lguest: fix writev returning short on console output

I've never seen it here, but I can't find anywhere that says writev
will write everything.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 8704600..02fa524 100644 (file)
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -836,7 +836,12 @@ static void handle_console_output(struct virtqueue *vq, bool timeout)
        while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) {
                if (in)
                        errx(1, "Input buffers in output queue?");
-               writev(STDOUT_FILENO, iov, out);
+               while (!iov_empty(iov, out)) {
+                       int len = writev(STDOUT_FILENO, iov, out);
+                       if (len <= 0)
+                               err(1, "Write to stdout gave %i", len);
+                       iov_consume(iov, out, len);
+               }
                add_used_and_trigger(vq, head, 0);
        }
 }