.\" Copyright (c) 1995
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software developed by the Computer Systems
.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract
.\" BG 91-66 and contributed to Berkeley.
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.Dd December 15, 1995
.Dt PW_LOCK 3
.Os
.Sh NAME
.Nm pw_lock ,
.Nm pw_mkdb ,
.Nm pw_abort
.Nd passwd file update functions
.Sh SYNOPSIS
.Fd #include <util.h>
.Ft int
.Fn pw_lock "int retries"
.Ft int
.Fn pw_mkdb
.Ft void
.Fn pw_abort
.Sh DESCRIPTION
The
.Fn pw_lock ,
.Fn pw_mkdb ,
and
.Fn pw_abort
functions allow a program to update the system passwd database.
.Pp
The
.Fn pw_lock
function attempts to lock the passwd database by creating the file
.Pa /etc/ptmp
with an exclusive lock (using
.Xr flock 2
semantics) and returns the file descriptor of that file.  If
.Fa retries
is greater than zero,
.Fn pw_lock
will try multiple times to open
.Pa /etc/ptmp ,
waiting one second between tries.  In addition to being a lock file,
.Pa /etc/ptmp
will also hold the contents of the new passwd file.
.Pp
The
.Fn pw_mkdb
function updates the passwd file from the contents of
.Pa /etc/ptmp .
You should finish writing to and close the file descriptor returned by
.Fn pw_lock
before calling
.Fn pw_mkdb .
If
.Fn pw_mkdb
fails and you do not wish to retry, you should make sure to call
.Fn pw_abort
to clean up the lock file.
.Pp
The
.Fn pw_abort
function aborts a passwd file update by deleting
.Pa /etc/ptmp .
The passwd database remains unchanged.
.Sh RETURN VALUES
The
.Fn pw_lock
and
.Fn pw_mkdb
functions return \-1 if they are unable to complete properly.
.Sh FILES
.Bl -tag -width /etc/master.passwd -compact
.It Pa /etc/master.passwd
.It Pa /etc/ptmp
.El
.Sh SEE ALSO
.Xr flock 2 ,
.Xr pw_init 3