1#ifndef LOCK_DEV 2#define LOCK_DEV 3 4/* Copyright 2005,2009 Alain Knaff. 5 * This file is part of mtools. 6 * 7 * Mtools is free software: you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation, either version 3 of the License, or 10 * (at your option) any later version. 11 * 12 * Mtools is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with Mtools. If not, see <http://www.gnu.org/licenses/>. 19 * 20 * Create an advisory lock on the device to prevent concurrent writes. 21 * Uses either lockf, flock, or fcntl locking methods. See the Makefile 22 * and the Configure files for how to specify the proper method. 23 */ 24 25int lock_dev(int fd, int mode, struct device *dev) 26{ 27#if (defined(HAVE_FLOCK) && defined (LOCK_EX) && defined(LOCK_NB)) 28 /**/ 29#else /* FLOCK */ 30 31#if (defined(HAVE_LOCKF) && defined(F_TLOCK)) 32 /**/ 33#else /* LOCKF */ 34 35#if (defined(F_SETLK) && defined(F_WRLCK)) 36 struct flock flk; 37 38#endif /* FCNTL */ 39#endif /* LOCKF */ 40#endif /* FLOCK */ 41 42 if(IS_NOLOCK(dev)) 43 return 0; 44 45#if (defined(HAVE_FLOCK) && defined (LOCK_EX) && defined(LOCK_NB)) 46 if (flock(fd, (mode ? LOCK_EX : LOCK_SH)|LOCK_NB) < 0) 47#else /* FLOCK */ 48 49#if (defined(HAVE_LOCKF) && defined(F_TLOCK)) 50 if (mode && lockf(fd, F_TLOCK, 0) < 0) 51#else /* LOCKF */ 52 53#if (defined(F_SETLK) && defined(F_WRLCK)) 54 flk.l_type = mode ? F_WRLCK : F_RDLCK; 55 flk.l_whence = 0; 56 flk.l_start = 0L; 57 flk.l_len = 0L; 58 59 if (fcntl(fd, F_SETLK, &flk) < 0) 60#endif /* FCNTL */ 61#endif /* LOCKF */ 62#endif /* FLOCK */ 63 { 64 if(errno == EINVAL 65#ifdef EOPNOTSUPP 66 || errno == EOPNOTSUPP 67#endif 68 ) 69 return 0; 70 else 71 return 1; 72 } 73 return 0; 74} 75 76 77#endif 78