| /* 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 Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; 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 (fd, operation) |
| 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: |
| __set_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); |
| } |
| |
| weak_alias (__flock, flock) |