Don't panic in thread dump parsing (#45)

wlog/diaglog/diag1log/thread_dump.go

@@ -92,18 +92,25 @@ func unmarshalFuncLine(funcLine []byte, frame *logging.StackFrameV1) {
 
 func unmarshalFileLine(fileLine []byte, frame *logging.StackFrameV1) {
 	segments := strings.Split(string(bytes.TrimSpace(fileLine)), " +")
-	frame.Address = &segments[1]
+
+	if len(segments) > 1 {
+		frame.Address = &segments[1]
+	}
 
 	sepIdx := strings.LastIndex(segments[0], ":")
-	absPath := segments[0][:sepIdx]
 
-	file := gopath.TrimPrefix(absPath)
-	frame.File = &file
+	if sepIdx > -1 {
+		absPath := segments[0][:sepIdx]
+		file := gopath.TrimPrefix(absPath)
+		frame.File = &file
+	}
 
-	lineNumStr := segments[0][sepIdx+1:]
-	lineNum, err := strconv.Atoi(lineNumStr)
-	if err == nil {
-		frame.Line = &lineNum
+	if sepIdx+1 < len(segments[0]) {
+		lineNumStr := segments[0][sepIdx+1:]
+		lineNum, err := strconv.Atoi(lineNumStr)
+		if err == nil {
+			frame.Line = &lineNum
+		}
 	}
 }
 

wlog/diaglog/diag1log/thread_dump_test.go

@@ -65,6 +65,42 @@ created by net/http.(*Transport).dialConn
 				},
 			},
 		},
+		{
+			Name: "missing fields",
+			Input: `goroutine 14 [select]:
+net/http.(*persistConn).writeLoop(0xc0000bd0e0)
+	/usr/local/Cellar/go/1.11.2/libexec/src/net/http/transport.go:1885
+created by net/http.(*Transport).dialConn
+	/usr/local/Cellar/go/1.11.2/libexec/src/net/http/transport.go +0x966
+`,
+			Expected: logging.ThreadDumpV1{
+				Threads: []logging.ThreadInfoV1{
+					{
+						Name:   strPtr("goroutine 14 [select]"),
+						Id:     safelongPtr(14),
+						Params: map[string]interface{}{"status": "select"},
+						StackTrace: []logging.StackFrameV1{
+							{
+								Address:   nil,
+								Procedure: strPtr("net/http.(*persistConn).writeLoop"),
+								File:      strPtr("net/http/transport.go"),
+								Line:      intPtr(1885),
+								Params:    map[string]interface{}{},
+							},
+							{
+								Address:   strPtr("0x966"),
+								Procedure: strPtr("net/http.(*Transport).dialConn"),
+								File:      nil,
+								Line:      nil,
+								Params: map[string]interface{}{
+									"goroutineCreator": true,
+								},
+							},
+						},
+					},
+				},
+			},
+		},
 	} {
 		t.Run(test.Name, func(t *testing.T) {
 			dump := diag1log.ThreadDumpV1FromGoroutines([]byte(test.Input))