minix/lib/libc/sys/__quotactl.2

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.\"	@(#)quotactl.2	8.2 (Berkeley) 3/10/95
.\"
.Dd February 11, 2012
.Dt __QUOTACTL 2
.Os
.Sh NAME
.Nm __quotactl
.Nd manipulate file system quotas
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/quota.h
.In sys/quotactl.h
.Ft int
.Fn __quotactl "const char *path" "struct quotactl_args *args"
.Sh DESCRIPTION
The
.Fn __quotactl
call manipulates file system quotas.
This is an internal interface and is documented for reference purposes
only.
All application and utility code should use the
.Xr libquota 3
interface.
.Pp
The
.Fn __quotactl
function performs one of several quota-related operations on the file
system named by
.Fa path .
The operation and arguments to that operation are passed in the
.Fa args
argument.
The operation is stored in the
.Fa qc_op
member of
.Fa args .
The arguments are placed in a union such that the first and second
arguments of the operation
.Dv QUOTACTL_EXAMPLE
are found as the members
.Fa u.example.qc_arg1
and
.Fa u.example.qc_arg2 .
The descriptions below will refer to the operations as functions of
the form
.Fn QUOTACTL_EXAMPLE "int arg1" "int arg2"
and elide the encoding of these arguments into the
.Fa args
structure.
Explicit mention of the
.Fa path
argument is also omitted.
.Pp
There are fourteen quota control operations.
These are:
.Bl -tag -width abcdef
.\" ************************************************************
.It Fn QUOTACTL_STAT "struct quotastat *info"
Information about the quota implementation on the selected volume is
returned in
.Fa info .
The
.Dv quotastat
structure contains the following members:
.Bl -tag -width qs_restrictions
.It qs_implname
A human-readable string describing the underlying implementation of
quotas.
This is suitable for display to users
.Pq and system administrators
but should not be interpreted by software.
See
.Xr quota_getimplname 3 .
.It qs_numidtypes
The number of ID types supported by this implementation.
See
.Xr quota_getnumidtypes 3 .
.It qs_numobjtypes
The number of object types supported by this implementation.
See
.Xr quota_getnumobjtypes 3 .
.It qs_restrictions
Flags identifying specific semantic limitations of the implementation.
See
.Xr quota_getrestrictions 3 .
.El
.\" ************************************************************
.It Fn QUOTACTL_IDTYPESTAT "int idtype" "struct quotaidtypestat *info"
Information about a particular ID type on the selected volume is
returned in
.Fa info .
The
.Dv quotaidtypestat
structure contains the following members:
.Bl -tag -width qs_restrictions
.It qis_name
The name of the ID type.
See
.Xr quota_idtype_getname 3 .
.El
.\" ************************************************************
.It Fn QUOTACTL_OBJYPESTAT "int objtype" "struct quotaobjtypestat *info"
Information about a particular object type on the selected volume is
returned in
.Fa info .
The
.Dv quotaobjtypestat
structure contains the following members:
.Bl -tag -width qs_restrictions
.It qos_name
The name of the object type.
See
.Xr quota_objtype_getname 3 .
.It qos_isbytes
A flag that is nonzero if the object type is something measured in
bytes.
See
.Xr quota_objtype_isbytes 3 .
.El
.\" ************************************************************
.It Fn QUOTACTL_GET "const struct quotakey *key" "struct quotaval *val"
Return in
.Fa val
the quota information selected by
.Fa key .
See
.Xr quota_get 3 .
.\" ************************************************************
.It Fn QUOTACTL_PUT "const struct quotakey *key" "const struct quotaval *val"
The quota information selected by
.Fa key
is updated to the values provided in
.Fa val .
Note that the current usage information, which is file system
meta-data, cannot be updated via this interface.
If the usage information is incorrect a tool such as
.Xr fsck 8
or
.Xr quotacheck 8
with file-system-specific knowledge must be used to repair the
on-disk information.
See
.Xr quota_put 3 .
.\" ************************************************************
.It Fn QUOTACTL_DELETE "const struct quotakey *key"
The quota information selected by
.Fa key
is removed.
See
.Xr quota_delete 3 .
.\" ************************************************************
.It Fn QUOTACTL_CURSOROPEN "struct quotakcursor *cursor"
A cursor for iterating the quota information is created.
The
.Dv quotakcursor
structure is a semi-opaque type holding the iteration state used by
the quota implementation.
The caller is responsible for allocating and maintaining storage for
the cursor.
Every cursor that is opened should be closed.
It is not specified whether a cursor remains valid if
.Xr memcpy 3
is used to move it to a different location in user memory.
It is not specified whether or how a cursor may be duplicated.
Passing an uninitialized, corrupted, or closed cursor to operations
other than
.Fn QUOTACTL_CURSOROPEN
will produce unspecified behavior.
