1.\"- 2.\" Copyright (c) 2007 Dag-Erling Coïdan Smørgrav 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD: head/lib/libutil/flopen.3 229784 2012-01-07 16:13:56Z uqs $ 27.\" 28.Dd June 6, 2009 29.Dt FLOPEN 3 30.Os 31.Sh NAME 32.Nm flopen 33.Nd "Reliably open and lock a file" 34.Sh LIBRARY 35.Lb libutil 36.Sh SYNOPSIS 37.In sys/fcntl.h 38.In libutil.h 39.Ft int 40.Fn flopen "const char *path" "int flags" 41.Ft int 42.Fn flopen "const char *path" "int flags" "mode_t mode" 43.Sh DESCRIPTION 44The 45.Fn flopen 46function opens or creates a file and acquires an exclusive lock on it. 47It is essentially equivalent with calling 48.Fn open 49with the same parameters followed by 50.Fn flock 51with an 52.Va operation 53argument of 54.Dv LOCK_EX , 55except that 56.Fn flopen 57will attempt to detect and handle races that may occur between opening 58/ creating the file and locking it. 59Thus, it is well suited for opening lock files, PID files, spool 60files, mailboxes and other kinds of files which are used for 61synchronization between processes. 62.Pp 63If 64.Va flags 65includes 66.Dv O_NONBLOCK 67and the file is already locked, 68.Fn flopen 69will fail and set 70.Va errno 71to 72.Er EWOULDBLOCK . 73.Pp 74As with 75.Fn open , 76the additional 77.Va mode 78argument is required if 79.Va flags 80includes 81.Dv O_CREAT . 82.Sh RETURN VALUES 83If successful, 84.Fn flopen 85returns a valid file descriptor. 86Otherwise, it returns -1, and sets 87.Va errno 88as described in 89.Xr flock 2 90and 91.Xr open 2 . 92.Sh SEE ALSO 93.Xr errno 2 , 94.Xr flock 2 , 95.Xr open 2 96.Sh AUTHORS 97.An -nosplit 98The 99.Nm 100function and this manual page were written by 101.An Dag-Erling Sm\(/orgrav Aq Mt des@FreeBSD.org . 102