ibm-information-center/dist/eclipse/plugins/i5OS.ic.apis_5.4.0.1/fchown.htm

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<title>fchown()--Change Owner and Group of File by Descriptor</title>
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<h2>fchown()--Change Owner and Group of File by Descriptor</h2>
<div class="box" style="width: 70%;">
<br>
&nbsp;&nbsp;Syntax<br>
<pre>
#include &lt;unistd.h&gt;
int fchown(int <em>fildes</em>, uid_t <em>owner</em>, gid_t <em>group</em>);
</pre>
&nbsp;&nbsp;Service Program Name: QP0LLIB1<br>
<!-- iddvc RMBR -->
<br>
&nbsp;&nbsp;Default Public Authority: *USE<br>
<!-- iddvc RMBR -->
<br>
&nbsp;&nbsp;Threadsafe: Conditional; see <a href="#USAGE_NOTES">Usage Notes</a>.<br>
<!-- iddvc RMBR -->
<br>
</div>
<p>The <strong>fchown()</strong> function changes the owner and group of a
file. The permissions of the previous owner or primary group to the object are
revoked.</p>
<p>If the file is checked out by another user (someone other than the user
profile of the current job), <strong>fchown()</strong> fails with the [EBUSY]
error.</p>
<p>When <strong>fchown()</strong> completes successfully, it marks the change
time of the file to be updated.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong><em>fildes</em></strong></dt>
<dd>(Input) The file descriptor of the file.<br>
</dd>
<dt><strong><em>owner</em></strong></dt>
<dd>(Input) The new user ID to be set for file.<br>
</dd>
<dt><strong><em>group</em></strong></dt>
<dd>(Input) The new group ID to be set for file.</dd>
</dl>
<p><strong>Note:</strong> Changing the owner or the primary group causes the
S_ISUID (set-user-ID) and S_ISGID (set-group-ID) bits of the file mode to be
cleared, unless the caller has *ALLOBJ special authority. If the caller does
have *ALLOBJ special authority, the bits are not changed. This does not apply
to directories, FIFO special files, or pipes. See the <a href="chmod.htm">
chmod()</a> documentation.</p>
<br>
<h3>Authorities</h3>
<p><strong>Note:</strong> Adopted authority is not used.</p>
<strong><a name="TBLAFCHOW">Authorization Required for fchown() (excluding
QSYS.LIB, independent ASP QSYS.LIB, and QDLS)</a></strong><br>
<br>
<table border cellpadding="5" width="80%">
<!-- cols="60 20 20" -->
<tr>
<th align="left" valign="bottom">Object Referred to</th>
<th align="left" valign="bottom">Authority Required</th>
<th align="left" valign="bottom">errno</th>
</tr>
<tr>
<td align="left" valign="top" width="45%">Object, when changing the owner</td>
<td align="left" valign="top" width="45%">Owner and *OBJEXIST<br>
(also see <strong>Note 1</strong>)</td>
<td align="left" valign="top" width="10%">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">Object, when changing the primary group</td>
<td align="left" valign="top">See <strong>Note 2</strong></td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">Previous owner's user profile, when changing the
owner</td>
<td align="left" valign="top">*DLT</td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">New owner's user profile, when changing the
owner</td>
<td align="left" valign="top">*ADD</td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">User profile of previous primary group, when
changing the primary group</td>
<td align="left" valign="top">*DLT</td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">New primary group's user profile, when changing
the primary group</td>
<td align="left" valign="top">*ADD</td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top" colspan="3"><strong>Note:</strong>
<ol type="1">
<li>You do not need the listed authority if you have *ALLOBJ special
authority.</li>
<li>At least one of the following must be true:
<ol type="a">
<li>You have *ALLOBJ special authority.</li>
<li>You are the owner <u>and</u> either of the following:
<ul>
<li>The new primary group is the primary group of the job.</li>
<li>The new primary group is one of the supplementary groups of the job.</li>
</ul>
</li>
</ol>
</li>
</ol>
</td>
</tr>
</table>
<br>
<p><strong><a name="TBLAFCHOW2">Authorization Required for fchown() in the
QSYS.LIB and independent ASP QSYS.LIB File Systems</a></strong><br>
</p>
<table border cellpadding="5" width="80%">
<!-- cols="60 20 20" -->
<tr>
<th align="left" valign="bottom">Object Referred to</th>
<th align="left" valign="bottom">Authority Required</th>
<th align="left" valign="bottom">errno</th>
</tr>
<tr>
<td align="left" valign="top" width="45%">Object, when changing the owner</td>
<td align="left" valign="top" width="45%">See <strong>Note</strong> (1)</td>
<td align="left" valign="top" width="10%">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">Object, when changing the primary group</td>
<td align="left" valign="top">See <strong>Note</strong> (2)</td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top" colspan="3"><strong>Note:</strong> The required
authorization varies for each object type. See the following commands in the <a
href="../bookssc415302.pdf" target="_blank">iSeries Security
Reference</a><img src="wbpdf.gif" alt="Link to PDF"> book for details:
<ol type="1">
<li>CHGOBJOWN</li>
<li>CHGOBJPGP</li>
</ol>
</td>
</tr>
</table>
<br>
<p><strong><a name="TBLAFCHOW3">Authorization Required for fchown() in the QDLS
File System</a></strong><br>
</p>
<table border cellpadding="5" width="80%">
<!-- cols="60 20 20" -->
<tr>
<th align="left" valign="bottom">Object Referred to</th>
<th align="left" valign="bottom">Authority Required</th>
<th align="left" valign="bottom">errno</th>
</tr>
<tr>
<td align="left" valign="top" width="45%">Object</td>
<td align="left" valign="top" width="45%">*ALLOBJ Special<br>
Authority or Owner</td>
<td align="left" valign="top" width="10%">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">Previous owner's user profile, when changing the
owner</td>
<td align="left" valign="top">*DLT</td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">New owner's user profile, when changing the
owner</td>
