1 files changed, 88 insertions, 0 deletions
diff --git a/libcons/cons-switch.c b/libcons/cons-switch.c
new file mode 100644
index 00000000..752af97e
--- /dev/null
+++ b/libcons/cons-switch.c
@@ -0,0 +1,88 @@
+/* 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 "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;
+
+  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)
+    {
+      mutex_unlock (&cons->lock);
+      return ESRCH;
+    }
+
+  if (vcons_entry->vcons)
+    {
+      *r_vcons = vcons_entry->vcons;
+      mutex_lock (&vcons_entry->vcons->lock);
+    }
+  else
+    {
+      err = cons_vcons_open (cons, vcons_entry, r_vcons);
+      if (!err)
+        vcons_entry->vcons = *r_vcons;
+    }
+
+  mutex_unlock (&cons->lock);
+  return err;
+}