libgo: Update to current master library sources.

From-SVN: r194460

4 files changed, 84 insertions, 13 deletions

diff --git a/libgo/go/bytes/buffer.go b/libgo/go/bytes/buffer.go
index efb9798ee01..3ae930384f6 100644
--- a/libgo/go/bytes/buffer.go
+++ b/libgo/go/bytes/buffer.go
@@ -360,16 +360,24 @@ func (b *Buffer) UnreadByte() error {
 // ReadBytes returns err != nil if and only if the returned data does not end in
 // delim.
 func (b *Buffer) ReadBytes(delim byte) (line []byte, err error) {
+	slice, err := b.readSlice(delim)
+	// return a copy of slice. The buffer's backing array may
+	// be overwritten by later calls.
+	line = append(line, slice...)
+	return
+}
+
+// readSlice is like readBytes but returns a reference to internal buffer data.
+func (b *Buffer) readSlice(delim byte) (line []byte, err error) {
 	i := IndexByte(b.buf[b.off:], delim)
-	size := i + 1
+	end := b.off + i + 1
 	if i < 0 {
-		size = len(b.buf) - b.off
+		end = len(b.buf)
 		err = io.EOF
 	}
-	line = make([]byte, size)
-	copy(line, b.buf[b.off:])
-	b.off += size
-	return
+	line = b.buf[b.off:end]
+	b.off = end
+	return line, err
 }
 
 // ReadString reads until the first occurrence of delim in the input,
@@ -379,8 +387,8 @@ func (b *Buffer) ReadBytes(delim byte) (line []byte, err error) {
 // ReadString returns err != nil if and only if the returned data does not end
 // in delim.
 func (b *Buffer) ReadString(delim byte) (line string, err error) {
-	bytes, err := b.ReadBytes(delim)
-	return string(bytes), err
+	slice, err := b.readSlice(delim)
+	return string(slice), err
 }
 
 // NewBuffer creates and initializes a new Buffer using buf as its initial
diff --git a/libgo/go/bytes/buffer_test.go b/libgo/go/bytes/buffer_test.go
index 92e29146b32..c53544a74a0 100644
--- a/libgo/go/bytes/buffer_test.go
+++ b/libgo/go/bytes/buffer_test.go
@@ -375,6 +375,41 @@ func TestReadBytes(t *testing.T) {
 	}
 }
 
+func TestReadString(t *testing.T) {
+	for _, test := range readBytesTests {
+		buf := NewBufferString(test.buffer)
+		var err error
+		for _, expected := range test.expected {
+			var s string
+			s, err = buf.ReadString(test.delim)
+			if s != expected {
+				t.Errorf("expected %q, got %q", expected, s)
+			}
+			if err != nil {
+				break
+			}
+		}
+		if err != test.err {
+			t.Errorf("expected error %v, got %v", test.err, err)
+		}
+	}
+}
+
+func BenchmarkReadString(b *testing.B) {
+	const n = 32 << 10
+
+	data := make([]byte, n)
+	data[n-1] = 'x'
+	b.SetBytes(int64(n))
+	for i := 0; i < b.N; i++ {
+		buf := NewBuffer(data)
+		_, err := buf.ReadString('x')
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
 func TestGrow(t *testing.T) {
 	x := []byte{'x'}
 	y := []byte{'y'}
diff --git a/libgo/go/bytes/reader.go b/libgo/go/bytes/reader.go
index b34dfc11bff..77511b94555 100644
--- a/libgo/go/bytes/reader.go
+++ b/libgo/go/bytes/reader.go
@@ -125,7 +125,7 @@ func (r *Reader) Seek(offset int64, whence int) (int64, error) {
 func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
 	r.prevRune = -1
 	if r.i >= len(r.s) {
-		return 0, io.EOF
+		return 0, nil
 	}
 	b := r.s[r.i:]
 	m, err := w.Write(b)
diff --git a/libgo/go/bytes/reader_test.go b/libgo/go/bytes/reader_test.go
index 66688188676..f0a3e26c4a7 100644
--- a/libgo/go/bytes/reader_test.go
+++ b/libgo/go/bytes/reader_test.go
@@ -8,6 +8,7 @@ import (
 	. "bytes"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"testing"
 )
@@ -88,16 +89,20 @@ func TestReaderAt(t *testing.T) {
 }
 
 func TestReaderWriteTo(t *testing.T) {
-	for i := 3; i < 30; i += 3 {
-		s := data[:len(data)/i]
-		r := NewReader(testBytes[:len(testBytes)/i])
+	for i := 0; i < 30; i += 3 {
+		var l int
+		if i > 0 {
+			l = len(data) / i
+		}
+		s := data[:l]
+		r := NewReader(testBytes[:l])
 		var b Buffer
 		n, err := r.WriteTo(&b)
 		if expect := int64(len(s)); n != expect {
 			t.Errorf("got %v; want %v", n, expect)
 		}
 		if err != nil {
-			t.Errorf("got error = %v; want nil", err)
+			t.Errorf("for length %d: got error = %v; want nil", l, err)
 		}
 		if b.String() != s {
 			t.Errorf("got string %q; want %q", b.String(), s)
@@ -107,3 +112,26 @@ func TestReaderWriteTo(t *testing.T) {
 		}
 	}
 }
+
+// verify that copying from an empty reader always has the same results,
+// regardless of the presence of a WriteTo method.
+func TestReaderCopyNothing(t *testing.T) {
+	type nErr struct {
+		n   int64
+		err error
+	}
+	type justReader struct {
+		io.Reader
+	}
+	type justWriter struct {
+		io.Writer
+	}
+	discard := justWriter{ioutil.Discard} // hide ReadFrom
+
+	var with, withOut nErr
+	with.n, with.err = io.Copy(discard, NewReader(nil))
+	withOut.n, withOut.err = io.Copy(discard, justReader{NewReader(nil)})
+	if with != withOut {
+		t.Errorf("behavior differs: with = %#v; without: %#v", with, withOut)
+	}
+}