Remove 'clearStatus' option from container.Wait*PID()

clearStatus was added to allow detached execution to wait
on the exec'd process and retrieve its exit status. However,
it's not currently used. Both docker and gvisor-containerd-shim
wait on the "shim" process and retrieve the exit status from
there. We could change gvisor-containerd-shim to use waits, but
it will end up also consuming a process for the wait, which is
similar to having the shim process.

Closes #234

PiperOrigin-RevId: 251349490

1 files changed, 10 insertions, 26 deletions

diff --git a/runsc/cmd/exec.go b/runsc/cmd/exec.go
index 52fd7ac4b..8cd070e61 100644
--- a/runsc/cmd/exec.go
+++ b/runsc/cmd/exec.go
@@ -40,8 +40,6 @@ import (
 	"gvisor.googlesource.com/gvisor/runsc/specutils"
 )
 
-const privateClearStatusFlag = "private-clear-status"
-
 // Exec implements subcommands.Command for the "exec" command.
 type Exec struct {
 	cwd string
@@ -51,7 +49,6 @@ type Exec struct {
 	extraKGIDs      stringSlice
 	caps            stringSlice
 	detach          bool
-	clearStatus     bool
 	processPath     string
 	pidFile         string
 	internalPidFile string
@@ -103,10 +100,6 @@ func (ex *Exec) SetFlags(f *flag.FlagSet) {
 	f.StringVar(&ex.pidFile, "pid-file", "", "filename that the container pid will be written to")
 	f.StringVar(&ex.internalPidFile, "internal-pid-file", "", "filename that the container-internal pid will be written to")
 	f.StringVar(&ex.consoleSocket, "console-socket", "", "path to an AF_UNIX socket which will receive a file descriptor referencing the master end of the console's pseudoterminal")
-
-	// This flag clears the status of the exec'd process upon completion. It is
-	// only used when we fork due to --detach being set on the parent.
-	f.BoolVar(&ex.clearStatus, privateClearStatusFlag, true, "private flag, do not use")
 }
 
 // Execute implements subcommands.Command.Execute. It starts a process in an
@@ -156,7 +149,7 @@ func (ex *Exec) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 	// Start the new process and get it pid.
 	pid, err := c.Execute(e)
 	if err != nil {
-		Fatalf("getting processes for container: %v", err)
+		Fatalf("executing processes for container: %v", err)
 	}
 
 	if e.StdioIsPty {
@@ -184,7 +177,7 @@ func (ex *Exec) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 	}
 
 	// Wait for the process to exit.
-	ws, err := c.WaitPID(pid, ex.clearStatus)
+	ws, err := c.WaitPID(pid)
 	if err != nil {
 		Fatalf("waiting on pid %d: %v", pid, err)
 	}
@@ -193,8 +186,12 @@ func (ex *Exec) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 }
 
 func (ex *Exec) execAndWait(waitStatus *syscall.WaitStatus) subcommands.ExitStatus {
-	binPath := specutils.ExePath
 	var args []string
+	for _, a := range os.Args[1:] {
+		if !strings.Contains(a, "detach") {
+			args = append(args, a)
+		}
+	}
 
 	// The command needs to write a pid file so that execAndWait can tell
 	// when it has started. If no pid-file was provided, we should use a
@@ -210,19 +207,7 @@ func (ex *Exec) execAndWait(waitStatus *syscall.WaitStatus) subcommands.ExitStat
 		args = append(args, "--pid-file="+pidFile)
 	}
 
-	// Add the rest of the args, excluding the "detach" flag.
-	for _, a := range os.Args[1:] {
-		if strings.Contains(a, "detach") {
-			// Replace with the "private-clear-status" flag, which tells
-			// the new process it's a detached child and shouldn't
-			// clear the exit status of the sentry process.
-			args = append(args, fmt.Sprintf("--%s=false", privateClearStatusFlag))
-		} else {
-			args = append(args, a)
-		}
-	}
-
-	cmd := exec.Command(binPath, args...)
+	cmd := exec.Command(specutils.ExePath, args...)
 	cmd.Args[0] = "runsc-exec"
 
 	// Exec stdio defaults to current process stdio.
@@ -233,8 +218,7 @@ func (ex *Exec) execAndWait(waitStatus *syscall.WaitStatus) subcommands.ExitStat
 	// If the console control socket file is provided, then create a new
 	// pty master/slave pair and set the TTY on the sandbox process.
 	if ex.consoleSocket != "" {
-		// Create a new TTY pair and send the master on the provided
-		// socket.
+		// Create a new TTY pair and send the master on the provided socket.
 		tty, err := console.NewWithSocket(ex.consoleSocket)
 		if err != nil {
 			Fatalf("setting up console with socket %q: %v", ex.consoleSocket, err)
@@ -256,7 +240,7 @@ func (ex *Exec) execAndWait(waitStatus *syscall.WaitStatus) subcommands.ExitStat
 		Fatalf("failure to start child exec process, err: %v", err)
 	}
 
-	log.Infof("Started child (PID: %d) to exec and wait: %s %s", cmd.Process.Pid, binPath, args)
+	log.Infof("Started child (PID: %d) to exec and wait: %s %s", cmd.Process.Pid, specutils.ExePath, args)
 
 	// Wait for PID file to ensure that child process has started. Otherwise,
 	// '--process' file is deleted as soon as this process returns and the child