[release-branch.go1.1] bufio: check buffer availability before reading in ReadFrom
This change was applied by hand, as bufio has seen some refactoring
since 1.1 was branched. The only difference between this and the
original patch is the offset of the change, and s/flush/Flush/.
««« CL 11801043 / 3ffbc06b4874
bufio: check buffer availability before reading in ReadFrom
Fixes issue 5947 .
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/11801043
»»»
Update #5928
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/12002043
diff --git a/src/pkg/bufio/bufio.go b/src/pkg/bufio/bufio.go
index df3501f..10e12d4 100644
--- a/src/pkg/bufio/bufio.go
+++ b/src/pkg/bufio/bufio.go
@@ -585,23 +585,28 @@
}
var m int
for {
+ if b.Available() == 0 {
+ if err1 := b.Flush(); err1 != nil {
+ return n, err1
+ }
+ }
m, err = r.Read(b.buf[b.n:])
if m == 0 {
break
}
b.n += m
n += int64(m)
- if b.Available() == 0 {
- if err1 := b.Flush(); err1 != nil {
- return n, err1
- }
- }
if err != nil {
break
}
}
if err == io.EOF {
- err = nil
+ // If we filled the buffer exactly, flush pre-emptively.
+ if b.Available() == 0 {
+ err = b.Flush()
+ } else {
+ err = nil
+ }
}
return n, err
}
diff --git a/src/pkg/bufio/bufio_test.go b/src/pkg/bufio/bufio_test.go
index 79ed0f1..9fcbfda 100644
--- a/src/pkg/bufio/bufio_test.go
+++ b/src/pkg/bufio/bufio_test.go
@@ -847,6 +847,10 @@
t.Errorf("ws[%d],rs[%d]: w.ReadFrom(r) = %d, %v, want %d, nil", wi, ri, n, err, len(input))
continue
}
+ if err := w.Flush(); err != nil {
+ t.Errorf("Flush returned %v", err)
+ continue
+ }
if got, want := b.String(), string(input); got != want {
t.Errorf("ws[%d], rs[%d]:\ngot %q\nwant %q\n", wi, ri, got, want)
}
@@ -1003,6 +1007,24 @@
}
}
+// Test for golang.org/issue/5947
+func TestWriterReadFromWhileFull(t *testing.T) {
+ buf := new(bytes.Buffer)
+ w := NewWriterSize(buf, 10)
+
+ // Fill buffer exactly.
+ n, err := w.Write([]byte("0123456789"))
+ if n != 10 || err != nil {
+ t.Fatalf("Write returned (%v, %v), want (10, nil)", n, err)
+ }
+
+ // Use ReadFrom to read in some data.
+ n2, err := w.ReadFrom(strings.NewReader("abcdef"))
+ if n2 != 6 || err != nil {
+ t.Fatalf("ReadFrom returned (%v, %v), want (6, nil)", n, err)
+ }
+}
+
// An onlyReader only implements io.Reader, no matter what other methods the underlying implementation may have.
type onlyReader struct {
r io.Reader
