Fix the log ending newline handling.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/server/io/logger.go

@@ -19,6 +19,7 @@ package io
 import (
 	"bufio"
 	"bytes"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"time"
@@ -61,6 +62,56 @@ func NewCRILogger(path string, w io.Writer, stream StreamType, maxLen int) (io.W
 	return pwc, stop
 }
 
+// bufio.ReadLine in golang eats both read errors and tailing newlines
+// (See https://golang.org/pkg/bufio/#Reader.ReadLine). When reading
+// to io.EOF, it is impossible for the caller to figure out whether
+// there is a newline at the end, for example:
+// 1) When reading "CONTENT\n", it returns "CONTENT" without error;
+// 2) When reading "CONTENT", it also returns "CONTENT" without error.
+//
+// To differentiate these 2 cases, we need to write a readLine function
+// ourselves to not ignore the error.
+//
+// The code is similar with https://golang.org/src/bufio/bufio.go?s=9537:9604#L359.
+// The only difference is that it returns all errors from `ReadSlice`.
+//
+// readLine returns err != nil if and only if line does not end with a new line.
+func readLine(b *bufio.Reader) (line []byte, isPrefix bool, err error) {
+	line, err = b.ReadSlice('\n')
+	if err == bufio.ErrBufferFull {
+		// Handle the case where "\r\n" straddles the buffer.
+		if len(line) > 0 && line[len(line)-1] == '\r' {
+			// Unread the last '\r'
+			if err := b.UnreadByte(); err != nil {
+				panic(fmt.Sprintf("invalid unread %v", err))
+			}
+			line = line[:len(line)-1]
+		}
+		return line, true, nil
+	}
+
+	if len(line) == 0 {
+		if err != nil {
+			line = nil
+		}
+		return
+	}
+
+	if line[len(line)-1] == '\n' {
+		// "ReadSlice returns err != nil if and only if line does not end in delim"
+		// (See https://golang.org/pkg/bufio/#Reader.ReadSlice).
+		if err != nil {
+			panic(fmt.Sprintf("full read with unexpected error %v", err))
+		}
+		drop := 1
+		if len(line) > 1 && line[len(line)-2] == '\r' {
+			drop = 2
+		}
+		line = line[:len(line)-drop]
+	}
+	return
+}
+
 func redirectLogs(path string, rc io.ReadCloser, w io.Writer, s StreamType, maxLen int) {
 	defer rc.Close()
 	var (
@@ -88,7 +139,16 @@ func redirectLogs(path string, rc io.ReadCloser, w io.Writer, s StreamType, maxL
 	}
 	for {
 		var stop bool
-		newLine, isPrefix, err := r.ReadLine()
+		newLine, isPrefix, err := readLine(r)
+		// NOTE(random-liu): readLine can return actual content even if there is an error.
+		if len(newLine) > 0 {
+			// Buffer returned by ReadLine will change after
+			// next read, copy it.
+			l := make([]byte, len(newLine))
+			copy(l, newLine)
+			buf = append(buf, l)
+			length += len(l)
+		}
 		if err != nil {
 			if err == io.EOF {
 				logrus.Debugf("Getting EOF from stream %q while redirecting to log file %q", s, path)
@@ -101,13 +161,6 @@ func redirectLogs(path string, rc io.ReadCloser, w io.Writer, s StreamType, maxL
 			}
 			// Stop after writing the content left in buffer.
 			stop = true
-		} else {
-			// Buffer returned by ReadLine will change after
-			// next read, copy it.
-			l := make([]byte, len(newLine))
-			copy(l, newLine)
-			buf = append(buf, l)
-			length += len(l)
 		}
 		if maxLen > 0 && length > maxLen {
 			exceedLen := length - maxLen
@@ -125,7 +178,14 @@ func redirectLogs(path string, rc io.ReadCloser, w io.Writer, s StreamType, maxL
 		if isPrefix {
 			continue
 		}
-		writeLine(full, bytes.Join(buf, nil))
+		if stop {
+			// readLine only returns error when the message doesn't
+			// end with a newline, in that case it should be treated
+			// as a partial line.
+			writeLine(partial, bytes.Join(buf, nil))
+		} else {
+			writeLine(full, bytes.Join(buf, nil))
+		}
 		buf = nil
 		length = 0
 		if stop {

pkg/server/io/logger_test.go

@@ -72,7 +72,7 @@ func TestRedirectLogs(t *testing.T) {
 			maxLen: maxLen,
 			tag: []runtime.LogTag{
 				runtime.LogTagFull,
-				runtime.LogTagFull,
+				runtime.LogTagPartial,
 			},
 			content: []string{
 				"test stderr log 1",
@@ -222,6 +222,19 @@ func TestRedirectLogs(t *testing.T) {
 				strings.Repeat("a", defaultBufSize*10+20),
 			},
 		},
+		"log length longer than buffer size with tailing \\r\\n": {
+			input:  strings.Repeat("a", defaultBufSize-1) + "\r\n" + strings.Repeat("a", defaultBufSize-1) + "\r\n",
+			stream: Stdout,
+			maxLen: -1,
+			tag: []runtime.LogTag{
+				runtime.LogTagFull,
+				runtime.LogTagFull,
+			},
+			content: []string{
+				strings.Repeat("a", defaultBufSize-1),
+				strings.Repeat("a", defaultBufSize-1),
+			},
+		},
 	} {
 		t.Logf("TestCase %q", desc)
 		rc := ioutil.NopCloser(strings.NewReader(test.input))