.\"-
.\" Copyright (c) 2008 Dag-Erling Coïdan Smørgrav
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.Dd February 14, 2009
.Dt QUOTAFILE 3
.Os
.Sh NAME
.Nm quota_open
.Nm quota_read
.Nm quota_write_limits
.Nm quota_write_usage
.Nm quota_close
.Nd "Manipulate quotas"
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In ufs/ufs/quota.h
.In libutil.h
.In fstab.h
.Ft "struct quotafile *"
.Fn quota_open "struct fstab *fs" "int quotatype" "int openflags"
.Ft int
.Fn quota_read "struct quotafile *qf" "struct dqblk *dqb" "int id"
.Ft int
.Fn quota_write_limits "struct quotafile *qf" "struct dqblk *dqb" "int id"
.Ft int
.Fn quota_write_usage "struct quotafile *qf" "struct dqblk *dqb" "int id"
.Ft int
.Fn quota_close "struct quotafile *qf"
.Sh DESCRIPTION
These functions are designed to simplify access to filesystem quotas.
If quotas are active on a filesystem,
these functions will access them directly from the kernel using the
.Fn quotactl
system call.
If quotas are not active,
these functions will access them by reading and writing
the quota files directly.
.Pp
The
.Fn quota_open
function takes a pointer to an
.Vt fstab
entry corresponding to the filesystem on which quotas
are to be accessed.
The
.Va quotatype
field indicates the type of quotas being sought, either
.Dv USRQUOTA
or
.Dv GRPQUOTA .
The
.Va openflags
are those used by the
.Fn open
system call, usually either
.Dv O_RDONLY
if the quotas are just to be read, or
.Dv O_RDWR
if the quotas are to be updated.
The
.Dv O_CREAT
flag should be specified if a new quota file of the requested type should
be created if it does not already exist.
.Pp
The
.Fn quota_read
function reads the quota from the filesystem and quota type referenced by
.Va qf
for the user (or group) specified by
.Va id
into the
.Vt dqblk
quota structure pointed to by
.Va dqb .
.Pp
The
.Fn quota_write_limits
function updates the limit fields (but not the usage fields)
for the filesystem and quota type referenced by
.Va qf
for the user (or group) specified by
.Va id
from the
.Vt dqblk
quota structure pointed to by
.Va dqb .
.Pp
The
.Fn quota_write_usage
function updates the usage fields (but not the limit fields)
for the filesystem and quota type referenced by
.Va qf
for the user (or group) specified by
.Va id
from the
.Vt dqblk
quota structure pointed to by
.Va dqb .
.Pp
The
.Fn quota_close
function closes any open file descriptors and frees any storage
associated with the filesystem and quota type referenced by
.Va qf .
.Sh RETURN VALUES
If the filesystem has quotas associated with it,
.Fn quota_open
returns a pointer to a 
.Vt quotafile
structure used in subsequent quota access calls.
If the filesystem has no quotas, or access permission is denied
.Dv NULL
is returned and
.Va errno
is set to indicate the cause of failure.
.Pp
The
.Fn quota_read ,
.Fn quota_write_limits ,
.Fn quota_write_usage ,
and
.Fn quota_close
functions return zero on success.
On error they return
.Dv -1
and set
.Va errno
to indicate the cause of failure.
.Sh SEE ALSO
.Xr quotactl 2 ,
.Xr quota.user 5 ,
.Xr quota.group 5
.Sh HISTORY
The
.Nm
functions first appeared in
.Fx 8.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
functions and this manual page were written by
.An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org 
and
.An Marshall Kirk McKusick .