@@ -99,6 +99,8 @@ func (msg Notification) send(unsetEnv bool) error {
 // the high-level interface of "net", and messing around with FileConn
 // and UnixConn.  Maybe we just drop to using unix.Socket and
 // unix.SendmsgN directly.
+//
+// See: net/sys_cloexec.go:sysSocket()
 func socketUnixgram(name string) (*net.UnixConn, error) {
 	syscall.ForkLock.RLock()
 	fd, err := unix.Socket(unix.AF_UNIX, unix.SOCK_DGRAM, 0)
@@ -110,9 +112,8 @@ func socketUnixgram(name string) (*net.UnixConn, error) {
 		return nil, os.NewSyscallError("socket", err)
 	}
 	defer unix.Close(fd)
-	if err = unix.SetNonblock(fd, true); err != nil {
-		return nil, os.NewSyscallError("setnonblock", err)
-	}
+	// Don't bother calling unix.SetNonblock(), net.FileConn()
+	// will call syscall.SetNonblock().
 	conn, err := net.FileConn(os.NewFile(uintptr(fd), name))
 	if err != nil {
 		return nil, err