diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/libc/sys/flock.2 | 44 |
1 files changed, 25 insertions, 19 deletions
diff --git a/lib/libc/sys/flock.2 b/lib/libc/sys/flock.2 index 4b486d80260..497444df477 100644 --- a/lib/libc/sys/flock.2 +++ b/lib/libc/sys/flock.2 @@ -1,4 +1,4 @@ -.\" $OpenBSD: flock.2,v 1.18 2013/08/14 06:32:28 jmc Exp $ +.\" $OpenBSD: flock.2,v 1.19 2014/11/30 19:56:12 schwarze Exp $ .\" $NetBSD: flock.2,v 1.5 1995/02/27 12:32:32 cgd Exp $ .\" .\" Copyright (c) 1983, 1991, 1993 @@ -30,19 +30,14 @@ .\" .\" @(#)flock.2 8.2 (Berkeley) 12/11/93 .\" -.Dd $Mdocdate: August 14 2013 $ +.Dd $Mdocdate: November 30 2014 $ .Dt FLOCK 2 .Os .Sh NAME .Nm flock .Nd apply or remove an advisory lock on an open file .Sh SYNOPSIS -.Fd #include <fcntl.h> -.Pp -.Fd #define LOCK_SH 1 /* shared lock */ -.Fd #define LOCK_EX 2 /* exclusive lock */ -.Fd #define LOCK_NB 4 /* don't block when locking */ -.Fd #define LOCK_UN 8 /* unlock */ +.In fcntl.h .Ft int .Fn flock "int fd" "int operation" .Sh DESCRIPTION @@ -51,18 +46,25 @@ applies or removes an .Em advisory lock on the file associated with the file descriptor .Fa fd . -A lock is applied by specifying an +The .Fa operation -parameter that is one of +argument is one of: +.Pp +.Bl -tag -width LOCK_SH -offset indent -compact +.It Dv LOCK_SH +Apply a shared lock. +.It Dv LOCK_EX +Apply an exclusive lock. +.It Dv LOCK_UN +Remove an existing lock. +.El +.Pp .Dv LOCK_SH -or +and .Dv LOCK_EX -with the optional addition of -.Dv LOCK_NB . -To unlock an existing lock, -.Fa operation -should be -.Dv LOCK_UN . +may be combined with the optional +.Dv LOCK_NB +for nonblocking mode. .Pp Advisory locks allow cooperating processes to perform consistent operations on files, but do not guarantee @@ -89,9 +91,13 @@ after other processes have gained and released the lock). Requesting a lock on an object that is already locked normally causes the caller to be blocked until the lock may be acquired. If +.Fa operation +is the bitwise OR of .Dv LOCK_NB -is included in -.Fa operation , +and +.Dv LOCK_SH +or +.Dv LOCK_EX , then this will not happen; instead the call will fail and the error .Er EWOULDBLOCK will be returned. |