Adding return error value to checkPortAvailability to enable testing of function. Adding checkport_test.go to test checkPortAvailability. Updated server-main.go to use error value from checkPortAvailability and calls fatalIf if an error is returned. (#2322)

checkport.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"errors"
+	"fmt"
 	"net"
 	"os"
 	"syscall"
@@ -32,7 +33,7 @@ import (
 // This causes confusion on Mac OSX that minio server is not reachable
 // on 127.0.0.1 even though minio server is running. So before we start
 // the minio server we make sure that the port is free on all the IPs.
-func checkPortAvailability(port int) {
+func checkPortAvailability(port int) error {
 	isAddrInUse := func(err error) bool {
 		// Check if the syscall error is EADDRINUSE.
 		// EADDRINUSE is the system call error if another process is
@@ -54,40 +55,48 @@ func checkPortAvailability(port int) {
 		}
 		return true
 	}
+
 	ifcs, err := net.Interfaces()
 	if err != nil {
-		fatalIf(err, "Unable to list interfaces.")
+		return err
 	}
+
 	for _, ifc := range ifcs {
 		addrs, err := ifc.Addrs()
 		if err != nil {
-			fatalIf(err, "Unable to list addresses on interface %s.", ifc.Name)
+			return err
 		}
+
 		for _, addr := range addrs {
 			ipnet, ok := addr.(*net.IPNet)
 			if !ok {
 				errorIf(errors.New(""), "Failed to assert type on (*net.IPNet) interface.")
 				continue
 			}
+
 			ip := ipnet.IP
 			network := "tcp4"
 			if ip.To4() == nil {
 				network = "tcp6"
 			}
-			tcpAddr := net.TCPAddr{IP: ip, Port: port, Zone: ifc.Name}
-			l, err := net.ListenTCP(network, &tcpAddr)
+
+			l, err := net.Listen(network, fmt.Sprintf(":%d", port))
 			if err != nil {
 				if isAddrInUse(err) {
 					// Fail if port is already in use.
-					fatalIf(err, "Unable to listen on %s:%.d.", tcpAddr.IP, tcpAddr.Port)
-				} else {
-					// Ignore other errors.
-					continue
+					return err
 				}
+
+				// Ignore other errors.
+				continue
+
 			}
+
 			if err = l.Close(); err != nil {
-				fatalIf(err, "Unable to close listener on %s:%.d.", tcpAddr.IP, tcpAddr.Port)
+				return err
 			}
 		}
 	}
+
+	return nil
 }

checkport_test.go

@@ -0,0 +1,54 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * 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 main
+
+import (
+	"fmt"
+	"net"
+	"runtime"
+	"testing"
+)
+
+func TestCheckPortAvailability(t *testing.T) {
+	tests := []struct {
+		port int
+	}{
+		{9000},
+		{10000},
+	}
+	for _, test := range tests {
+		// This test should pass if the ports are available
+		err := checkPortAvailability(test.port)
+		if err != nil {
+			t.Fatalf("checkPortAvailability test failed for port: %d. Error: %v", test.port, err)
+		}
+
+		// Now use the ports and check again
+		ln, err := net.Listen("tcp", fmt.Sprintf(":%d", test.port))
+		if err != nil {
+			t.Fail()
+		}
+		defer ln.Close()
+
+		err = checkPortAvailability(test.port)
+
+		// Skip if the os is windows due to https://github.com/golang/go/issues/7598
+		if err == nil && runtime.GOOS != "windows" {
+			t.Fatalf("checkPortAvailability should fail for port: %d. Error: %v", test.port, err)
+		}
+	}
+}

server-main.go

@@ -246,7 +246,9 @@ func serverMain(c *cli.Context) {
 	serverAddress := c.String("address")
 
 	// Check if requested port is available.
-	checkPortAvailability(getPort(serverAddress))
+	port := getPort(serverAddress)
+	err := checkPortAvailability(port)
+	fatalIf(err, "Port unavailable %d", port)
 
 	// Disks to be ignored in server init, to skip format healing.
 	ignoredDisks := strings.Split(c.String("ignore-disks"), ",")
@@ -268,7 +270,6 @@ func serverMain(c *cli.Context) {
 	printStartupMessage(endPoints)
 
 	// Start server.
-	var err error
 	// Configure TLS if certs are available.
 	if tls {
 		err = apiServer.ListenAndServeTLS(mustGetCertFile(), mustGetKeyFile())