Don't block on STDIN open

This was found testing other runtime shims that are faster than runc(no
containerization).  This is a race that can cause the shim to block
forever.  It's not an issue for out/err because we open both sides of
the pipe, but for stdin, it expects the client to have it opened.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

runtime/v1/linux/proc/exec.go

@@ -164,10 +164,7 @@ func (e *execProcess) start(ctx context.Context) (err error) {
 		return e.parent.runtimeError(err, "OCI runtime exec failed")
 	}
 	if e.stdio.Stdin != "" {
-		fifoCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
+		sc, err := fifo.OpenFifo(ctx, e.stdio.Stdin, syscall.O_WRONLY|syscall.O_NONBLOCK, 0)
-		defer cancel()
-
-		sc, err := fifo.OpenFifo(fifoCtx, e.stdio.Stdin, syscall.O_WRONLY|syscall.O_NONBLOCK, 0)
 		if err != nil {
 			return errors.Wrapf(err, "failed to open stdin fifo %s", e.stdio.Stdin)
 		}
@@ -184,10 +181,7 @@ func (e *execProcess) start(ctx context.Context) (err error) {
 			return errors.Wrap(err, "failed to start console copy")
 		}
 	} else if !e.stdio.IsNull() {
-		fifoCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
+		if err := copyPipes(ctx, e.io, e.stdio.Stdin, e.stdio.Stdout, e.stdio.Stderr, &e.wg, &copyWaitGroup); err != nil {
-		defer cancel()
-
-		if err := copyPipes(fifoCtx, e.io, e.stdio.Stdin, e.stdio.Stdout, e.stdio.Stderr, &e.wg, &copyWaitGroup); err != nil {
 			return errors.Wrap(err, "failed to start io pipe copy")
 		}
 	}

runtime/v1/linux/proc/io.go

@@ -112,7 +112,7 @@ func copyPipes(ctx context.Context, rio runc.IO, stdin, stdout, stderr string, w
 		rio.Stdin().Close()
 		return nil
 	}
-	f, err := fifo.OpenFifo(ctx, stdin, syscall.O_RDONLY, 0)
+	f, err := fifo.OpenFifo(ctx, stdin, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
 	if err != nil {
 		return fmt.Errorf("containerd-shim: opening %s failed: %s", stdin, err)
 	}

runtime/v2/runc/service.go

@@ -98,8 +98,7 @@ type service struct {
 	ec        chan runcC.Exit
 	ep        *epoller
 
-	id string
+	id     string
-	// Filled by Create()
 	bundle string
 	cg     cgroups.Cgroup
 }

runtime/v2/runc/service_linux.go

@@ -42,7 +42,7 @@ func (p *linuxPlatform) CopyConsole(ctx context.Context, console console.Console
 	}
 
 	if stdin != "" {
-		in, err := fifo.OpenFifo(ctx, stdin, syscall.O_RDONLY, 0)
+		in, err := fifo.OpenFifo(ctx, stdin, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
 		if err != nil {
 			return nil, err
 		}