add directory Ref-docs
This commit is contained in:
gohigh
188
Ref-docs/POSIX/susv3/functions/getgroups.html
Normal file
188
Ref-docs/POSIX/susv3/functions/getgroups.html
Normal file
@@ -0,0 +1,188 @@
|
||||
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
||||
<html>
|
||||
<head>
|
||||
<meta name="generator" content="HTML Tidy, see www.w3.org">
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
|
||||
<link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 -->
|
||||
<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
|
||||
<title>getgroups</title>
|
||||
</head>
|
||||
<body bgcolor="white">
|
||||
|
||||
<basefont size="3"> <a name="getgroups"></a> <a name="tag_03_224"></a><!-- getgroups -->
|
||||
<!--header start-->
|
||||
<center><font size="2">The Open Group Base Specifications Issue 6<br>
|
||||
IEEE Std 1003.1-2001<br>
|
||||
Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
|
||||
|
||||
<!--header end-->
|
||||
<hr size="2" noshade>
|
||||
<h4><a name="tag_03_224_01"></a>NAME</h4>
|
||||
|
||||
<blockquote>getgroups - get supplementary group IDs</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_02"></a>SYNOPSIS</h4>
|
||||
|
||||
<blockquote class="synopsis">
|
||||
<p><code><tt>#include <<a href="../basedefs/unistd.h.html">unistd.h</a>><br>
|
||||
<br>
|
||||
int getgroups(int</tt> <i>gidsetsize</i><tt>, gid_t</tt> <i>grouplist</i><tt>[]);<br>
|
||||
</tt></code></p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_03"></a>DESCRIPTION</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>The <i>getgroups</i>() function shall fill in the array <i>grouplist</i> with the current supplementary group IDs of the calling
|
||||
process. It is implementation-defined whether <i>getgroups</i>() also returns the effective group ID in the <i>grouplist</i>
|
||||
array.</p>
|
||||
|
||||
<p>The <i>gidsetsize</i> argument specifies the number of elements in the array <i>grouplist</i>. The actual number of group IDs
|
||||
stored in the array shall be returned. The values of array entries with indices greater than or equal to the value returned are
|
||||
undefined.</p>
|
||||
|
||||
<p>If <i>gidsetsize</i> is 0, <i>getgroups</i>() shall return the number of group IDs that it would otherwise return without
|
||||
modifying the array pointed to by <i>grouplist</i>.</p>
|
||||
|
||||
<p>If the effective group ID of the process is returned with the supplementary group IDs, the value returned shall always be
|
||||
greater than or equal to one and less than or equal to the value of {NGROUPS_MAX}+1.</p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_04"></a>RETURN VALUE</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>Upon successful completion, the number of supplementary group IDs shall be returned. A return value of -1 indicates failure and
|
||||
<i>errno</i> shall be set to indicate the error.</p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_05"></a>ERRORS</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>The <i>getgroups</i>() function shall fail if:</p>
|
||||
|
||||
<dl compact>
|
||||
<dt>[EINVAL]</dt>
|
||||
|
||||
<dd>The <i>gidsetsize</i> argument is non-zero and less than the number of group IDs that would have been returned.</dd>
|
||||
</dl>
|
||||
</blockquote>
|
||||
|
||||
<hr>
|
||||
<div class="box"><em>The following sections are informative.</em></div>
|
||||
|
||||
<h4><a name="tag_03_224_06"></a>EXAMPLES</h4>
|
||||
|
||||
<blockquote>
|
||||
<h5><a name="tag_03_224_06_01"></a>Getting the Supplementary Group IDs of the Calling Process</h5>
|
||||
|
||||
<p>The following example places the current supplementary group IDs of the calling process into the <i>group</i> array.</p>
|
||||
|
||||
<pre>
|
||||
<tt>#include <sys/types.h>
|
||||
#include <unistd.h>
|
||||
...
