Create a fake mapping for profile.proto profiles (#135)

* Create a fake mapping for profile.proto profiles

If a profile has mappings but no profiles, pprof may be unable to
symbolize it offline, as it uses the mappings to keep track of which
locations need symbolization.

This fixes #120.

Added the test, verified it fails on Mac with Go 1.7 before the fix, and
passes with the fix. The test is done by augmenting the existing test
for handling https+insecure:// schema in URLs. This is a bit vague but I
figured that this test needed an updated anyway since as we moved it
recently we stopped exercising the symbolization as part of the test
which was its original intention in fixing #94. Can split the tests if
things do look too ugly.

* Fix the test to include the failed regex matching error in the message.

internal/driver/fetch.go

 			}
 		}
 	}
+	if len(p.Mapping) == 0 {
+		// If there are no mappings, add a fake mapping to attempt symbolization.
+		// This is useful for some profiles generated by the golang runtime, which
+		// do not include any mappings. Symbolization with a fake mapping will only
+		// be successful against a non-PIE binary.
+		m := &profile.Mapping{ID: 1}
+		p.Mapping = []*profile.Mapping{m}
+		for _, l := range p.Location {
+			l.Mapping = m
+		}
+	}
 	// Replace executable filename/buildID with the overrides from source.
 	// Assumes the executable is the first Mapping entry.
 	if execName, buildID := s.ExecName, s.BuildID; execName != "" || buildID != "" {
-		if len(p.Mapping) == 0 {
-			// If there are no mappings, add a fake mapping to attempt symbolization.
-			// This is useful for some profiles generated by the golang runtime, which
-			// do not include any mappings. Symbolization with a fake mapping will only
-			// be successful against a non-PIE binary.
-			m := &profile.Mapping{ID: 1}
-			p.Mapping = []*profile.Mapping{m}
-			for _, l := range p.Location {
-				l.Mapping = m
-			}
-		}
 		m := p.Mapping[0]
 		if execName != "" {
 			m.File = execName

internal/driver/fetch_test.go

 	"testing"
 	"time"
 
+	"github.com/google/pprof/internal/binutils"
 	"github.com/google/pprof/internal/plugin"
 	"github.com/google/pprof/internal/proftest"
+	"github.com/google/pprof/internal/symbolizer"
 	"github.com/google/pprof/profile"
 )
 
 	defer os.Remove(outputTempFile.Name())
 	defer outputTempFile.Close()
 
-	address := "https+insecure://" + l.Addr().String() + "/debug/pprof/profile?seconds=5"
-	p, _, _, err := grabProfile(&source{}, address, 0, nil, testObj{}, &proftest.TestUI{T: t})
+	address := "https+insecure://" + l.Addr().String() + "/debug/pprof/profile"
+	s := &source{
+		Sources:   []string{address},
+		Seconds:   10,
+		Timeout:   10,
+		Symbolize: "remote",
+	}
+	o := &plugin.Options{
+		Obj: &binutils.Binutils{},
+		UI:  &proftest.TestUI{T: t, IgnoreRx: "Saved profile in"},
+	}
+	o.Sym = &symbolizer.Symbolizer{Obj: o.Obj, UI: o.UI}
+	p, err := fetchProfiles(s, o)
 	if err != nil {
 		t.Fatal(err)
 	}
 	if len(p.SampleType) == 0 {
 		t.Fatalf("grabProfile(%s) got empty profile: len(p.SampleType)==0", address)
 	}
+	if err := checkProfileHasFunction(p, "TestHttpsInsecure"); err != nil {
+		t.Fatalf("grabProfile(%s) %v", address, err)
+	}
+}
+
+func checkProfileHasFunction(p *profile.Profile, fname string) error {
+	for _, f := range p.Function {
+		if strings.Contains(f.Name, fname) {
+			return nil
+		}
+	}
+	return fmt.Errorf("got %s, want function %q", p.String(), fname)
 }
 
 func selfSignedCert(t *testing.T) tls.Certificate {

internal/proftest/proftest.go

 	"io/ioutil"
 	"os"
 	"os/exec"
+	"regexp"
 	"testing"
 )
 
 }
 
 // TestUI implements the plugin.UI interface, triggering test failures
-// if more than Ignore errors are printed.
+// if more than Ignore errors not matching IgnoreRx are printed.
 type TestUI struct {
-	T      *testing.T
-	Ignore int
+	T        *testing.T
+	Ignore   int
+	IgnoreRx string
 }
 
 // ReadLine returns no input, as no input is expected during testing.
 // PrintErr messages may trigger an error failure. A fixed number of
 // error messages are permitted when appropriate.
 func (ui *TestUI) PrintErr(args ...interface{}) {
+	if ui.IgnoreRx != "" {
+		if matched, err := regexp.MatchString(ui.IgnoreRx, fmt.Sprint(args)); matched || err != nil {
+			if err != nil {
+				ui.T.Errorf("failed to match against regex %q: %v", ui.IgnoreRx, err)
+			}
+			return
+		}
+	}
 	if ui.Ignore > 0 {
 		ui.Ignore--
 		return