plugins: add plugins from containernetworking/cni

Plugins prepared from the containernetworking/cni repo as follows:

1) git reset --hard 1a9288c3c0
2) git remove everything not in plugins/
3) git remove plugins/test
4) git merge into containernetworking/plugins repo
5) adjust import paths for containernetworking/cni -> containernetworking/plugins

plugins/ipam/host-local/backend/disk/backend.go

@@ -0,0 +1,115 @@
+// Copyright 2015 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 disk
+
+import (
+	"io/ioutil"
+	"net"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/containernetworking/plugins/plugins/ipam/host-local/backend"
+)
+
+const lastIPFile = "last_reserved_ip"
+
+var defaultDataDir = "/var/lib/cni/networks"
+
+type Store struct {
+	FileLock
+	dataDir string
+}
+
+// Store implements the Store interface
+var _ backend.Store = &Store{}
+
+func New(network, dataDir string) (*Store, error) {
+	if dataDir == "" {
+		dataDir = defaultDataDir
+	}
+	dir := filepath.Join(dataDir, network)
+	if err := os.MkdirAll(dir, 0644); err != nil {
+		return nil, err
+	}
+
+	lk, err := NewFileLock(dir)
+	if err != nil {
+		return nil, err
+	}
+	return &Store{*lk, dir}, nil
+}
+
+func (s *Store) Reserve(id string, ip net.IP) (bool, error) {
+	fname := filepath.Join(s.dataDir, ip.String())
+	f, err := os.OpenFile(fname, os.O_RDWR|os.O_EXCL|os.O_CREATE, 0644)
+	if os.IsExist(err) {
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	if _, err := f.WriteString(strings.TrimSpace(id)); err != nil {
+		f.Close()
+		os.Remove(f.Name())
+		return false, err
+	}
+	if err := f.Close(); err != nil {
+		os.Remove(f.Name())
+		return false, err
+	}
+	// store the reserved ip in lastIPFile
+	ipfile := filepath.Join(s.dataDir, lastIPFile)
+	err = ioutil.WriteFile(ipfile, []byte(ip.String()), 0644)
+	if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+// LastReservedIP returns the last reserved IP if exists
+func (s *Store) LastReservedIP() (net.IP, error) {
+	ipfile := filepath.Join(s.dataDir, lastIPFile)
+	data, err := ioutil.ReadFile(ipfile)
+	if err != nil {
+		return nil, err
+	}
+	return net.ParseIP(string(data)), nil
+}
+
+func (s *Store) Release(ip net.IP) error {
+	return os.Remove(filepath.Join(s.dataDir, ip.String()))
+}
+
+// N.B. This function eats errors to be tolerant and
+// release as much as possible
+func (s *Store) ReleaseByID(id string) error {
+	err := filepath.Walk(s.dataDir, func(path string, info os.FileInfo, err error) error {
+		if err != nil || info.IsDir() {
+			return nil
+		}
+		data, err := ioutil.ReadFile(path)
+		if err != nil {
+			return nil
+		}
+		if strings.TrimSpace(string(data)) == strings.TrimSpace(id) {
+			if err := os.Remove(path); err != nil {
+				return nil
+			}
+		}
+		return nil
+	})
+	return err
+}

plugins/ipam/host-local/backend/disk/lock.go

@@ -0,0 +1,50 @@
+// Copyright 2015 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 disk
+
+import (
+	"os"
+	"syscall"
+)
+
+// FileLock wraps os.File to be used as a lock using flock
+type FileLock struct {
+	f *os.File
+}
+
+// NewFileLock opens file/dir at path and returns unlocked FileLock object
+func NewFileLock(path string) (*FileLock, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return &FileLock{f}, nil
+}
+
+// Close closes underlying file
+func (l *FileLock) Close() error {
+	return l.f.Close()
+}
+
+// Lock acquires an exclusive lock
+func (l *FileLock) Lock() error {
+	return syscall.Flock(int(l.f.Fd()), syscall.LOCK_EX)
+}
+
+// Unlock releases the lock
+func (l *FileLock) Unlock() error {
+	return syscall.Flock(int(l.f.Fd()), syscall.LOCK_UN)
+}