savelij13
47e601681a
- Fixed a complie error when FF_FS_LOCK != 0. - Fixed a potential issue when work FatFs concurrency with FF_FS_REENTRANT, FF_VOLUMES >= 2 and FF_FS_LOCK > 0. - Made f_setlabel() accept a volume label in Unix style volume ID when FF_STR_VOLUME_ID == 2. - Made FatFs update PercInUse field in exFAT VBR. (A preceding f_getfree() is needed for the accuracy)
88 lines
3.0 KiB
HTML
88 lines
3.0 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
|
|
<html lang="en">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">
|
|
<title>FatFs - f_sync</title>
|
|
</head>
|
|
|
|
<body>
|
|
|
|
<div class="para func">
|
|
<h2>f_sync</h2>
|
|
<p>The f_sync function flushes the cached information of a writing file.</p>
|
|
<pre>
|
|
FRESULT f_sync (
|
|
FIL* <span class="arg">fp</span> <span class="c">/* [IN] File object */</span>
|
|
);
|
|
</pre>
|
|
</div>
|
|
|
|
<div class="para arg">
|
|
<h4>Parameter</h4>
|
|
<dl class="par">
|
|
<dt>fp</dt>
|
|
<dd>Pointer to the open file object to be flushed.</dd>
|
|
</dl>
|
|
</div>
|
|
|
|
|
|
<div class="para ret">
|
|
<h4>Return Values</h4>
|
|
<p>
|
|
<a href="rc.html#ok">FR_OK</a>,
|
|
<a href="rc.html#de">FR_DISK_ERR</a>,
|
|
<a href="rc.html#ie">FR_INT_ERR</a>,
|
|
<a href="rc.html#io">FR_INVALID_OBJECT</a>,
|
|
<a href="rc.html#tm">FR_TIMEOUT</a>
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<div class="para desc">
|
|
<h4>Description</h4>
|
|
<p>The <tt>f_sync</tt> function performs the same process as <tt>f_close</tt> function but the file is left opened and can continue read/write/seek operations to the file. This is suitable for the applications that open files for a long time in write mode, such as data logger. Performing <tt>f_sync</tt> function in certain interval can minimize the risk of data loss due to a sudden blackout, wrong media removal or unrecoverable disk error. For more information, refer to <a href="appnote.html#critical">application note</a>.</p>
|
|
<pre>
|
|
Case 1. Normal write sequence
|
|
|
|
Time --> ↓Normal shutdown
|
|
OwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwC <Power off>
|
|
|
|
|
|
Case 2. Without using f_sync()
|
|
|
|
Time --> ↓System crush
|
|
O<span class="e">wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww</span>
|
|
|<--------------- All data written will be lost ------------------>|
|
|
|
|
|
|
Case 3. Using f_sync()
|
|
Time --> ↓System crush
|
|
OwwwwwwwwSwwwwwwwwSwwwwwwwwSwwwwwwwwSwwwwwwwwSwwwwwwwwSwwwwwwwwS<span class="e">wwwww</span>
|
|
Data after last f_sync will be lost |<->|
|
|
O - f_open()
|
|
C - f_close()
|
|
w - f_write()
|
|
S - f_sync()
|
|
</pre>
|
|
<p>However there is no sense in <tt>f_sync</tt> function jsut before <tt>f_close</tt> function, because the <tt>f_close</tt> performs <tt>f_sync</tt> in it. Actually, the differnce between these functions is that the file object is invalidated or not.</p>
|
|
</div>
|
|
|
|
|
|
<div class="para comp">
|
|
<h4>QuickInfo</h4>
|
|
<p>Available when <tt><a href="config.html#fs_readonly">FF_FS_READONLY</a> == 0</tt>.</p>
|
|
</div>
|
|
|
|
|
|
<div class="para ref">
|
|
<h4>See Also</h4>
|
|
<p><tt><a href="close.html">f_close</a></tt>, <a href="appnote.html#critical">Critical section</a></p>
|
|
</div>
|
|
|
|
|
|
<p class="foot"><a href="../00index_e.html">Return</a></p>
|
|
</body>
|
|
</html>
|