Diff: features/storage/filesystem/fat/FATFileSystem.cpp

Revision:

0:5b88d5760320

Child:

1:9db0e321a9f4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/features/storage/filesystem/fat/FATFileSystem.cpp	Tue Dec 17 23:23:45 2019 +0000
@@ -0,0 +1,862 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2012 ARM Limited
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "diskio.h"
+#include "ffconf.h"
+#include "platform/mbed_debug.h"
+#include "platform/mbed_critical.h"
+#include "filesystem/mbed_filesystem.h"
+#include "FATFileSystem.h"
+
+#include <errno.h>
+#include <stdlib.h>
+
+namespace mbed {
+
+using namespace mbed;
+
+static int fat_error_remap(FRESULT res)
+{
+    switch (res) {
+        case FR_OK:                   // (0) Succeeded
+            return 0;
+        case FR_DISK_ERR:             // (1) A hard error occurred in the low level disk I/O layer
+            return -EIO;
+        case FR_INT_ERR:              // (2) Assertion failed
+            return -1;
+        case FR_NOT_READY:            // (3) The physical drive cannot work
+            return -EIO;
+        case FR_NO_FILE:              // (4) Could not find the file
+            return -ENOENT;
+        case FR_NO_PATH:              // (5) Could not find the path
+            return -ENOTDIR;
+        case FR_INVALID_NAME:         // (6) The path name format is invalid
+            return -EINVAL;
+        case FR_DENIED:               // (7) Access denied due to prohibited access or directory full
+            return -EACCES;
+        case FR_EXIST:                // (8) Access denied due to prohibited access
+            return -EEXIST;
+        case FR_INVALID_OBJECT:       // (9) The file/directory object is invalid
+            return -EBADF;
+        case FR_WRITE_PROTECTED:      // (10) The physical drive is write protected
+            return -EACCES;
+        case FR_INVALID_DRIVE:        // (11) The logical drive number is invalid
+            return -ENODEV;
+        case FR_NOT_ENABLED:          // (12) The volume has no work area
+            return -ENODEV;
+        case FR_NO_FILESYSTEM:        // (13) There is no valid FAT volume
+            return -EINVAL;
+        case FR_MKFS_ABORTED:         // (14) The f_mkfs() aborted due to any problem
+            return -EIO;
+        case FR_TIMEOUT:              // (15) Could not get a grant to access the volume within defined period
+            return -ETIMEDOUT;
+        case FR_LOCKED:               // (16) The operation is rejected according to the file sharing policy
+            return -EBUSY;
+        case FR_NOT_ENOUGH_CORE:      // (17) LFN working buffer could not be allocated
+            return -ENOMEM;
+        case FR_TOO_MANY_OPEN_FILES:  // (18) Number of open files > FF_FS_LOCK
+            return -ENFILE;
+        case FR_INVALID_PARAMETER:    // (19) Given parameter is invalid
+            return -EINVAL;
+        default:
+            return -res;
+    }
+}
+
+// Helper class for deferring operations when variable falls out of scope
+template <typename T>
+class Deferred {
+public:
+    T _t;
+    Callback<void(T)> _ondefer;
+
+    Deferred(const Deferred &);
+    Deferred &operator=(const Deferred &);
+
+public:
+    Deferred(T t, Callback<void(T)> ondefer = NULL)
+        : _t(t), _ondefer(ondefer)
+    {
+    }
+
+    operator T()
+    {
+        return _t;
+    }
+
+    ~Deferred()
+    {
+        if (_ondefer) {
+            _ondefer(_t);
+        }
+    }
+};
+
+static void dodelete(const char *data)
+{
+    delete[] data;
+}
+
+// Adds prefix needed internally by fatfs, this can be avoided for the first fatfs
+// (id 0) otherwise a prefix of "id:/" is inserted in front of the string.
