io: fixes for Read with n > 0, os.EOF
R=rsc
CC=golang-dev
https://golang.org/cl/4271080
diff --git a/src/pkg/io/io.go b/src/pkg/io/io.go
index 3b87918..c0bc54d 100644
--- a/src/pkg/io/io.go
+++ b/src/pkg/io/io.go
@@ -182,16 +182,16 @@
if len(buf) < min {
return 0, ErrShortBuffer
}
- for n < min {
- nn, e := r.Read(buf[n:])
- if nn > 0 {
- n += nn
- }
- if e != nil {
- if e == os.EOF && n > 0 {
- e = ErrUnexpectedEOF
- }
- return n, e
+ for n < min && err == nil {
+ var nn int
+ nn, err = r.Read(buf[n:])
+ n += nn
+ }
+ if err == os.EOF {
+ if n >= min {
+ err = nil
+ } else if n > 0 {
+ err = ErrUnexpectedEOF
}
}
return
diff --git a/src/pkg/io/io_test.go b/src/pkg/io/io_test.go
index 4fcd85e..bc4f354 100644
--- a/src/pkg/io/io_test.go
+++ b/src/pkg/io/io_test.go
@@ -118,27 +118,50 @@
func TestReadAtLeast(t *testing.T) {
var rb bytes.Buffer
+ testReadAtLeast(t, &rb)
+}
+
+// A version of bytes.Buffer that returns n > 0, os.EOF on Read
+// when the input is exhausted.
+type dataAndEOFBuffer struct {
+ bytes.Buffer
+}
+
+func (r *dataAndEOFBuffer) Read(p []byte) (n int, err os.Error) {
+ n, err = r.Buffer.Read(p)
+ if n > 0 && r.Buffer.Len() == 0 && err == nil {
+ err = os.EOF
+ }
+ return
+}
+
+func TestReadAtLeastWithDataAndEOF(t *testing.T) {
+ var rb dataAndEOFBuffer
+ testReadAtLeast(t, &rb)
+}
+
+func testReadAtLeast(t *testing.T, rb ReadWriter) {
rb.Write([]byte("0123"))
buf := make([]byte, 2)
- n, err := ReadAtLeast(&rb, buf, 2)
+ n, err := ReadAtLeast(rb, buf, 2)
if err != nil {
t.Error(err)
}
- n, err = ReadAtLeast(&rb, buf, 4)
+ n, err = ReadAtLeast(rb, buf, 4)
if err != ErrShortBuffer {
t.Errorf("expected ErrShortBuffer got %v", err)
}
if n != 0 {
t.Errorf("expected to have read 0 bytes, got %v", n)
}
- n, err = ReadAtLeast(&rb, buf, 1)
+ n, err = ReadAtLeast(rb, buf, 1)
if err != nil {
t.Error(err)
}
if n != 2 {
t.Errorf("expected to have read 2 bytes, got %v", n)
}
- n, err = ReadAtLeast(&rb, buf, 2)
+ n, err = ReadAtLeast(rb, buf, 2)
if err != os.EOF {
t.Errorf("expected EOF, got %v", err)
}
@@ -146,7 +169,7 @@
t.Errorf("expected to have read 0 bytes, got %v", n)
}
rb.Write([]byte("4"))
- n, err = ReadAtLeast(&rb, buf, 2)
+ n, err = ReadAtLeast(rb, buf, 2)
if err != ErrUnexpectedEOF {
t.Errorf("expected ErrUnexpectedEOF, got %v", err)
}
diff --git a/src/pkg/io/multi.go b/src/pkg/io/multi.go
index 88e4f1b..d702d46 100644
--- a/src/pkg/io/multi.go
+++ b/src/pkg/io/multi.go
@@ -15,10 +15,8 @@
n, err = mr.readers[0].Read(p)
if n > 0 || err != os.EOF {
if err == os.EOF {
- // This shouldn't happen.
- // Well-behaved Readers should never
- // return non-zero bytes read with an
- // EOF. But if so, we clean it.
+ // Don't return EOF yet. There may be more bytes
+ // in the remaining readers.
err = nil
}
return
