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fs: Improve documentation for FS API

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Simple improvements in text and formatting of the documentation
the the FS API.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
This commit is contained in:
Dominik Ermel 2020-09-23 15:04:07 +00:00 • committed by Carles Cufí
commit 81dc347b84
2 changed files with 131 additions and 125 deletions
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250
include/fs/fs.h
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@ -133,23 +133,24 @@ struct fs_statvfs {
* @brief File System interface structure
*
* @param open Opens or creates a file, depending on flags given
* @param read Reads items of data of size bytes long
* @param write Writes items of data of size bytes long
* @param read Reads nbytes number of bytes
* @param write Writes nbytes number of bytes
* @param lseek Moves the file position to a new location in the file
* @param tell Retrieves the current position in the file
* @param truncate Truncates the file to the new length
* @param sync Flush the cache of an open file
* @param truncate Truncates/expands the file to the new length
* @param sync Flushes the cache of an open file
* @param close Flushes the associated stream and closes the file
* @param opendir Opens an existing directory specified by the path
* @param readdir Reads directory entries of a open directory
* @param readdir Reads directory entries of an open directory
* @param closedir Closes an open directory
* @param mount Mount a file system
* @param unmount Unmount a file system
* @param mount Mounts a file system
* @param unmount Unmounts a file system
* @param unlink Deletes the specified file or directory
* @param rename Renames a file or directory
* @param mkdir Creates a new directory using specified path
* @param stat Checks the status of a file or directory specified by the path
* @param statvfs Returns the total and available space in the filesystem volume
* @param statvfs Returns the total and available space on the file system
* volume
*/
struct fs_file_system_t {
/* File operations */
@ -202,56 +203,59 @@ struct fs_file_system_t {
#endif
/**
* @brief File open
* @brief Open or create file
*
* Opens or creates, if does not exist, file depending on flags provided
* and associates a stream with it.
* Opens or possibly creates a file and associates a stream with it.
*
* @param zfp Pointer to file object
* @param file_name The name of file to open
* @details
* @p flags can be 0 or a binary combination of one or more of the following
* identifiers:
* - @c FS_O_READ open for read
* - @c FS_O_WRITE open for write
* - @c FS_O_RDWR open for read/write (<tt>FS_O_READ | FS_O_WRITE</tt>)
* - @c FS_O_CREATE create file if it does not exist
* - @c FS_O_APPEND move to end of file before each write
*
* If @p flags are set to 0 the function will attempt to open an existing file
* with no read/write access; this may be used to e.g. check if the file exists.
*
* @param zfp Pointer to a file object
* @param file_name The name of a file to open
* @param flags The mode flags
*
* @p flags can be empty, or combination of one or more of following flags:
* FS_O_READ open for read
* FS_O_WRITE open for write
* FS_O_RDWR open for read/write (<tt>FS_O_READ | FS_O_WRITE</tt>)
* FS_O_CREATE create file if it does not exist
* FS_O_APPEND move to end of file before each write
*
* @retval 0 Success
* @retval -EINVAL when bad file name is given
* @retval -NOENT when file path is not possible (bad mount point)
* @retval other negative error code, depending on file system back-end.
* @retval 0 on success;
* @retval -EINVAL when a bad file name is given;
* @retval -ENOENT when the file path is not possible (bad mount point);
* @retval <0 an other negative errno code, depending on a file system back-end.
*/
int fs_open(struct fs_file_t *zfp, const char *file_name, fs_mode_t flags);
/**
* @brief File close
* @brief Close file
*
* Flushes the associated stream and closes
* the file.
* Flushes the associated stream and closes the file.
*
* @param zfp Pointer to the file object
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error.
*/
int fs_close(struct fs_file_t *zfp);
/**
* @brief File unlink
* @brief Unlink file
*
* Deletes the specified file or directory
*
* @param path Path to the file or directory to delete
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error.
*/
int fs_unlink(const char *path);
/**
* @brief File o directory rename
* @brief Rename file or directory
*
* Performs a rename and / or move of the specified source path to the
* specified destination. The source path can refer to either a file or a
@ -261,87 +265,88 @@ int fs_unlink(const char *path);
* directory. If an object already exists at the specified destination path,
* this function causes it to be unlinked prior to the rename (i.e., the
* destination gets clobbered).
* @note Current implementation does not allow moving files between mount
* points.
*
* @param from The source path.
* @param to The destination path.
* @param from The source path
* @param to The destination path
*
* @retval 0 Success;
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error.
