Merge pull request #32 from wade-k/master

Adds hook to allow pprof to handle perf.data files.

internal/driver/fetch.go

 package driver
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strconv"
 	"sync"
 		}
 		f, err = fetchURL(sourceURL, timeout)
 		src = sourceURL
+	} else if isPerfFile(source) {
+		f, err = convertPerfData(source, ui)
 	} else {
 		f, err = os.Open(source)
 	}
 	return resp.Body, nil
 }
 
+// isPerfFile checks if a file is in perf.data format. It also returns false
+// if it encounters an error during the check.
+func isPerfFile(path string) bool {
+	sourceFile, openErr := os.Open(path)
+	if openErr != nil {
+		return false
+	}
+	defer sourceFile.Close()
+
+	// If the file is the output of a perf record command, it should begin
+	// with the string PERFILE2.
+	perfHeader := []byte("PERFILE2")
+	actualHeader := make([]byte, len(perfHeader))
+	if _, readErr := sourceFile.Read(actualHeader); readErr != nil {
+		return false
+	}
+	return bytes.Equal(actualHeader, perfHeader)
+}
+
+// convertPerfData converts the file at path which should be in perf.data format
+// using the perf_to_profile tool and returns the file containing the
+// profile.proto formatted data.
+func convertPerfData(perfPath string, ui plugin.UI) (*os.File, error) {
+	ui.Print(fmt.Sprintf(
+		"Converting %s to a profile.proto... (May take a few minutes)",
+		perfPath))
+	profile, err := newTempFile("/tmp", "pprof_", ".pb.gz")
+	if err != nil {
+		return nil, err
+	}
+	deferDeleteTempFile(profile.Name())
+	cmd := exec.Command("perf_to_profile", perfPath, profile.Name())
+	if err := cmd.Run(); err != nil {
+		profile.Close()
+		return nil, err
+	}
+	return profile, nil
+}
+
 // adjustURL validates if a profile source is a URL and returns an
 // cleaned up URL and the timeout to use for retrieval over HTTP.
 // If the source cannot be recognized as a URL it returns an empty string.

internal/driver/tempfile.go

 	"sync"
 )
 
-// newTempFile returns an unused filename for output files.
+// newTempFile returns a new output file in dir with the provided prefix and suffix.
 func newTempFile(dir, prefix, suffix string) (*os.File, error) {
 	for index := 1; index < 10000; index++ {
 		path := filepath.Join(dir, fmt.Sprintf("%s%03d%s", prefix, index, suffix))