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 internal interface and is documented for reference purposes only. All application and utility code should use the libquota(3) interface.

The __quotactl() function performs one of several quota-related operations 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 following members:

qs_implname

A human-readable string describing the underlying 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 implementation. 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 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 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 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 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 otherwise. 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 iteration. 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 quotacheck 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 ALSO

quota(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 current __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).