freebsd-skq/lib/libutil/quotafile.3

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.\" Copyright (c) 2009 Dag-Erling Coïdan Smørgrav and
.\" Marshall Kirk McKusick. All rights reserved.
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.Dd December 28, 2009
.Dt QUOTAFILE 3
.Os
.Sh NAME
.Nm quota_open
.Nm quota_close
.Nm quota_on
.Nm quota_off
.Nm quota_read
.Nm quota_write_limits
.Nm quota_write_usage
.Nm quota_fsname
.Nm quota_qfname
.Nm quota_maxid
.Nm quota_check_path
.Nm quota_convert
.Nd "Manipulate quotas"
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In sys/param.h
.In sys/mount.h
.In ufs/ufs/quota.h
.In fcntl.h
.In fstab.h
.In libutil.h
.Ft "struct quotafile *"
.Fn quota_open "struct fstab *fs" "int quotatype" "int openflags"
.Ft int
.Fn quota_close "struct quotafile *qf"
.Ft int
.Fn quota_on "const struct quotafile *qf"
.Ft int
.Fn quota_off "const struct quotafile *qf"
.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 "const char *"
.Fn quota_fsname "const struct quotafile *qf"
.Ft "const char *"
.Fn quota_qfname "const struct quotafile *qf"
.Ft int
.Fn quota_maxid "const struct quotafile *qf"
.Ft int
.Fn quota_check_path "const struct quotafile *qf" "const char *path"
.Ft int
.Fn quota_convert "struct quotafile *qf" "int wordsize"
.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_close
function closes any open file descriptors and frees any storage
associated with the filesystem and quota type referenced by
.Va qf .
.Pp
The
.Fn quota_on
function enables quotas for the filesystem associated with its
.Va qf
argument which may have been opened with
.Dv O_RDONLY
or
.Dv O_RDWR .
The
.Fn quota_on
function returns 0 if successful;
otherwise the value\~-1 is returned and the global variable
.Va errno
is set to indicate the error, see
.Xr quotactl 2
for the possible errors.
.Pp
The
.Fn quota_off
function disables quotas for the filesystem associated with its
.Va qf
argument which may have been opened with
.Dv O_RDONLY
or
.Dv O_RDWR .
The
.Fn quota_off
function returns 0 if successful;
otherwise the value\~-1 is returned and the global variable
.Va errno
is set to indicate the error, see
.Xr quotactl 2
for the possible errors.
.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_fsname
function returns a pointer to a buffer containing the path to the root
of the file system that corresponds to its
.Va qf
argument, as listed in
.Pa /etc/fstab .
Note that this may be a symbolic link to the actual directory.
.Pp
The
.Fn quota_qfname
function returns a pointer to a buffer containing the name of the
quota file that corresponds to its
.Va qf
argument.
Note that this may be a symbolic link to the actual file.
.Pp
The
.Fn quota_maxid
function returns the maximum user (or group)
.Va id
contained in the quota file associated with its
.Va qf
argument.
.Pp
The
.Fn quota_check_path
function checks if the specified path is within the filesystem that
corresponds to its
.Va qf
argument.
If the
.Va path
argument refers to a symbolic link,
.Fn quota_check_path
will follow it.
.Pp
The
.Fn quota_convert
function converts the quota file associated with its
.Va qf
argument to the data size specified by its
.Va wordsize
argument.
The supported wordsize arguments are 32 for the old 32-bit
quota file format and 64 for the new 64-bit quota file format.
The
.Fn quota_convert
function may only be called to operate on quota files that
are not currently active.
.Sh IMPLEMENTATION NOTES
If the underlying quota file is in or converted to the old 32-bit format,
limit and usage values written to the quota file will be clipped to 32 bits.
.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 error.
.Pp
The
.Fn quota_check_path
function returns\~1 for a positive result and\~0 for a negative
result.
If an error occurs, it returns\~-1 and sets
.Va errno
to indicate the error.
.Pp
The
.Fn quota_read ,
.Fn quota_write_limits ,
.Fn quota_write_usage ,
.Fn quota_convert ,
and
.Fn quota_close
functions return zero on success.
On error they return\~-1
and set
.Va errno
to indicate the error.
.Sh SEE ALSO
.Xr quotactl 2 ,
.Xr quota.user 5 ,
.Xr quota.group 5
.Sh HISTORY
The
.Nm quotafile
functions first appeared in
.Fx 8.1 .
.Sh AUTHORS
.An -nosplit
The
.Nm quotafile
functions and this manual page were written by
.An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org 
and
.An Marshall Kirk McKusick Aq mckusick@mckusick.com .