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/* Helper routines for dealing with translators
Copyright (C) 1995 Free Software Foundation, Inc.
Written by Miles Bader <miles@gnu.ai.mit.edu>
This file is part of the GNU Hurd.
The GNU Hurd is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
The GNU Hurd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "trivfs.h"
/* Return the active translator control port for NODE. If there is no
translator, active or passive, MACH_PORT_NULL is returned in CONTROL_PORT.
If there is a translator, it is started if necessary, and returned in
CONTROL_PORT. *DIR_PORT should be a port right to use as the new
translators parent directory. If it is MACH_PORT_NULL, a port is created
from DIR and PARENT_PORT and stored in *DIR_PORT; otherwise DIR and
PARENT_PORT are not used. Neither NODE or DIR should be locked when
calling this function. */
error_t
treefs_node_get_active_trans (struct treefs_node *node,
struct treefs_node *dir,
mach_port_t parent_port,
mach_port_t *control_port,
mach_port_t *dir_port)
{
/* Fill in dir_port */
void make_dir_port ()
{
mutex_lock (&dir->lock);
*dir_port = treefs_node_make_right (dir, 0, parent_port, 0);
mach_port_insert_right (mach_task_self (),
*dir_port, *dir_port, MACH_MSG_TYPE_MAKE_SEND);
mutex_unlock (&dir->lock);
}
mutex_lock (&node->active_trans.lock);
if (node->active_trans.control != MACH_PORT_NULL)
{
mach_port_t control = node->active_trans.control;
mach_port_mod_refs (mach_task_self (), control,
MACH_PORT_RIGHT_SEND, 1);
mutex_unlock (&node->active_trans.lock);
/* Now we have a copy of the translator port that isn't
dependent on the translator lock itself. Relock
the directory, make a port from it, and then call
fsys_getroot. */
if (*dir_port == MACH_PORT_NULL)
make_dir_port ();
*control_port = control;
return 0;
}
mutex_unlock (&node->active_trans.lock);
/* If we get here, then we have no active control port.
Check to see if there is a passive translator, and if so
repeat the translator check. */
mutex_lock (&node->lock);
if (!node->istranslated)
{
*control_port = MACH_PORT_NULL;
return 0;
}
err = treefs_node_get_translator (node, trans, &trans_len);
if (err == E2BIG)
{
trans = alloca (trans_len);
err = treefs_node_get_translator (node, trans, &trans_len);
}
if (err)
{
mutex_unlock (&node->lock);
return err;
}
if (*dir_port == MACH_PORT_NULL)
{
mutex_unlock (&node->lock);
make_dir_port ();
mutex_lock (&node->lock);
}
/* Try starting the translator (this unlocks NODE). */
err = treefs_start_translator (node, trans, trans_len, *dir_port);
if (err)
return err;
/* Try again now that we've started the translator... This call
should be tail recursive. */
return
treefs_node_get_active_trans (node, dir, parent_port,
control_port, dir_port);
}
/* Drop the active translator CONTROL_PORT on NODE, unless it's no longer the
current active translator, in which case just drop a reference to it. */
void
treefs_node_drop_active_trans (struct treefs_node *node,
mach_port_t control_port)
{
mutex_lock (&node->active_trans.lock);
/* Only zero the control port if it hasn't changed. */
if (node->active_trans.control == control)
fshelp_translator_drop (&node->active_trans);
mutex_unlock (&node->active_trans.lock);
/* And we're done with this port. */
mach_port_deallocate (mach_task_self (), control_port);
}
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