+static Deferred<const char *> fat_path_prefix(int id, const char *path)
+{
+    // We can avoid dynamic allocation when only on fatfs is in use
+    if (id == 0) {
+        return path;
+    }
+
+    // Prefix path with id, will look something like 2:/hi/hello/filehere.txt
+    char *buffer = new char[strlen("0:/") + strlen(path) + 1];
+    if (!buffer) {
+        return NULL;
+    }
+
+    buffer[0] = '0' + id;
+    buffer[1] = ':';
+    buffer[2] = '/';
+    strcpy(buffer + strlen("0:/"), path);
+    return Deferred<const char *>(buffer, dodelete);
+}
+
+////// Disk operations //////
+
+// Global access to block device from FAT driver
+static mbed::BlockDevice *_ffs[FF_VOLUMES] = {0};
+static SingletonPtr<PlatformMutex> _ffs_mutex;
+
+// FAT driver functions
+extern "C" DWORD get_fattime(void)
+{
+    time_t rawtime;
+    time(&rawtime);
+    struct tm *ptm = localtime(&rawtime);
+    return (DWORD)(ptm->tm_year - 80) << 25
+           | (DWORD)(ptm->tm_mon + 1) << 21
+           | (DWORD)(ptm->tm_mday) << 16
+           | (DWORD)(ptm->tm_hour) << 11
+           | (DWORD)(ptm->tm_min) << 5
+           | (DWORD)(ptm->tm_sec / 2);
+}
+
+extern "C" void *ff_memalloc(UINT size)
+{
+    return malloc(size);
+}
+
+extern "C" void ff_memfree(void *p)
+{
+    free(p);
+}
+
+// Implementation of diskio functions (see ChaN/diskio.h)
+static WORD disk_get_sector_size(BYTE pdrv)
+{
+    bd_size_t sector_size = _ffs[pdrv]->get_erase_size();
+    MBED_ASSERT(sector_size <= WORD(-1));
+
+    WORD ssize = sector_size;
+    if (ssize < 512) {
+        ssize = 512;
+    }
+
+    MBED_ASSERT(ssize >= FF_MIN_SS && ssize <= FF_MAX_SS);
+    MBED_ASSERT(_ffs[pdrv]->get_read_size() <= _ffs[pdrv]->get_erase_size());
+    MBED_ASSERT(_ffs[pdrv]->get_program_size() <= _ffs[pdrv]->get_erase_size());
+    return ssize;
+}
+
+static DWORD disk_get_sector_count(BYTE pdrv)
+{
+    DWORD scount = _ffs[pdrv]->size() / disk_get_sector_size(pdrv);
+    MBED_ASSERT(scount >= 64);
+    return scount;
+}
+
+extern "C" DSTATUS disk_status(BYTE pdrv)
+{
+    debug_if(FFS_DBG, "disk_status on pdrv [%d]\n", pdrv);
+    return RES_OK;
+}
+
+extern "C" DSTATUS disk_initialize(BYTE pdrv)
+{
+    debug_if(FFS_DBG, "disk_initialize on pdrv [%d]\n", pdrv);
+    return (DSTATUS)_ffs[pdrv]->init();
+}
+
+extern "C" DRESULT disk_read(BYTE pdrv, BYTE *buff, DWORD sector, UINT count)
+{
+    debug_if(FFS_DBG, "disk_read(sector %lu, count %u) on pdrv [%d]\n", sector, count, pdrv);
+    DWORD ssize = disk_get_sector_size(pdrv);
+    mbed::bd_addr_t addr = (mbed::bd_addr_t)sector * ssize;
+    mbed::bd_size_t size = (mbed::bd_size_t)count * ssize;
+    int err = _ffs[pdrv]->read(buff, addr, size);
+    return err ? RES_PARERR : RES_OK;
+}
+
+extern "C" DRESULT disk_write(BYTE pdrv, const BYTE *buff, DWORD sector, UINT count)
+{
+    debug_if(FFS_DBG, "disk_write(sector %lu, count %u) on pdrv [%d]\n", sector, count, pdrv);
+    DWORD ssize = disk_get_sector_size(pdrv);
+    mbed::bd_addr_t addr = (mbed::bd_addr_t)sector * ssize;
+    mbed::bd_size_t size = (mbed::bd_size_t)count * ssize;
+
+    int err = _ffs[pdrv]->erase(addr, size);
+    if (err) {
+        return RES_PARERR;
+    }
+
+    err = _ffs[pdrv]->program(buff, addr, size);
+    if (err) {
+        return RES_PARERR;
+    }
+
+    return RES_OK;
+}
+
+extern "C" DRESULT disk_ioctl(BYTE pdrv, BYTE cmd, void *buff)
+{
+    debug_if(FFS_DBG, "disk_ioctl(%d)\n", cmd);
+    switch (cmd) {
