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<title>22.1.1 File Operations </title>
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<H2><A NAME="SECTION0024110000000000000000"></A><A NAME="msvcrt-files"></A>
<BR>
22.1.1 File Operations
</H2>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5240' xml:id='l2h-5240' class="function">locking</tt></b>(</nobr></td>
<td><var>fd, mode, nbytes</var>)</td></tr></table></dt>
<dd>
Lock part of a file based on file descriptor <var>fd</var> from the C
runtime. Raises <tt class="exception">IOError</tt> on failure. The locked region
of the file extends from the current file position for <var>nbytes</var>
bytes, and may continue beyond the end of the file. <var>mode</var> must
be one of the <tt class="constant">LK_<var>*</var></tt> constants listed below.
Multiple regions in a file may be locked at the same time, but may
not overlap. Adjacent regions are not merged; they must be unlocked
individually.
</dl>
<P>
<dl><dt><b><tt id='l2h-5241' xml:id='l2h-5241'>LK_LOCK</tt></b></dt>
<dd>
<dt><b><tt id='l2h-5247' xml:id='l2h-5247'>LK_RLCK</tt></b></dt><dd>
Locks the specified bytes. If the bytes cannot be locked, the
program immediately tries again after 1 second. If, after 10
attempts, the bytes cannot be locked, <tt class="exception">IOError</tt> is
raised.
</dd></dl>
<P>
<dl><dt><b><tt id='l2h-5242' xml:id='l2h-5242'>LK_NBLCK</tt></b></dt>
<dd>
<dt><b><tt id='l2h-5248' xml:id='l2h-5248'>LK_NBRLCK</tt></b></dt><dd>
Locks the specified bytes. If the bytes cannot be locked,
<tt class="exception">IOError</tt> is raised.
</dd></dl>
<P>
<dl><dt><b><tt id='l2h-5243' xml:id='l2h-5243'>LK_UNLCK</tt></b></dt>
<dd>
Unlocks the specified bytes, which must have been previously locked.
</dd></dl>
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<td><nobr><b><tt id='l2h-5244' xml:id='l2h-5244' class="function">setmode</tt></b>(</nobr></td>
<td><var>fd, flags</var>)</td></tr></table></dt>
<dd>
Set the line-end translation mode for the file descriptor <var>fd</var>.
To set it to text mode, <var>flags</var> should be <tt class="constant">os.O_TEXT</tt>;
for binary, it should be <tt class="constant">os.O_BINARY</tt>.
</dl>
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<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5245' xml:id='l2h-5245' class="function">open_osfhandle</tt></b>(</nobr></td>
<td><var>handle, flags</var>)</td></tr></table></dt>
<dd>
Create a C runtime file descriptor from the file handle
<var>handle</var>. The <var>flags</var> parameter should be a bit-wise OR of
<tt class="constant">os.O_APPEND</tt>, <tt class="constant">os.O_RDONLY</tt>, and
<tt class="constant">os.O_TEXT</tt>. The returned file descriptor may be used as a
parameter to <tt class="function">os.fdopen()</tt> to create a file object.
</dl>
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<td><nobr><b><tt id='l2h-5246' xml:id='l2h-5246' class="function">get_osfhandle</tt></b>(</nobr></td>
<td><var>fd</var>)</td></tr></table></dt>
<dd>
Return the file handle for the file descriptor <var>fd</var>. Raises
<tt class="exception">IOError</tt> if <var>fd</var> is not recognized.
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<span class="release-info">Release 2.4.3, documentation updated on 29 March 2006.</span>
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