diff options
Diffstat (limited to 'pkg/sentry/kernel')
| -rw-r--r-- | pkg/sentry/kernel/msgqueue/msgqueue.go | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/pkg/sentry/kernel/msgqueue/msgqueue.go b/pkg/sentry/kernel/msgqueue/msgqueue.go index 28520b19a..c111297d7 100644 --- a/pkg/sentry/kernel/msgqueue/msgqueue.go +++ b/pkg/sentry/kernel/msgqueue/msgqueue.go @@ -386,13 +386,21 @@ func (q *Queue) pop(ctx context.Context, creds *auth.Credentials, mType int64, m return msg, nil } -// Copy copies a message from the queue without deleting it. See -// msgrcv(MSG_COPY). -func (q *Queue) Copy() (*Message, error) { +// Copy copies a message from the queue without deleting it. If no message +// exists, an error is returned. See msgrcv(MSG_COPY). +func (q *Queue) Copy(mType int64) (*Message, error) { q.mu.Lock() defer q.mu.Unlock() - return nil, linuxerr.ENOSYS + if mType < 0 || q.messages.Empty() { + return nil, linuxerr.ENOMSG + } + + msg := q.msgAtIndex(mType) + if msg == nil { + return nil, linuxerr.ENOMSG + } + return msg, nil } // msgOfType returns the first message with the specified type, nil if no @@ -433,6 +441,17 @@ func (q *Queue) msgOfTypeLessThan(mType int64) (m *Message) { return m } +// msgAtIndex returns a pointer to a message at given index, nil if non exits. +// +// Precondition: caller must hold q.mu. +func (q *Queue) msgAtIndex(mType int64) *Message { + msg := q.messages.Front() + for ; mType != 0 && msg != nil; mType-- { + msg = msg.Next() + } + return msg +} + // Lock implements ipc.Mechanism.Lock. func (q *Queue) Lock() { q.mu.Lock() |