From 40bd571489518695a09109bf1a5bc897cbd9423d Mon Sep 17 00:00:00 2001
From: QLeelulu <qleelulu@gmail.com>
Date: Fri, 23 Aug 2013 18:04:21 +0800
Subject: [PATCH] add Tell to return the file's current position, like stdio's
 ftell().

---
 tail.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tail.go b/tail.go
index 36cb4b9..19e1a38 100644
--- a/tail.go
+++ b/tail.go
@@ -91,6 +91,16 @@ func TailFile(filename string, config Config) (*Tail, error) {
 	return t, nil
 }
 
+// Return the file's current position, like stdio's ftell().
+// But this value is not very accurate.
+func (tail *Tail) Tell() (offser int64, err error) {
+	offset, err = tail.file.Seek(0, os.SEEK_CUR)
+	if err == nil {
+		offset -= int64(tail.reader.Buffered())
+	}
+	return
+}
+
 // Stop stops the tailing activity.
 func (tail *Tail) Stop() error {
 	tail.Kill(nil)