Mbed OS Reference | LittleFileSystem2.h Source File

 /* mbed Microcontroller Library
  * Copyright (c) 2017 ARM Limited
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 /** \addtogroup storage */
 /** @{*/
 
 #ifndef MBED_LFS2FILESYSTEM_H
 #define MBED_LFS2FILESYSTEM_H
 
 #include "FileSystem.h"
 #include "BlockDevice.h"
 #include "PlatformMutex.h"
 #include "lfs2.h"
 
 namespace mbed {
 
 /**
  * LittleFileSystem2, a little file system
  *
  * Synchronization level: Thread safe
  */
 class LittleFileSystem2 : public mbed::FileSystem {
 public:
     /** Lifetime of the LittleFileSystem2
      *
      *  @param name     Name of the file system in the tree.
      *  @param bd       Block device to mount. Mounted immediately if not NULL.
      *  @param block_size
      *      Size of a logical block. This does not impact ram consumption and
      *      may be larger than the physical erase block. If the physical erase
      *      block is larger, littlefs will use that instead. Larger values will
      *      be faster but waste more storage when files are not aligned to a
      *      block size.
      *  @param block_cycles
      *      Number of erase cycles before a block is forcefully evicted. Larger
      *      values are more efficient but cause less even wear distribution. 0
      *      disables dynamic wear-leveling.
      *  @param cache_size
      *      Size of read/program caches. Each file uses 1 cache, and littlefs
      *      allocates 2 caches for internal operations. Larger values should be
      *      faster but uses more RAM.
      *  @param lookahead_size
      *      Size of the lookahead buffer. A larger lookahead reduces the
      *      allocation scans and results in a faster filesystem but uses
      *      more RAM.
      */
     LittleFileSystem2(const char *name = NULL, mbed::BlockDevice *bd = NULL,
                       lfs2_size_t block_size = MBED_LFS2_BLOCK_SIZE,
                       uint32_t   block_cycles = MBED_LFS2_BLOCK_CYCLES,
                       lfs2_size_t cache_size = MBED_LFS2_CACHE_SIZE,
                       lfs2_size_t lookahead = MBED_LFS2_LOOKAHEAD_SIZE);
 
     virtual ~LittleFileSystem2();
 
     /** Format a block device with the LittleFileSystem2.
      *
      *  The block device to format should be mounted when this function is called.
      *
      *  @param bd       This is the block device that will be formatted.
      *  @param block_size
      *      Size of a logical block. This does not impact ram consumption and
      *      may be larger than the physical erase block. If the physical erase
      *      block is larger, littlefs will use that instead. Larger values will
      *      be faster but waste more storage when files are not aligned to a
      *      block size.
      *  @param block_cycles
      *      Number of erase cycles before a block is forcefully evicted. Larger
      *      values are more efficient but cause less even wear distribution. 0
      *      disables dynamic wear-leveling.
      *  @param cache_size
      *      Size of read/program caches. Each file uses 1 cache, and littlefs
      *      allocates 2 caches for internal operations. Larger values should be
      *      faster but uses more RAM.
      *  @param lookahead_size
      *      Size of the lookahead buffer. A larger lookahead reduces the
      *      allocation scans and results in a faster filesystem but uses
      *      more RAM.
      */
     static int format(mbed::BlockDevice *bd,
                       lfs2_size_t block_size = MBED_LFS2_BLOCK_SIZE,
                       uint32_t   block_cycles = MBED_LFS2_BLOCK_CYCLES,
                       lfs2_size_t cache_size = MBED_LFS2_CACHE_SIZE,
                       lfs2_size_t lookahead_size = MBED_LFS2_LOOKAHEAD_SIZE);
 
     /** Mount a file system to a block device.
      *
      *  @param bd       Block device to mount to.
      *  @return         0 on success, negative error code on failure.
      */
     virtual int mount(mbed::BlockDevice *bd);
 
     /** Unmount a file system from the underlying block device.
      *
      *  @return         0 on success, negative error code on failure
      */
     virtual int unmount();
 
     /** Reformat a file system. Results in an empty and mounted file system.
      *
      *  @param bd
      *      Block device to reformat and mount. If NULL, the mounted
      *      Block device is used.
      *      Note: If mount fails, bd must be provided.
      *      Default: NULL
      *
      *  @return         0 on success, negative error code on failure
      */
     virtual int reformat(mbed::BlockDevice *bd);
 
     /** Remove a file from the file system.
      *
      *  @param path     The name of the file to remove.
      *  @return         0 on success, negative error code on failure
      */
     virtual int remove(const char *path);
 
     /** Rename a file in the file system.
      *
      *  @param path     The name of the file to rename.
      *  @param newpath  The name to rename it to.
      *  @return         0 on success, negative error code on failure
      */
     virtual int rename(const char *path, const char *newpath);
 
     /** Store information about the file in a stat structure
      *
      *  @param path     The name of the file to find information about.
      *  @param st       The stat buffer to write to.
      *  @return         0 on success, negative error code on failure
      */
     virtual int stat(const char *path, struct stat *st);
 
     /** Create a directory in the file system.
      *
      *  @param path     The name of the directory to create.
      *  @param mode     The permissions with which to create the directory.
      *  @return         0 on success, negative error code on failure
      */
     virtual int mkdir(const char *path, mode_t mode);
 
