dma: lock temp files on creation

Lock the temporary files after creating them to protect from a "dma -q"
run at just the wrong time causing a double delivery attempt for
the same message.

Submitted-by: Peter Pentchev <roam@ringlet.net>

diff --git a/libexec/dma/dma.c b/libexec/dma/dma.c
index 3ca9826..6599635 100644 (file)
--- a/libexec/dma/dma.c
+++ b/libexec/dma/dma.c
@@ -223,6 +223,8 @@ gentempf(struct queue *queue)
        fd = mkstemp(fn);
        if (fd < 0)
                return (-1);
+       if (flock(fd, LOCK_EX) == -1)
+               return (-1);
        queue->mailfd = fd;
        queue->tmpf = strdup(fn);
        if (queue->tmpf == NULL) {