<td align="left" valign="top">*ADD</td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">Previous primary group's user profile, when
changing the primary group</td>
<td align="left" valign="top">*DLT</td>
<td align="left" valign="top">EPERM</td>
</tr>
<tr>
<td align="left" valign="top">New primary group's user profile, when changing
the primary group</td>
<td align="left" valign="top">*ADD</td>
<td align="left" valign="top">EPERM</td>
</tr>
</table>
<br>
<p><strong><a name="TBLAFCHOW4">Authorization Required for fchown() in the QOPT
File System</a></strong><br>
</p>
<table border cellpadding="5" width="80%">
<!-- cols="60 20 20" -->
<tr>
<th align="left" valign="bottom">Object Referred to</th>
<th align="left" valign="bottom">Authority Required</th>
<th align="left" valign="bottom">errno</th>
</tr>
<tr>
<td align="left" valign="top" width="45%">Volume authorization list</td>
<td align="left" valign="top" width="45%">*CHANGE</td>
<td align="left" valign="top" width="10%">EACCES</td>
</tr>
<tr>
<td align="left" valign="top">Each directory in the path name preceding the
object.</td>
<td align="left" valign="top">*X</td>
<td align="left" valign="top">EACCES</td>
</tr>
<tr>
<td align="left" valign="top">Object</td>
<td align="left" valign="top">*ALLOBJ Special<br>
Authority or Owner</td>
<td align="left" valign="top">EPERM</td>
</tr>
</table>
<br>
<h3>Return Value</h3>
<dl compact>
<dt><em>0</em></dt>
<dd><strong>fchown()</strong> was successful.</dd>
<dt><em>-1</em></dt>
<dd><strong>fchown()</strong> was not successful. The <em>errno</em> global
variable is set to indicate the error.</dd>
</dl>
<br>
<h3>Error Conditions</h3>
<p>If <strong>fchown()</strong> is not successful, <em>errno</em> usually
indicates one of the following errors. Under some conditions, <em>errno</em>
could indicate an error other than those listed here.</p>
<table cellpadding="5">
<!-- cols="25 75" -->
<tr>
<th align="left" valign="bottom">Error condition</th>
<th align="left" valign="bottom">Additional information</th>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EACCES">EACCES</a>]</em></td>
<td align="left" valign="top">
<p>If you are accessing a remote file through the Network File System, update
operations to file permissions at the server are not reflected at the client
until updates to data that is stored locally by the Network File System take
place. (Several options on the Add Mounted File System (ADDMFS) command
determine the time between refresh operations of local data.) Access to a
remote file may also fail due to different mappings of user IDs (UID) or group
IDs (GID) on the local and remote systems.</p>
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EAGAIN">EAGAIN</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EBADF">EBADF</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EBADFID">EBADFID</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EBADNAME">EBADNAME</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EBUSY">EBUSY</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ECONVERT">ECONVERT</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EDAMAGE">EDAMAGE</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EINTR">EINTR</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EINVAL">EINVAL</a>]</em></td>
<td align="left" valign="top">
<p>For example, <em>owner</em> or <em>group</em> is not a valid user ID (UID) or group ID
(GID). Or, the <em>owner</em> is the current primary group of the object.</p>
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EIO">EIO</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EJRNDAMAGE">EJRNDAMAGE</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EJRNENTTOOLONG">EJRNENTTOOLONG</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EJRNINACTIVE">EJRNINACTIVE</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EJRNRCVSPC">EJRNRCVSPC</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr><tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENAMETOOLONG">ENAMETOOLONG</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENEWJRN">ENEWJRN</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENEWJRNRCV">ENEWJRNRCV</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENOENT">ENOENT</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENOSPC">ENOSPC</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENOSYS">ENOSYS</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENOSYSRSC">ENOSYSRSC</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENOTAVAIL">ENOTAVAIL</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENOTDIR">ENOTDIR</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENOTSAFE">ENOTSAFE</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ENOTSUP">ENOTSUP</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EPERM">EPERM</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EROOBJ">EROOBJ</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#ESTALE">ESTALE</a>]</em></td>
<td align="left" valign="top">
<p>If you are accessing a remote file through the Network File System, the file
may have been deleted at the server.</p>
</td>
</tr>
<tr>
<td align="left" valign="top">
<em>[<a href="unix14.htm#EUNKNOWN">EUNKNOWN</a>]</em></td>
<td align="left" valign="top">
&nbsp;
</td>
</tr>
</table>
<br>
<br>
<h3>Error Messages</h3>
<p>The following messages may be sent from this function:</p>
<table width="100%">
<tr>
<th align="left" valign="top">Message ID</th>
<th align="left" valign="top">Error Message Text</th>
</tr>
<tr>
<td width="15%" valign="top">CPE3418 E</td>
<td width="85%" valign="top">Possible APAR condition or hardware failure.</td>
</tr>
<tr>
<td valign="top">CPFA0D4 E</td>
<td valign="top">File system error occurred. Error number &amp;1.</td>
</tr>
<tr>
<td valign="top">CPF3CF2 E</td>
<td valign="top">Error(s) occurred during running of &amp;1 API.</td>
</tr>
<tr>
<td valign="top">CPF9872 E</td>
<td valign="top">Program or service program &amp;1 in library &amp;2 ended.
