Add io_select_timeout to the io interface

This change fixes a problem that can occur with non-blocking (and also
blocking for very short times) select/poll calls. The problem occurs because
the timeout is implemented at the client side. For a non-blocking call, this
means that (depending on the code path taken in the C library) the client
could get a timeout without a full RPC round-trip to the server. Moving the
implementation of the timeout to the servers guarantees a full round-trip,
and correct results for non-blocking calls.

The modifications in this change depend on the availability of the recently
added pthread_hurd_cond_timedwait_np function in libpthread.

* boot/boot.c (io_select_common): New static function.
(S_io_select): Use io_select_common.
(S_io_select_timeout): New function which makes use of io_select_common.
* console-client/kbd-repeat.c (repeater_select): Add a timeout parameter.
* console-client/pc-mouse.c (repeater_select): Likewise.
* console-client/trans.c (io_select_common): New static function.
(netfs_S_io_select): Use io_select_common.
(netfs_S_io_select_timeout): New function which makes use of io_select_common.
* console-client/trans.h (struct consnode): Add a timeout parameter.
* hurd/io.defs (io_select_timeout): New MIG routine.
* hurd/io_reply.defs (io_select_timeout_reply): New MIG simpleroutine.
* hurd/io_request.defs (io_select_timeout_request): Likewise.
* libdiskfs/io-select.c (diskfs_S_io_select_timeout): New function.
* libnetfs/io-select.c (netfs_S_io_select_timeout): Likewise.
* libpipe/pipe.c (pipe_pair_select): Add a timeout parameter.
* libpipe/pipe.h (pipe_select_readable): Likewise.
(pipe_select_writable): Likewise.
(pipe_pair_select): Likewise.
* libpipe/pq.h: Include <hurd/hurd_types.h>.
* libtrivfs/io-select.c (trivfs_S_io_select_timeout): New function.
* pfinet/glue-include/linux/sched.h: Include <errno.h>.
(interruptible_sleep_on): Function removed, replaced with ...
(interruptible_sleep_on_timeout): New function.
(schedule): Update to use interruptible_sleep_on_timeout.
(schedule_timeout): Likewise.
* pfinet/io-ops.c (io_select_common): New static function.
(S_io_select): Use io_select_common.
(S_io_select_timeout): New function which makes use of io_select_common.
* pfinet/tunnel.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.
* pflocal/connq.c (connq_listen): Replace noblock with a timeout parameter.
* pflocal/connq.h: Include <hurd/hurd_types.h>.
(connq_listen): Update declaration to replace noblock with a timeout parameter.
* pflocal/io.c (io_select_common): New static function.
(S_io_select): Use io_select_common.
(S_io_select_timeout): New function which makes use of io_select_common.
* pflocal/socket.c (S_socket_accept): Update call to connq_listen to match new
declaration.
* storeio/io.c (trivfs_S_io_select_timeout): New function.
* term/ptyio.c (pty_io_select): Add a timeout parameter.
* term/term.h (pty_io_select): Likewise.
* term/users.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.
* trans/fifo.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.
* trans/firmlink.c (trivfs_S_io_select_timeout): New function.
* trans/new-fifo.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.
* trans/null.c (trivfs_S_io_select_timeout): New function.
* trans/streamio.c (io_select_common): New static function.
(trivfs_S_io_select): Use io_select_common.
(trivfs_S_io_select_timeout): New function which makes use of io_select_common.

1 files changed, 11 insertions, 5 deletions

diff --git a/libpipe/pipe.c b/libpipe/pipe.c
index dd306f60..1ddaf126 100644
--- a/libpipe/pipe.c
+++ b/libpipe/pipe.c
@@ -209,7 +209,7 @@ void _pipe_no_writers (struct pipe *pipe)
    this function (unlike most pipe functions).  */
 error_t
 pipe_pair_select (struct pipe *rpipe, struct pipe *wpipe,
-		  int *select_type, int data_only)
+		  struct timespec *tsp, int *select_type, int data_only)
 {
   error_t err = 0;
 
@@ -218,13 +218,13 @@ pipe_pair_select (struct pipe *rpipe, struct pipe *wpipe,
   if (*select_type == SELECT_READ)
     {
       pthread_mutex_lock (&rpipe->lock);
-      err = pipe_select_readable (rpipe, data_only);
+      err = pipe_select_readable (rpipe, tsp, data_only);
       pthread_mutex_unlock (&rpipe->lock);
     }
   else if (*select_type == SELECT_WRITE)
     {
       pthread_mutex_lock (&wpipe->lock);
-      err = pipe_select_writable (wpipe);
+      err = pipe_select_writable (wpipe, tsp);
       pthread_mutex_unlock (&wpipe->lock);
     }
   else
@@ -260,8 +260,8 @@ pipe_pair_select (struct pipe *rpipe, struct pipe *wpipe,
 	      pthread_mutex_unlock (&rpipe->lock);
 	      pthread_mutex_unlock (&wpipe->lock);
 	    }
-	  if (pthread_hurd_cond_wait_np (&pending_select.cond, lock))
-	    err = EINTR;
+	  err = pthread_hurd_cond_timedwait_np (&pending_select.cond, lock,
+						tsp);
 	  if (rpipe != wpipe)
 	    {
 	      pthread_mutex_lock (&rpipe->lock);
@@ -295,6 +295,12 @@ pipe_pair_select (struct pipe *rpipe, struct pipe *wpipe,
       pthread_mutex_unlock (lock);
     }
 
+  if (err == ETIMEDOUT)
+    {
+      err = 0;
+      *select_type = 0;
+    }
+
   return err;
 }