Add "-trace" flag (record execution trace)

Uses the runtime/trace functionality.

TODO: add to man page.

cli_args.go

@@ -8,12 +8,12 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/hanwen/go-fuse/fuse"
 	"github.com/rfjakob/gocryptfs/internal/configfile"
 	"github.com/rfjakob/gocryptfs/internal/exitcodes"
 	"github.com/rfjakob/gocryptfs/internal/prefer_openssl"
 	"github.com/rfjakob/gocryptfs/internal/stupidgcm"
 	"github.com/rfjakob/gocryptfs/internal/tlog"
-	"github.com/hanwen/go-fuse/fuse"
 )
 
 // argContainer stores the parsed CLI options and arguments
@@ -23,7 +23,7 @@ type argContainer struct {
 	longnames, allow_other, ro, reverse, aessiv, nonempty, raw64,
 	noprealloc, speed, hkdf, serialize_reads, forcedecode, hh, info bool
 	masterkey, mountpoint, cipherdir, cpuprofile, extpass,
-	memprofile, ko, passfile, ctlsock, fsname, force_owner string
+	memprofile, ko, passfile, ctlsock, fsname, force_owner, trace string
 	// Configuration file name override
 	config             string
 	notifypid, scryptn int
@@ -33,7 +33,7 @@ type argContainer struct {
 	// _ctlsockFd stores the control socket file descriptor (ctlsock stores the path)
 	_ctlsockFd net.Listener
 	// _forceOwner is, if non-nil, a parsed, validated Owner (as opposed to the string above)
-	_forceOwner        *fuse.Owner
+	_forceOwner *fuse.Owner
 }
 
 var flagSet *flag.FlagSet
@@ -140,6 +140,7 @@ func parseCliOpts() (args argContainer) {
 	flagSet.StringVar(&args.ctlsock, "ctlsock", "", "Create control socket at specified path")
 	flagSet.StringVar(&args.fsname, "fsname", "", "Override the filesystem name")
 	flagSet.StringVar(&args.force_owner, "force_owner", "", "uid:gid pair to coerce ownership")
+	flagSet.StringVar(&args.trace, "trace", "", "Write execution trace to file")
 	flagSet.IntVar(&args.notifypid, "notifypid", 0, "Send USR1 to the specified process after "+
 		"successful mount - used internally for daemonization")
 	flagSet.IntVar(&args.scryptn, "scryptn", configfile.ScryptDefaultLogN, "scrypt cost parameter logN. Possible values: 10-28. "+

internal/exitcodes/exitcodes.go

@@ -58,6 +58,9 @@ const (
 	OpenConf = 23
 	// WriteConf - could not write the gocryptfs.conf
 	WriteConf = 24
+	// Profiler - error occoured when trying to write cpu or memory profile or
+	// execution trace
+	Profiler = 25
 )
 
 // Err wraps an error with an associated numeric exit code

main.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"runtime/pprof"
+	"runtime/trace"
 	"strconv"
 	"strings"
 	"time"
@@ -212,9 +213,13 @@ func main() {
 		f, err = os.Create(args.cpuprofile)
 		if err != nil {
 			tlog.Fatal.Println(err)
-			os.Exit(exitcodes.Init)
+			os.Exit(exitcodes.Profiler)
+		}
+		err = pprof.StartCPUProfile(f)
+		if err != nil {
+			tlog.Fatal.Println(err)
+			os.Exit(exitcodes.Profiler)
 		}
-		pprof.StartCPUProfile(f)
 		defer pprof.StopCPUProfile()
 	}
 	// "-memprofile"
@@ -224,7 +229,7 @@ func main() {
 		f, err = os.Create(args.memprofile)
 		if err != nil {
 			tlog.Fatal.Println(err)
-			os.Exit(exitcodes.Init)
+			os.Exit(exitcodes.Profiler)
 		}
 		defer func() {
 			pprof.WriteHeapProfile(f)
@@ -232,7 +237,22 @@ func main() {
 			return
 		}()
 	}
-	if args.cpuprofile != "" || args.memprofile != "" {
+	// "-trace"
+	if args.trace != "" {
+		tlog.Info.Printf("Writing execution trace to %s", args.trace)
+		f, err := os.Create(args.trace)
+		if err != nil {
+			tlog.Fatal.Println(err)
+			os.Exit(exitcodes.Profiler)
+		}
+		err = trace.Start(f)
+		if err != nil {
+			tlog.Fatal.Println(err)
+			os.Exit(exitcodes.Profiler)
+		}
+		defer trace.Stop()
+	}
+	if args.cpuprofile != "" || args.memprofile != "" || args.trace != "" {
 		tlog.Info.Printf("Note: You must unmount gracefully, otherwise the profile file(s) will stay empty!\n")
 	}
 	// "-openssl"