pkg/ns: refactored so that builds succeed on non-linux platforms

moved functions that depend on linux packages (sys/unix) into a separate file
and added nop methods with a build tag for non-linux platforms in a new file.

pkg/ns/ns.go

@@ -15,15 +15,12 @@
 package ns
 
 import (
-	"crypto/rand"
+	"errors"
 	"fmt"
 	"os"
-	"path"
 	"runtime"
 	"sync"
 	"syscall"
-
-	"golang.org/x/sys/unix"
 )
 
 type NetNS interface {
@@ -65,12 +62,8 @@ type netNS struct {
 // netNS implements the NetNS interface
 var _ NetNS = &netNS{}
 
-func getCurrentThreadNetNSPath() string {
+// NotImplementedError is used to indicate that a method is not implemented for the given platform
-	// /proc/self/ns/net returns the namespace of the main thread, not
+var NotImplementedError = errors.New("Not Implemented")
-	// of whatever thread this goroutine is running on.  Make sure we
-	// use the thread's net namespace since the thread is switching around
-	return fmt.Sprintf("/proc/%d/task/%d/ns/net", os.Getpid(), unix.Gettid())
-}
 
 // Returns an object representing the current OS thread's network namespace
 func GetCurrentNS() (NetNS, error) {
@@ -125,82 +118,6 @@ func GetNS(nspath string) (NetNS, error) {
 	return &netNS{file: fd}, nil
 }
 
-// Creates a new persistent network namespace and returns an object
-// representing that namespace, without switching to it
-func NewNS() (NetNS, error) {
-	const nsRunDir = "/var/run/netns"
-
-	b := make([]byte, 16)
-	_, err := rand.Reader.Read(b)
-	if err != nil {
-		return nil, fmt.Errorf("failed to generate random netns name: %v", err)
-	}
-
-	err = os.MkdirAll(nsRunDir, 0755)
-	if err != nil {
-		return nil, err
-	}
-
-	// create an empty file at the mount point
-	nsName := fmt.Sprintf("cni-%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
-	nsPath := path.Join(nsRunDir, nsName)
-	mountPointFd, err := os.Create(nsPath)
-	if err != nil {
-		return nil, err
-	}
-	mountPointFd.Close()
-
-	// Ensure the mount point is cleaned up on errors; if the namespace
-	// was successfully mounted this will have no effect because the file
-	// is in-use
-	defer os.RemoveAll(nsPath)
-
-	var wg sync.WaitGroup
-	wg.Add(1)
-
-	// do namespace work in a dedicated goroutine, so that we can safely
-	// Lock/Unlock OSThread without upsetting the lock/unlock state of
-	// the caller of this function
-	var fd *os.File
-	go (func() {
-		defer wg.Done()
-		runtime.LockOSThread()
-
-		var origNS NetNS
-		origNS, err = GetNS(getCurrentThreadNetNSPath())
-		if err != nil {
-			return
-		}
-		defer origNS.Close()
-
-		// create a new netns on the current thread
-		err = unix.Unshare(unix.CLONE_NEWNET)
-		if err != nil {
-			return
-		}
-		defer origNS.Set()
-
-		// bind mount the new netns from the current thread onto the mount point
-		err = unix.Mount(getCurrentThreadNetNSPath(), nsPath, "none", unix.MS_BIND, "")
-		if err != nil {
-			return
-		}
-
-		fd, err = os.Open(nsPath)
-		if err != nil {
-			return
-		}
-	})()
-	wg.Wait()
-
-	if err != nil {
-		unix.Unmount(nsPath, unix.MNT_DETACH)
-		return nil, fmt.Errorf("failed to create namespace: %v", err)
-	}
-
-	return &netNS{file: fd, mounted: true}, nil
-}
-
 func (ns *netNS) Path() string {
 	return ns.file.Name()
 }
@@ -216,29 +133,6 @@ func (ns *netNS) errorIfClosed() error {
 	return nil
 }
 
-func (ns *netNS) Close() error {
-	if err := ns.errorIfClosed(); err != nil {
-		return err
-	}
-
-	if err := ns.file.Close(); err != nil {
-		return fmt.Errorf("Failed to close %q: %v", ns.file.Name(), err)
-	}
-	ns.closed = true
-
-	if ns.mounted {
-		if err := unix.Unmount(ns.file.Name(), unix.MNT_DETACH); err != nil {
-			return fmt.Errorf("Failed to unmount namespace %s: %v", ns.file.Name(), err)
-		}
-		if err := os.RemoveAll(ns.file.Name()); err != nil {
-			return fmt.Errorf("Failed to clean up namespace %s: %v", ns.file.Name(), err)
-		}
-		ns.mounted = false
-	}
-
-	return nil
-}
-
 func (ns *netNS) Do(toRun func(NetNS) error) error {
 	if err := ns.errorIfClosed(); err != nil {
 		return err
@@ -281,18 +175,6 @@ func (ns *netNS) Do(toRun func(NetNS) error) error {
 	return innerError
 }
 
