cmd/dlv: Add flag to replay for rr onprocess pid (#3281)

Add `-p` or `rr-onprocess-pid` to replay
command to pass `-p` or `--onprocess` pid
to `rr`.

Documentation/usage/dlv_replay.md

@@ -17,7 +17,8 @@ dlv replay [trace directory] [flags]
 ### Options
 
 ```
-  -h, --help   help for replay
+  -h, --help            help for replay
+  -p, --onprocess int   Pass onprocess pid to rr.
 ```
 
 ### Options inherited from parent commands

cmd/dlv/cmds/commands.go

@@ -91,6 +91,8 @@ var (
 
 	conf        *config.Config
 	loadConfErr error
+
+	rrOnProcessPid int
 )
 
 const dlvCommandLongDesc = `Delve is a source level debugger for Go programs.
@@ -368,6 +370,10 @@ https://github.com/mozilla/rr
 				os.Exit(execute(0, []string{}, conf, args[0], debugger.ExecutingOther, args, buildFlags))
 			},
 		}
+
+		replayCommand.Flags().IntVarP(&rrOnProcessPid, "onprocess", "p", 0,
+			"Pass onprocess pid to rr.")
+
 		rootCommand.AddCommand(replayCommand)
 	}
 
@@ -981,6 +987,7 @@ func execute(attachPid int, processArgs []string, conf *config.Config, coreFile
 				TTY:                  tty,
 				Redirects:            redirects,
 				DisableASLR:          disableASLR,
+				RrOnProcessPid:       rrOnProcessPid,
 			},
 		})
 	default:

pkg/proc/gdbserial/rr.go

@@ -124,12 +124,21 @@ func Record(cmd []string, wd string, quiet bool, redirects [3]string) (tracedir
 
 // Replay starts an instance of rr in replay mode, with the specified trace
 // directory, and connects to it.
-func Replay(tracedir string, quiet, deleteOnDetach bool, debugInfoDirs []string) (*proc.TargetGroup, error) {
+func Replay(tracedir string, quiet, deleteOnDetach bool, debugInfoDirs []string, rrOnProcessPid int) (*proc.TargetGroup, error) {
 	if err := checkRRAvailable(); err != nil {
 		return nil, err
 	}
 
-	rrcmd := exec.Command("rr", "replay", "--dbgport=0", tracedir)
+	args := []string{
+		"replay",
+		"--dbgport=0",
+	}
+	if rrOnProcessPid != 0 {
+		args = append(args, fmt.Sprintf("--onprocess=%d", rrOnProcessPid))
+	}
+	args = append(args, tracedir)
+
+	rrcmd := exec.Command("rr", args...)
 	rrcmd.Stdout = os.Stdout
 	stderr, err := rrcmd.StderrPipe()
 	if err != nil {
@@ -284,7 +293,7 @@ func RecordAndReplay(cmd []string, wd string, quiet bool, debugInfoDirs []string
 	if tracedir == "" {
 		return nil, "", err
 	}
-	t, err := Replay(tracedir, quiet, true, debugInfoDirs)
+	t, err := Replay(tracedir, quiet, true, debugInfoDirs, 0)
 	return t, tracedir, err
 }
 

service/debugger/debugger.go

@@ -141,6 +141,8 @@ type Config struct {
 
 	// DisableASLR disables ASLR
 	DisableASLR bool
+
+	RrOnProcessPid int
 }
 
 // New creates a new Debugger. ProcessArgs specify the commandline arguments for the
@@ -174,7 +176,7 @@ func New(config *Config, processArgs []string) (*Debugger, error) {
 		switch d.config.Backend {
 		case "rr":
 			d.log.Infof("opening trace %s", d.config.CoreFile)
-			d.target, err = gdbserial.Replay(d.config.CoreFile, false, false, d.config.DebugInfoDirectories)
+			d.target, err = gdbserial.Replay(d.config.CoreFile, false, false, d.config.DebugInfoDirectories, d.config.RrOnProcessPid)
 		default:
 			d.log.Infof("opening core file %s (executable %s)", d.config.CoreFile, d.processArgs[0])
 			d.target, err = core.OpenCore(d.config.CoreFile, d.processArgs[0], d.config.DebugInfoDirectories)
@@ -333,7 +335,7 @@ func (d *Debugger) recordingRun(run func() (string, error)) (*proc.TargetGroup,
 		return nil, err
 	}
 
-	return gdbserial.Replay(tracedir, false, true, d.config.DebugInfoDirectories)
+	return gdbserial.Replay(tracedir, false, true, d.config.DebugInfoDirectories, 0)
 }
 
 // Attach will attach to the process specified by 'pid'.