FreeRTOS/Demo/Common/FileSystem/FatFs-0.7e/doc/en/open.html - third_party/github/FreeRTOS/FreeRTOS-Kernel - Git at Google

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 <title>FatFs - f_open</title>
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 <div class="para">
 <h2>f_open</h2>
 <p>The f_open function creates a <em>file object</em> to be used to access the file.</p>
 <pre>
 FRESULT f_open (
   FIL* <em>FileObject</em>,       /* Pointer to the blank file object structure */
   const XCHAR* <em>FileName</em>, /* Pointer to the file neme */
   BYTE <em>ModeFlags</em>         /* Mode flags */
 );
 </pre>
 </div>

 <div class="para">
 <h4>Parameters</h4>
 <dl class="par">
 <dt>FileObject</dt>
 <dd>Pointer to the file object structure to be created.</dd>
 <dt>FileName</dt>
 <dd>Pointer to a null-terminated string that specifies the <a href="filename.html">file name</a> to create or open.</dd>
 <dt>ModeFlags</dt>
 <dd>Specifies the type of access and open method for the file. It is specified by a combination of following flags.<br>
 <table class="lst">
 <tr><th>Value</th><th>Description</th></tr>
 <tr><td>FA_READ</td><td>Specifies read access to the object. Data can be read from the file.<br>Combine with FA_WRITE for read-write access.</td></tr>
 <tr><td>FA_WRITE</td><td>Specifies write access to the object. Data can be written to the file.<br>Combine with FA_READ for read-write access.</td></tr>
 <tr><td>FA_OPEN_EXISTING</td><td>Opens the file. The function fails if the file is not existing. (Default)</td></tr>
 <tr><td>FA_OPEN_ALWAYS</td><td>Opens the file, if it is existing. If not, a new file is created.</td></tr>
 <tr><td>FA_CREATE_NEW</td><td>Creates a new file. The function fails if the file is already existing.</td></tr>
 <tr><td>FA_CREATE_ALWAYS</td><td>Creates a new file. If the file is existing, it is truncated and overwritten.</td></tr>
 </table>
 </dd>
 </dl>
 </div>


 <div class="para">
 <h4>Return Values</h4>
 <dl class="ret">
 <dt>FR_OK (0)</dt>
 <dd>The function succeeded and the file object is valid.</dd>
 <dt>FR_NO_FILE</dt>
 <dd>Could not find the file.</dd>
 <dt>FR_NO_PATH</dt>
 <dd>Could not find the path.</dd>
 <dt>FR_INVALID_NAME</dt>
 <dd>The file name is invalid.</dd>
 <dt>FR_INVALID_DRIVE</dt>
 <dd>The drive number is invalid.</dd>
 <dt>FR_EXIST</dt>
 <dd>The file is already existing.</dd>
 <dt>FR_DENIED</dt>
 <dd>The required access was denied due to one of the following reasons:
 <ul><li>Write mode open of a read-only file.</li>
 <li>File cannot be created due to a read-only file or same name directory is existing.</li>
 <li>File cannot be created due to the directory table or disk is full.</li></ul></dd>
 <dt>FR_NOT_READY</dt>
 <dd>The disk drive cannot work due to no medium in the drive or any other reason.</dd>
 <dt>FR_WRITE_PROTECTED</dt>
 <dd>Write mode open or creation under the medium is write protected.</dd>
 <dt>FR_DISK_ERR</dt>
 <dd>The function failed due to an error in the disk function.</dd>
 <dt>FR_INT_ERR</dt>
 <dd>The function failed due to a wrong FAT structure or an internal error.</dd>
 <dt>FR_NOT_ENABLED</dt>
 <dd>The logical drive has no work area.</dd>
 <dt>FR_NO_FILESYSTEM</dt>
 <dd>There is no valid FAT volume on the disk.</dd>
 </dl>
 </div>


 <div class="para">
 <h4>Description</h4>
 <p>A file object is created when the function succeeded. The file object is used for subsequent read/write functions to refer to the file. When close an open file object, use <a href="close.html">f_close</a> function. If the modified file is not closed, the file may be collapsed.</p>
 <p>Before using any file function, a work area (file system object) must be given to the logical drive with <a href="mount.html">f_mount</a> function. All file functions can work after this procedure.</p>
 </div>


