__QUOTACTL(2) BSD System Calls Manual __QUOTACTL(2)NAME__quotactl — manipulate file system quotas
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/quota.h>
#include <sys/quotactl.h>
int
__quotactl(const char *path, struct quotactl_args *args);
DESCRIPTION
The __quotactl() call manipulates file system quotas. This is an inter‐
nal interface and is documented for reference purposes only. All appli‐
cation and utility code should use the libquota(3) interface.
The __quotactl() function performs one of several quota-related opera‐
tions on the file system named by path. The operation and arguments to
that operation are passed in the args argument. The operation is stored
in the qc_op member of args. The arguments are placed in a union such
that the first and second arguments of the operation QUOTACTL_EXAMPLE are
found as the members u.example.qc_arg1 and u.example.qc_arg2. The
descriptions below will refer to the operations as functions of the form
QUOTACTL_EXAMPLE(int arg1, int arg2) and elide the encoding of these
arguments into the args structure. Explicit mention of the path argument
is also omitted.
There are fourteen quota control operations. These are:
QUOTACTL_STAT(struct quotastat *info)
Information about the quota implementation on the selected volume
is returned in info. The quotastat structure contains the fol‐
lowing members:
qs_implname A human-readable string describing the underly‐
ing implementation of quotas. This is suitable
for display to users (and system administrators)
but should not be interpreted by software. See
quota_getimplname(3).
qs_numidtypes The number of ID types supported by this imple‐
mentation. See quota_getnumidtypes(3).
qs_numobjtypes The number of object types supported by this
implementation. See quota_getnumobjtypes(3).
qs_restrictions Flags identifying specific semantic limitations
of the implementation. See
quota_getrestrictions(3).
QUOTACTL_IDTYPESTAT(int idtype, struct quotaidtypestat *info)
Information about a particular ID type on the selected volume is
returned in info. The quotaidtypestat structure contains the
following members:
qis_name The name of the ID type. See
quota_idtype_getname(3).
QUOTACTL_OBJYPESTAT(int objtype, struct quotaobjtypestat *info)
Information about a particular object type on the selected volume
is returned in info. The quotaobjtypestat structure contains the
following members:
qos_name The name of the object type. See
quota_objtype_getname(3).
qos_isbytes A flag that is nonzero if the object type is
something measured in bytes. See
quota_objtype_isbytes(3).
QUOTACTL_GET(const struct quotakey *key, struct quotaval *val)
Return in val the quota information selected by key. See
quota_get(3).
QUOTACTL_PUT(const struct quotakey *key, const struct quotaval *val)
The quota information selected by key is updated to the values
provided in 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 fsck(8) or
quotacheck(8) with file-system-specific knowledge must be used to
repair the on-disk information. See quota_put(3).
QUOTACTL_DELETE(const struct quotakey *key)
The quota information selected by key is removed. See
quota_delete(3).
QUOTACTL_CURSOROPEN(struct quotakcursor *cursor)
A cursor for iterating the quota information is created. The
quotakcursor structure is a semi-opaque type holding the itera‐
tion state used by the quota implementation. The caller is
responsible for allocating and maintaining storage for the cur‐
sor. Every cursor that is opened should be closed. It is not
specified whether a cursor remains valid if memcpy(3) is used to
move it to a different location in user memory. It is not speci‐
fied whether or how a cursor may be duplicated. Passing an
uninitialized, corrupted, or closed cursor to operations other
than QUOTACTL_CURSOROPEN() will produce unspecified behavior. As
per general standards for system calls such actions must not pro‐
duce undefined or materially adverse behavior in the kernel; how‐
ever, the effect on a user process may be arbitrary. The
libquota(3) interface wraps the system call level quota cursors
in a friendlier interface. See quota_opencursor(3).
QUOTACTL_CURSORCLOSE(struct quotakcursor *cursor)
The cursor passed in is closed. See quotacursor_close(3).
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 quotacursor_skipidtype(3).
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 maxnum quota records are retrieved and stored
into the arrays named by keys and vals. The number of records
retrieved is stored into the variable pointed to by ret. See
quotacursor_get(3) and quotacursor_getn(3).
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 oth‐
erwise. The generated value is stored into the variable pointed
to by ret. See quotacursor_atend(3).
QUOTACTL_CURSORREWIND(struct quotakcursor *cursor)
This operation updates the cursor state so that further calls to
QUOTACTL_CURSORGET() will begin again at the start of the itera‐
tion. See quotacursor_rewind(3).
QUOTACTL_QUOTAON(int idtype, const char *quotafile)
This operation is accepted only by old-style (“quota1”) quota
implementations. Quotas for the ID type named by idtype are
switched on, and the file 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 QUOTACTL_QUOTAON()
except in single-user mode. See quotaon(8) for more information.
Normally quotaon 8 is run during the boot sequence after quo‐
tacheck 8 . Also see quota_quotaon(3).
QUOTACTL_QUOTAOFF(int idtype)
This operation is accepted only by old-style (“quota1”) quota
implementations. Quotas for the ID type named by 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 quota_quotaoff(3).
RETURN VALUES
On success, __quotactl() returns 0. Otherwise the value -1 is returned
and an error code reflecting the reason for the failure is placed in
errno.
ERRORS__quotactl() failures include:
[EFAULT] A pointer points outside the process's allocated
address space.
[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.
[ENODEV] The requested action was inappropriate for (or not
supported by) the selected volume.
[ENOENT] No quota information exists for the requested key.
[ENOMEM] Memory could not be allocated within the kernel.
[ENXIO] The target file system type is capable of supporting
quotas, but quotas are not enabled on the selected
volume.
[EOPNOTSUPP] The target file system does not support quotas.
SEE ALSOquota(1), libquota(3), fstab(5), edquota(8), quotacheck(8), quotaon(8),
quotarestore(8), repquota(8)HISTORY
The original quotactl() function call appeared in 4.3BSD-Reno. The cur‐
rent __quotactl() interface appeared in NetBSD 6.0.
BUGS
As of this writing the error returns that occur in practice are not
always completely consistent with the intent documented above.
There should be some way to integrate this call with the resource limit
interface provided by setrlimit(2) and getrlimit(2).
BSD February 11, 2012 BSD
