Fix panic: runtime error: index out of range

If the measurement started with a quote, a panic would happen.  This
is a reegression due to cb7f0b8.

This also uncovered that measurement names were being escaped incorrectly.
The escape codes for tag and fields also includes `=` and '"` which should
not be escaped for measurement names.

Fixes #3681

tsdb/points.go

@@ -91,6 +91,11 @@ var (
 	}
 
 	escapeCodesStr = map[string]string{}
+
+	measurementEscapeCodes = map[byte][]byte{
+		',': []byte(`\,`),
+		' ': []byte(`\ `),
+	}
 )
 
 func init() {
@@ -707,7 +712,7 @@ func scanLine(buf []byte, i int) (int, []byte) {
 		}
 
 		// If we see a double quote, makes sure it is not escaped
-		if buf[i] == '"' && buf[i-1] != '\\' {
+		if buf[i] == '"' && (i-1 > 0 && buf[i-1] != '\\') {
 			i += 1
 			quoted = !quoted
 			continue
@@ -827,6 +832,20 @@ func scanFieldValue(buf []byte, i int) (int, []byte) {
 	return i, buf[start:i]
 }
 
+func escapeMeasurement(in []byte) []byte {
+	for b, esc := range measurementEscapeCodes {
+		in = bytes.Replace(in, []byte{b}, esc, -1)
+	}
+	return in
+}
+
+func unescapeMeasurement(in []byte) []byte {
+	for b, esc := range measurementEscapeCodes {
+		in = bytes.Replace(in, esc, []byte{b}, -1)
+	}
+	return in
+}
+
 func escape(in []byte) []byte {
 	for b, esc := range escapeCodes {
 		in = bytes.Replace(in, []byte{b}, esc, -1)
@@ -948,7 +967,7 @@ func (p *point) Tags() Tags {
 func MakeKey(name []byte, tags Tags) []byte {
 	// unescape the name and then re-escape it to avoid double escaping.
 	// The key should always be stored in escaped form.
-	return append(escape(unescape(name)), tags.HashKey()...)
+	return append(escapeMeasurement(unescapeMeasurement(name)), tags.HashKey()...)
 }
 
 // SetTags replaces the tags for the point

tsdb/points_test.go

@@ -740,7 +740,22 @@ func TestParsePointWithStringWithCommas(t *testing.T) {
 			},
 			time.Unix(1, 0)),
 	)
+}
 
+func TestParsePointQuotedMeasurement(t *testing.T) {
+	// non-escaped comma
+	test(t, `"cpu",host=serverA,region=us-east value=1.0 1000000000`,
+		tsdb.NewPoint(
+			`"cpu"`,
+			tsdb.Tags{
+				"host":   "serverA",
+				"region": "us-east",
+			},
+			tsdb.Fields{
+				"value": 1.0,
+			},
+			time.Unix(1, 0)),
+	)
 }
 
 func TestParsePointEscapedStringsAndCommas(t *testing.T) {
@@ -771,7 +786,6 @@ func TestParsePointEscapedStringsAndCommas(t *testing.T) {
 			},
 			time.Unix(1, 0)),
 	)
-
 }
 
 func TestParsePointWithStringWithEquals(t *testing.T) {
@@ -1193,7 +1207,7 @@ func TestNewPointEscaped(t *testing.T) {
 
 	// equals
 	pt = tsdb.NewPoint("cpu=main", tsdb.Tags{"tag=bar": "value=foo"}, tsdb.Fields{"name=bar": 1.0}, time.Unix(0, 0))
-	if exp := `cpu\=main,tag\=bar=value\=foo name\=bar=1.0 0`; pt.String() != exp {
+	if exp := `cpu=main,tag\=bar=value\=foo name\=bar=1.0 0`; pt.String() != exp {
 		t.Errorf("NewPoint().String() mismatch.\ngot %v\nexp %v", pt.String(), exp)
 	}
 }