Add an example servicev0.1.0

6 files changed, 147 insertions, 0 deletions

diff --git a/example/.gitignore b/example/.gitignore
new file mode 100644
index 0000000..33a9488
--- /dev/null
+++ b/example/.gitignore
@@ -0,0 +1 @@
+example
diff --git a/example/example.service b/example/example.service
new file mode 100644
index 0000000..c02b755
--- /dev/null
+++ b/example/example.service
@@ -0,0 +1,9 @@
+[Unit]
+Description=gosdd Example Service
+
+[Service]
+Type=simple
+ExecStart=%h/example
+
+[Install]
+WantedBy=default.target
diff --git a/example/example.socket b/example/example.socket
new file mode 100644
index 0000000..467e437
--- /dev/null
+++ b/example/example.socket
@@ -0,0 +1,8 @@
+[Unit]
+Description=gosdd Example Socket
+
+[Socket]
+ListenStream=127.0.0.1:9999
+
+[Install]
+WantedBy=sockets.target
diff --git a/example/main.go b/example/main.go
new file mode 100644
index 0000000..66eace2
--- /dev/null
+++ b/example/main.go
@@ -0,0 +1,125 @@
+// This implements a simple example that can be tested on a machine
+// running systemd.
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"os/signal"
+	"strings"
+	"sync"
+
+	"golang.org/x/sys/unix"
+
+	"go.awhk.org/gosdd"
+)
+
+var useNames = flag.Bool("use-names", false, "whether to use SDListenFDsWithNames or not")
+
+func main() {
+	flag.Parse()
+	log.SetFlags(log.Lshortfile)
+
+	if !*useNames {
+		fds, err := gosdd.SDListenFDs(true)
+		if err != nil {
+			log.Fatalln(err)
+		}
+		log.Printf("Received %d file descriptors from systemd.", len(fds))
+		listenAll(fds)
+		return
+	}
+
+	namedFDs, err := gosdd.SDListenFDsWithNames(true)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	log.Printf("Received %d named file descriptors from systemd.", len(namedFDs))
+	fds := make([]*os.File, 0, len(namedFDs))
+	for name, fd := range namedFDs {
+		log.Printf("Adding %q.", name)
+		fds = append(fds, fd)
+	}
+	listenAll(fds)
+}
+
+func listenAll(fds []*os.File) {
+	sig := make(chan os.Signal, 1)
+	signal.Notify(sig, os.Interrupt, unix.SIGTERM)
+
+	srvs := make([]echoServer, 0, len(fds))
+	wg := &sync.WaitGroup{}
+	for _, fd := range fds {
+		ln, err := net.FileListener(fd)
+		if err != nil {
+			log.Printf("Failed to make a listener: %s.", err)
+			continue
+		}
+		srv := echoServer{ln, wg}
+		srvs = append(srvs, srv)
+		go srv.start()
+	}
+
+	<-sig
+	for _, srv := range srvs {
+		srv.stop()
+	}
+	wg.Wait()
+}
+
+type echoServer struct {
+	ln net.Listener
+	wg *sync.WaitGroup
+}
+
+func (*echoServer) handle(conn net.Conn) {
+	defer func() {
+		if err := conn.Close(); err != nil {
+			log.Println(err)
+		}
+	}()
+
+	log.Printf("New connection, local address is %s, remote address is %s.", conn.LocalAddr(), conn.RemoteAddr())
+	if _, err := fmt.Fprintln(conn, "Hello World!"); err != nil {
+		log.Println(err)
+		return
+	}
+	r := bufio.NewReader(conn)
+	for {
+		s, err := r.ReadString('\n')
+		if err != nil {
+			log.Println(err)
+			return
+		}
+		s = strings.Trim(s, "\n ")
+		log.Printf("Received %q.", s)
+		if _, err := fmt.Fprintf(conn, "You said %q!\n", s); err != nil {
+			log.Println(err)
+			return
+		}
+	}
+}
+
+func (srv *echoServer) start() {
+	defer srv.wg.Done()
+	srv.wg.Add(1)
+
+	for {
+		conn, err := srv.ln.Accept()
+		if err != nil {
+			log.Println(err)
+			return
+		}
+		go srv.handle(conn)
+	}
+}
+
+func (srv *echoServer) stop() {
+	if err := srv.ln.Close(); err != nil {
+		log.Println(err)
+	}
+}
diff --git a/go.mod b/go.mod
index 832b735..ecee8ab 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module go.awhk.org/gosdd
 
 go 1.16
+
+require golang.org/x/sys v0.0.0-20210616094352-59db8d763f22
diff --git a/go.sum b/go.sum
index e69de29..9f05d9d 100644
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,2 @@
+golang.org/x/sys v0.0.0-20210616094352-59db8d763f22 h1:RqytpXGR1iVNX7psjB3ff8y7sNFinVFvkx1c8SjBkio=
+golang.org/x/sys v0.0.0-20210616094352-59db8d763f22/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=