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/* Hurd unionfs
Copyright (C) 2001, 2002 Free Software Foundation, Inc.
Written by Moritz Schulte <moritz@duesseldorf.ccc.de>.
This program 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 of the
License, or * (at your option) any later version.
This program 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 02111-1307
USA. */
/* Underlying filesystem management. */
#define _GNU_SOURCE
#include <hurd/netfs.h>
#include <stdlib.h>
#include <error.h>
#include <string.h>
#include "ulfs.h"
/* The start of the ulfs chain. */
ulfs_t *ulfs_chain_start;
/* The end of the ulfs chain, we need this, to go through the chain in
reversed order. */
ulfs_t *ulfs_chain_end;
/* Number of registered underlying filesystems. */
unsigned int ulfs_num;
/* The lock protecting the ulfs data structures. */
struct mutex ulfs_lock = MUTEX_INITIALIZER;
/* Create a new ulfs element. */
error_t
ulfs_create (char *path, ulfs_t **ulfs)
{
ulfs_t *ulfs_new = malloc (sizeof (ulfs_t));
error_t err = 0;
if (! ulfs_new)
err = ENOMEM;
else
{
char *path_cp = path ? strdup (path) : NULL;
if (path && (! path_cp))
{
err = ENOMEM;
free (ulfs_new);
}
else
{
ulfs_new->path = path_cp;
ulfs_new->flags = 0;
ulfs_new->next = NULL;
ulfs_new->prev = NULL;
ulfs_new->prevp = NULL;
*ulfs = ulfs_new;
}
}
return err;
}
/* Destroy an ulfs element. */
void
ulfs_destroy (ulfs_t *ulfs)
{
free (ulfs->path);
free (ulfs);
}
/* Install ULFS into the linked list of registered filesystems. */
void
ulfs_install (ulfs_t *ulfs)
{
ulfs->next = ulfs_chain_start;
ulfs->prev = NULL;
ulfs->prevp = &ulfs_chain_start;
if (ulfs_chain_start)
{
ulfs_chain_start->prev = ulfs;
ulfs_chain_start->prevp = &ulfs->next;
}
else
ulfs_chain_end = ulfs;
ulfs_chain_start = ulfs;
}
/* Remove ULFS from the linked list of registered filesystems. */
void
ulfs_uninstall (ulfs_t *ulfs)
{
*ulfs->prevp = ulfs->next;
if (ulfs->next)
{
ulfs->next->prev = ulfs->prev;
ulfs->next->prevp = &ulfs->next;
}
else
ulfs_chain_end = ulfs->prev;
}
/* Get an ulfs element by it's index. */
error_t
ulfs_get_num (int num, ulfs_t **ulfs)
{
error_t err = EINVAL;
ulfs_t *u;
int i;
for (u = ulfs_chain_start, i = 0;
u && i < num;
u = u->next, i++);
if (u)
{
err = 0;
*ulfs = u;
}
return err;
}
/* Get an ulfs element by the associated path. */
error_t
ulfs_get_path (char *path, ulfs_t **ulfs)
{
error_t err = ENOENT;
ulfs_t *u;
for (u = ulfs_chain_start;
u && (! (((! path) && path == u->path)
|| (path && u->path && (! strcmp (path, u->path)))));
u = u->next);
if (u)
{
err = 0;
*ulfs = u;
}
return err;
}
/* Register a new underlying filesystem. */
error_t
ulfs_register (char *path, int flags)
{
ulfs_t *ulfs;
error_t err;
mutex_lock (&ulfs_lock);
err = ulfs_create (path, &ulfs);
if (! err)
{
ulfs->flags = flags;
ulfs_install (ulfs);
ulfs_num++;
}
mutex_unlock (&ulfs_lock);
return err;
}
/* Unregister an underlying filesystem. */
error_t
ulfs_unregister (char *path)
{
ulfs_t *ulfs;
error_t err;
mutex_lock (&ulfs_lock);
err = ulfs_get_path (path, &ulfs);
if (! err)
{
ulfs_uninstall (ulfs);
ulfs_destroy (ulfs);
ulfs_num--;
}
mutex_unlock (&ulfs_lock);
return err;
}
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