FreeRTOS/Common/FileSystem/FatFs-0.7e/doc/en/open.html

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   8 <title>FatFs - f_open</title>
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  11 <body>
  12
  13 <div class="para">
  14 <h2>f_open</h2>
  15 <p>The f_open function creates a <em>file object</em> to be used to access the file.</p>
  16 <pre>
  17 FRESULT f_open (
  18   FIL* <em>FileObject</em>,       /* Pointer to the blank file object structure */
  19   const XCHAR* <em>FileName</em>, /* Pointer to the file neme */
  20   BYTE <em>ModeFlags</em>         /* Mode flags */
  21 );
  22 </pre>
  23 </div>
  24
  25 <div class="para">
  26 <h4>Parameters</h4>
  27 <dl class="par">
  28 <dt>FileObject</dt>
  29 <dd>Pointer to the file object structure to be created.</dd>
  30 <dt>FileName</dt>
  31 <dd>Pointer to a null-terminated string that specifies the <a href="filename.html">file name</a> to create or open.</dd>
  32 <dt>ModeFlags</dt>
  33 <dd>Specifies the type of access and open method for the file. It is specified by a combination of following flags.<br>
  34 <table class="lst">
  35 <tr><th>Value</th><th>Description</th></tr>
  36 <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>
  37 <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>
  38 <tr><td>FA_OPEN_EXISTING</td><td>Opens the file. The function fails if the file is not existing. (Default)</td></tr>
  39 <tr><td>FA_OPEN_ALWAYS</td><td>Opens the file, if it is existing. If not, a new file is created.</td></tr>
  40 <tr><td>FA_CREATE_NEW</td><td>Creates a new file. The function fails if the file is already existing.</td></tr>
  41 <tr><td>FA_CREATE_ALWAYS</td><td>Creates a new file. If the file is existing, it is truncated and overwritten.</td></tr>
  42 </table>
  43 </dd>
  44 </dl>
  45 </div>
  46
  47
  48 <div class="para">
  49 <h4>Return Values</h4>
  50 <dl class="ret">
  51 <dt>FR_OK (0)</dt>
  52 <dd>The function succeeded and the file object is valid.</dd>
  53 <dt>FR_NO_FILE</dt>
  54 <dd>Could not find the file.</dd>
  55 <dt>FR_NO_PATH</dt>
  56 <dd>Could not find the path.</dd>
  57 <dt>FR_INVALID_NAME</dt>
  58 <dd>The file name is invalid.</dd>
  59 <dt>FR_INVALID_DRIVE</dt>
  60 <dd>The drive number is invalid.</dd>
  61 <dt>FR_EXIST</dt>
  62 <dd>The file is already existing.</dd>
  63 <dt>FR_DENIED</dt>
  64 <dd>The required access was denied due to one of the following reasons:
  65 <ul><li>Write mode open of a read-only file.</li>
  66 <li>File cannot be created due to a read-only file or same name directory is existing.</li>
  67 <li>File cannot be created due to the directory table or disk is full.</li></ul></dd>
  68 <dt>FR_NOT_READY</dt>
  69 <dd>The disk drive cannot work due to no medium in the drive or any other reason.</dd>
  70 <dt>FR_WRITE_PROTECTED</dt>
  71 <dd>Write mode open or creation under the medium is write protected.</dd>
  72 <dt>FR_DISK_ERR</dt>
  73 <dd>The function failed due to an error in the disk function.</dd>
  74 <dt>FR_INT_ERR</dt>
  75 <dd>The function failed due to a wrong FAT structure or an internal error.</dd>
  76 <dt>FR_NOT_ENABLED</dt>
  77 <dd>The logical drive has no work area.</dd>
  78 <dt>FR_NO_FILESYSTEM</dt>
  79 <dd>There is no valid FAT volume on the disk.</dd>
  80 </dl>
  81 </div>
  82
  83
  84 <div class="para">
  85 <h4>Description</h4>
  86 <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>
  87 <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>
  88 </div>
  89
  90
  91 <div class="para">
  92 <h4>QuickInfo</h4>
  93 <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>
  94 </div>
  95
  96
  97 <div class="para">
  98 <h4>Example (File Copy)</h4>
  99 <pre>
 100 void main (void)
 101 {
 102     FATFS fs[2];         /* Work area (file system object) for logical drives */
 103     FIL fsrc, fdst;      /* file objects */
 104     BYTE buffer[4096];   /* file copy buffer */
 105     FRESULT res;         /* FatFs function common result code */
 106     UINT br, bw;         /* File R/W count */
 107
 108
 109     /* Register work area for logical drives */
 110     f_mount(0, &amp;fs[0]);
 111     f_mount(1, &amp;fs[1]);
 112
 113     /* Open source file on the drive 1 */
 114     res = f_open(&amp;fsrc, "1:srcfile.dat", FA_OPEN_EXISTING | FA_READ);
 115     if (res) die(res);
 116
 117     /* Create destination file on the drive 0 */
 118     res = f_open(&amp;fdst, "0:dstfile.dat", FA_CREATE_ALWAYS | FA_WRITE);
 119     if (res) die(res);
 120
 121     /* Copy source to destination */
 122     for (;;) {
 123         res = f_read(&amp;fsrc, buffer, sizeof(buffer), &amp;br);
 124         if (res || br == 0) break;   /* error or eof */
 125         res = f_write(&amp;fdst, buffer, br, &amp;bw);
 126         if (res || bw &lt; br) break;   /* error or disk full */
 127     }
 128
 129     /* Close open files */
 130     f_close(&amp;fsrc);
 131     f_close(&amp;fdst);
 132
 133     /* Unregister work area prior to discard it */
 134     f_mount(0, NULL);
 135     f_mount(1, NULL);
 136 }
 137 </pre>
 138 </div>
 139
 140
 141 <div class="para">
 142 <h4>See Also</h4>
 143 <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>
 144 </div>
 145
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