*/
int fs_rename(const char *from, const char *to);
/**
* @brief File read
* @brief Read file
*
* Reads items of data of size bytes long.
* Reads up to @p size bytes of data to @p ptr pointed buffer, returns number
* of bytes read. A returned value may be lower than @p size if there were
* fewer bytes available than requested.
*
* @param zfp Pointer to the file object
* @param ptr Pointer to the data buffer
* @param size Number of bytes to be read
*
* @return Number of bytes read. On success, it will be equal to number of
* items requested to be read. Returns less than number of bytes
* requested if there are not enough bytes available in file. Will return
* -ERRNO code on error.
* @retval >=0 a number of bytes read, on success;
* @retval <0 a negative errno code on error.
*/
ssize_t fs_read(struct fs_file_t *zfp, void *ptr, size_t size);
/**
* @brief File write
* @brief Write file
*
* Writes items of data of size bytes long.
* Attempts to write @p size number of bytes to the specified file.
* If a negative value is returned from the function, the file pointer has not
* been advanced.
* If the function returns a non-negative number that is lower than @p size,
* the global @c errno variable should be checked for an error code,
* as the device may have no free space for data.
*
* @param zfp Pointer to the file object
* @param ptr Pointer to the data buffer
* @param size Number of bytes to be write
* @param size Number of bytes to be written
*
* @return Number of bytes written. On success, it will be equal to the number
* of bytes requested to be written. Any other value, indicates an error. Will
* return -ERRNO code on error.
* In the case where -ERRNO is returned, the file pointer will not be
* advanced because it couldn't start the operation.
* In the case where it is able to write, but is not able to complete writing
* all of the requested number of bytes, then it is because the disk got full.
* In that case, it returns less number of bytes written than requested, but
* not a negative -ERRNO value as in regular error case.
* @retval >=0 a number of bytes written, on success;
* @retval <0 a negative errno code on error.
*/
ssize_t fs_write(struct fs_file_t *zfp, const void *ptr, size_t size);
/**
* @brief File seek
* @brief Seek file
*
* Moves the file position to a new location in the file. The offset is added
* to file position based on the 'whence' parameter.
* Moves the file position to a new location in the file. The @p offset is added
* to file position based on the @p whence parameter.
*
* @param zfp Pointer to the file object
* @param offset Relative location to move the file pointer to
* @param whence Relative location from where offset is to be calculated.
* - FS_SEEK_SET = from beginning of file
* - FS_SEEK_CUR = from current position,
* - FS_SEEK_END = from end of file.
* - @c FS_SEEK_SET for the beginning of the file;
* - @c FS_SEEK_CUR for the current position;
* - @c FS_SEEK_END for the end of the file.
*
* @retval 0 Success
* @retval -ENOTSUP if underlying file system does not support seeking
* @retval < 0 negative errno code
* @retval 0 on success;
* @retval -ENOTSUP if not supported by underlying file system driver;
* @retval <0 an other negative errno code on error.
*/
int fs_seek(struct fs_file_t *zfp, off_t offset, int whence);
/**
* @brief Get current file position.
*
* Retrieves the current position in the file.
* Retrieves and returns the current position in the file stream.
*
* @param zfp Pointer to the file object
*
* @retval >= 0 position Current position in file
* @retval -ENOTSUP if underlying file system does not support seeking
* @retval < 0 negative errno code
* Current revision does not validate the file object.
* @retval >= 0 a current position in file;
* @retval -ENOTSUP if not supported by underlying file system driver;
* @retval <0 an other negative errno code on error.
*
* The current revision does not validate the file object.
*/
off_t fs_tell(struct fs_file_t *zfp);
/**
* @brief Change the size of an open file
* @brief Truncate or extend an open file to a given size
*
* Truncates the file to the new length if it is shorter than the current
* size of the file. Expands the file if the new length is greater than the
@ -349,30 +354,30 @@ off_t fs_tell(struct fs_file_t *zfp);
*
* @note In the case of expansion, if the volume got full during the
* expansion process, the function will expand to the maximum possible length
* and returns success. Caller should check if the expanded size matches the
* and return success. Caller should check if the expanded size matches the
* requested length.
*
* @param zfp Pointer to the file object
* @param length New size of the file in bytes
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error.
*/
int fs_truncate(struct fs_file_t *zfp, off_t length);
/**
* @brief Flushes any cached write of an open file
* @brief Flush cached write data buffers of an open file
*
* This function can be used to flush the cache of an open file. This can
* be called to ensure data gets written to the storage media immediately.
