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/*
* Copyright (C) 2004,2005 Heinz Mauelshagen, Red Hat GmbH.
* All rights reserved.
*
* See file LICENSE at the top of this source tree for license information.
*/
#ifndef __KLIBC__
# include <sys/file.h>
#endif
#include "internal.h"
/* File locking private data. */
static const char *lock_file = "/var/lock/dmraid/.lock";
static int lf = -1;
/* flock file. */
static int
lock(struct lib_context *lc, struct resource *res)
{
/* Already locked. */
if (lf > -1)
return 1;
log_warn(lc, "locking %s", lock_file);
if ((lf = open(lock_file, O_CREAT | O_APPEND | O_RDWR, 0777)) < 0)
LOG_ERR(lc, 0, "opening lockfile %s", lock_file);
if (flock(lf, LOCK_EX)) {
close(lf);
lf = -1;
LOG_ERR(lc, 0, "flock lockfile %s", lock_file);
}
return 1;
}
/* Unlock file. */
static void
unlock(struct lib_context *lc, struct resource *res)
{
/* Not locked! */
if (lf == -1)
return;
log_warn(lc, "unlocking %s", lock_file);
unlink(lock_file);
if (flock(lf, LOCK_NB | LOCK_UN))
log_err(lc, "flock lockfile %s", lock_file);
if (close(lf))
log_err(lc, "close lockfile %s", lock_file);
lf = -1;
}
/* File base locking interface. */
static struct locking file_locking = {
.name = "file",
.lock = lock,
.unlock = unlock,
};
static int
init_file_locking(struct lib_context *lc)
{
int ret = 0;
char *dir;
if (!(dir = get_dirname(lc, (char *) lock_file)))
return 0;
if (!mk_dir(lc, dir))
goto out;
/* Fail on read-only file system. */
if (access(dir, R_OK | W_OK) && errno == EROFS)
goto out;
lc->lock = &file_locking;
ret = 1;
out:
dbg_free(dir);
return ret;
}
/*
* External locking interface.
*/
/* Initialize locking. */
int
init_locking(struct lib_context *lc)
{
if (OPT_IGNORELOCKING(lc))
return 1;
if (lc->locking_name)
BUG(lc, 0, "no locking selection yet");
return init_file_locking(lc);
}
/* Hide locking. */
int
lock_resource(struct lib_context *lc, struct resource *res)
{
return OPT_IGNORELOCKING(lc) ? 1 : lc->lock->lock(lc, res);
}
/* Hide unlocking. */
void
unlock_resource(struct lib_context *lc, struct resource *res)
{
return OPT_IGNORELOCKING(lc) ? 1 : lc->lock->unlock(lc, res);
}
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