fatfs/doc/en/readdir.html

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   9 <title>FatFs - f_readdir</title>
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  13
  14 <div class="para func">
  15 <h2>f_readdir</h2>
  16 <p>The f_readdir function reads an item of the directory.</p>
  17 <pre>
  18 FRESULT f_readdir (
  19   DIR* <span class="arg">dp</span>,      <span class="c">/* [IN] Directory object */</span>
  20   FILINFO* <span class="arg">fno</span>  <span class="c">/* [OUT] File information structure */</span>
  21 );
  22 </pre>
  23 </div>
  24
  25 <div class="para arg">
  26 <h4>Parameters</h4>
  27 <dl class="par">
  28 <dt>dp</dt>
  29 <dd>Pointer to the open directory object or null pointer.</dd>
  30 <dt>fno</dt>
  31 <dd>Pointer to the <a href="sfileinfo.html">file information structure</a> to store the information about read item.</dd>
  32 </dl>
  33 </div>
  34
  35
  36 <div class="para ret">
  37 <h4>Return Values</h4>
  38 <p>
  39 <a href="rc.html#ok">FR_OK</a>,
  40 <a href="rc.html#de">FR_DISK_ERR</a>,
  41 <a href="rc.html#ie">FR_INT_ERR</a>,
  42 <a href="rc.html#io">FR_INVALID_OBJECT</a>,
  43 <a href="rc.html#tm">FR_TIMEOUT</a>,
  44 <a href="rc.html#nc">FR_NOT_ENOUGH_CORE</a>
  45 </p>
  46 </div>
  47
  48
  49 <div class="para desc">
  50 <h4>Description</h4>
  51 <p>The <tt>f_readdir</tt> function reads a directory item, informations about the object. All items in the directory can be read in sequence by <tt>f_readdir</tt> function calls. Dot entries (<tt>"."</tt> and <tt>".."</tt>) in the sub-directory are filtered out and they will never appear in the read items. When all directory items have been read and no item to read, a nul string is stored into the <tt>fno-&gt;fname[]</tt> without any error. When a null pointer is given to the <tt class="arg">fno</tt>, the read index of the directory object is rewinded.</p>
  52 <p>When support of long file name (LFN) is enabled, a member <tt>altname[]</tt> is defined in the file information structure to store the short file name of the object. In case of the some conditions listed below, short file name is stored into the <tt>fname[]</tt> and <tt>altname[]</tt> has a null string.</p>
  53 <ul>
  54 <li>The item has no long file name. (Not the case at exFAT volume)</li>
  55 <li>Setting of <tt>_MAX_LFN</tt> is insufficient for the long file name. (Not the case at <tt>_MAX_LFN == 255</tt>)</li>
  56 <li>The long file name contains any character not allowed in ANSI/OEM code. (Not the case at <tt>_LFN_UNICODE == 1</tt>)</li>
  57 </ul>
  58 <p>There is a problem on reading a directory of exFAT volume. The exFAT does not support short file name. This means no name can be returned on the condition above. If it is the case, a "?" is returned as file name to indicate that the object is not accessible. To avoid this problem, configure FatFs <tt>_LFN_UNICODE = 1</tt> and <tt>_MAX_LFN = 255</tt> to support the full feature of LFN specification.</p>
  59 </div>
  60
  61
  62 <div class="para comp">
  63 <h4>QuickInfo</h4>
  64 <p>Available when <tt>_FS_MINIMIZE &lt;= 1</tt>.</p>
  65 </div>
  66
  67
  68 <div class="para use">
  69 <h4>Sample Code</h4>
  70 <pre>
  71 FRESULT scan_files (
  72     char* path        <span class="c">/* Start node to be scanned (***also used as work area***) */</span>
  73 )
  74 {
  75     FRESULT res;
  76     DIR dir;
  77     UINT i;
  78     static FILINFO fno;
  79
  80
  81     res = f_opendir(&amp;dir, path);                       <span class="c">/* Open the directory */</span>
  82     if (res == FR_OK) {
  83         for (;;) {
  84             res = f_readdir(&amp;dir, &amp;fno);                   <span class="c">/* Read a directory item */</span>
  85             if (res != FR_OK || fno.fname[0] == 0) break;  <span class="c">/* Break on error or end of dir */</span>
  86             if (fno.fattrib &amp; AM_DIR) {                    <span class="c">/* It is a directory */</span>
  87                 i = strlen(path);
  88                 sprintf(&amp;path[i], "/%s", fno.fname);
  89                 res = scan_files(path);                    <span class="c">/* Enter the directory */</span>
  90                 if (res != FR_OK) break;
  91                 path[i] = 0;
  92             } else {                                       <span class="c">/* It is a file. */</span>
  93                 printf("%s/%s\n", path, fno.fname);
  94             }
  95         }
  96         f_closedir(&amp;dir)
  97     }
  98
  99     return res;
 100 }
 101
 102
 103 int main (void)
 104 {
 105     FATFS fs;
 106     FRESULT res;
 107     char buff[256];
 108
 109
 110     res = f_mount(&amp;fs, "", 1);
 111     if (res == FR_OK) {
 112         strcpy(buff, "/");
 113         res = scan_files(buff);
 114     }
 115
 116     return res;
 117 }
 118 </pre>
 119 </div>
 120
 121
 122 <div class="para ref">
 123 <h4>See Also</h4>
 124 <p><tt><a href="opendir.html">f_opendir</a>, <a href="closedir.html">f_closedir</a>, <a href="stat.html">f_stat</a>, <a href="sfileinfo.html">FILINFO</a>, <a href="sdir.html">DIR</a></tt></p>
 125 </div>
 126
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