170 lines
5.7 KiB
HTML
170 lines
5.7 KiB
HTML
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<title>posix_fallocate</title>
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<basefont size="3"> <a name="posix_fallocate"></a> <a name="tag_03_422"></a><!-- posix_fallocate -->
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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_422_01"></a>NAME</h4>
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<blockquote>posix_fallocate - file space control (<b>ADVANCED REALTIME</b>)</blockquote>
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<h4><a name="tag_03_422_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('ADV')">ADV</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <<a href="../basedefs/fcntl.h.html">fcntl.h</a>><br>
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<br>
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int posix_fallocate(int</tt> <i>fd</i><tt>, off_t</tt> <i>offset</i><tt>, size_t</tt> <i>len</i><tt>); <img src=
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"../images/opt-end.gif" alt="[Option End]" 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_422_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>posix_fallocate</i>() function shall ensure that any required storage for regular file data starting at <i>offset</i> and
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continuing for <i>len</i> bytes is allocated on the file system storage media. If <i>posix_fallocate</i>() returns successfully,
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subsequent writes to the specified file data shall not fail due to the lack of free space on the file system storage media.</p>
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<p>If the <i>offset</i>+ <i>len</i> is beyond the current file size, then <i>posix_fallocate</i>() shall adjust the file size to
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<i>offset</i>+ <i>len</i>. Otherwise, the file size shall not be changed.</p>
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<p>It is implementation-defined whether a previous <a href="../functions/posix_fadvise.html"><i>posix_fadvise</i>()</a> call
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influences allocation strategy.</p>
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<p>Space allocated via <i>posix_fallocate</i>() shall be freed by a successful call to <a href=
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"../functions/creat.html"><i>creat</i>()</a> or <a href="../functions/open.html"><i>open</i>()</a> that truncates the size of the
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file. Space allocated via <i>posix_fallocate</i>() may be freed by a successful call to <a href=
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"../functions/ftruncate.html"><i>ftruncate</i>()</a> that reduces the file size to a size smaller than <i>offset</i>+
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<i>len</i>.</p>
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</blockquote>
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<h4><a name="tag_03_422_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, <i>posix_fallocate</i>() shall return zero; otherwise, an error number shall be returned to indicate
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the error.</p>
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</blockquote>
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<h4><a name="tag_03_422_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>posix_fallocate</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EBADF]</dt>
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<dd>The <i>fd</i> argument is not a valid file descriptor.</dd>
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<dt>[EBADF]</dt>
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<dd>The <i>fd</i> argument references a file that was opened without write permission.</dd>
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<dt>[EFBIG]</dt>
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<dd>The value of <i>offset</i>+ <i>len</i> is greater than the maximum file size.</dd>
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<dt>[EINTR]</dt>
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<dd>A signal was caught during execution.</dd>
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<dt>[EINVAL]</dt>
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<dd>The <i>len</i> argument was zero or the <i>offset</i> argument was less than zero.</dd>
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<dt>[EIO]</dt>
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<dd>An I/O error occurred while reading from or writing to a file system.</dd>
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<dt>[ENODEV]</dt>
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<dd>The <i>fd</i> argument does not refer to a regular file.</dd>
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<dt>[ENOSPC]</dt>
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<dd>There is insufficient free space remaining on the file system storage media.</dd>
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<dt>[ESPIPE]</dt>
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<dd>The <i>fd</i> argument is associated with a pipe or FIFO.</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_422_06"></a>EXAMPLES</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_422_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The <i>posix_fallocate</i>() function is part of the Advisory Information option and need not be provided on all
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implementations.</p>
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</blockquote>
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<h4><a name="tag_03_422_08"></a>RATIONALE</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_422_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_422_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="creat.html"><i>creat</i>()</a> , <a href="ftruncate.html"><i>ftruncate</i>()</a> , <a href=
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"open.html"><i>open</i>()</a> , <a href="unlink.html"><i>unlink</i>()</a> , the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/fcntl.h.html"><i><fcntl.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_422_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 6. Derived from IEEE Std 1003.1d-1999.</p>
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<p>In the SYNOPSIS, the inclusion of <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> is no longer
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required.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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