+        case CTRL_SYNC:
+            if (_ffs[pdrv] == NULL) {
+                return RES_NOTRDY;
+            } else {
+                return RES_OK;
+            }
+        case GET_SECTOR_COUNT:
+            if (_ffs[pdrv] == NULL) {
+                return RES_NOTRDY;
+            } else {
+                *((DWORD *)buff) = disk_get_sector_count(pdrv);
+                return RES_OK;
+            }
+        case GET_SECTOR_SIZE:
+            if (_ffs[pdrv] == NULL) {
+                return RES_NOTRDY;
+            } else {
+                *((WORD *)buff) = disk_get_sector_size(pdrv);
+                return RES_OK;
+            }
+        case GET_BLOCK_SIZE:
+            *((DWORD *)buff) = 1; // default when not known
+            return RES_OK;
+        case CTRL_TRIM:
+            if (_ffs[pdrv] == NULL) {
+                return RES_NOTRDY;
+            } else {
+                DWORD *sectors = (DWORD *)buff;
+                DWORD ssize = disk_get_sector_size(pdrv);
+                mbed::bd_addr_t addr = (mbed::bd_addr_t)sectors[0] * ssize;
+                mbed::bd_size_t size = (mbed::bd_size_t)(sectors[1] - sectors[0] + 1) * ssize;
+                int err = _ffs[pdrv]->trim(addr, size);
+                return err ? RES_PARERR : RES_OK;
+            }
+    }
+
+    return RES_PARERR;
+}
+
+////// Generic filesystem operations //////
+
+// Filesystem implementation (See FATFilySystem.h)
+FATFileSystem::FATFileSystem(const char *name, BlockDevice *bd)
+    : FileSystem(name), _id(-1)
+{
+    if (bd) {
+        mount(bd);
+    }
+}
+
+FATFileSystem::~FATFileSystem()
+{
+    // nop if unmounted
+    unmount();
+}
+
+int FATFileSystem::mount(BlockDevice *bd)
+{
+    // requires duplicate definition to allow virtual overload to work
+    return mount(bd, true);
+}
+
+int FATFileSystem::mount(BlockDevice *bd, bool mount)
+{
+    lock();
+    if (_id != -1) {
+        unlock();
+        return -EINVAL;
+    }
+
+    for (int i = 0; i < FF_VOLUMES; i++) {
+        if (!_ffs[i]) {
+            _id = i;
+            _ffs[_id] = bd;
+            _fsid[0] = '0' + _id;
+            _fsid[1] = ':';
+            _fsid[2] = '\0';
+            debug_if(FFS_DBG, "Mounting [%s] on ffs drive [%s]\n", getName(), _fsid);
+            FRESULT res = f_mount(&_fs, _fsid, mount);
+            unlock();
+            return fat_error_remap(res);
+        }
+    }
+
+    unlock();
+    return -ENOMEM;
+}
+
+int FATFileSystem::unmount()
+{
+    lock();
+    if (_id == -1) {
+        unlock();
+        return -EINVAL;
+    }
+
+    FRESULT res = f_mount(NULL, _fsid, 0);
+    _ffs[_id] = NULL;
+    _id = -1;
+    unlock();
+    return fat_error_remap(res);
+}
+
+/* See http://elm-chan.org/fsw/ff/en/mkfs.html for details of f_mkfs() and
+ * associated arguments. */
+int FATFileSystem::format(BlockDevice *bd, bd_size_t cluster_size)
+{
+    FATFileSystem fs;
+    fs.lock();
+
+    int err = bd->init();
+    if (err) {
+        fs.unlock();
+        return err;
+    }
+
+    // erase first handful of blocks
+    bd_size_t header = 2 * bd->get_erase_size();
+    err = bd->erase(0, header);
+    if (err) {
+        bd->deinit();
+        fs.unlock();
+        return err;
+    }
+
+    if (bd->get_erase_value() < 0) {
+        // erase is unknown, need to write 1s
+        bd_size_t program_size = bd->get_program_size();
+        void *buf = malloc(program_size);
+        if (!buf) {
+            bd->deinit();
+            fs.unlock();