-func (ns *netNS) Set() error {
-	if err := ns.errorIfClosed(); err != nil {
-		return err
-	}
-
-	if _, _, err := unix.Syscall(unix.SYS_SETNS, ns.Fd(), uintptr(unix.CLONE_NEWNET), 0); err != 0 {
-		return fmt.Errorf("Error switching to ns %v: %v", ns.file.Name(), err)
-	}
-
-	return nil
-}
-
 // WithNetNSPath executes the passed closure under the given network
 // namespace, restoring the original namespace afterwards.
 func WithNetNSPath(nspath string, toRun func(NetNS) error) error {

pkg/ns/ns_linux.go

@@ -0,0 +1,144 @@
+// Copyright 2015-2017 CNI authors
+//
+// 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 ns
+
+import (
+	"crypto/rand"
+	"fmt"
+	"os"
+	"path"
+	"runtime"
+	"sync"
+
+	"golang.org/x/sys/unix"
+)
+
+func getCurrentThreadNetNSPath() string {
+	// /proc/self/ns/net returns the namespace of the main thread, not
+	// of whatever thread this goroutine is running on.  Make sure we
+	// use the thread's net namespace since the thread is switching around
+	return fmt.Sprintf("/proc/%d/task/%d/ns/net", os.Getpid(), unix.Gettid())
+}
+
+// Creates a new persistent network namespace and returns an object
+// representing that namespace, without switching to it
+func NewNS() (NetNS, error) {
+	const nsRunDir = "/var/run/netns"
+
+	b := make([]byte, 16)
+	_, err := rand.Reader.Read(b)
+	if err != nil {
+		return nil, fmt.Errorf("failed to generate random netns name: %v", err)
+	}
+
+	err = os.MkdirAll(nsRunDir, 0755)
+	if err != nil {
+		return nil, err
+	}
+
+	// create an empty file at the mount point
+	nsName := fmt.Sprintf("cni-%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
+	nsPath := path.Join(nsRunDir, nsName)
+	mountPointFd, err := os.Create(nsPath)
+	if err != nil {
+		return nil, err
+	}
+	mountPointFd.Close()
+
+	// Ensure the mount point is cleaned up on errors; if the namespace
+	// was successfully mounted this will have no effect because the file
+	// is in-use
+	defer os.RemoveAll(nsPath)
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	// do namespace work in a dedicated goroutine, so that we can safely
+	// Lock/Unlock OSThread without upsetting the lock/unlock state of
+	// the caller of this function
+	var fd *os.File
+	go (func() {
+		defer wg.Done()
+		runtime.LockOSThread()
+
+		var origNS NetNS
+		origNS, err = GetNS(getCurrentThreadNetNSPath())
+		if err != nil {
+			return
+		}
+		defer origNS.Close()
+
+		// create a new netns on the current thread
+		err = unix.Unshare(unix.CLONE_NEWNET)
+		if err != nil {
+			return
+		}
+		defer origNS.Set()
+
+		// bind mount the new netns from the current thread onto the mount point
+		err = unix.Mount(getCurrentThreadNetNSPath(), nsPath, "none", unix.MS_BIND, "")
+		if err != nil {
+			return
+		}
+
+		fd, err = os.Open(nsPath)
+		if err != nil {
+			return
+		}
+	})()
+	wg.Wait()
+
+	if err != nil {
+		unix.Unmount(nsPath, unix.MNT_DETACH)
+		return nil, fmt.Errorf("failed to create namespace: %v", err)
+	}
+
+	return &netNS{file: fd, mounted: true}, nil
+}
+
+func (ns *netNS) Close() error {
+	if err := ns.errorIfClosed(); err != nil {
+		return err
+	}
+
+	if err := ns.file.Close(); err != nil {
+		return fmt.Errorf("Failed to close %q: %v", ns.file.Name(), err)
+	}
+	ns.closed = true
+
+	if ns.mounted {
+		if err := unix.Unmount(ns.file.Name(), unix.MNT_DETACH); err != nil {
+			return fmt.Errorf("Failed to unmount namespace %s: %v", ns.file.Name(), err)
+		}
+		if err := os.RemoveAll(ns.file.Name()); err != nil {
+			return fmt.Errorf("Failed to clean up namespace %s: %v", ns.file.Name(), err)
+		}
+		ns.mounted = false
+	}
+
+	return nil
+}
+
+func (ns *netNS) Set() error {
+	if err := ns.errorIfClosed(); err != nil {
+		return err
+	}
+
+	if _, _, err := unix.Syscall(unix.SYS_SETNS, ns.Fd(), uintptr(unix.CLONE_NEWNET), 0); err != 0 {
+		return fmt.Errorf("Error switching to ns %v: %v", ns.file.Name(), err)
+	}
+
+	return nil
+}

pkg/ns/ns_unspecified.go

@@ -0,0 +1,33 @@
+// Copyright 2015-2017 CNI authors
+//
+// 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.
+
+// +build !linux
+
+package ns
+
+func getCurrentThreadNetNSPath() string {
+	return ""
+}
+
+func NewNS() (NetNS, error) {
+	return nil, NotImplementedError
+}
+
+func (ns *netNS) Close() error {
+	return NotImplementedError
+}
+
+func (ns *netNS) Set() error {
+	return NotImplementedError
+}