encoding/csv, encoding/xml: report write errors
Fixes #3773.
R=bradfitz, rsc
CC=golang-dev
https://golang.org/cl/6327053
diff --git a/src/pkg/encoding/csv/writer.go b/src/pkg/encoding/csv/writer.go
index c4dcba5..324944c 100644
--- a/src/pkg/encoding/csv/writer.go
+++ b/src/pkg/encoding/csv/writer.go
@@ -101,11 +101,10 @@
for _, record := range records {
err = w.Write(record)
if err != nil {
- break
+ return err
}
}
- w.Flush()
- return nil
+ return w.w.Flush()
}
// fieldNeedsQuotes returns true if our field must be enclosed in quotes.
diff --git a/src/pkg/encoding/xml/marshal.go b/src/pkg/encoding/xml/marshal.go
index 51e1dc8..8592a0c 100644
--- a/src/pkg/encoding/xml/marshal.go
+++ b/src/pkg/encoding/xml/marshal.go
@@ -83,9 +83,7 @@
enc := NewEncoder(&b)
enc.prefix = prefix
enc.indent = indent
- err := enc.marshalValue(reflect.ValueOf(v), nil)
- enc.Flush()
- if err != nil {
+ if err := enc.Encode(v); err != nil {
return nil, err
}
return b.Bytes(), nil
@@ -107,8 +105,10 @@
// of Go values to XML.
func (enc *Encoder) Encode(v interface{}) error {
err := enc.marshalValue(reflect.ValueOf(v), nil)
- enc.Flush()
- return err
+ if err != nil {
+ return err
+ }
+ return enc.Flush()
}
type printer struct {
@@ -224,7 +224,7 @@
p.WriteString(name)
p.WriteByte('>')
- return nil
+ return p.cachedWriteError()
}
var timeType = reflect.TypeOf(time.Time{})
@@ -260,15 +260,15 @@
default:
return &UnsupportedTypeError{typ}
}
- return nil
+ return p.cachedWriteError()
}
var ddBytes = []byte("--")
func (p *printer) marshalStruct(tinfo *typeInfo, val reflect.Value) error {
if val.Type() == timeType {
- p.WriteString(val.Interface().(time.Time).Format(time.RFC3339Nano))
- return nil
+ _, err := p.WriteString(val.Interface().(time.Time).Format(time.RFC3339Nano))
+ return err
}
s := parentStack{printer: p}
for i := range tinfo.fields {
@@ -353,7 +353,13 @@
}
}
s.trim(nil)
- return nil
+ return p.cachedWriteError()
+}
+
+// return the bufio Writer's cached write error
+func (p *printer) cachedWriteError() error {
+ _, err := p.Write(nil)
+ return err
}
func (p *printer) writeIndent(depthDelta int) {
diff --git a/src/pkg/encoding/xml/marshal_test.go b/src/pkg/encoding/xml/marshal_test.go
index 90b4925..e729a24 100644
--- a/src/pkg/encoding/xml/marshal_test.go
+++ b/src/pkg/encoding/xml/marshal_test.go
@@ -5,6 +5,9 @@
package xml
import (
+ "bytes"
+ "errors"
+ "io"
"reflect"
"strconv"
"strings"
@@ -779,6 +782,55 @@
}
}
+type limitedBytesWriter struct {
+ w io.Writer
+ remain int // until writes fail
+}
+
+func (lw *limitedBytesWriter) Write(p []byte) (n int, err error) {
+ if lw.remain <= 0 {
+ println("error")
+ return 0, errors.New("write limit hit")
+ }
+ if len(p) > lw.remain {
+ p = p[:lw.remain]
+ n, _ = lw.w.Write(p)
+ lw.remain = 0
+ return n, errors.New("write limit hit")
+ }
+ n, err = lw.w.Write(p)
+ lw.remain -= n
+ return n, err
+}
+
+func TestMarshalWriteErrors(t *testing.T) {
+ var buf bytes.Buffer
+ const writeCap = 1024
+ w := &limitedBytesWriter{&buf, writeCap}
+ enc := NewEncoder(w)
+ var err error
+ var i int
+ const n = 4000
+ for i = 1; i <= n; i++ {
+ err = enc.Encode(&Passenger{
+ Name: []string{"Alice", "Bob"},
+ Weight: 5,
+ })
+ if err != nil {
+ break
+ }
+ }
+ if err == nil {
+ t.Error("expected an error")
+ }
+ if i == n {
+ t.Errorf("expected to fail before the end")
+ }
+ if buf.Len() != writeCap {
+ t.Errorf("buf.Len() = %d; want %d", buf.Len(), writeCap)
+ }
+}
+
func BenchmarkMarshal(b *testing.B) {
for i := 0; i < b.N; i++ {
Marshal(atomValue)
