internal/app: compensate shim timeout

This catches cases where the shim has somehow locked up, so it should wait out the full shim WaitDelay as well.

Signed-off-by: Ophestra <cat@gensokyo.uk>

2 files changed, 20 insertions, 3 deletions

diff --git a/internal/app/process.go b/internal/app/process.go
index 50d5dc83..daa7832a 100644
--- a/internal/app/process.go
+++ b/internal/app/process.go
@@ -20,8 +20,14 @@ import (
 	"hakurei.app/system"
 )
 
+// duration to wait for shim to exit, after container WaitDelay has elapsed.
 const shimWaitTimeout = 5 * time.Second
 
+// ErrShimTimeout is returned when shim did not exit within shimWaitTimeout, after its WaitDelay has elapsed.
+// This is different from the container failing to terminate within its timeout period, as that is enforced
+// by the shim. This error is instead returned when there is a lockup in shim preventing it from completing.
+var ErrShimTimeout = errors.New("shim did not exit")
+
 // RunState stores the outcome of a call to [Outcome.Run].
 type RunState struct {
 	// Time is the exact point in time where the process was created.
@@ -186,7 +192,14 @@ func (seal *Outcome) Run(rs *RunState) error {
 	deferredStoreFunc = func(c state.Cursor) error { return c.Destroy(seal.id.unwrap()) }
 
 	waitTimeout := make(chan struct{})
-	go func() { <-seal.ctx.Done(); time.Sleep(shimWaitTimeout); close(waitTimeout) }()
+	// TODO(ophestra): enforce this limit early so it does not have to be done twice
+	shimTimeoutCompensated := shimWaitTimeout
+	if seal.waitDelay > MaxShimWaitDelay {
+		shimTimeoutCompensated += MaxShimWaitDelay
+	} else {
+		shimTimeoutCompensated += seal.waitDelay
+	}
+	go func() { <-seal.ctx.Done(); time.Sleep(shimTimeoutCompensated); close(waitTimeout) }()
 
 	select {
 	case rs.WaitErr = <-waitErr:
@@ -206,9 +219,11 @@ func (seal *Outcome) Run(rs *RunState) error {
 				hlog.Verbosef("process %d exited with status %#x", cmd.Process.Pid, rs.WaitStatus)
 			}
 		}
+
 	case <-waitTimeout:
-		rs.WaitErr = syscall.ETIMEDOUT
+		rs.WaitErr = ErrShimTimeout
 		hlog.Resume()
+		// TODO(ophestra): verify this behaviour in vm tests
 		log.Printf("process %d did not terminate", cmd.Process.Pid)
 	}
 
diff --git a/internal/app/shim.go b/internal/app/shim.go
index 5eaf8333..e38104c9 100644
--- a/internal/app/shim.go
+++ b/internal/app/shim.go
@@ -45,8 +45,10 @@ const (
 	// ShimExitOrphan is returned when the shim is orphaned before monitor delivers a signal.
 	ShimExitOrphan = 3
 
+	// DefaultShimWaitDelay is used when WaitDelay has its zero value.
 	DefaultShimWaitDelay = 5 * time.Second
-	MaxShimWaitDelay     = 30 * time.Second
+	// MaxShimWaitDelay is used instead if WaitDelay exceeds its value.
+	MaxShimWaitDelay = 30 * time.Second
 )
 
 // ShimMain is the main function of the shim process and runs as the unconstrained target user.