diff options
Diffstat (limited to 'libc/misc/lock/flock.c')
| -rw-r--r-- | libc/misc/lock/flock.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/libc/misc/lock/flock.c b/libc/misc/lock/flock.c new file mode 100644 index 000000000..3c1264655 --- /dev/null +++ b/libc/misc/lock/flock.c @@ -0,0 +1,54 @@ +/* Copyright (C) 1992, 1995, 1996, 1997 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +/* This file implements the `flock' function in terms of the POSIX.1 `fcntl' + locking mechanism. In 4BSD, these are two incompatible locking mechanisms, + perhaps with different semantics? */ + +#include <errno.h> +#include <unistd.h> +#include <fcntl.h> +#include <sys/file.h> + +/* Apply or remove an advisory lock, according to OPERATION, + on the file FD refers to. */ +int flock( int fd, int operation) +{ + struct flock lbuf; + + switch (operation & ~LOCK_NB) { + case LOCK_SH: + lbuf.l_type = F_RDLCK; + break; + case LOCK_EX: + lbuf.l_type = F_WRLCK; + break; + case LOCK_UN: + lbuf.l_type = F_UNLCK; + break; + default: + errno = EINVAL; + return -1; + } + + lbuf.l_whence = SEEK_SET; + lbuf.l_start = lbuf.l_len = 0L; /* Lock the whole file. */ + + return fcntl(fd, (operation & LOCK_NB) ? F_SETLK : F_SETLKW, &lbuf); +} + |