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<title>22.1.1 File Operations
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<H2><A NAME=
"SECTION0024110000000000000000"></A><A NAME=
"msvcrt-files"></A>
<dl><dt><table cellpadding=
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"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>
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
<dl><dt><b><tt id='l2h-
5241' xml:id='l2h-
5241'
>LK_LOCK
</tt></b></dt>
<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
<dl><dt><b><tt id='l2h-
5242' xml:id='l2h-
5242'
>LK_NBLCK
</tt></b></dt>
<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.
<dl><dt><b><tt id='l2h-
5243' xml:id='l2h-
5243'
>LK_UNLCK
</tt></b></dt>
Unlocks the specified bytes, which must have been previously locked.
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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>
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><dt><table cellpadding=
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<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>
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.
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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>
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=
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2.4.2, documentation updated on
28 September
2005.
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