vendor update for E2E framework

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

vendor/k8s.io/utils/io/read.go

@@ -0,0 +1,74 @@
+/*
+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 io
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+)
+
+// ErrLimitReached means that the read limit is reached.
+var ErrLimitReached = errors.New("the read limit is reached")
+
+// ConsistentRead repeatedly reads a file until it gets the same content twice.
+// This is useful when reading files in /proc that are larger than page size
+// and kernel may modify them between individual read() syscalls.
+func ConsistentRead(filename string, attempts int) ([]byte, error) {
+	return consistentReadSync(filename, attempts, nil)
+}
+
+// consistentReadSync is the main functionality of ConsistentRead but
+// introduces a sync callback that can be used by the tests to mutate the file
+// from which the test data is being read
+func consistentReadSync(filename string, attempts int, sync func(int)) ([]byte, error) {
+	oldContent, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+	for i := 0; i < attempts; i++ {
+		if sync != nil {
+			sync(i)
+		}
+		newContent, err := ioutil.ReadFile(filename)
+		if err != nil {
+			return nil, err
+		}
+		if bytes.Compare(oldContent, newContent) == 0 {
+			return newContent, nil
+		}
+		// Files are different, continue reading
+		oldContent = newContent
+	}
+	return nil, fmt.Errorf("could not get consistent content of %s after %d attempts", filename, attempts)
+}
+
+// ReadAtMost reads up to `limit` bytes from `r`, and reports an error
+// when `limit` bytes are read.
+func ReadAtMost(r io.Reader, limit int64) ([]byte, error) {
+	limitedReader := &io.LimitedReader{R: r, N: limit}
+	data, err := ioutil.ReadAll(limitedReader)
+	if err != nil {
+		return data, err
+	}
+	if limitedReader.N <= 0 {
+		return data, ErrLimitReached
+	}
+	return data, nil
+}