FatFs - f_readdir

f_readdir

The f_readdir function reads directory entries.

FRESULT f_readdir (
  DIR* dp,      /* [IN] Directory object */
  FILINFO* fno  /* [OUT] File information structure */
);

Parameters

dp: Pointer to the open directory object.
fno: Pointer to the file information structure to store the read item.

Return Values

FR_OK, FR_DISK_ERR, FR_INT_ERR, FR_NOT_READY, FR_INVALID_OBJECT, FR_TIMEOUT, FR_NOT_ENOUGH_CORE

Description

The f_readdir() function reads directory items, file and directory, in sequence. All items in the directory can be read by calling f_readdir() function repeatedly. When relative path feature is enabled (_FS_RPATH >= 1), dot entries ("." and "..") are not filtered out and they will appear in the read items. When all directory items have been read and no item to read, a null string is returned into the fname[] without any error. When a null pointer is given to the fno, the read index of the directory object is rewinded.

When LFN feature is enabled, lfname and lfsize in the file information structure must be initialized with valid value prior to use it. The lfname is a pointer to the LFN read buffer. The lfsize is size of the LFN read buffer in unit of TCHAR. If the LFN is not needed, set a null pointer to the lfname and the LFN is not returned. A null string will be returned into the LFN read buffer in case of following conditions.

The directory item has no LFN information.
Either the size of read buffer or LFN working buffer is insufficient for the LFN.
The LFN contains any Unicode character that cannot be converted to OEM code. (not the case at Unicode API cfg.)

When the directory item has no LFN information, lower case characters can be contained in the fname[].

QuickInfo

Available when _FS_MINIMIZE <= 1.

Sample Code

FRESULT scan_files (
    char* path        /* Start node to be scanned (also used as work area) */
)
{
    FRESULT res;
    FILINFO fno;
    DIR dir;
    int i;
    char *fn;   /* This function is assuming non-Unicode cfg. */
#if _USE_LFN
    static char lfn[_MAX_LFN + 1];   /* Buffer to store the LFN */
    fno.lfname = lfn;
    fno.lfsize = sizeof lfn;
#endif


    res = f_opendir(&dir, path);                       /* Open the directory */
    if (res == FR_OK) {
        i = strlen(path);
        for (;;) {
            res = f_readdir(&dir, &fno);                   /* Read a directory item */
            if (res != FR_OK || fno.fname[0] == 0) break;  /* Break on error or end of dir */
            if (fno.fname[0] == '.') continue;             /* Ignore dot entry */
#if _USE_LFN
            fn = *fno.lfname ? fno.lfname : fno.fname;
#else
            fn = fno.fname;
#endif
            if (fno.fattrib & AM_DIR) {                    /* It is a directory */
                sprintf(&path[i], "/%s", fn);
                res = scan_files(path);
                if (res != FR_OK) break;
                path[i] = 0;
            } else {                                       /* It is a file. */
                printf("%s/%s\n", path, fn);
            }
        }
        f_closedir(&dir)
    }

    return res;
}