encoding/xml: fix to allow xml declaration with EncodeToken
This changes allows the first token encoded to be a xml declaration. A ProcInst with target of xml. Any other ProcInst after that with a target of xml will fail
Fixes #7380.
LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/72410043
diff --git a/src/pkg/encoding/xml/marshal.go b/src/pkg/encoding/xml/marshal.go
index d9522e0..8c63420 100644
--- a/src/pkg/encoding/xml/marshal.go
+++ b/src/pkg/encoding/xml/marshal.go
@@ -184,10 +184,12 @@
// EncodeToken does not call Flush, because usually it is part of a larger operation
// such as Encode or EncodeElement (or a custom Marshaler's MarshalXML invoked
// during those), and those will call Flush when finished.
-//
// Callers that create an Encoder and then invoke EncodeToken directly, without
// using Encode or EncodeElement, need to call Flush when finished to ensure
// that the XML is written to the underlying writer.
+//
+// EncodeToken allows writing a ProcInst with Target set to "xml" only as the first token
+// in the stream.
func (enc *Encoder) EncodeToken(t Token) error {
p := &enc.p
switch t := t.(type) {
@@ -210,7 +212,12 @@
p.WriteString("-->")
return p.cachedWriteError()
case ProcInst:
- if t.Target == "xml" || !isNameString(t.Target) {
+ // First token to be encoded which is also a ProcInst with target of xml
+ // is the xml declaration. The only ProcInst where target of xml is allowed.
+ if t.Target == "xml" && p.Buffered() != 0 {
+ return fmt.Errorf("xml: EncodeToken of ProcInst xml target only valid for xml declaration, first token encoded")
+ }
+ if !isNameString(t.Target) {
return fmt.Errorf("xml: EncodeToken of ProcInst with invalid Target")
}
if bytes.Contains(t.Inst, endProcInst) {
diff --git a/src/pkg/encoding/xml/marshal_test.go b/src/pkg/encoding/xml/marshal_test.go
index ecb9998..6381583 100644
--- a/src/pkg/encoding/xml/marshal_test.go
+++ b/src/pkg/encoding/xml/marshal_test.go
@@ -1203,7 +1203,7 @@
{Comment("foo"), "<!--foo-->", true},
{Comment("foo-->"), "", false},
{ProcInst{"Target", []byte("Instruction")}, "<?Target Instruction?>", true},
- {ProcInst{"xml", []byte("Instruction")}, "", false},
+ {ProcInst{"", []byte("Instruction")}, "", false},
{ProcInst{"Target", []byte("Instruction?>")}, "", false},
{Directive("foo"), "<!foo>", true},
{Directive("foo>"), "", false},
@@ -1230,3 +1230,37 @@
}
}
}
+
+func TestProcInstEncodeToken(t *testing.T) {
+ var buf bytes.Buffer
+ enc := NewEncoder(&buf)
+
+ if err := enc.EncodeToken(ProcInst{"xml", []byte("Instruction")}); err != nil {
+ t.Fatalf("enc.EncodeToken: expected to be able to encode xml target ProcInst as first token, %s", err)
+ }
+
+ if err := enc.EncodeToken(ProcInst{"Target", []byte("Instruction")}); err != nil {
+ t.Fatalf("enc.EncodeToken: expected to be able to add non-xml target ProcInst")
+ }
+
+ if err := enc.EncodeToken(ProcInst{"xml", []byte("Instruction")}); err == nil {
+ t.Fatalf("enc.EncodeToken: expected to not be allowed to encode xml target ProcInst when not first token")
+ }
+}
+
+func TestDecodeEncode(t *testing.T) {
+ var in, out bytes.Buffer
+ in.WriteString(`<?xml version="1.0" encoding="UTF-8"?>
+<?Target Instruction?>
+<root>
+</root>
+`)
+ dec := NewDecoder(&in)
+ enc := NewEncoder(&out)
+ for tok, err := dec.Token(); err == nil; tok, err = dec.Token() {
+ err = enc.EncodeToken(tok)
+ if err != nil {
+ t.Fatalf("enc.EncodeToken: Unable to encode token (%#v), %d", tok, err)
+ }
+ }
+}