Reason code &amp;3.</td>
</tr>
</table>
<br>
<br>
<h3><a name="usage_notes">Usage Notes</a></h3>
<ol type="1">
<li>This function will fail with error code [ENOTSAFE] when all the following
conditions are true:<br>
<br>
<ul>
<li>Where multiple threads exist in the job.<br>
</li>
<li>The object on which this function is operating resides in a file system
that is not threadsafe. Only the following file systems are threadsafe for this
function:<br>
<br>
<ul>
<li>"Root" (/)</li>
<li>QOpenSys</li>
<li>User-defined</li>
<li>QNTC</li>
<li>QSYS.LIB</li>
<li>Independent ASP QSYS.LIB</li>
<li>QOPT</li>
<li>Network File System</li>
<li>QFileSvr.400</li>
</ul>
</li>
</ul>
<br>
</li>
<li>QDLS File System Differences
<p>The owner and primary group of the /QDLS directory (root folder) cannot be
changed. If an attempt is made to change the owner and primary group, a
[ENOTSUP] error is returned.</p>
<br>
</li>
<li>QOPT File System Differences
<p>Changing the owner and primary group is allowed only for an object that
exists on a volume formatted in Universal Disk Format (UDF). For all other
media formats, ENOTSUP will be returned.</p>
<p>QOPT file system objects that have owners will not be recognized by the Work
with Objects by Owner (WRKOBJOWN) CL command. Likewise, QOPT objects that have
a primary group will not be recognized by the Work Objects by Primary Group
(WRKOBJPGP) CL command.</p>
<br>
</li>
<li>QFileSvr.400 File System Differences
<p>The QFileSvr.400 file system does not support <strong>fchown()</strong>.</p>
<br>
</li>
<li>QNetWare File System Differences
<p>Primary group is not supported. The GID must be zero on this API.</p>
<br>
</li>
<li>QNTC File System Differences
<p>The owner of files and directories cannot be changed. All files and
directories in QNTC are owned by the QDFTOWN user profile.</p>
</li>
</ol>
<br>
<h3>Related Information</h3>
<ul>
<li>The &lt;<strong>unistd.h</strong>&gt; file (see <a href="unix13.htm">Header
Files for UNIX-Type Functions</a>)<br>
</li>
<li><a href="chown.htm">chown()</a>--Change Owner and Group of File<br>
</li>
<li><a href="chmod.htm">chmod()</a>--Change File Authorizations<br>
</li>
<li><a href="fchmod.htm">fchmod()</a>--Change File Authorizations by
Descriptor<br>
</li>
<li><a href="mkdir.htm">mkdir()</a>--Make Directory<br>
</li>
<li><a href="open.htm">open()</a>--Open File<br>
</li>
<li><a href="stat.htm">stat()</a>--Get File Information</li>
</ul>
<br>
<h3>Example</h3>
<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
for information pertaining to code examples.</p>
<p>The following example changes the owner ID and group ID:</p>
<pre>
#include &lt;stdio.h&gt;
#include &lt;fcntl.h&gt;
#include &lt;unistd.h&gt;
#include &lt;sys/stat.h&gt;
#include &lt;sys/types.h&gt;
main() {
char fn[]="temp.file";
int file_descriptor;
struct stat info;
if ((file_descriptor = creat(fn, S_IWUSR)) &lt; 0)
perror("creat() error");
else {
stat(fn, &amp;info);
printf("original owner was %d and group was %d\n", info.st_uid,
info.st_gid);
if (fchown(file_descriptor, 152, 0) != 0)
perror("fchown() error");
else {
stat(fn, &amp;info);
printf("after fchown(), owner is %d and group is %d\n",
info.st_uid, info.st_gid);
}
close(file_descriptor);
unlink(fn);
}
}
</pre>
<p><strong>Output:</strong></p>
<pre>
original owner was 137 and group was 0
after fchown(), owner is 152 and group is 0
</pre>
<br>
<hr>
API introduced: V3R1
<hr>
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