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R0.15a

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Nov 22, 2024

Fixed a complie error when FF_FS_LOCK != 0. (appeared at R0.15)

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 with 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)
This commit is contained in:
Christopher Williams
2024-11-25 16:44:32 -07:00
parent b11f089319
commit 44b3c38b23
59 changed files with 940 additions and 939 deletions
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documents/doc/lseek.html
+10 -10
View File
@@ -3,8 +3,6 @@
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Style-Type" content="text/css">
<link rel="up" title="FatFs" href="../00index_e.html">
<link rel="alternate" hreflang="ja" title="Japanese" href="../ja/lseek.html">
<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">
<title>FatFs - f_lseek</title>
</head>
@@ -32,7 +30,7 @@ FRESULT f_rewind (
<h4>Parameters</h4>
<dl class="par">
<dt>fp</dt>
<dd>Pointer to the open file object.</dd>
<dd>Pointer to the open file object. If a null pointer is given, the function fails with <tt>FR_INVALID_OBJECT</tt>.</dd>
<dt>ofs</dt>
<dd>Byte offset from top of the file to set read/write pointer. The data type <tt>FSIZE_t</tt> is an alias of either <tt>DWORD</tt>(32-bit) or <tt>QWORD</tt>(64-bit) depends on the configuration option <tt><a href="config.html#fs_exfat">FF_FS_EXFAT</a></tt>.</dd>
</dl>
@@ -53,11 +51,12 @@ FRESULT f_rewind (
<div class="para desc">
<h4>Description</h4>
<p>File read/write ponter in the open file object points the data byte to be read/written at next read/write operation. It advances as the number of bytes read/written. The <tt>f_lseek</tt> function moves the file read/write pointer without any read/write operation to the file. The <tt>f_rewind</tt> function is impremented as a macro.</p>
<p>File read/write ponter in the open file object points the data byte to be read/written at next read/write operation. It advances as the number of bytes read/written. The <tt>f_lseek</tt> function moves the file read/write pointer without read/write operation to the file. The <tt>f_rewind</tt> function is impremented as a macro.</p>
<pre>
#define <em>f_rewind</em>(fp) f_lseek((fp), 0)
</pre>
<p>If an offset beyond the file size is specified in write mode, the file size is expanded to the specified offset. The file data in the expanded part is <em>undefined</em>, because no data is written to the file in this process. This is suitable to pre-allocate a data area to the file quickly for fast write operation. When a contiguous data area needs to be allocated to the file, use <tt>f_expand</tt> function instead. After the <tt>f_lseek</tt> function succeeded, the current read/write pointer should be checked in order to make sure the read/write pointer has been moved correctry. In case of the read/write pointer is not pointing expected offset, either of followings has been occured.</p>
<p>When an offset beyond the file size is specified in write mode, the file size is expanded to the specified offset <em>in this function</em>. The file data in the expanded part is <em>undefined</em>, because no data is written to the file in this process. Be careful about these behaviours differ from POSIX <tt>fseek</tt> function. This is suitable to pre-allocate a data area to the file for subsequent fast write operation. If a contiguous data area needs to be allocated to the file, use <tt>f_expand</tt> function instead.</p>
<p>After the <tt>f_lseek</tt> function succeeded, the current read/write pointer should be checked in order to make sure the read/write pointer has been moved correctry. In case of the read/write pointer is not pointing expected offset, either of followings has been occured.</p>
<ul>
<li>End of file. The specified <tt class="arg">ofs</tt> was clipped at end of the file in read-only mode.</li>
<li>Disk full. There is no free space on the volume to expand the file.</li>
@@ -78,7 +77,7 @@ FRESULT f_rewind (
<pre>
<span class="c">/* Open file */</span>
fp = malloc(sizeof (FIL));
res = f_open(fp, "file.dat", FA_READ|FA_WRITE);
res = <em>f_open</em>(fp, "file.dat", FA_READ|FA_WRITE);
if (res) ...
<span class="c">/* Set read/write pointer to 5000 */</span>
@@ -96,15 +95,15 @@ FRESULT f_rewind (
<pre>
<span class="c">/* Cluster pre-allocation (to prevent buffer overrun on streaming write) */</span>
res = f_open(fp, recfile, FA_CREATE_NEW | FA_WRITE); <span class="c">/* Create a file */</span>
res = <em>f_open</em>(fp, recfile, FA_CREATE_NEW | FA_WRITE); <span class="c">/* Create a file */</span>
res = <em>f_lseek</em>(fp, PRE_SIZE); <span class="c">/* Expand file size (cluster pre-allocation) */</span>
if (res || f_tell(fp) != PRE_SIZE) ... <span class="c">/* Check if the file has been expanded successfly */</span>
if (res || <em>f_tell</em>(fp) != PRE_SIZE) ... <span class="c">/* Check if the file has been expanded successfly */</span>
res = <em>f_lseek</em>(fp, OFS_DATA); <span class="c">/* Record data stream with free from cluster allocation delay */</span>
... <span class="c">/* Write operation should be aligned to sector boundary to optimize the write throughput */</span>
res = f_truncate(fp); <span class="c">/* Truncate unused area */</span>
res = <em>f_truncate</em>(fp); <span class="c">/* Truncate unused area */</span>
res = <em>f_lseek</em>(fp, OFS_HEADER); <span class="c">/* Set file header */</span>
...
@@ -115,7 +114,7 @@ FRESULT f_rewind (
DWORD clmt[SZ_TBL]; <span class="c">/* Cluster link map table buffer */</span>
res = f_open(fp, fname, FA_READ | FA_WRITE); <span class="c">/* Open a file */</span>
res = <em>f_open</em>(fp, fname, FA_READ | FA_WRITE); <span class="c">/* Open a file */</span>
res = <em>f_lseek</em>(fp, ofs1); <span class="c">/* This is normal seek (cltbl is nulled on file open) */</span>
@@ -134,6 +133,7 @@ FRESULT f_rewind (
<p><tt><a href="open.html">f_open</a>, <a href="truncate.html">f_truncate</a>, <a href="expand.html">f_expand</a>, <a href="sfile.html">FIL</a></tt></p>
</div>
<p class="foot"><a href="../00index_e.html">Return</a></p>
</body>
</html>