54c963102e
Because {NGROUPS_MAX} may become variable, its value should be obtained
using sysconf(3). If a #define is used anyway, it should be obtained by
including <limits.h> as that is in POSIX like getgroups(2) itself is.
<sys/param.h> is not in POSIX.
MFC after: 1 week
108 lines
3.1 KiB
Groff
108 lines
3.1 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getgroups.2 8.2 (Berkeley) 4/16/94
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.\" $FreeBSD$
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.\"
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.Dd January 21, 2011
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.Dt GETGROUPS 2
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.Os
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.Sh NAME
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.Nm getgroups
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.Nd get group access list
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft int
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.Fn getgroups "int gidsetlen" "gid_t *gidset"
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.Sh DESCRIPTION
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The
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.Fn getgroups
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system call
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gets the current group access list of the user process
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and stores it in the array
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.Fa gidset .
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The
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.Fa gidsetlen
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argument
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indicates the number of entries that may be placed in
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.Fa gidset .
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The
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.Fn getgroups
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system call
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returns the actual number of groups returned in
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.Fa gidset .
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At least one and as many as {NGROUPS_MAX}+1 values may be returned.
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If
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.Fa gidsetlen
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is zero,
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.Fn getgroups
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returns the number of supplementary group IDs associated with
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the calling process without modifying the array pointed to by
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.Fa gidset .
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.Pp
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The value of
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.Dv {NGROUPS_MAX}
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should be obtained using
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.Xr sysconf 3
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to avoid hard-coding it into the executable.
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.Sh RETURN VALUES
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A successful call returns the number of groups in the group set.
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A value of -1 indicates that an error occurred, and the error
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code is stored in the global variable
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.Va errno .
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.Sh ERRORS
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The possible errors for
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.Fn getgroups
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are:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The argument
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.Fa gidsetlen
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is smaller than the number of groups in the group set.
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.It Bq Er EFAULT
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The argument
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.Fa gidset
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specifies
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an invalid address.
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.El
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.Sh SEE ALSO
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.Xr setgroups 2 ,
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.Xr initgroups 3 ,
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.Xr sysconf 3
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.Sh STANDARDS
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The
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.Fn getgroups
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system call conforms to
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.St -p1003.1-2008 .
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.Sh HISTORY
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The
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.Fn getgroups
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system call appeared in
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.Bx 4.2 .
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