[apple/xnu.git] / bsd / man / man2 / getgroups.2

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.\" Copyright (c) 2008-2011 Apple Inc.  All rights reserved.
.\"
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.\" This file contains Original Code and/or Modifications of Original Code
.\" as defined in and that are subject to the Apple Public Source License
.\" Version 2.0 (the 'License'). You may not use this file except in
.\" compliance with the License. Please obtain a copy of the License at
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.\" The Original Code and all software distributed under the License are
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.\"
.\"	$NetBSD: getgroups.2,v 1.8 1995/02/27 12:32:57 cgd Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)getgroups.2	8.2 (Berkeley) 4/16/94
.\"
.Dd October 28, 2011
.Dt GETGROUPS 2
.Os BSD 4.2
.Sh NAME
.Nm getgroups
.Nd get group access list
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fo getgroups
.Fa "int gidsetsize"
.Fa "gid_t grouplist[]"
.Fc
.Sh DESCRIPTION
.Fn getgroups
gets the current group access list of the current user process
and stores it in the array 
.Fa grouplist[] .
The parameter
.Fa gidsetsize
indicates the number of entries that may be placed in 
.Fa grouplist[] .
.Fn getgroups
returns the actual number of groups returned in
.Fa grouplist[] .
However, no more than
.Dv {NGROUPS_MAX}
will be returned. If
.Fa gidsetsize
is 0, 
.Fn getgroups
returns the number of groups without modifying the
.Fa grouplist[]
array.
.Pp
Calling
.Xr initgroups 3
to opt-in for supplementary groups will cause
.Fn getgroups
to return a single entry, the GID that was passed to 
.Xr initgroups 3 .
.Pp
To provide compatibility with applications that use
.Fn getgroups
in environments where users may be in more than
.Dv {NGROUPS_MAX}
groups, a variant of
.Fn getgroups ,
obtained when compiling with either the macros
.Dv _DARWIN_UNLIMITED_GETGROUPS
or
.Dv _DARWIN_C_SOURCE
defined, can be used that is not limited to
.Dv {NGROUPS_MAX}
groups.
However, this variant only returns the user's default group access list and
not the group list modified by a call to
.Xr setgroups 2
(either in the current process or an ancestor process).
Use of
.Xr setgroups 2
is highly discouraged, and there is no foolproof way to determine if it has
been previously called.
.Sh RETURN VALUES
A successful call returns the number of groups in the group set.
Otherwise, a value of -1 is returned and the global integer variable
.Va errno
is set to indicate the error.
.Sh ERRORS
The possible errors for
.Fn getgroups
are:
.Bl -tag -width Er
.\" ==========
.It Bq Er EFAULT
The argument
.Fa grouplist
specifies an invalid address.
.\" ==========
.It Bq Er EINVAL
The argument
.Fa gidsetsize ,
although non-zero,
is smaller than the number of groups in the group set.
.El
.Sh LEGACY SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/types.h>
.Fd #include <unistd.h>
.Pp
The include files
.In sys/param.h
and
.In sys/types.h
are necessary.
.Sh SEE ALSO
.Xr setgroups 2 ,
.Xr initgroups 3 ,
.Xr compat 5
.Sh HISTORY
The
.Fn getgroups
function call appeared in
.Bx 4.2 .
Commit	Line	Data
b0d623f7	1	.\"
316670eb	2	.\" Copyright (c) 2008-2011 Apple Inc. All rights reserved.
b0d623f7 A	3	.\"
	4	.\" @APPLE_LICENSE_HEADER_START@
	5	.\"
	6	.\" This file contains Original Code and/or Modifications of Original Code
	7	.\" as defined in and that are subject to the Apple Public Source License
	8	.\" Version 2.0 (the 'License'). You may not use this file except in
	9	.\" compliance with the License. Please obtain a copy of the License at
	10	.\" http://www.opensource.apple.com/apsl/ and read it before using this
	11	.\" file.
	12	.\"
	13	.\" The Original Code and all software distributed under the License are
	14	.\" distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	15	.\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	16	.\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	17	.\" FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	18	.\" Please see the License for the specific language governing rights and
	19	.\" limitations under the License.
	20	.\"
	21	.\" @APPLE_LICENSE_HEADER_END@
	22	.\"
	23	.\"
9bccf70c A	24	.\" $NetBSD: getgroups.2,v 1.8 1995/02/27 12:32:57 cgd Exp $
	25	.\"
	26	.\" Copyright (c) 1983, 1991, 1993
	27	.\" The Regents of the University of California. All rights reserved.
	28	.\"
	29	.\" Redistribution and use in source and binary forms, with or without
	30	.\" modification, are permitted provided that the following conditions
	31	.\" are met:
	32	.\" 1. Redistributions of source code must retain the above copyright
	33	.\" notice, this list of conditions and the following disclaimer.
	34	.\" 2. Redistributions in binary form must reproduce the above copyright
	35	.\" notice, this list of conditions and the following disclaimer in the
	36	.\" documentation and/or other materials provided with the distribution.
