QUOTACTL(2)

QUOTACTL(2) | System Calls Manual | QUOTACTL(2)

# NAME

quotactl — manipulate file system quotas

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

#include <prop/proplib.h>
#include <sys/quota.h>

int
quotactl(const char *path, struct plistref *pref);

# DESCRIPTION

The quotactl() call manipulates file system quotas. A quota control command described by struct plistref * operates on the given filename path.

The top-level object of the property list sent to the kernel is a dictionary. It holds an integer with key "interface version", which must be 1 at this time. The key "commands" holds an array of dictionaries, each dictionary describe a command.

A command dictionary has the following keys:

command
  A string describing the command to execute.
data
  An array of arguments to the command.
type
  A string describing the type of quota to address. At this time this can be either "user" or "group".

The data array is an array of dictionaries, the dictionary structure depends on the command. If the command takes no arguments, the array must be present and empty. A dictionary describing a quota entry is common to many commands arguments or replies. It has the following keys:

block
  A dictionary describing quota values and limits for block usage.
file
  A dictionary describing quota values and limits for inode usage.
id
  either an unsigned integer, or the string "default". If this key is an integer, the value is the user or group id this quota entry belongs to. If this key is the string "default", this quota entry describe the default quotas for this file system.

The block or file dictionaries have the following structures:

usage
  an unsigned integer which contains the current usage.
soft
  unsigned integer containing the soft limit. The value defined by the macro UQUAD_MAX means there is no limit.
hard
  unsigned integer containing the hard limit. The value defined by the macro UQUAD_MAX means there is no limit.
grace time
  integer, the grace delay in seconds which should be applied when usage goes over the soft limit.
expire time
  integer, the time (in seconds since epoch) at which the grace delay expires. This key is only valid when usage is over the soft limit.

On return the "struct plistref *" contains an updated plist. It has the same structure as the plist sent to the kernel. The command dictionary gains an additional key "return", and integer holding an errno which is the status of the command. The data array is updated with replies from the command.

Commands are:

get version
  get the kernel quota version implementation for the specified file system and type. The data array in the reply has a single dictionary, which has a single integer key "version". At this time version can be "1" (the legacy quota implementation, with usages and limits stored in an external file) or "2" (the new quota implementation, where usages and limits are integrated in the file system metadata).
get
  Get a quota entry for the specified id. The command argument is one or more "id" keys. The command reply is the requested quota entries, as described above.
getall
  Get all quota entries (kernel quota version 2 only). This command takes no arguments, the reply is all the existing quota entries for this file system and type.
set
  create or update quota limits. Argument is one or more quota entries holding the updated quota limits. There is no reply.
clear
  clear specified quota entries (kernel quota version 2 only). Each quota entry is either returned to the free list if both block and file usage is 0, or limits are reverted to the default values otherwise. The command argument is one or more "id" keys. There is no reply.
quotaon
  enable the specified quota type on the specified file system (kernel quota version 1 only). Argument is a string with key "quotafile", which contains the path to the external file holding usages and limits. There is no reply.
quotaoff
  disable the specified quota type on the specified file system (kernel quota version 1 only). There is no arguments and no replies.

# RETURN VALUES

A successful call returns 0, otherwise the value -1 is returned and the global variable errno indicates the reason for the failure.

# FILES

Example of usage of the quotactl syscall, with construction of the pref argument an interpretation of the reply, can be found in the following NetBSD source files:

src/usr.bin/quota/getvfsquota.c
src/usr.sbin/repquota/repquota.c
src/usr.sbin/edquota/edquota.c
src/usr.sbin/quotaon/quotaon.c
src/sys/ufs/ufs/quota2_prop.c

# ERRORS

A quotactl() call will fail if:

[EFAULT]
  struct plistref * points outside the process's allocated address space, or an invalid addr was supplied; the associated structure could not be copied in or out of the kernel.
[EINVAL]
  The plist is invalid.
[ENOMEM]
  Memory could not be allocated to handle the plist.
[EOPNOTSUPP]
  Either the kernel has not been compiled with the QUOTA or QUOTA2 options, or the mounted file system doesn't support quota.

# SEE ALSO

quota(1), prop_send_syscall(3), proplib(3), fstab(5), edquota(8), quotacheck(8), quotactl(8), quotaon(8), repquota(8)

# HISTORY

The quotactl() function call appeared in 4.3BSD-Reno.

# BUGS

There should be some way to integrate this call with the resource limit interface provided by setrlimit(2) and getrlimit(2).

February 11, 2011 | NetBSD 5.99