flopen (3)

Leading comments

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 Copyright (c) 2007 Dag-Erling Coïdan Smørgrav
 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.
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    ...

(The comments found at the beginning of the groff file "man3/flopen.3bsd".)

NAME

flopen - reliably open and lock a file

LIBRARY

Lb libbsd

SYNOPSIS

In sys/fcntl.h In libutil.h (See libbsd(7) for include usage.) Ft int Fn flopen const char *path int flags Ft int Fn flopen const char *path int flags mode_t mode

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 operation argument of 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.

If flags includes O_NONBLOCK and the file is already locked, Fn flopen will fail and set errno to EWOULDBLOCK

As with Fn open , the additional mode argument is required if flags includes O_CREAT

RETURN VALUES

If successful, Fn flopen returns a valid file descriptor. Otherwise, it returns -1, and sets errno as described in flock(2) and open(2).

SEE ALSO

errno(2), flock(2), open(2)

AUTHORS

An -nosplit The function and this manual page were written by An Dag-Erling Sm/orgrav Aq des@FreeBSD.org .