1 files changed, 440 insertions, 0 deletions
diff --git a/vendor/github.com/nxadm/tail/tail.go b/vendor/github.com/nxadm/tail/tail.go
new file mode 100644
index 000000000..58d3c4b95
--- /dev/null
+++ b/vendor/github.com/nxadm/tail/tail.go
@@ -0,0 +1,440 @@
+// Copyright (c) 2015 HPE Software Inc. All rights reserved.
+// Copyright (c) 2013 ActiveState Software Inc. All rights reserved.
+
+package tail
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/nxadm/tail/ratelimiter"
+	"github.com/nxadm/tail/util"
+	"github.com/nxadm/tail/watch"
+	"gopkg.in/tomb.v1"
+)
+
+var (
+	ErrStop = errors.New("tail should now stop")
+)
+
+type Line struct {
+	Text     string
+	Num      int
+	SeekInfo SeekInfo
+	Time     time.Time
+	Err      error // Error from tail
+}
+
+// NewLine returns a Line with present time.
+func NewLine(text string, lineNum int) *Line {
+	return &Line{text, lineNum, SeekInfo{}, time.Now(), nil}
+}
+
+// SeekInfo represents arguments to `io.Seek`
+type SeekInfo struct {
+	Offset int64
+	Whence int // io.Seek*
+}
+
+type logger interface {
+	Fatal(v ...interface{})
+	Fatalf(format string, v ...interface{})
+	Fatalln(v ...interface{})
+	Panic(v ...interface{})
+	Panicf(format string, v ...interface{})
+	Panicln(v ...interface{})
+	Print(v ...interface{})
+	Printf(format string, v ...interface{})
+	Println(v ...interface{})
+}
+
+// Config is used to specify how a file must be tailed.
+type Config struct {
+	// File-specifc
+	Location    *SeekInfo // Seek to this location before tailing
+	ReOpen      bool      // Reopen recreated files (tail -F)
+	MustExist   bool      // Fail early if the file does not exist
+	Poll        bool      // Poll for file changes instead of using inotify
+	Pipe        bool      // Is a named pipe (mkfifo)
+	RateLimiter *ratelimiter.LeakyBucket
+
+	// Generic IO
+	Follow      bool // Continue looking for new lines (tail -f)
+	MaxLineSize int  // If non-zero, split longer lines into multiple lines
+
+	// Logger, when nil, is set to tail.DefaultLogger
+	// To disable logging: set field to tail.DiscardingLogger
+	Logger logger
+}
+
+type Tail struct {
+	Filename string
+	Lines    chan *Line
+	Config
+
+	file    *os.File
+	reader  *bufio.Reader
+	lineNum int
+
+	watcher watch.FileWatcher
+	changes *watch.FileChanges
+
+	tomb.Tomb // provides: Done, Kill, Dying
+
+	lk sync.Mutex
+}
+
+var (
+	// DefaultLogger is used when Config.Logger == nil
+	DefaultLogger = log.New(os.Stderr, "", log.LstdFlags)
+	// DiscardingLogger can be used to disable logging output
+	DiscardingLogger = log.New(ioutil.Discard, "", 0)
+)
+
+// TailFile begins tailing the file. Output stream is made available
+// via the `Tail.Lines` channel. To handle errors during tailing,
+// invoke the `Wait` or `Err` method after finishing reading from the
+// `Lines` channel.
+func TailFile(filename string, config Config) (*Tail, error) {
+	if config.ReOpen && !config.Follow {
+		util.Fatal("cannot set ReOpen without Follow.")
+	}
+
+	t := &Tail{
+		Filename: filename,
+		Lines:    make(chan *Line),
+		Config:   config,
+	}
+
+	// when Logger was not specified in config, use default logger
+	if t.Logger == nil {
+		t.Logger = DefaultLogger
+	}
+
+	if t.Poll {
+		t.watcher = watch.NewPollingFileWatcher(filename)
+	} else {
+		t.watcher = watch.NewInotifyFileWatcher(filename)
+	}
+
+	if t.MustExist {
+		var err error
+		t.file, err = OpenFile(t.Filename)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	go t.tailFileSync()
+
+	return t, nil
+}
+
+// Tell returns the file's current position, like stdio's ftell().
+// But this value is not very accurate.
+// One line from the chan(tail.Lines) may have been read,
+// so it may have lost one line.
