vendor files

vendor/k8s.io/kubernetes/pkg/util/tail/tail.go

@@ -0,0 +1,99 @@
+/*
+Copyright 2017 The Kubernetes 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 tail
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"os"
+)
+
+const (
+	// blockSize is the block size used in tail.
+	blockSize = 1024
+)
+
+var (
+	// eol is the end-of-line sign in the log.
+	eol = []byte{'\n'}
+)
+
+// ReadAtMost reads at most max bytes from the end of the file identified by path or
+// returns an error. It returns true if the file was longer than max. It will
+// allocate up to max bytes.
+func ReadAtMost(path string, max int64) ([]byte, bool, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, false, err
+	}
+	defer f.Close()
+	fi, err := f.Stat()
+	if err != nil {
+		return nil, false, err
+	}
+	size := fi.Size()
+	if size == 0 {
+		return nil, false, nil
+	}
+	if size < max {
+		max = size
+	}
+	offset, err := f.Seek(-max, os.SEEK_END)
+	if err != nil {
+		return nil, false, err
+	}
+	data, err := ioutil.ReadAll(f)
+	return data, offset > 0, err
+}
+
+// FindTailLineStartIndex returns the start of last nth line.
+// * If n < 0, return the beginning of the file.
+// * If n >= 0, return the beginning of last nth line.
+// Notice that if the last line is incomplete (no end-of-line), it will not be counted
+// as one line.
+func FindTailLineStartIndex(f io.ReadSeeker, n int64) (int64, error) {
+	if n < 0 {
+		return 0, nil
+	}
+	size, err := f.Seek(0, os.SEEK_END)
+	if err != nil {
+		return 0, err
+	}
+	var left, cnt int64
+	buf := make([]byte, blockSize)
+	for right := size; right > 0 && cnt <= n; right -= blockSize {
+		left = right - blockSize
+		if left < 0 {
+			left = 0
+			buf = make([]byte, right)
+		}
+		if _, err := f.Seek(left, os.SEEK_SET); err != nil {
+			return 0, err
+		}
+		if _, err := f.Read(buf); err != nil {
+			return 0, err
+		}
+		cnt += int64(bytes.Count(buf, eol))
+	}
+	for ; cnt > n; cnt-- {
+		idx := bytes.Index(buf, eol) + 1
+		buf = buf[idx:]
+		left += int64(idx)
+	}
+	return left, nil
+}