As per general standards for system calls such actions must not
produce undefined or materially adverse behavior in the kernel;
however, the effect on a user process may be arbitrary.
The
.Xr libquota 3
interface wraps the system call level quota cursors in a friendlier
interface.
See
.Xr quota_opencursor 3 .
.\" ************************************************************
.It Fn QUOTACTL_CURSORCLOSE "struct quotakcursor *cursor"
The cursor passed in is closed.
See
.Xr quotacursor_close 3 .
.\" ************************************************************
.It Fn QUOTACTL_CURSORSKIPIDTYPE "struct quotakcursor *cursor" "int idtype"
This operation provides a hint that iteration can skip over a
particular ID type.
The implementation is not obliged to honor the hint.
See
.Xr quotacursor_skipidtype 3 .
.\" ************************************************************
.It Fn QUOTACTL_CURSORGET "struct quotakcursor *cursor" "struct quotakey *keys" "struct quotaval *vals" "unsigned maxnum" "unsigned *ret"
This operation retrieves data at the current cursor position and
advances it.
Up to
.Fa maxnum
quota records are retrieved and stored into the arrays named by
.Fa keys
and
.Fa vals .
The number of records retrieved is stored into the variable pointed to
by
.Fa ret .
See
.Xr quotacursor_get 3
and
.Xr quotacursor_getn 3 .
.\" ************************************************************
.It Fn QUOTACTL_CURSORATEND "struct quotakcursor *cursor" "int *ret"
This operation generates a nonzero value if the cursor has reached the
end of the available quota information and zero otherwise.
The generated value is stored into the variable pointed to by
.Fa ret .
See
.Xr quotacursor_atend 3 .
.\" ************************************************************
.It Fn QUOTACTL_CURSORREWIND "struct quotakcursor *cursor"
This operation updates the cursor state so that further calls to
.Fn QUOTACTL_CURSORGET
will begin again at the start of the iteration.
See
.Xr quotacursor_rewind 3 .
.\" ************************************************************
.It Fn QUOTACTL_QUOTAON "int idtype" "const char *quotafile"
This operation is accepted only by old-style
.Pq Dq quota1
quota implementations.
Quotas for the ID type named by
.Fa idtype
are switched on, and the file
.Fa quotafile
is used to hold the quota information.
This operation can also be used when quotas are already switched on
to change the file used to hold the quota information.
Note however that as the current usage information in the file must be
consistent with the current state of the file system, in general it is
not safe to call
.Fn QUOTACTL_QUOTAON
except in single-user mode.
See
.Xr quotaon 8
for more information.
Normally
quotaon 8
is run during the boot sequence after
quotacheck 8 .
Also see
.Xr quota_quotaon 3 .
.\" ************************************************************
.It Fn QUOTACTL_QUOTAOFF "int idtype"
This operation is accepted only by old-style
.Pq Dq quota1
quota implementations.
Quotas for the ID type named by
.Fa idtype
are switched off.
Once quotas are switched off the file system behaves as if no quotas
are present.
Normally
quotaoff 8
is run during the shutdown sequence.
Also see
.Xr quota_quotaoff 3 .
.\" ************************************************************
.El
.Sh RETURN VALUES
On success,
.Fn __quotactl
returns 0.
Otherwise the value \-1 is returned and an error code reflecting the
reason for the failure is placed in
.Va errno .
.Sh ERRORS
.Fn __quotactl
failures include:
.Bl -tag -width Er
.It Bq Er EFAULT
A pointer points outside the process's allocated address space.
.It Bq Er EINVAL
The operation code was out of range; or
a requested ID or object type was out of range; or
a corrupted or invalid cursor was passed in.
.It Bq Er ENODEV
The requested action was inappropriate for
.Pq or not supported by
the selected volume.
.It Bq Er ENOENT
No quota information exists for the requested key.
.It Bq Er ENOMEM
Memory could not be allocated within the kernel.
.It Bq Er ENXIO
The target file system type is capable of supporting quotas, but
quotas are not enabled on the selected volume.
.It Bq Er EOPNOTSUPP
The target file system does not support quotas.
.El
.Sh SEE ALSO
.Xr quota 1 ,
.Xr libquota 3 ,
.Xr fstab 5 ,
.Xr edquota 8 ,
.Xr quotacheck 8 ,
.Xr quotaon 8 ,
.Xr quotarestore 8 ,
.Xr repquota 8
.Sh HISTORY
The original
.Fn quotactl
function call appeared in
.Bx 4.3 Reno .
The current
.Fn __quotactl
interface appeared in
.Nx 6.0 .
.Sh BUGS
As of this writing the error returns that occur in practice are not
always completely consistent with the intent documented above.
.Pp
There should be some way to integrate this call with the resource
limit interface provided by
.Xr setrlimit 2
and
.Xr getrlimit 2 .