+            return -ENOMEM;
+        }
+
+        memset(buf, 0xff, program_size);
+
+        for (bd_addr_t i = 0; i < header; i += program_size) {
+            err = bd->program(buf, i, program_size);
+            if (err) {
+                free(buf);
+                bd->deinit();
+                fs.unlock();
+                return err;
+            }
+        }
+
+        free(buf);
+    }
+
+    // trim entire device to indicate it is unneeded
+    err = bd->trim(0, bd->size());
+    if (err) {
+        bd->deinit();
+        fs.unlock();
+        return err;
+    }
+
+    err = bd->deinit();
+    if (err) {
+        fs.unlock();
+        return err;
+    }
+
+    err = fs.mount(bd, false);
+    if (err) {
+        fs.unlock();
+        return err;
+    }
+
+    // Logical drive number, Partitioning rule, Allocation unit size (bytes per cluster)
+    FRESULT res = f_mkfs(fs._fsid, FM_ANY | FM_SFD, cluster_size, NULL, 0);
+    if (res != FR_OK) {
+        fs.unmount();
+        fs.unlock();
+        return fat_error_remap(res);
+    }
+
+    err = fs.unmount();
+    if (err) {
+        fs.unlock();
+        return err;
+    }
+
+    fs.unlock();
+    return 0;
+}
+
+int FATFileSystem::reformat(BlockDevice *bd, int allocation_unit)
+{
+    lock();
+    if (_id != -1) {
+        if (!bd) {
+            bd = _ffs[_id];
+        }
+
+        int err = unmount();
+        if (err) {
+            unlock();
+            return err;
+        }
+    }
+
+    if (!bd) {
+        unlock();
+        return -ENODEV;
+    }
+
+    int err = FATFileSystem::format(bd, allocation_unit);
+    if (err) {
+        unlock();
+        return err;
+    }
+
+    err = mount(bd);
+    unlock();
+    return err;
+}
+
+int FATFileSystem::remove(const char *path)
+{
+    Deferred<const char *> fpath = fat_path_prefix(_id, path);
+
+    lock();
+    FRESULT res = f_unlink(fpath);
+    unlock();
+
+    if (res != FR_OK) {
+        debug_if(FFS_DBG, "f_unlink() failed: %d\n", res);
+        if (res == FR_DENIED) {
+            return -ENOTEMPTY;
+        }
+    }
+    return fat_error_remap(res);
+}
+
+int FATFileSystem::rename(const char *oldpath, const char *newpath)
+{
+    Deferred<const char *> oldfpath = fat_path_prefix(_id, oldpath);
+    Deferred<const char *> newfpath = fat_path_prefix(_id, newpath);
+
+    lock();
+    FRESULT res = f_rename(oldfpath, newfpath);
+    unlock();
+
+    if (res != FR_OK) {
+        debug_if(FFS_DBG, "f_rename() failed: %d\n", res);
+    }
+    return fat_error_remap(res);
+}
+
+int FATFileSystem::mkdir(const char *path, mode_t mode)
+{
+    Deferred<const char *> fpath = fat_path_prefix(_id, path);
+
+    lock();
+    FRESULT res = f_mkdir(fpath);
+    unlock();
+
+    if (res != FR_OK) {
+        debug_if(FFS_DBG, "f_mkdir() failed: %d\n", res);
+    }
+    return fat_error_remap(res);
+}
+
+int FATFileSystem::stat(const char *path, struct stat *st)
+{
+    Deferred<const char *> fpath = fat_path_prefix(_id, path);
+
+    lock();
+    FILINFO f;
+    memset(&f, 0, sizeof(f));
+
+    FRESULT res = f_stat(fpath, &f);
+    if (res != FR_OK) {
+        unlock();
+        return fat_error_remap(res);
+    }
+
+    /* ARMCC doesnt support stat(), and these symbols are not defined by the toolchain. */
+#ifdef TOOLCHAIN_GCC
+    st->st_size = f.fsize;
+    st->st_mode = 0;
+    st->st_mode |= (f.fattrib & AM_DIR) ? S_IFDIR : S_IFREG;
+    st->st_mode |= (f.fattrib & AM_RDO) ?
