Update vendor directory

vendor/github.com/ncw/swift/watchdog_reader.go

@@ -7,12 +7,18 @@ import (
 
 // An io.Reader which resets a watchdog timer whenever data is read
 type watchdogReader struct {
-	timeout time.Duration
-	reader  io.Reader
-	timer   *time.Timer
+	timeout     time.Duration
+	reader      io.Reader
+	timer       *time.Timer
+	bytes       int64
+	replayFirst bool
+	readFirst   bool
+	first       byte
 }
 
 // Returns a new reader which will kick the watchdog timer whenever data is read
+//
+// It also has a 1 byte buffer which can be reset with the Reset() method.
 func newWatchdogReader(reader io.Reader, timeout time.Duration, timer *time.Timer) *watchdogReader {
 	return &watchdogReader{
 		timeout: timeout,
@@ -23,12 +29,43 @@ func newWatchdogReader(reader io.Reader, timeout time.Duration, timer *time.Time
 
 // Read reads up to len(p) bytes into p
 func (t *watchdogReader) Read(p []byte) (n int, err error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
 	// FIXME limit the amount of data read in one chunk so as to not exceed the timeout?
 	resetTimer(t.timer, t.timeout)
-	n, err = t.reader.Read(p)
+	if t.replayFirst {
+		p[0] = t.first
+		t.replayFirst = false
+		n = 1
+		err = nil
+	} else {
+		n, err = t.reader.Read(p)
+		if !t.readFirst && n > 0 {
+			t.first = p[0]
+			t.readFirst = true
+		}
+		t.bytes += int64(n)
+	}
 	resetTimer(t.timer, t.timeout)
 	return
 }
 
+// Resets the buffer if only 1 byte read
+//
+// Returns true if successful
+func (t *watchdogReader) Reset() bool {
+	switch t.bytes {
+	case 0:
+		t.replayFirst = false
+		return true
+	case 1:
+		t.replayFirst = true
+		return true
+	default:
+		return false
+	}
+}
+
 // Check it satisfies the interface
 var _ io.Reader = &watchdogReader{}