encoding/xml: rewrite invalid code points to U+FFFD in Marshal, Escape

Fixes #4235.

R=rsc, dave, r, dr.volker.dobler
CC=golang-dev
https://golang.org/cl/7438051

diff --git a/src/pkg/encoding/xml/xml.go b/src/pkg/encoding/xml/xml.go
index 96d97dbe2a0a3a1f5d9d39b694023d3a84ccbd5e..021f7e47d91d31ca9200c0b8ae04a9c2a7330b55 100644 (file)
--- a/src/pkg/encoding/xml/xml.go
+++ b/src/pkg/encoding/xml/xml.go
@@ -1729,6 +1729,7 @@ var (
        esc_tab  = []byte("	")
        esc_nl   = []byte("
")
        esc_cr   = []byte("
")
+       esc_fffd = []byte("\uFFFD") // Unicode replacement character
 )
 
 // EscapeText writes to w the properly escaped XML equivalent
@@ -1736,8 +1737,10 @@ var (
 func EscapeText(w io.Writer, s []byte) error {
        var esc []byte
        last := 0
-       for i, c := range s {
-               switch c {
+       for i := 0; i < len(s); {
+               r, width := utf8.DecodeRune(s[i:])
+               i += width
+               switch r {
                case '"':
                        esc = esc_quot
                case '\'':
@@ -1755,15 +1758,19 @@ func EscapeText(w io.Writer, s []byte) error {
                case '\r':
                        esc = esc_cr
                default:
+                       if !isInCharacterRange(r) {
+                               esc = esc_fffd
+                               break
+                       }
                        continue
                }
-               if _, err := w.Write(s[last:i]); err != nil {
+               if _, err := w.Write(s[last : i-width]); err != nil {
                        return err
                }
                if _, err := w.Write(esc); err != nil {
                        return err
                }
-               last = i + 1
+               last = i
        }
        if _, err := w.Write(s[last:]); err != nil {
                return err

diff --git a/src/pkg/encoding/xml/xml_test.go b/src/pkg/encoding/xml/xml_test.go
index 5a4e2147101a4e7987667be077405021b01e330f..eeedbe575f8b76fb99489d8134c46eb5d380c0f5 100644 (file)
--- a/src/pkg/encoding/xml/xml_test.go
+++ b/src/pkg/encoding/xml/xml_test.go
@@ -5,6 +5,7 @@
 package xml
 
 import (
+       "bytes"
        "fmt"
        "io"
        "reflect"
@@ -695,6 +696,21 @@ func TestEscapeTextIOErrors(t *testing.T) {
        err := EscapeText(errWriter{}, []byte{'A'})
 
        if err == nil || err.Error() != expectErr {
-               t.Errorf("EscapeTest = [error] %v, want %v", err, expectErr)
+               t.Errorf("have %v, want %v", err, expectErr)
+       }
+}
+
+func TestEscapeTextInvalidChar(t *testing.T) {
+       input := []byte("A \x00 terminated string.")
+       expected := "A \uFFFD terminated string."
+
+       buff := new(bytes.Buffer)
+       if err := EscapeText(buff, input); err != nil {
+               t.Fatalf("have %v, want nil", err)
+       }
+       text := buff.String()
+
+       if text != expected {
+               t.Errorf("have %v, want %v", text, expected)
        }
 }