internal/trace: err if binary is not supplied for old trace

Change-Id: Id25c90993c4cbb7449d7031301b6d214a67d7633
Reviewed-on: https://go-review.googlesource.com/24134
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

2 files changed, 22 insertions, 7 deletions

diff --git a/src/internal/trace/parser.go b/src/internal/trace/parser.go
index 843d0eaf63..c31517f683 100644
--- a/src/internal/trace/parser.go
+++ b/src/internal/trace/parser.go
@@ -60,21 +60,34 @@ const (
 
 // Parse parses, post-processes and verifies the trace.
 func Parse(r io.Reader, bin string) ([]*Event, error) {
-	ver, rawEvents, strings, err := readTrace(r)
+	ver, events, err := parse(r, bin)
 	if err != nil {
 		return nil, err
 	}
+	if ver < 1007 && bin == "" {
+		return nil, fmt.Errorf("for traces produced by go 1.6 or below, the binary argument must be provided")
+	}
+	return events, nil
+}
+
+// parse parses, post-processes and verifies the trace. It returns the
+// trace version and the list of events.
+func parse(r io.Reader, bin string) (int, []*Event, error) {
+	ver, rawEvents, strings, err := readTrace(r)
+	if err != nil {
+		return 0, nil, err
+	}
 	events, stacks, err := parseEvents(ver, rawEvents, strings)
 	if err != nil {
-		return nil, err
+		return 0, nil, err
 	}
 	events, err = removeFutile(events)
 	if err != nil {
-		return nil, err
+		return 0, nil, err
 	}
 	err = postProcessTrace(ver, events)
 	if err != nil {
-		return nil, err
+		return 0, nil, err
 	}
 	// Attach stack traces.
 	for _, ev := range events {
@@ -84,10 +97,10 @@ func Parse(r io.Reader, bin string) ([]*Event, error) {
 	}
 	if ver < 1007 && bin != "" {
 		if err := symbolize(events, bin); err != nil {
-			return nil, err
+			return 0, nil, err
 		}
 	}
-	return events, nil
+	return ver, events, nil
 }
 
 // rawEvent is a helper type used during parsing.
diff --git a/src/internal/trace/parser_test.go b/src/internal/trace/parser_test.go
index 340f106484..daad3e3ad7 100644
--- a/src/internal/trace/parser_test.go
+++ b/src/internal/trace/parser_test.go
@@ -42,7 +42,9 @@ func TestParseCanned(t *testing.T) {
 		if err != nil {
 			t.Fatalf("failed to read input file: %v", err)
 		}
-		_, err = Parse(bytes.NewReader(data), "")
+		// Instead of Parse that requires a proper binary name for old traces,
+		// we use 'parse' that omits symbol lookup if an empty string is given.
+		_, _, err = parse(bytes.NewReader(data), "")
 		switch {
 		case strings.HasSuffix(f.Name(), "_good"):
 			if err != nil {