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/* cons-switch.c - Switch to another virtual console.
Copyright (C) 2002 Free Software Foundation, Inc.
Written by Marcus Brinkmann.
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., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
#include <errno.h>
#include <assert.h>
#include <pthread.h>
#include "cons.h"
/* Open the virtual console ID or the virtual console DELTA steps away
from VCONS in the linked list and return it in R_VCONS, which will
be locked. */
error_t
cons_switch (vcons_t vcons, int id, int delta, vcons_t *r_vcons)
{
error_t err = 0;
cons_t cons = vcons->cons;
vcons_list_t vcons_entry = NULL;
if (!id && !delta)
return 0;
pthread_mutex_lock (&cons->lock);
if (id)
{
vcons_entry = cons->vcons_list;
while (vcons_entry && vcons_entry->id != id)
vcons_entry = vcons_entry->next;
}
else if (delta > 0)
{
vcons_entry = vcons->vcons_entry;
while (delta-- > 0)
{
vcons_entry = vcons_entry->next;
if (!vcons_entry)
vcons_entry = cons->vcons_list;
}
}
else
{
assert (delta < 0);
vcons_entry = vcons->vcons_entry;
while (delta++ < 0)
{
vcons_entry = vcons_entry->prev;
if (!vcons_entry)
vcons_entry = cons->vcons_last;
}
}
if (!vcons_entry)
{
pthread_mutex_unlock (&cons->lock);
return ESRCH;
}
if (vcons_entry->vcons)
{
*r_vcons = vcons_entry->vcons;
pthread_mutex_lock (&vcons_entry->vcons->lock);
}
else
{
err = cons_vcons_open (cons, vcons_entry, r_vcons);
if (!err)
vcons_entry->vcons = *r_vcons;
}
pthread_mutex_unlock (&cons->lock);
return err;
}
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