+func (tail *Tail) Tell() (offset int64, err error) {
+	if tail.file == nil {
+		return
+	}
+	offset, err = tail.file.Seek(0, io.SeekCurrent)
+	if err != nil {
+		return
+	}
+
+	tail.lk.Lock()
+	defer tail.lk.Unlock()
+	if tail.reader == nil {
+		return
+	}
+
+	offset -= int64(tail.reader.Buffered())
+	return
+}
+
+// Stop stops the tailing activity.
+func (tail *Tail) Stop() error {
+	tail.Kill(nil)
+	return tail.Wait()
+}
+
+// StopAtEOF stops tailing as soon as the end of the file is reached.
+func (tail *Tail) StopAtEOF() error {
+	tail.Kill(errStopAtEOF)
+	return tail.Wait()
+}
+
+var errStopAtEOF = errors.New("tail: stop at eof")
+
+func (tail *Tail) close() {
+	close(tail.Lines)
+	tail.closeFile()
+}
+
+func (tail *Tail) closeFile() {
+	if tail.file != nil {
+		tail.file.Close()
+		tail.file = nil
+	}
+}
+
+func (tail *Tail) reopen() error {
+	tail.closeFile()
+	tail.lineNum = 0
+	for {
+		var err error
+		tail.file, err = OpenFile(tail.Filename)
+		if err != nil {
+			if os.IsNotExist(err) {
+				tail.Logger.Printf("Waiting for %s to appear...", tail.Filename)
+				if err := tail.watcher.BlockUntilExists(&tail.Tomb); err != nil {
+					if err == tomb.ErrDying {
+						return err
+					}
+					return fmt.Errorf("Failed to detect creation of %s: %s", tail.Filename, err)
+				}
+				continue
+			}
+			return fmt.Errorf("Unable to open file %s: %s", tail.Filename, err)
+		}
+		break
+	}
+	return nil
+}
+
+func (tail *Tail) readLine() (string, error) {
+	tail.lk.Lock()
+	line, err := tail.reader.ReadString('\n')
+	tail.lk.Unlock()
+	if err != nil {
+		// Note ReadString "returns the data read before the error" in
+		// case of an error, including EOF, so we return it as is. The
+		// caller is expected to process it if err is EOF.
+		return line, err
+	}
+
+	line = strings.TrimRight(line, "\n")
+
+	return line, err
+}
+
+func (tail *Tail) tailFileSync() {
+	defer tail.Done()
+	defer tail.close()
+
+	if !tail.MustExist {
+		// deferred first open.
+		err := tail.reopen()
+		if err != nil {
+			if err != tomb.ErrDying {
+				tail.Kill(err)
+			}
+			return
+		}
+	}
+
+	// Seek to requested location on first open of the file.
+	if tail.Location != nil {
+		_, err := tail.file.Seek(tail.Location.Offset, tail.Location.Whence)
+		if err != nil {
+			tail.Killf("Seek error on %s: %s", tail.Filename, err)
+			return
+		}
+	}
+
+	tail.openReader()
+
+	// Read line by line.
+	for {
+		// do not seek in named pipes
+		if !tail.Pipe {
+			// grab the position in case we need to back up in the event of a half-line
+			if _, err := tail.Tell(); err != nil {
+				tail.Kill(err)
+				return
+			}
+		}
+
+		line, err := tail.readLine()
+
+		// Process `line` even if err is EOF.
+		if err == nil {
+			cooloff := !tail.sendLine(line)
+			if cooloff {
+				// Wait a second before seeking till the end of
+				// file when rate limit is reached.
+				msg := ("Too much log activity; waiting a second before resuming tailing")
+				offset, _ := tail.Tell()
+				tail.Lines <- &Line{msg, tail.lineNum, SeekInfo{Offset: offset}, time.Now(), errors.New(msg)}
+				select {
+				case <-time.After(time.Second):
+				case <-tail.Dying():
+					return
+				}
+				if err := tail.seekEnd(); err != nil {
+					tail.Kill(err)
+					return
+				}
+			}
+		} else if err == io.EOF {
+			if !tail.Follow {
+				if line != "" {
+					tail.sendLine(line)
+				}
+				return
+			}
+
+			if tail.Follow && line != "" {
+				tail.sendLine(line)
+				if err := tail.seekEnd(); err != nil {
+					tail.Kill(err)
+					return
+				}
+			}
+
+			// When EOF is reached, wait for more data to become
+			// available. Wait strategy is based on the `tail.watcher`
+			// implementation (inotify or polling).
