encoding/xml: fix token decoder on early EOF

The documentation for TokenReader suggests that implementations of the interface may return a token and io.EOF together, indicating that it is the last token in the stream. This is similar to io.Reader. However, if you wrap such a TokenReader in a Decoder it complained about the EOF. A test was added to ensure this behavior on Decoder's. Change-Id: I9083c91d9626180d3bcf5c069a017050f3c7c4a8 Reviewed-on: https://go-review.googlesource.com/c/go/+/130556 Run-TryBot: Sam Whited <sam@samwhited.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

encoding/xml: fix token decoder on early EOF
The documentation for TokenReader suggests that implementations of the interface may return a token and io.EOF together, indicating that it is the last token in the stream. This is similar to io.Reader. However, if you wrap such a TokenReader in a Decoder it complained about the EOF. A test was added to ensure this behavior on Decoder's. Change-Id: I9083c91d9626180d3bcf5c069a017050f3c7c4a8 Reviewed-on: https://go-review.googlesource.com/c/go/+/130556 Run-TryBot: Sam Whited <sam@samwhited.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
a0593463 · Sam Whited · Brad Fitzpatrick · cf6e6abc · a0593463 · a0593463
Commit a0593463 authored Aug 21, 2018 by Sam Whited Committed by Brad Fitzpatrick Oct 30, 2019
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Showing with 49 additions and 1 deletion

src/encoding/xml/xml.go src/encoding/xml/xml.go +4 -1

src/encoding/xml/xml_test.go src/encoding/xml/xml_test.go +45 -0

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--- a/src/encoding/xml/xml.go
+++ b/src/encoding/xml/xml.go
@@ -286,7 +286,10 @@ func (d *Decoder) Token() (Token, error) {
 		t = d.nextToken
 		d.nextToken = nil
 	} else if t, err = d.rawToken(); err != nil {
-		if err == io.EOF && d.stk != nil && d.stk.kind != stkEOF {
+		switch {
+		case err == io.EOF && d.t != nil:
+			err = nil
+		case err == io.EOF && d.stk != nil && d.stk.kind != stkEOF:
 			err = d.syntaxError("unexpected EOF")
 		}
 		return t, err

--- a/src/encoding/xml/xml_test.go
+++ b/src/encoding/xml/xml_test.go
@@ -14,6 +14,51 @@ import (
 	"unicode/utf8"
 )

+type toks struct {
+	earlyEOF bool
+	t        []Token
+}
+
+func (t *toks) Token() (Token, error) {
+	if len(t.t) == 0 {
+		return nil, io.EOF
+	}
+	var tok Token
+	tok, t.t = t.t[0], t.t[1:]
+	if t.earlyEOF && len(t.t) == 0 {
+		return tok, io.EOF
+	}
+	return tok, nil
+}
+
+func TestDecodeEOF(t *testing.T) {
+	start := StartElement{Name: Name{Local: "test"}}
+	t.Run("EarlyEOF", func(t *testing.T) {
+		d := NewTokenDecoder(&toks{earlyEOF: true, t: []Token{
+			start,
+			start.End(),
+		}})
+		err := d.Decode(&struct {
+			XMLName Name `xml:"test"`
+		}{})
+		if err != nil {
+			t.Error(err)
+		}
+	})
+	t.Run("LateEOF", func(t *testing.T) {
+		d := NewTokenDecoder(&toks{t: []Token{
+			start,
+			start.End(),
+		}})
+		err := d.Decode(&struct {
+			XMLName Name `xml:"test"`
+		}{})
+		if err != nil {
+			t.Error(err)
+		}
+	})
+}
+
 const testInput = `
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"