 <div class="para">
 <h4>QuickInfo</h4>
 <p>Always available. The mode flags, <tt>FA_WRITE, FA_CREATE_ALWAYS, FA_CREATE_NEW, FA_OPEN_ALWAYS</tt>, are not available when <tt>_FS_READONLY == 1</tt>.</p>
 </div>


 <div class="para">
 <h4>Example (File Copy)</h4>
 <pre>
 void main (void)
 {
     FATFS fs[2];         /* Work area (file system object) for logical drives */
     FIL fsrc, fdst;      /* file objects */
     BYTE buffer[4096];   /* file copy buffer */
     FRESULT res;         /* FatFs function common result code */
     UINT br, bw;         /* File R/W count */


     /* Register work area for logical drives */
     f_mount(0, &amp;fs[0]);
     f_mount(1, &amp;fs[1]);

     /* Open source file on the drive 1 */
     res = f_open(&amp;fsrc, "1:srcfile.dat", FA_OPEN_EXISTING | FA_READ);
     if (res) die(res);

     /* Create destination file on the drive 0 */
     res = f_open(&amp;fdst, "0:dstfile.dat", FA_CREATE_ALWAYS | FA_WRITE);
     if (res) die(res);

     /* Copy source to destination */
     for (;;) {
         res = f_read(&amp;fsrc, buffer, sizeof(buffer), &amp;br);
         if (res || br == 0) break;   /* error or eof */
         res = f_write(&amp;fdst, buffer, br, &amp;bw);
         if (res || bw &lt; br) break;   /* error or disk full */
     }

     /* Close open files */
     f_close(&amp;fsrc);
     f_close(&amp;fdst);

     /* Unregister work area prior to discard it */
     f_mount(0, NULL);
     f_mount(1, NULL);
 }
 </pre>
 </div>


 <div class="para">
 <h4>See Also</h4>
 <p><tt><a href="read.html">f_read</a>, <a href="write.html">f_write</a>, <a href="close.html">f_close</a>, <a href="sfile.html">FIL</a>, <a href="sfatfs.html">FATFS</a></tt></p>
 </div>

 <p class="foot"><a href="../00index_e.html">Return</a></p>
 </body>
 </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=iso-8859-1">
	<meta http-equiv="Content-Style-Type" content="text/css">
	<link rel="up" title="FatFs" href="../00index_e.html">
	<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">
	<title>FatFs - f_open</title>
	</head>

	<body>

	<div class="para">
	<h2>f_open</h2>
	<p>The f_open function creates a <em>file object</em> to be used to access the file.</p>
	<pre>
	FRESULT f_open (
	FIL* <em>FileObject</em>, /* Pointer to the blank file object structure */
	const XCHAR* <em>FileName</em>, /* Pointer to the file neme */
	BYTE <em>ModeFlags</em> /* Mode flags */
	);
	</pre>
	</div>

	<div class="para">
	<h4>Parameters</h4>
	<dl class="par">
	<dt>FileObject</dt>
	<dd>Pointer to the file object structure to be created.</dd>
	<dt>FileName</dt>
	<dd>Pointer to a null-terminated string that specifies the <a href="filename.html">file name</a> to create or open.</dd>
	<dt>ModeFlags</dt>
	<dd>Specifies the type of access and open method for the file. It is specified by a combination of following flags.<br>
	<table class="lst">
	<tr><th>Value</th><th>Description</th></tr>
	<tr><td>FA_READ</td><td>Specifies read access to the object. Data can be read from the file.<br>Combine with FA_WRITE for read-write access.</td></tr>
	<tr><td>FA_WRITE</td><td>Specifies write access to the object. Data can be written to the file.<br>Combine with FA_READ for read-write access.</td></tr>
	<tr><td>FA_OPEN_EXISTING</td><td>Opens the file. The function fails if the file is not existing. (Default)</td></tr>
	<tr><td>FA_OPEN_ALWAYS</td><td>Opens the file, if it is existing. If not, a new file is created.</td></tr>
	<tr><td>FA_CREATE_NEW</td><td>Creates a new file. The function fails if the file is already existing.</td></tr>
	<tr><td>FA_CREATE_ALWAYS</td><td>Creates a new file. If the file is existing, it is truncated and overwritten.</td></tr>
	</table>
	</dd>
	</dl>
	</div>