+                   (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH) :
+                   (S_IRWXU | S_IRWXG | S_IRWXO);
+#endif /* TOOLCHAIN_GCC */
+    unlock();
+
+    return 0;
+}
+
+int FATFileSystem::statvfs(const char *path, struct statvfs *buf)
+{
+
+    memset(buf, 0, sizeof(struct statvfs));
+    FATFS *fs;
+    DWORD fre_clust;
+
+    lock();
+    FRESULT res = f_getfree(_fsid, &fre_clust, &fs);
+    if (res != FR_OK) {
+        unlock();
+        return fat_error_remap(res);
+    }
+
+    buf->f_bsize = fs->ssize;
+    buf->f_frsize = fs->ssize;
+    buf->f_blocks = (fs->n_fatent - 2) * fs->csize;
+    buf->f_bfree = fre_clust * fs->csize;
+    buf->f_bavail = buf->f_bfree;
+#if FF_USE_LFN
+    buf->f_namemax = FF_LFN_BUF;
+#else
+    buf->f_namemax = FF_SFN_BUF;
+#endif
+
+    unlock();
+    return 0;
+}
+
+void FATFileSystem::lock()
+{
+    _ffs_mutex->lock();
+}
+
+void FATFileSystem::unlock()
+{
+    _ffs_mutex->unlock();
+}
+
+
+////// File operations //////
+int FATFileSystem::file_open(fs_file_t *file, const char *path, int flags)
+{
+    debug_if(FFS_DBG, "open(%s) on filesystem [%s], drv [%d]\n", path, getName(), _id);
+
+    FIL *fh = new FIL;
+    Deferred<const char *> fpath = fat_path_prefix(_id, path);
+
+    /* POSIX flags -> FatFS open mode */
+    BYTE openmode;
+    if (flags & O_RDWR) {
+        openmode = FA_READ | FA_WRITE;
+    } else if (flags & O_WRONLY) {
+        openmode = FA_WRITE;
+    } else {
+        openmode = FA_READ;
+    }
+
+    if (flags & O_CREAT) {
+        if (flags & O_TRUNC) {
+            openmode |= FA_CREATE_ALWAYS;
+        } else {
+            openmode |= FA_OPEN_ALWAYS;
+        }
+    }
+
+    if (flags & O_APPEND) {
+        openmode |= FA_OPEN_APPEND;
+    }
+
+    lock();
+    FRESULT res = f_open(fh, fpath, openmode);
+
+    if (res != FR_OK) {
+        unlock();
+        debug_if(FFS_DBG, "f_open('w') failed: %d\n", res);
+        delete fh;
+        return fat_error_remap(res);
+    }
+
+    unlock();
+
+    *file = fh;
+    return 0;
+}
+
+int FATFileSystem::file_close(fs_file_t file)
+{
+    FIL *fh = static_cast<FIL *>(file);
+
+    lock();
+    FRESULT res = f_close(fh);
+    unlock();
+
+    delete fh;
+    return fat_error_remap(res);
+}
+
+ssize_t FATFileSystem::file_read(fs_file_t file, void *buffer, size_t len)
+{
+    FIL *fh = static_cast<FIL *>(file);
+
+    lock();
+    UINT n;
+    FRESULT res = f_read(fh, buffer, len, &n);
+    unlock();
+
+    if (res != FR_OK) {
+        debug_if(FFS_DBG, "f_read() failed: %d\n", res);
+        return fat_error_remap(res);
+    } else {
+        return n;
+    }
+}
+
+ssize_t FATFileSystem::file_write(fs_file_t file, const void *buffer, size_t len)
+{
+    FIL *fh = static_cast<FIL *>(file);
+
+    lock();
+    UINT n;
+    FRESULT res = f_write(fh, buffer, len, &n);
+    unlock();
+
+    if (res != FR_OK) {
+        debug_if(FFS_DBG, "f_write() failed: %d", res);
+        return fat_error_remap(res);
+    } else {
+        return n;
+    }
+}
+
+int FATFileSystem::file_sync(fs_file_t file)
+{
+    FIL *fh = static_cast<FIL *>(file);
+
+    lock();
+    FRESULT res = f_sync(fh);
+    unlock();
+
+    if (res != FR_OK) {
+        debug_if(FFS_DBG, "f_sync() failed: %d\n", res);
+    }
+    return fat_error_remap(res);
+}
+
+off_t FATFileSystem::file_seek(fs_file_t file, off_t offset, int whence)
+{
+    FIL *fh = static_cast<FIL *>(file);
+
+    lock();
+    if (whence == SEEK_END) {
+        offset += f_size(fh);
+    } else if (whence == SEEK_CUR) {
