libpipe: fix spurious calls to pipe_send

* libpipe/pipe.c (pipe_send): Skip processing if there is nothing to send.

1 files changed, 5 insertions, 1 deletions

diff --git a/libpipe/pipe.c b/libpipe/pipe.c
index f9300e7c..b7ee8515 100644
--- a/libpipe/pipe.c
+++ b/libpipe/pipe.c
@@ -316,7 +316,11 @@ pipe_send (struct pipe *pipe, int noblock, void *source,
 	   mach_port_t *ports, size_t num_ports,
 	   size_t *amount)
 {
-  error_t err = 0;
+  error_t err;
+
+  /* Nothing to do.  */
+  if (data_len == 0 && control_len == 0 && num_ports == 0)
+    return 0;
 
   err = pipe_wait_writable (pipe, noblock);
   if (err)