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.

3 files changed, 47 insertions, 13 deletions

diff --git a/term/ptyio.c b/term/ptyio.c
index 0f5ddb01..44a215bb 100644
--- a/term/ptyio.c
+++ b/term/ptyio.c
@@ -459,9 +459,10 @@ pty_io_readable (size_t *amt)
 /* Validation has already been done by trivfs_S_io_select. */
 error_t
 pty_io_select (struct trivfs_protid *cred, mach_port_t reply,
-	       int *type)
+	       struct timespec *tsp, int *type)
 {
   int avail = 0;
+  error_t err;
 
   if (*type == 0)
     return 0;
@@ -488,13 +489,18 @@ pty_io_select (struct trivfs_protid *cred, mach_port_t reply,
 	}
 
       ports_interrupt_self_on_port_death (cred, reply);
-
       pty_read_blocked = 1;
-      if (pthread_hurd_cond_wait_np (&pty_select_wakeup, &global_lock))
+      err = pthread_hurd_cond_timedwait_np (&pty_select_wakeup, &global_lock,
+					    tsp);
+      if (err)
 	{
 	  *type = 0;
 	  pthread_mutex_unlock (&global_lock);
-	  return EINTR;
+
+	  if (err == ETIMEDOUT)
+	    err = 0;
+
+	  return err;
 	}
     }
 }
diff --git a/term/term.h b/term/term.h
index f154d4c0..df82b6c9 100644
--- a/term/term.h
+++ b/term/term.h
@@ -386,7 +386,8 @@ error_t pty_io_write (struct trivfs_protid *, char *,
 error_t pty_io_read (struct trivfs_protid *, char **,
 		     mach_msg_type_number_t *, mach_msg_type_number_t);
 error_t pty_io_readable (size_t *);
-error_t pty_io_select (struct trivfs_protid *, mach_port_t, int *);
+error_t pty_io_select (struct trivfs_protid *, mach_port_t,
+		       struct timespec *, int *);
 error_t pty_open_hook (struct trivfs_control *, struct iouser *, int);
 error_t pty_po_create_hook (struct trivfs_peropen *);
 error_t pty_po_destroy_hook (struct trivfs_peropen *);
diff --git a/term/users.c b/term/users.c
index 9fc1dc23..529693e8 100644
--- a/term/users.c
+++ b/term/users.c
@@ -2002,17 +2002,17 @@ trivfs_S_io_async (struct trivfs_protid *cred,
   return 0;
 }
 
-error_t
-trivfs_S_io_select (struct trivfs_protid *cred,
-		    mach_port_t reply,
-		    mach_msg_type_name_t reply_type,
-		    int *type)
+static error_t
+io_select_common (struct trivfs_protid *cred,
+		  mach_port_t reply,
+		  mach_msg_type_name_t reply_type,
+		  struct timespec *tsp, int *type)
 {
   if (!cred)
     return EOPNOTSUPP;
 
   if (cred->pi.class == pty_class)
-    return pty_io_select (cred, reply, type);
+    return pty_io_select (cred, reply, tsp, type);
 
   if ((cred->po->openmodes & O_READ) == 0)
     *type &= ~SELECT_READ;
@@ -2024,6 +2024,8 @@ trivfs_S_io_select (struct trivfs_protid *cred,
   while (1)
     {
       int available = 0;
+      error_t err = 0;
+
       if ((*type & SELECT_READ) && qsize (inputq))
 	available |= SELECT_READ;
       if ((*type & SELECT_WRITE) && qavail (outputq))
@@ -2032,16 +2034,41 @@ trivfs_S_io_select (struct trivfs_protid *cred,
       if (available == 0)
 	{
 	  ports_interrupt_self_on_port_death (cred, reply);
-	  if (pthread_hurd_cond_wait_np (&select_alert, &global_lock) == 0)
+	  err = pthread_hurd_cond_timedwait_np (&select_alert, &global_lock,
+						tsp);
+	  if (!err)
 	    continue;
 	}
 
       *type = available;
       pthread_mutex_unlock (&global_lock);
-      return available ? 0 : EINTR;
+
+      if (err == ETIMEDOUT)
+	err = 0;
+
+      return err;
     }
 }
 
+error_t
+trivfs_S_io_select (struct trivfs_protid *cred,
+		    mach_port_t reply,
+		    mach_msg_type_name_t reply_type,
+		    int *type)
+{
+  return io_select_common (cred, reply, reply_type, NULL, type);
+}
+
+error_t
+trivfs_S_io_select_timeout (struct trivfs_protid *cred,
+			    mach_port_t reply,
+			    mach_msg_type_name_t reply_type,
+			    struct timespec ts,
+			    int *type)
+{
+  return io_select_common (cred, reply, reply_type, &ts, type);
+}
+
 kern_return_t
 trivfs_S_io_map  (struct trivfs_protid *cred,
 		  mach_port_t reply,