+        offset += f_tell(fh);
+    }
+
+    FRESULT res = f_lseek(fh, offset);
+    off_t noffset = fh->fptr;
+    unlock();
+
+    if (res != FR_OK) {
+        debug_if(FFS_DBG, "lseek failed: %d\n", res);
+        return fat_error_remap(res);
+    } else {
+        return noffset;
+    }
+}
+
+off_t FATFileSystem::file_tell(fs_file_t file)
+{
+    FIL *fh = static_cast<FIL *>(file);
+
+    lock();
+    off_t res = f_tell(fh);
+    unlock();
+
+    return res;
+}
+
+off_t FATFileSystem::file_size(fs_file_t file)
+{
+    FIL *fh = static_cast<FIL *>(file);
+
+    lock();
+    off_t res = f_size(fh);
+    unlock();
+
+    return res;
+}
+
+int FATFileSystem::file_truncate(fs_file_t file, off_t length)
+{
+    FIL *fh = static_cast<FIL *>(file);
+
+    lock();
+    // save current position
+    FSIZE_t oldoff = f_tell(fh);
+
+    // seek to new file size and truncate
+    FRESULT res = f_lseek(fh, length);
+    if (res) {
+        unlock();
+        return fat_error_remap(res);
+    }
+
+    res = f_truncate(fh);
+    if (res) {
+        unlock();
+        return fat_error_remap(res);
+    }
+
+    // restore old position
+    res = f_lseek(fh, oldoff);
+    if (res) {
+        unlock();
+        return fat_error_remap(res);
+    }
+
+    return 0;
+}
+
+
+////// Dir operations //////
+int FATFileSystem::dir_open(fs_dir_t *dir, const char *path)
+{
+    FATFS_DIR *dh = new FATFS_DIR;
+    Deferred<const char *> fpath = fat_path_prefix(_id, path);
+
+    lock();
+    FRESULT res = f_opendir(dh, fpath);
+    unlock();
+
+    if (res != FR_OK) {
+        debug_if(FFS_DBG, "f_opendir() failed: %d\n", res);
+        delete dh;
+        return fat_error_remap(res);
+    }
+
+    *dir = dh;
+    return 0;
+}
+
+int FATFileSystem::dir_close(fs_dir_t dir)
+{
+    FATFS_DIR *dh = static_cast<FATFS_DIR *>(dir);
+
+    lock();
+    FRESULT res = f_closedir(dh);
+    unlock();
+
+    delete dh;
+    return fat_error_remap(res);
+}
+
+ssize_t FATFileSystem::dir_read(fs_dir_t dir, struct dirent *ent)
+{
+    FATFS_DIR *dh = static_cast<FATFS_DIR *>(dir);
+    FILINFO finfo;
+
+    lock();
+    FRESULT res = f_readdir(dh, &finfo);
+    unlock();
+
+    if (res != FR_OK) {
+        return fat_error_remap(res);
+    } else if (finfo.fname[0] == 0) {
+        return 0;
+    }
+
+    ent->d_type = (finfo.fattrib & AM_DIR) ? DT_DIR : DT_REG;
+
+#if FF_USE_LFN
+    if (ent->d_name[0] == 0) {
+        // No long filename so use short filename.
+        strncpy(ent->d_name, finfo.fname, FF_LFN_BUF);
+    }
+#else
+    strncpy(ent->d_name, finfo.fname, FF_SFN_BUF);
+#endif
+
+    return 1;
+}
+
+void FATFileSystem::dir_seek(fs_dir_t dir, off_t offset)
+{
+    FATFS_DIR *dh = static_cast<FATFS_DIR *>(dir);
+    off_t dptr = static_cast<off_t>(dh->dptr);
+
+    lock();
+
+    if (offset < dptr) {
+        f_rewinddir(dh);
+    }
+    while (dptr < offset) {
+        FILINFO finfo;
+        FRESULT res;
+
+        res = f_readdir(dh, &finfo);
+        dptr = dh->dptr;
+        if (res != FR_OK) {
+            break;
+        } else if (finfo.fname[0] == 0) {
+            break;
+        }
+    }
+    unlock();
+}
+
+off_t FATFileSystem::dir_tell(fs_dir_t dir)
+{
+    FATFS_DIR *dh = static_cast<FATFS_DIR *>(dir);
+
+    lock();
+    off_t offset = dh->dptr;
+    unlock();
+
+    return offset;
+}
+
+void FATFileSystem::dir_rewind(fs_dir_t dir)
+{
+    FATFS_DIR *dh = static_cast<FATFS_DIR *>(dir);
+
+    lock();
+    f_rewinddir(dh);
+    unlock();
+}
+
+} // namespace mbed