|
||||
gid_t *group;
|
||||
int nogroups;
|
||||
long ngroups_max;
|
||||
<br>
|
||||
ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
|
||||
group = (gid_t *)malloc(ngroups_max *sizeof(gid_t));
|
||||
<br>
|
||||
ngroups = getgroups(ngroups_max, group);
|
||||
</tt>
|
||||
</pre>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_07"></a>APPLICATION USAGE</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>None.</p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_08"></a>RATIONALE</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>The related function <i>setgroups</i>() is a privileged operation and therefore is not covered by this volume of
|
||||
IEEE Std 1003.1-2001.</p>
|
||||
|
||||
<p>As implied by the definition of supplementary groups, the effective group ID may appear in the array returned by
|
||||
<i>getgroups</i>() or it may be returned only by <a href="../functions/getegid.html"><i>getegid</i>()</a>. Duplication may exist,
|
||||
but the application needs to call <a href="../functions/getegid.html"><i>getegid</i>()</a> to be sure of getting all of the
|
||||
information. Various implementation variations and administrative sequences cause the set of groups appearing in the result of
|
||||
<i>getgroups</i>() to vary in order and as to whether the effective group ID is included, even when the set of groups is the same
|
||||
(in the mathematical sense of "set"). (The history of a process and its parents could affect the details of the result.)</p>
|
||||
|
||||
<p>Application writers should note that {NGROUPS_MAX} is not necessarily a constant on all implementations.</p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_09"></a>FUTURE DIRECTIONS</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>None.</p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_10"></a>SEE ALSO</h4>
|
||||
|
||||
<blockquote>
|
||||
<p><a href="getegid.html"><i>getegid</i>()</a> , <a href="setgid.html"><i>setgid</i>()</a> , the Base Definitions volume of
|
||||
IEEE Std 1003.1-2001, <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a>, <a href=
|
||||
"../basedefs/unistd.h.html"><i><unistd.h></i></a></p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_11"></a>CHANGE HISTORY</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>First released in Issue 3. Included for alignment with the POSIX.1-1988 standard.</p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_12"></a>Issue 5</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>Normative text previously in the APPLICATION USAGE section is moved to the DESCRIPTION.</p>
|
||||
</blockquote>
|
||||
|
||||
<h4><a name="tag_03_224_13"></a>Issue 6</h4>
|
||||
|
||||
<blockquote>
|
||||
<p>In the SYNOPSIS, the optional include of the <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> header is
|
||||
removed.</p>
|
||||
|
||||
<p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p>
|
||||
|
||||
<ul>
|
||||
<li>
|
||||
<p>The requirement to include <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> has been removed. Although <a
|
||||
href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> was required for conforming implementations of previous POSIX
|
||||
specifications, it was not required for UNIX applications.</p>
|
||||
</li>
|
||||
|
||||
<li>
|
||||
<p>A return value of 0 is not permitted, because {NGROUPS_MAX} cannot be 0. This is a FIPS requirement.</p>
|
||||
</li>
|
||||
</ul>
|
||||
|
||||
<p>The following changes were made to align with the IEEE P1003.1a draft standard:</p>
|
||||
|
||||
<ul>
|
||||
<li>
|
||||
<p>Explanation added that the effective group ID may be included in the supplementary group list.</p>
|
||||
</li>
|
||||
</ul>
|
||||
</blockquote>
|
||||
|
||||
<div class="box"><em>End of informative text.</em></div>
|
||||
|
||||
<hr>
|
||||
<hr size="2" noshade>
|
||||
<center><font size="2"><!--footer start-->
|
||||
UNIX ® is a registered Trademark of The Open Group.<br>
|
||||
POSIX ® is a registered Trademark of The IEEE.<br>
|
||||
[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
|
||||
"../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>
|
||||
]</font></center>
|
||||
|
||||
<!--footer end-->
|
||||
<hr size="2" noshade>
|
||||
</body>
|
||||
</html>
|
||||
|
||||
Reference in New Issue
Block a user