os161 / man / syscall / __getcwd.html
__getcwd.html
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<head>
<title>__getcwd</title>
<body bgcolor=#ffffff>
<h2 align=center>__getcwd</h2>
<h4 align=center>OS/161 Reference Manual</h4>

<h3>Name</h3>
<p>
__getcwd - get name of current working directory (backend)
</p>

<h3>Library</h3>
<p>
Standard C Library (libc, -lc)
</p>

<h3>Synopsis</h3>
<p>
<tt>#include &lt;unistd.h&gt;</tt><br>
<br>
<tt>int</tt><br>
<tt>__getcwd(char *</tt><em>buf</em><tt>,
size_t </tt><em>buflen</em><tt>);</tt>
</p>

<h3>Description</h3>
<p>
The name of the current directory is computed and stored in
<em>buf</em>, an area of size <em>buflen</em>. The length of data
actually stored, which must be non-negative, is returned.
</p>

<p>
Note: this call behaves like <A HREF=read.html>read</A> - the name
stored in <em>buf</em> is not 0-terminated.
</p>

<p>
This function is not meant to be called except by the C library;
application programmers should use <A HREF=../libc/getcwd.html>getcwd</A>
instead.
</p>

<p>
<tt>__getcwd</tt> (like all system calls) should be atomic. In
practice, because of complications associated with locking both up and
down trees, it often isn't quite.
Note that the kernel is not obliged to (and generally cannot) make the
<tt>__getcwd</tt> call atomic with respect to other threads in the same
process accessing the transfer buffer during the operation.
</p>

<h3>Return Values</h3>
<p>
On success, <tt>__getcwd</tt> returns the length of the data returned.
On error, -1 is returned, and <A HREF=errno.html>errno</A> is set
according to the error encountered.
</p>

<h3>Errors</h3>
<p>
The following error codes should be returned under the conditions
given. Other error codes may be returned for other cases not
mentioned here.

<table width=90%>
<tr><td width=5% rowspan=3>&nbsp;</td>
    <td width=10% valign=top>ENOENT</td>
				<td>A component of the pathname no
				longer exists.</td></tr>
<tr><td valign=top>EIO</td>	<td>A hard I/O error occurred.</td></tr>
<tr><td valign=top>EFAULT</td>	<td><em>buf</em> points to an invalid
				address.</td></tr>
</table>
</p>

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