1 files changed, 51 insertions, 0 deletions
diff --git a/sd-daemon/listen_fds.go b/sd-daemon/listen_fds.go
new file mode 100644
index 0000000..c90d373
--- /dev/null
+++ b/sd-daemon/listen_fds.go
@@ -0,0 +1,51 @@
+// Copyright 2015 CoreOS, Inc.
+// Copyright 2015 Luke Shumaker
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package activation implements primitives for systemd socket activation.
+package listen
+
+import (
+	"os"
+	"strconv"
+	"syscall"
+)
+
+//#include <systemd/sd-daemon.h>
+import "C"
+
+func ListenFds(unsetEnv bool) []*os.File {
+	if unsetEnv {
+		defer os.Unsetenv("LISTEN_PID")
+		defer os.Unsetenv("LISTEN_FDS")
+	}
+
+	pid, err := strconv.Atoi(os.Getenv("LISTEN_PID"))
+	if err != nil || pid != os.Getpid() {
+		return nil
+	}
+
+	nfds, err := strconv.Atoi(os.Getenv("LISTEN_FDS"))
+	if err != nil || nfds == 0 {
+		return nil
+	}
+
+	files := make([]*os.File, 0, nfds)
+	for fd := C.SD_LISTEN_FDS_START; fd < C.SD_LISTEN_FDS_START+nfds; fd++ {
+		syscall.CloseOnExec(fd)
+		files = append(files, os.NewFile(uintptr(fd), "LISTEN_FD_"+strconv.Itoa(fd)))
+	}
+
+	return files
+}