+			err := tail.waitForChanges()
+			if err != nil {
+				if err != ErrStop {
+					tail.Kill(err)
+				}
+				return
+			}
+		} else {
+			// non-EOF error
+			tail.Killf("Error reading %s: %s", tail.Filename, err)
+			return
+		}
+
+		select {
+		case <-tail.Dying():
+			if tail.Err() == errStopAtEOF {
+				continue
+			}
+			return
+		default:
+		}
+	}
+}
+
+// waitForChanges waits until the file has been appended, deleted,
+// moved or truncated. When moved or deleted - the file will be
+// reopened if ReOpen is true. Truncated files are always reopened.
+func (tail *Tail) waitForChanges() error {
+	if tail.changes == nil {
+		pos, err := tail.file.Seek(0, io.SeekCurrent)
+		if err != nil {
+			return err
+		}
+		tail.changes, err = tail.watcher.ChangeEvents(&tail.Tomb, pos)
+		if err != nil {
+			return err
+		}
+	}
+
+	select {
+	case <-tail.changes.Modified:
+		return nil
+	case <-tail.changes.Deleted:
+		tail.changes = nil
+		if tail.ReOpen {
+			// XXX: we must not log from a library.
+			tail.Logger.Printf("Re-opening moved/deleted file %s ...", tail.Filename)
+			if err := tail.reopen(); err != nil {
+				return err
+			}
+			tail.Logger.Printf("Successfully reopened %s", tail.Filename)
+			tail.openReader()
+			return nil
+		}
+		tail.Logger.Printf("Stopping tail as file no longer exists: %s", tail.Filename)
+		return ErrStop
+	case <-tail.changes.Truncated:
+		// Always reopen truncated files (Follow is true)
+		tail.Logger.Printf("Re-opening truncated file %s ...", tail.Filename)
+		if err := tail.reopen(); err != nil {
+			return err
+		}
+		tail.Logger.Printf("Successfully reopened truncated %s", tail.Filename)
+		tail.openReader()
+		return nil
+	case <-tail.Dying():
+		return ErrStop
+	}
+}
+
+func (tail *Tail) openReader() {
+	tail.lk.Lock()
+	if tail.MaxLineSize > 0 {
+		// add 2 to account for newline characters
+		tail.reader = bufio.NewReaderSize(tail.file, tail.MaxLineSize+2)
+	} else {
+		tail.reader = bufio.NewReader(tail.file)
+	}
+	tail.lk.Unlock()
+}
+
+func (tail *Tail) seekEnd() error {
+	return tail.seekTo(SeekInfo{Offset: 0, Whence: io.SeekEnd})
+}
+
+func (tail *Tail) seekTo(pos SeekInfo) error {
+	_, err := tail.file.Seek(pos.Offset, pos.Whence)
+	if err != nil {
+		return fmt.Errorf("Seek error on %s: %s", tail.Filename, err)
+	}
+	// Reset the read buffer whenever the file is re-seek'ed
+	tail.reader.Reset(tail.file)
+	return nil
+}
+
+// sendLine sends the line(s) to Lines channel, splitting longer lines
+// if necessary. Return false if rate limit is reached.
+func (tail *Tail) sendLine(line string) bool {
+	now := time.Now()
+	lines := []string{line}
+
+	// Split longer lines
+	if tail.MaxLineSize > 0 && len(line) > tail.MaxLineSize {
+		lines = util.PartitionString(line, tail.MaxLineSize)
+	}
+
+	for _, line := range lines {
+		tail.lineNum++
+		offset, _ := tail.Tell()
+		select {
+		case tail.Lines <- &Line{line, tail.lineNum, SeekInfo{Offset: offset}, now, nil}:
+		case <-tail.Dying():
+			return true
+		}
+	}
+
+	if tail.Config.RateLimiter != nil {
+		ok := tail.Config.RateLimiter.Pour(uint16(len(lines)))
+		if !ok {
+			tail.Logger.Printf("Leaky bucket full (%v); entering 1s cooloff period.",
+				tail.Filename)
+			return false
+		}
+	}
+
+	return true
+}
+
+// Cleanup removes inotify watches added by the tail package. This function is
+// meant to be invoked from a process's exit handler. Linux kernel may not
+// automatically remove inotify watches after the process exits.
+func (tail *Tail) Cleanup() {
+	watch.Cleanup(tail.Filename)
+}