diff options
Diffstat (limited to 'lockdev.h')
-rw-r--r-- | lockdev.h | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/lockdev.h b/lockdev.h new file mode 100644 index 0000000..4467bc2 --- /dev/null +++ b/lockdev.h @@ -0,0 +1,77 @@ +#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 |