debug/gosym: parse remote packages correctly

Fixes #15675

Change-Id: I8bad220988e5d690f20804db970b2db037c81187
Reviewed-on: https://go-review.googlesource.com/23086Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/debug/gosym/symtab.go

@@ -40,8 +40,13 @@ func (s *Sym) Static() bool { return s.Type >= 'a' }
 // PackageName returns the package part of the symbol name,
 // or the empty string if there is none.
 func (s *Sym) PackageName() string {
-	if i := strings.Index(s.Name, "."); i != -1 {
-		return s.Name[0:i]
+	pathend := strings.LastIndex(s.Name, "/")
+	if pathend < 0 {
+		pathend = 0
+	}
+
+	if i := strings.Index(s.Name[pathend:], "."); i != -1 {
+		return s.Name[:pathend+i]
 	}
 	return ""
 }
@@ -49,12 +54,16 @@ func (s *Sym) PackageName() string {
 // ReceiverName returns the receiver type name of this symbol,
 // or the empty string if there is none.
 func (s *Sym) ReceiverName() string {
-	l := strings.Index(s.Name, ".")
-	r := strings.LastIndex(s.Name, ".")
+	pathend := strings.LastIndex(s.Name, "/")
+	if pathend < 0 {
+		pathend = 0
+	}
+	l := strings.Index(s.Name[pathend:], ".")
+	r := strings.LastIndex(s.Name[pathend:], ".")
 	if l == -1 || r == -1 || l == r {
 		return ""
 	}
-	return s.Name[l+1 : r]
+	return s.Name[pathend+l+1 : pathend+r]
 }
 
 // BaseName returns the symbol name without the package or receiver name.

src/debug/gosym/symtab_test.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gosym
+
+import (
+	"fmt"
+	"testing"
+)
+
+func assertString(t *testing.T, dsc, out, tgt string) {
+	if out != tgt {
+		t.Fatalf("Expected: %q Actual: %q for %s", tgt, out, dsc)
+	}
+}
+
+func TestStandardLibPackage(t *testing.T) {
+	s1 := Sym{Name: "io.(*LimitedReader).Read"}
+	s2 := Sym{Name: "io.NewSectionReader"}
+	assertString(t, fmt.Sprintf("package of %q", s1.Name), s1.PackageName(), "io")
+	assertString(t, fmt.Sprintf("package of %q", s2.Name), s2.PackageName(), "io")
+	assertString(t, fmt.Sprintf("receiver of %q", s1.Name), s1.ReceiverName(), "(*LimitedReader)")
+	assertString(t, fmt.Sprintf("receiver of %q", s2.Name), s2.ReceiverName(), "")
+}
+
+func TestStandardLibPathPackage(t *testing.T) {
+	s1 := Sym{Name: "debug/gosym.(*LineTable).PCToLine"}
+	s2 := Sym{Name: "debug/gosym.NewTable"}
+	assertString(t, fmt.Sprintf("package of %q", s1.Name), s1.PackageName(), "debug/gosym")
+	assertString(t, fmt.Sprintf("package of %q", s2.Name), s2.PackageName(), "debug/gosym")
+	assertString(t, fmt.Sprintf("receiver of %q", s1.Name), s1.ReceiverName(), "(*LineTable)")
+	assertString(t, fmt.Sprintf("receiver of %q", s2.Name), s2.ReceiverName(), "")
+}
+
+func TestRemotePackage(t *testing.T) {
+	s1 := Sym{Name: "github.com/docker/doc.ker/pkg/mflag.(*FlagSet).PrintDefaults"}
+	s2 := Sym{Name: "github.com/docker/doc.ker/pkg/mflag.PrintDefaults"}
+	assertString(t, fmt.Sprintf("package of %q", s1.Name), s1.PackageName(), "github.com/docker/doc.ker/pkg/mflag")
+	assertString(t, fmt.Sprintf("package of %q", s2.Name), s2.PackageName(), "github.com/docker/doc.ker/pkg/mflag")
+	assertString(t, fmt.Sprintf("receiver of %q", s1.Name), s1.ReceiverName(), "(*FlagSet)")
+	assertString(t, fmt.Sprintf("receiver of %q", s2.Name), s2.ReceiverName(), "")
+}