Add ErrInvalidHandle and fix list stats (#1276) (#1277)

When querying the stats of a container that is in the process of being
stopped, an ERROR_INVALID_HANDLE (0x6) may be returned. This change
ignores that error and returns an empty stats object.

This change also fixes the return values of Stats() when encountering
one of the expected errors. Returning nil stats when error is nil will
break caller assumptions of finding a valid value when error is nil.
Instead, an ErrNotFound is returned.

Signed-off-by: Gabriel Adrian Samfira <[email protected]>
(cherry picked from commit 790bcae)
Signed-off-by: Daniel Canter <[email protected]>

cmd/containerd-shim-runhcs-v1/task.go

@@ -110,5 +110,6 @@ func isStatsNotFound(err error) bool {
 		hcs.IsNotExist(err) ||
 		hcs.IsOperationInvalidState(err) ||
 		gcs.IsNotExist(err) ||
-		hcs.IsAccessIsDenied(err)
+		hcs.IsAccessIsDenied(err) ||
+		hcs.IsErrorInvalidHandle(err)
 }

cmd/containerd-shim-runhcs-v1/task_hcs.go

@@ -920,9 +920,13 @@ func hcsPropertiesToWindowsStats(props *hcsschema.Properties) *stats.Statistics_
 func (ht *hcsTask) Stats(ctx context.Context) (*stats.Statistics, error) {
 	s := &stats.Statistics{}
 	props, err := ht.c.PropertiesV2(ctx, hcsschema.PTStatistics)
-	if err != nil && !isStatsNotFound(err) {
+	if err != nil {
+		if isStatsNotFound(err) {
+			return nil, errors.Wrapf(errdefs.ErrNotFound, "failed to fetch stats: %s", err)
+		}
 		return nil, err
 	}
+
 	if props != nil {
 		if ht.isWCOW {
 			s.Container = hcsPropertiesToWindowsStats(props)

internal/hcs/errors.go

@@ -81,6 +81,10 @@ var (
 
 	// ErrProcessAlreadyStopped is returned by hcs if the process we're trying to kill has already been stopped.
 	ErrProcessAlreadyStopped = syscall.Errno(0x8037011f)
+
+	// ErrInvalidHandle is an error that can be encountrered when querying the properties of a compute system when the handle to that
+	// compute system has already been closed.
+	ErrInvalidHandle = syscall.Errno(0x6)
 )
 
 type ErrorEvent struct {
@@ -252,6 +256,14 @@ func IsNotExist(err error) bool {
 		err == ErrElementNotFound
 }
 
+// IsErrorInvalidHandle checks whether the error is the result of an operation carried
+// out on a handle that is invalid/closed. This error popped up while trying to query
+// stats on a container in the process of being stopped.
+func IsErrorInvalidHandle(err error) bool {
+	err = getInnerError(err)
+	return err == ErrInvalidHandle
+}
+
 // IsAlreadyClosed checks if an error is caused by the Container or Process having been
 // already closed by a call to the Close() method.
 func IsAlreadyClosed(err error) bool {