NAME
flopen, flopenat — Reliably open and lock a fileLIBRARY
library “libbsd”SYNOPSIS
#include <sys/fcntl.h>#include <libutil.h> (See libbsd(7) for include usage.)
int
flopen(const char *path, int flags); int
flopen(const char *path, int flags, mode_t mode); int
flopenat(int fd, const char *path, int flags); int
flopenat(int fd, 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 ofLOCK_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, mailboxes 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
.
The flopenat() function is equivalent to the
flopen() function except in the case where the
path specifies a relative path. In this case
the file to be opened is determined relative to the directory associated with
the file descriptor fd instead of the current
working directory. If flopenat() is passed the
special value AT_FDCWD
in the
fd parameter, the current working directory
is used and the behavior is identical to a call to
flopen().
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)AUTHORS
The flopen function and this manual page were written by Dag-Erling Smørgrav <[email protected]>.July 28, 2017 | Debian |