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#ifndef LOCK_DEV
#define LOCK_DEV
/* Copyright 2005,2009 Alain Knaff.
* This file is part of mtools.
*
* Mtools 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 3 of the License, or
* (at your option) any later version.
*
* Mtools 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 Mtools. If not, see <http://www.gnu.org/licenses/>.
*
* Create an advisory lock on the device to prevent concurrent writes.
* Uses either lockf, flock, or fcntl locking methods. See the Makefile
* and the Configure files for how to specify the proper method.
*/
int lock_dev(int fd, int mode, struct device *dev)
{
#if (defined(HAVE_FLOCK) && defined (LOCK_EX) && defined(LOCK_NB))
/**/
#else /* FLOCK */
#if (defined(HAVE_LOCKF) && defined(F_TLOCK))
/**/
#else /* LOCKF */
#if (defined(F_SETLK) && defined(F_WRLCK))
struct flock flk;
#endif /* FCNTL */
#endif /* LOCKF */
#endif /* FLOCK */
if(IS_NOLOCK(dev))
return 0;
#if (defined(HAVE_FLOCK) && defined (LOCK_EX) && defined(LOCK_NB))
if (flock(fd, (mode ? LOCK_EX : LOCK_SH)|LOCK_NB) < 0)
#else /* FLOCK */
#if (defined(HAVE_LOCKF) && defined(F_TLOCK))
if (mode && lockf(fd, F_TLOCK, 0) < 0)
#else /* LOCKF */
#if (defined(F_SETLK) && defined(F_WRLCK))
flk.l_type = mode ? F_WRLCK : F_RDLCK;
flk.l_whence = 0;
flk.l_start = 0L;
flk.l_len = 0L;
if (fcntl(fd, F_SETLK, &flk) < 0)
#endif /* FCNTL */
#endif /* LOCKF */
#endif /* FLOCK */
{
if(errno == EINVAL
#ifdef EOPNOTSUPP
|| errno == EOPNOTSUPP
#endif
)
return 0;
else
return 1;
}
return 0;
}
#endif
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