add vendoring with go dep

vendor/github.com/vmware/govmomi/govc/datastore/tail.go

@@ -0,0 +1,135 @@
+/*
+Copyright (c) 2016 VMware, Inc. All Rights Reserved.
+
+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 datastore
+
+import (
+	"context"
+	"flag"
+	"io"
+	"os"
+	"time"
+
+	"github.com/vmware/govmomi/govc/cli"
+	"github.com/vmware/govmomi/govc/flags"
+)
+
+type tail struct {
+	*flags.DatastoreFlag
+	*flags.HostSystemFlag
+
+	count  int64
+	lines  int
+	follow bool
+}
+
+func init() {
+	cli.Register("datastore.tail", &tail{})
+}
+
+func (cmd *tail) Register(ctx context.Context, f *flag.FlagSet) {
+	cmd.DatastoreFlag, ctx = flags.NewDatastoreFlag(ctx)
+	cmd.DatastoreFlag.Register(ctx, f)
+
+	cmd.HostSystemFlag, ctx = flags.NewHostSystemFlag(ctx)
+	cmd.HostSystemFlag.Register(ctx, f)
+
+	f.Int64Var(&cmd.count, "c", -1, "Output the last NUM bytes")
+	f.IntVar(&cmd.lines, "n", 10, "Output the last NUM lines")
+	f.BoolVar(&cmd.follow, "f", false, "Output appended data as the file grows")
+}
+
+func (cmd *tail) Description() string {
+	return `Output the last part of datastore files.
+
+Examples:
+  govc datastore.tail -n 100 vm-name/vmware.log
+  govc datastore.tail -n 0 -f vm-name/vmware.log`
+}
+
+func (cmd *tail) Process(ctx context.Context) error {
+	if err := cmd.DatastoreFlag.Process(ctx); err != nil {
+		return err
+	}
+	if err := cmd.HostSystemFlag.Process(ctx); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (cmd *tail) Usage() string {
+	return "PATH"
+}
+
+func (cmd *tail) Run(ctx context.Context, f *flag.FlagSet) error {
+	if f.NArg() != 1 {
+		return flag.ErrHelp
+	}
+
+	ds, err := cmd.Datastore()
+	if err != nil {
+		return err
+	}
+
+	h, err := cmd.HostSystemIfSpecified()
+	if err != nil {
+		return err
+	}
+
+	if h != nil {
+		ctx = ds.HostContext(ctx, h)
+	}
+
+	file, err := ds.Open(ctx, f.Arg(0))
+	if err != nil {
+		return err
+	}
+
+	var reader io.ReadCloser = file
+
+	var offset int64
+
+	if cmd.count >= 0 {
+		info, serr := file.Stat()
+		if serr != nil {
+			return serr
+		}
+
+		if info.Size() > cmd.count {
+			offset = info.Size() - cmd.count
+
+			_, err = file.Seek(offset, io.SeekStart)
+			if err != nil {
+				return err
+			}
+		}
+	} else if cmd.lines >= 0 {
+		err = file.Tail(cmd.lines)
+		if err != nil {
+			return err
+		}
+	}
+
+	if cmd.follow {
+		reader = file.Follow(time.Second)
+	}
+
+	_, err = io.Copy(os.Stdout, reader)
+
+	_ = reader.Close()
+
+	return err
+}