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FLOPEN(3)	       FreeBSD Library Functions Manual		     FLOPEN(3)

NAME
     flopen -- Reliably	open and lock a	file

LIBRARY
     System Utilities Library (libutil,	-lutil)

SYNOPSIS
     #include <sys/fcntl.h>
     #include <libutil.h>

     int
     flopen(const char *path, int flags);

     int
     flopen(const char *path, int flags, mode_t	mode);

DESCRIPTION
     The flopen() function opens or creates a file and acquires	an exclusive
     lock on it.  It is	essentially equivalent with calling open() with	the
     same parameters followed by flock() with an operation argument of
     LOCK_EX, except that 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, mail-
     boxes and other kinds of files which are used for synchronization between
     processes.

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

     As	with open(), the additional mode argument is required if flags
     includes O_CREAT.

RETURN VALUES
     If	successful, 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)

HISTORY
     The flopen() function first appeared in FreeBSD 6.3.

AUTHORS
     The flopen	function and this manual page were written by Dag-Erling
     Smorgrav <des@FreeBSD.org>.

FreeBSD	10.1			 May 10, 2007			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | HISTORY | AUTHORS

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