02-21-2009
Like jim says, read your system documentation on fcntl(). You can do advisory locking, in which you:
- Open the file
- Call ioctl(fileno, F_GETLK, &lockdata) where lockdata is a properly filled 'struct flock' structure, details on which are in the fcntl documentation.
- If the lock succeeds, you have the file. If you don't, you don't.
- If you locked the file, call ioctl again with F_SETLK to release your lock.
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LEARN ABOUT FREEBSD
vop_advlock
VOP_ADVLOCK(9) BSD Kernel Developer's Manual VOP_ADVLOCK(9)
NAME
VOP_ADVLOCK -- advisory record locking
SYNOPSIS
#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/fcntl.h>
#include <sys/lockf.h>
int
VOP_ADVLOCK(struct vnode *vp, caddr_t id, int op, struct flock *fl, int flags);
DESCRIPTION
The arguments are:
vp The vnode being manipulated.
id The id token which is changing the lock.
op The operation to perform (see fcntl(2)).
fl Description of the lock.
flags One of more of the following:
F_RDLCK Shared or read lock.
F_UNLCK Unlock.
F_WRLCK Exclusive or write lock.
F_WAIT Wait until lock is granted.
F_FLOCK Use flock(2) semantics for lock.
F_POSIX Use POSIX semantics for lock.
This entry point manipulates advisory record locks on the file. Most file systems delegate the work for this call to lf_advlock().
RETURN VALUES
Zero is returned on success, otherwise an error is returned.
SEE ALSO
fcntl(2), flock(2), vnode(9)
AUTHORS
This manual page was written by Doug Rabson.
BSD
June 30, 1999 BSD