	<div class="para">
	<h4>Return Values</h4>
	<dl class="ret">
	<dt>FR_OK (0)</dt>
	<dd>The function succeeded and the file object is valid.</dd>
	<dt>FR_NO_FILE</dt>
	<dd>Could not find the file.</dd>
	<dt>FR_NO_PATH</dt>
	<dd>Could not find the path.</dd>
	<dt>FR_INVALID_NAME</dt>
	<dd>The file name is invalid.</dd>
	<dt>FR_INVALID_DRIVE</dt>
	<dd>The drive number is invalid.</dd>
	<dt>FR_EXIST</dt>
	<dd>The file is already existing.</dd>
	<dt>FR_DENIED</dt>
	<dd>The required access was denied due to one of the following reasons:
	<ul><li>Write mode open of a read-only file.</li>
	<li>File cannot be created due to a read-only file or same name directory is existing.</li>
	<li>File cannot be created due to the directory table or disk is full.</li></ul></dd>
	<dt>FR_NOT_READY</dt>
	<dd>The disk drive cannot work due to no medium in the drive or any other reason.</dd>
	<dt>FR_WRITE_PROTECTED</dt>
	<dd>Write mode open or creation under the medium is write protected.</dd>
	<dt>FR_DISK_ERR</dt>
	<dd>The function failed due to an error in the disk function.</dd>
	<dt>FR_INT_ERR</dt>
	<dd>The function failed due to a wrong FAT structure or an internal error.</dd>
	<dt>FR_NOT_ENABLED</dt>
	<dd>The logical drive has no work area.</dd>
	<dt>FR_NO_FILESYSTEM</dt>
	<dd>There is no valid FAT volume on the disk.</dd>
	</dl>
	</div>


	<div class="para">
	<h4>Description</h4>
	<p>A file object is created when the function succeeded. The file object is used for subsequent read/write functions to refer to the file. When close an open file object, use <a href="close.html">f_close</a> function. If the modified file is not closed, the file may be collapsed.</p>
	<p>Before using any file function, a work area (file system object) must be given to the logical drive with <a href="mount.html">f_mount</a> function. All file functions can work after this procedure.</p>
	</div>


	<div class="para">
	<h4>QuickInfo</h4>
	<p>Always available. The mode flags, <tt>FA_WRITE, FA_CREATE_ALWAYS, FA_CREATE_NEW, FA_OPEN_ALWAYS</tt>, are not available when <tt>_FS_READONLY == 1</tt>.</p>
	</div>


	<div class="para">
	<h4>Example (File Copy)</h4>
	<pre>
	void main (void)
	{
	FATFS fs[2]; /* Work area (file system object) for logical drives */
	FIL fsrc, fdst; /* file objects */
	BYTE buffer[4096]; /* file copy buffer */
	FRESULT res; /* FatFs function common result code */
	UINT br, bw; /* File R/W count */


	/* Register work area for logical drives */
	f_mount(0, &fs[0]);
	f_mount(1, &fs[1]);

	/* Open source file on the drive 1 */
	res = f_open(&fsrc, "1:srcfile.dat", FA_OPEN_EXISTING \| FA_READ);
	if (res) die(res);

	/* Create destination file on the drive 0 */
	res = f_open(&fdst, "0:dstfile.dat", FA_CREATE_ALWAYS \| FA_WRITE);
	if (res) die(res);

	/* Copy source to destination */
	for (;;) {
	res = f_read(&fsrc, buffer, sizeof(buffer), &br);
	if (res \|\| br == 0) break; /* error or eof */
	res = f_write(&fdst, buffer, br, &bw);
	if (res \|\| bw < br) break; /* error or disk full */
	}

	/* Close open files */
	f_close(&fsrc);
	f_close(&fdst);

	/* Unregister work area prior to discard it */
	f_mount(0, NULL);
	f_mount(1, NULL);
	}
	</pre>
	</div>


	<div class="para">
	<h4>See Also</h4>
	<p><tt><a href="read.html">f_read</a>, <a href="write.html">f_write</a>, <a href="close.html">f_close</a>, <a href="sfile.html">FIL</a>, <a href="sfatfs.html">FATFS</a></tt></p>
	</div>

	<p class="foot"><a href="../00index_e.html">Return</a></p>
	</body>
	</html>