226 lines
8.4 KiB
HTML
226 lines
8.4 KiB
HTML
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<title>fattach</title>
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<basefont size="3"> <a name="fattach"></a> <a name="tag_03_136"></a><!-- fattach -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_136_01"></a>NAME</h4>
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<blockquote>fattach - attach a STREAMS-based file descriptor to a file in the file system name space (<b>STREAMS</b>)</blockquote>
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<h4><a name="tag_03_136_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<div class="box"><code><tt><sup>[<a href="javascript:open_code('XSR')">XSR</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <<a href="../basedefs/stropts.h.html">stropts.h</a>><br>
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<br>
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int fattach(int</tt> <i>fildes</i><tt>, const char *</tt><i>path</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]"
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border="0"></tt></code></div>
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<tt><br>
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</tt></blockquote>
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<h4><a name="tag_03_136_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>fattach</i>() function shall attach a STREAMS-based file descriptor to a file, effectively associating a pathname with
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<i>fildes</i>. The application shall ensure that the <i>fildes</i> argument is a valid open file descriptor associated with a
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STREAMS file. The <i>path</i> argument points to a pathname of an existing file. The application shall have the appropriate
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privileges or be the owner of the file named by <i>path</i> and have write permission. A successful call to <i>fattach</i>() shall
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cause all pathnames that name the file named by <i>path</i> to name the STREAMS file associated with <i>fildes</i>, until the
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STREAMS file is detached from the file. A STREAMS file can be attached to more than one file and can have several pathnames
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associated with it.</p>
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<p>The attributes of the named STREAMS file shall be initialized as follows: the permissions, user ID, group ID, and times are set
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to those of the file named by <i>path</i>, the number of links is set to 1, and the size and device identifier are set to those of
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the STREAMS file associated with <i>fildes</i>. If any attributes of the named STREAMS file are subsequently changed (for example,
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by <a href="../functions/chmod.html"><i>chmod</i>()</a>), neither the attributes of the underlying file nor the attributes of the
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STREAMS file to which <i>fildes</i> refers shall be affected.</p>
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<p>File descriptors referring to the underlying file, opened prior to an <i>fattach</i>() call, shall continue to refer to the
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underlying file.</p>
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</blockquote>
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<h4><a name="tag_03_136_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, <i>fattach</i>() shall return 0. Otherwise, -1 shall be returned and <i>errno</i> set to indicate
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the error.</p>
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</blockquote>
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<h4><a name="tag_03_136_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>fattach</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EACCES]</dt>
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<dd>Search permission is denied for a component of the path prefix, or the process is the owner of <i>path</i> but does not have
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write permissions on the file named by <i>path</i>.</dd>
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<dt>[EBADF]</dt>
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<dd>The <i>fildes</i> argument is not a valid open file descriptor.</dd>
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<dt>[EBUSY]</dt>
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<dd>The file named by <i>path</i> is currently a mount point or has a STREAMS file attached to it.</dd>
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<dt>[ELOOP]</dt>
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<dd>A loop exists in symbolic links encountered during resolution of the <i>path</i> argument.</dd>
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<dt>[ENAMETOOLONG]</dt>
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<dd>
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The size of <i>path</i> exceeds {PATH_MAX} or a component of <i>path</i> is longer than {NAME_MAX}.</dd>
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<dt>[ENOENT]</dt>
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<dd>A component of <i>path</i> does not name an existing file or <i>path</i> is an empty string.</dd>
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<dt>[ENOTDIR]</dt>
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<dd>A component of the path prefix is not a directory.</dd>
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<dt>[EPERM]</dt>
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<dd>The effective user ID of the process is not the owner of the file named by <i>path</i> and the process does not have
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appropriate privilege.</dd>
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</dl>
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<p>The <i>fattach</i>() function may fail if:</p>
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<dl compact>
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<dt>[EINVAL]</dt>
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<dd>The <i>fildes</i> argument does not refer to a STREAMS file.</dd>
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<dt>[ELOOP]</dt>
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<dd>More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the <i>path</i> argument.</dd>
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<dt>[ENAMETOOLONG]</dt>
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<dd>
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Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.</dd>
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<dt>[EXDEV]</dt>
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<dd>A link to a file on another file system was attempted.</dd>
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</dl>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_136_06"></a>EXAMPLES</h4>
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<blockquote>
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<h5><a name="tag_03_136_06_01"></a>Attaching a File Descriptor to a File</h5>
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<p>In the following example, <i>fd</i> refers to an open STREAMS file. The call to <i>fattach</i>() associates this STREAM with the
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file <b>/tmp/named-STREAM</b>, such that any future calls to open <b>/tmp/named-STREAM</b>, prior to breaking the attachment via a
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call to <a href="../functions/fdetach.html"><i>fdetach</i>()</a>, will instead create a new file handle referring to the STREAMS
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file associated with <i>fd</i>.</p>
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<pre>
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<tt>#include <stropts.h>
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...
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int fd;
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char *filename = "/tmp/named-STREAM";
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int ret;
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<br>
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ret = fattach(fd, filename);
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</tt>
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</pre>
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</blockquote>
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<h4><a name="tag_03_136_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The <i>fattach</i>() function behaves similarly to the traditional <i>mount</i>() function in the way a file is temporarily
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replaced by the root directory of the mounted file system. In the case of <i>fattach</i>(), the replaced file need not be a
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directory and the replacing file is a STREAMS file.</p>
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</blockquote>
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<h4><a name="tag_03_136_08"></a>RATIONALE</h4>
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<blockquote>
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<p>The file attributes of a file which has been the subject of an <i>fattach</i>() call are specifically set because of an artefact
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of the original implementation. The internal mechanism was the same as for the <i>mount</i>() function. Since <i>mount</i>() is
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typically only applied to directories, the effects when applied to a regular file are a little surprising, especially as regards
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the link count which rigidly remains one, even if there were several links originally and despite the fact that all original links
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refer to the STREAM as long as the <i>fattach</i>() remains in effect.</p>
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</blockquote>
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<h4><a name="tag_03_136_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_136_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="fdetach.html"><i>fdetach</i>()</a> , <a href="isastream.html"><i>isastream</i>()</a> , the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/stropts.h.html"><i><stropts.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_136_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 4, Version 2.</p>
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</blockquote>
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<h4><a name="tag_03_136_12"></a>Issue 5</h4>
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<blockquote>
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<p>Moved from X/OPEN UNIX extension to BASE.</p>
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<p>The [EXDEV] error is added to the list of optional errors in the ERRORS section.</p>
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</blockquote>
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<h4><a name="tag_03_136_13"></a>Issue 6</h4>
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<blockquote>
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<p>This function is marked as part of the XSI STREAMS Option Group.</p>
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<p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p>
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<p>The wording of the mandatory [ELOOP] error condition is updated, and a second optional [ELOOP] error condition is added.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<hr>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
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"../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>
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