dma: don't block when trying to aquire a queue file

We might race with some other process, so it is imperative to treat a
locked file as a soft error instead of blocking on the file until the
other process unlocks it.

diff --git a/libexec/dma/spool.c b/libexec/dma/spool.c
index d9d17e2..9a74620 100644 (file)
--- a/libexec/dma/spool.c
+++ b/libexec/dma/spool.c
@@ -308,7 +308,7 @@ aquirespool(struct qitem *it)
        int queuefd;
 
        if (it->queuef == NULL) {
-               queuefd = open_locked(it->queuefn, O_RDWR);
+               queuefd = open_locked(it->queuefn, O_RDWR|O_NONBLOCK);
                if (queuefd < 0)
                        goto fail;
                it->queuef = fdopen(queuefd, "r+");