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) {