	37	.\" 3. All advertising materials mentioning features or use of this software
	38	.\" must display the following acknowledgement:
	39	.\" This product includes software developed by the University of
	40	.\" California, Berkeley and its contributors.
	41	.\" 4. Neither the name of the University nor the names of its contributors
	42	.\" may be used to endorse or promote products derived from this software
	43	.\" without specific prior written permission.
	44	.\"
	45	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	46	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	47	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	48	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	49	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	50	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	51	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	52	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	53	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	54	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	55	.\" SUCH DAMAGE.
	56	.\"
	57	.\" @(#)getgroups.2 8.2 (Berkeley) 4/16/94
	58	.\"
316670eb	59	.Dd October 28, 2011
9bccf70c A	60	.Dt GETGROUPS 2
	61	.Os BSD 4.2
	62	.Sh NAME
	63	.Nm getgroups
	64	.Nd get group access list
	65	.Sh SYNOPSIS
9bccf70c A	66	.Fd #include <unistd.h>
9bccf70c A	67	.Ft int
2d21ac55 A	68	.Fo getgroups
	69	.Fa "int gidsetsize"
	70	.Fa "gid_t grouplist[]"
	71	.Fc
9bccf70c	72	.Sh DESCRIPTION
b0d623f7	73	.Fn getgroups
9bccf70c A	74	gets the current group access list of the current user process
9bccf70c A	75	and stores it in the array
2d21ac55	76	.Fa grouplist[] .
9bccf70c	77	The parameter
2d21ac55	78	.Fa gidsetsize
9bccf70c	79	indicates the number of entries that may be placed in
2d21ac55	80	.Fa grouplist[] .
b0d623f7	81	.Fn getgroups
9bccf70c	82	returns the actual number of groups returned in
2d21ac55	83	.Fa grouplist[] .
b0d623f7	84	However, no more than
9bccf70c	85	.Dv {NGROUPS_MAX}
b0d623f7	86	will be returned. If
2d21ac55	87	.Fa gidsetsize
9bccf70c A	88	is 0,
	89	.Fn getgroups
	90	returns the number of groups without modifying the
2d21ac55	91	.Fa grouplist[]
9bccf70c	92	array.
6d2010ae	93	.Pp
316670eb A	94	Calling
	95	.Xr initgroups 3
	96	to opt-in for supplementary groups will cause
	97	.Fn getgroups
	98	to return a single entry, the GID that was passed to
	99	.Xr initgroups 3 .
	100	.Pp
6d2010ae A	101	To provide compatibility with applications that use
	102	.Fn getgroups
	103	in environments where users may be in more than
	104	.Dv {NGROUPS_MAX}
	105	groups, a variant of
	106	.Fn getgroups ,
	107	obtained when compiling with either the macros
	108	.Dv _DARWIN_UNLIMITED_GETGROUPS
	109	or
	110	.Dv _DARWIN_C_SOURCE
	111	defined, can be used that is not limited to
	112	.Dv {NGROUPS_MAX}
	113	groups.
	114	However, this variant only returns the user's default group access list and
	115	not the group list modified by a call to
	116	.Xr setgroups 2
	117	(either in the current process or an ancestor process).
	118	Use of
	119	.Xr setgroups 2
	120	is highly discouraged, and there is no foolproof way to determine if it has
	121	been previously called.
9bccf70c A	122	.Sh RETURN VALUES
9bccf70c A	123	A successful call returns the number of groups in the group set.
2d21ac55 A	124	Otherwise, a value of -1 is returned and the global integer variable
	125	.Va errno
	126	is set to indicate the error.
9bccf70c A	127	.Sh ERRORS
	128	The possible errors for
	129	.Fn getgroups
	130	are:
	131	.Bl -tag -width Er
2d21ac55 A	132	.\" ==========
	133	.It Bq Er EFAULT
	134	The argument
	135	.Fa grouplist
	136	specifies an invalid address.
	137	.\" ==========
9bccf70c A	138	.It Bq Er EINVAL
9bccf70c A	139	The argument
2d21ac55 A	140	.Fa gidsetsize ,
2d21ac55 A	141	although non-zero,
9bccf70c	142	is smaller than the number of groups in the group set.
9bccf70c	143	.El
2d21ac55 A	144	.Sh LEGACY SYNOPSIS
	145	.Fd #include <sys/param.h>
	146	.Fd #include <sys/types.h>
	147	.Fd #include <unistd.h>
	148	.Pp
	149	The include files
	150	.In sys/param.h
	151	and
	152	.In sys/types.h
	153	are necessary.
9bccf70c A	154	.Sh SEE ALSO
9bccf70c A	155	.Xr setgroups 2 ,
2d21ac55 A	156	.Xr initgroups 3 ,
2d21ac55 A	157	.Xr compat 5
9bccf70c A	158	.Sh HISTORY
	159	The
	160	.Fn getgroups
	161	function call appeared in
	162	.Bx 4.2 .