-
Copyright (c) 2007 Dag-Erling Co�dan Sm�rgrav
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
$FreeBSD$
.Dd June 6, 2009 .Dt FLOPEN 3 .Os .Sh NAME .Nm flopen .Nd "Reliably open and lock a file" .Sh LIBRARY .Lb libutil .Sh SYNOPSIS n sys/fcntl.h n libutil.h .Ft int .Fn flopen "const char *path" "int flags" .Ft int .Fn flopen "const char *path" "int flags" "mode_t mode" .Sh DESCRIPTION The .Fn flopen function opens or creates a file and acquires an exclusive lock on it. It is essentially equivalent with calling .Fn open with the same parameters followed by .Fn flock with an .Va operation argument of .Dv LOCK_EX , except that .Fn flopen will attempt to detect and handle races that may occur between opening / creating the file and locking it. Thus, it is well suited for opening lock files, PID files, spool files, mailboxes and other kinds of files which are used for synchronization between processes.
Copyright (c) 2007 Dag-Erling Co�dan Sm�rgrav
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
$FreeBSD$
.Dd June 6, 2009 .Dt FLOPEN 3 .Os .Sh NAME .Nm flopen .Nd "Reliably open and lock a file" .Sh LIBRARY .Lb libutil .Sh SYNOPSIS n sys/fcntl.h n libutil.h .Ft int .Fn flopen "const char *path" "int flags" .Ft int .Fn flopen "const char *path" "int flags" "mode_t mode" .Sh DESCRIPTION The .Fn flopen function opens or creates a file and acquires an exclusive lock on it. It is essentially equivalent with calling .Fn open with the same parameters followed by .Fn flock with an .Va operation argument of .Dv LOCK_EX , except that .Fn flopen will attempt to detect and handle races that may occur between opening / creating the file and locking it. Thus, it is well suited for opening lock files, PID files, spool files, mailboxes and other kinds of files which are used for synchronization between processes.
p If .Va flags includes .Dv O_NONBLOCK and the file is already locked, .Fn flopen will fail and set .Va errno to .Dv EWOULDBLOCK .
p As with .Fn open , the additional .Va mode argument is required if .Va flags includes .Dv O_CREAT . .Sh RETURN VALUES If successful, .Fn flopen returns a valid file descriptor. Otherwise, it returns -1, and sets .Va errno as described in .Xr flock 2 and .Xr open 2 . .Sh SEE ALSO .Xr errno 2 , .Xr flock 2 , .Xr open 2 .Sh AUTHORS .An -nosplit The .Nm function and this manual page were written by .An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org .