     /** Store information about the mounted file system in a statvfs structure.
      *
      *  @param path     The name of the file to find information about.
      *  @param buf      The stat buffer to write to.
      *  @return         0 on success, negative error code on failure
      */
     virtual int statvfs(const char *path, struct statvfs *buf);
 
 protected:
 #if !(DOXYGEN_ONLY)
     /** Open a file on the file system.
      *
      *  @param file     Destination of the newly created handle to the referenced file.
      *  @param path     The name of the file to open.
      *  @param flags    The flags that trigger opening of the file. These flags are O_RDONLY, O_WRONLY, and O_RDWR,
      *                  with an O_CREAT, O_TRUNC, or O_APPEND bitwise OR operator.
      *  @return         0 on success, negative error code on failure.
      */
     virtual int file_open(mbed::fs_file_t *file, const char *path, int flags);
 
     /** Close a file
      *
      *  @param file     File handle.
      *  return          0 on success, negative error code on failure
      */
     virtual int file_close(mbed::fs_file_t file);
 
     /** Read the contents of a file into a buffer
      *
      *  @param file     File handle.
      *  @param buffer   The buffer to read in to.
      *  @param size     The number of bytes to read.
      *  @return         The number of bytes read, 0 at end of file, negative error on failure
      */
     virtual ssize_t file_read(mbed::fs_file_t file, void *buffer, size_t size);
 
     /** Write the contents of a buffer to a file
      *
      *  @param file     File handle.
      *  @param buffer   The buffer to write from.
      *  @param size     The number of bytes to write.
      *  @return         The number of bytes written, negative error on failure
      */
     virtual ssize_t file_write(mbed::fs_file_t file, const void *buffer, size_t size);
 
     /** Flush any buffers associated with the file
      *
      *  @param file     File handle.
      *  @return         0 on success, negative error code on failure
      */
     virtual int file_sync(mbed::fs_file_t file);
 
     /** Move the file position to a given offset from a given location
      *
      *  @param file     File handle.
      *  @param offset   The offset from whence to move to.
      *  @param whence   The start of where to seek.
      *      SEEK_SET to start from beginning of file,
      *      SEEK_CUR to start from current position in file,
      *      SEEK_END to start from end of file.
      *  @return         The new offset of the file
      */
     virtual off_t file_seek(mbed::fs_file_t file, off_t offset, int whence);
 
     /** Get the file position of the file
      *
      *  @param file     File handle.
      *  @return         The current offset in the file
      */
     virtual off_t file_tell(mbed::fs_file_t file);
 
     /** Get the size of the file
      *
      *  @param file     File handle.
      *  @return         Size of the file in bytes
      */
     virtual off_t file_size(mbed::fs_file_t file);
 
     /** Truncate or extend a file.
      *
      * The file's length is set to the specified value. The seek pointer is
      * not changed. If the file is extended, the extended area appears as if
      * it were zero-filled.
      *
      *  @param file     File handle.
      *  @param length   The requested new length for the file
      *
      *  @return         Zero on success, negative error code on failure
      */
     virtual int file_truncate(mbed::fs_file_t file, off_t length);
 
     /** Open a directory on the file system.
      *
      *  @param dir      Destination for the handle to the directory.
      *  @param path     Name of the directory to open.
      *  @return         0 on success, negative error code on failure
      */
     virtual int dir_open(mbed::fs_dir_t *dir, const char *path);
 
     /** Close a directory
      *
      *  @param dir      Dir handle.
      *  return          0 on success, negative error code on failure
      */
     virtual int dir_close(mbed::fs_dir_t dir);
 
     /** Read the next directory entry
      *
      *  @param dir      Dir handle.
      *  @param ent      The directory entry to fill out.
      *  @return         1 on reading a filename, 0 at end of directory, negative error on failure
      */
     virtual ssize_t dir_read(mbed::fs_dir_t dir, struct dirent *ent);
 
     /** Set the current position of the directory
      *
      *  @param dir      Dir handle.
      *  @param offset   Offset of the location to seek to,
      *                  must be a value returned from dir_tell
      */
     virtual void dir_seek(mbed::fs_dir_t dir, off_t offset);
 
     /** Get the current position of the directory
      *
      *  @param dir      Dir handle.
      *  @return         Position of the directory that can be passed to dir_rewind
      */
     virtual off_t dir_tell(mbed::fs_dir_t dir);
 
     /** Rewind the current position to the beginning of the directory
      *
      *  @param dir      Dir handle
      */
     virtual void dir_rewind(mbed::fs_dir_t dir);
 #endif //!(DOXYGEN_ONLY)
 
 private:
     lfs2_t _lfs; // The actual file system
     struct lfs2_config _config;
     mbed::BlockDevice *_bd; // The block device
 
     // thread-safe locking
     PlatformMutex _mutex;
 };
 
 } // namespace mbed
 
 // Added "using" for backwards compatibility
 #ifndef MBED_NO_GLOBAL_USING_DIRECTIVE
 using mbed::LittleFileSystem2;
 #endif
 
 #endif
 
 /** @}*/
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