exp/html: Convert \r and \r\n to \n when tokenizing

Also escape "\r" as "" when rendering HTML. Pass 2 additional tests. R=nigeltao CC=golang-dev https://golang.org/cl/6260046

exp/html: Convert \r and \r\n to \n when tokenizing
Also escape "\r" as "" when rendering HTML. Pass 2 additional tests. R=nigeltao CC=golang-dev https://golang.org/cl/6260046
4e0749a4 · Andrew Balholm · Nigel Tao · afe0e97a · 4e0749a4 · 4e0749a4
Commit 4e0749a4 authored May 30, 2012 by Andrew Balholm Committed by Nigel Tao May 30, 2012
4 changed files
--- a/src/pkg/exp/html/escape.go
+++ b/src/pkg/exp/html/escape.go
@@ -192,7 +192,7 @@ func lower(b []byte) []byte {
 	return b
 }

-const escapedChars = `&'<>"`
+const escapedChars = "&'<>\"\r"

 func escape(w writer, s string) error {
 	i := strings.IndexAny(s, escapedChars)
@@ -214,6 +214,8 @@ func escape(w writer, s string) error {
 		case '"':
 			// "&#34;" is shorter than "&quot;".
 			esc = "&#34;"
+		case '\r':
+			esc = "&#13;"
 		default:
 			panic("unrecognized escape character")
 		}

--- a/src/pkg/exp/html/testlogs/plain-text-unsafe.dat.log
+++ b/src/pkg/exp/html/testlogs/plain-text-unsafe.dat.log
@@ -21,8 +21,8 @@ PASS "<svg>\x00 </svg><frameset>"
 FAIL "<svg>\x00a</svg><frameset>"
 PASS "<svg><path></path></svg><frameset>"
 PASS "<svg><p><frameset>"
-FAIL "<!DOCTYPE html><pre>\r\n\r\nA</pre>"
-FAIL "<!DOCTYPE html><pre>\r\rA</pre>"
+PASS "<!DOCTYPE html><pre>\r\n\r\nA</pre>"
+PASS "<!DOCTYPE html><pre>\r\rA</pre>"
 PASS "<!DOCTYPE html><pre>\rA</pre>"
 PASS "<!DOCTYPE html><table><tr><td><math><mtext>\x00a"
 PASS "<!DOCTYPE html><table><tr><td><svg><foreignObject>\x00a"

--- a/src/pkg/exp/html/token.go
+++ b/src/pkg/exp/html/token.go
@@ -696,6 +696,38 @@ func (z *Tokenizer) Raw() []byte {
 	return z.buf[z.raw.start:z.raw.end]
 }

+// convertNewlines converts "\r" and "\r\n" in s to "\n".
+// The conversion happens in place, but the resulting slice may be shorter.
+func convertNewlines(s []byte) []byte {
+	for i, c := range s {
+		if c != '\r' {
+			continue
+		}
+
+		src := i + 1
+		if src >= len(s) || s[src] != '\n' {
+			s[i] = '\n'
+			continue
+		}
+
+		dst := i
+		for src < len(s) {
+			if s[src] == '\r' {
+				if src+1 < len(s) && s[src+1] == '\n' {
+					src++
+				}
+				s[dst] = '\n'
+			} else {
+				s[dst] = s[src]
+			}
+			src++
+			dst++
+		}
+		return s[:dst]
+	}
+	return s
+}
+
 // Text returns the unescaped text of a text, comment or doctype token. The
 // contents of the returned slice may change on the next call to Next.
 func (z *Tokenizer) Text() []byte {
@@ -704,6 +736,7 @@ func (z *Tokenizer) Text() []byte {
 		s := z.buf[z.data.start:z.data.end]
 		z.data.start = z.raw.end
 		z.data.end = z.raw.end
+		s = convertNewlines(s)
 		if !z.textIsRaw {
 			s = unescape(s)
 		}
@@ -739,7 +772,7 @@ func (z *Tokenizer) TagAttr() (key, val []byte, moreAttr bool) {
 			z.nAttrReturned++
 			key = z.buf[x[0].start:x[0].end]
 			val = z.buf[x[1].start:x[1].end]
-			return lower(key), unescape(val), z.nAttrReturned < len(z.attr)
+			return lower(key), unescape(convertNewlines(val)), z.nAttrReturned < len(z.attr)
 		}
 	}
 	return nil, nil, false

--- a/src/pkg/exp/html/token_test.go
+++ b/src/pkg/exp/html/token_test.go
@@ -592,6 +592,33 @@ loop:
 	}
 }

+func TestConvertNewlines(t *testing.T) {
+	testCases := map[string]string{
+		"Mac\rDOS\r\nUnix\n":    "Mac\nDOS\nUnix\n",
+		"Unix\nMac\rDOS\r\n":    "Unix\nMac\nDOS\n",
+		"DOS\r\nDOS\r\nDOS\r\n": "DOS\nDOS\nDOS\n",
+		"":                      "",
+		"\n":                    "\n",
+		"\n\r":                  "\n\n",
+		"\r":                    "\n",
+		"\r\n":                  "\n",
+		"\r\n\n":                "\n\n",
+		"\r\n\r":                "\n\n",
+		"\r\n\r\n":              "\n\n",
+		"\r\r":                  "\n\n",
+		"\r\r\n":                "\n\n",
+		"\r\r\n\n":              "\n\n\n",
+		"\r\r\r\n":              "\n\n\n",
+		"\r \n":                 "\n \n",
+		"xyz":                   "xyz",
+	}
+	for in, want := range testCases {
+		if got := string(convertNewlines([]byte(in))); got != want {
+			t.Errorf("input %q: got %q, want %q", in, got, want)
+		}
+	}
+}
+
 const (
 	rawLevel = iota
 	lowLevel