* This may be done to avoid data loss if power is removed unexpectedly.
* Note that closing a file will cause caches to be flushed correctly so it
* need not be called if the file is being closed.
* The function flushes the cache of an open file; it can be invoked to ensure
* data gets written to the storage media immediately, e.g. to avoid data loss
* in case if power is removed unexpectedly.
* @note Closing a file will cause caches to be flushed correctly so the
* function need not be called when the file is being closed.
*
* @param zfp Pointer to the file object
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error.
*/
int fs_sync(struct fs_file_t *zfp);
@ -383,8 +388,8 @@ int fs_sync(struct fs_file_t *zfp);
*
* @param path Path to the directory to create
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error
*/
int fs_mkdir(const char *path);
@ -396,15 +401,16 @@ int fs_mkdir(const char *path);
* @param zdp Pointer to the directory object
* @param path Path to the directory to open
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error.
*/
int fs_opendir(struct fs_dir_t *zdp, const char *path);
/**
* @brief Directory read entry
*
* Reads directory entries of a open directory.
* Reads directory entries of an open directory. In end-of-dir condition,
* the function will return 0 and set the <tt>entry->name[0]</tt> to 0.
*
* @note: Most existing underlying file systems do not generate POSIX
* special directory entries "." or "..". For consistency the
@ -414,10 +420,8 @@ int fs_opendir(struct fs_dir_t *zdp, const char *path);
* @param zdp Pointer to the directory object
* @param entry Pointer to zfs_dirent structure to read the entry into
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @return In end-of-dir condition, this will return 0 and set
* entry->name[0] = 0
* @retval 0 on success or end-of-dir;;
* @retval <0 a negative errno code on error.
*/
int fs_readdir(struct fs_dir_t *zdp, struct fs_dirent *entry);
@ -428,8 +432,8 @@ int fs_readdir(struct fs_dir_t *zdp, struct fs_dirent *entry);
*
* @param zdp Pointer to the directory object
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error.
*/
int fs_closedir(struct fs_dir_t *zdp);
@ -442,53 +446,54 @@ int fs_closedir(struct fs_dir_t *zdp);
*
* @param mp Pointer to the fs_mount_t structure
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 a negative errno code on error.
*/
int fs_mount(struct fs_mount_t *mp);
/**
* @brief Unmount filesystem
*
* Perform steps needed for unmounting a file system like
* Perform steps needed to unmount a file system like
* calling the file system specific unmount function and removing
* the mount point from mounted file system list.
*
*
* @param mp Pointer to the fs_mount_t structure
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 negative errno code on error.
*/
int fs_unmount(struct fs_mount_t *mp);
/**
* @brief Mount point read entry
* @brief Get path of mount point at index
*
* Read mount point entry
* This function iterates through the list of mount points and returns
* the directory name of the mount point at the given @p index.
* On success @p index is incremented and @p name is set to the mount directory
* name. If a mount point with the given @p index does not exist, @p name will
* be set to @c NULL.
*
* @param number Pointer to mount point number
* @param name Pointer to mount point name
* @param index Pointer to mount point index
* @param name Pointer to pointer to path name
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @return On success \p number is incremented and \p name is set to mount
* point name. In case no mount point exists for the given \p number
* -ENOENT is returned and \p name is set to NULL.
* @retval 0 on success;
* @retval -ENOENT if there is no mount point with given index.
*/
int fs_readmount(int *number, const char **name);
int fs_readmount(int *index, const char **name);
/**
* @brief File or directory status
*
* Checks the status of a file or directory specified by the path
* Checks the status of a file or directory specified by the @p path.
* @note The file on a storage device may not be updated until it is closed.
*
* @param path Path to the file or directory
* @param entry Pointer to zfs_dirent structure to fill if file or directory
* exists.
* @param entry Pointer to the zfs_dirent structure to fill if the file or
* directory exists.
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 negative errno code on error.
*/
int fs_stat(const char *path, struct fs_dirent *entry);
@ -498,10 +503,11 @@ int fs_stat(const char *path, struct fs_dirent *entry);
* Returns the total and available space in the file system volume.
*
* @param path Path to the mounted directory
* @param stat Pointer to zfs_statvfs structure to receive the fs statistics
* @param stat Pointer to the zfs_statvfs structure to receive the fs
* statistics
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 negative errno code on error.
*/
int fs_statvfs(const char *path, struct fs_statvfs *stat);
@ -510,11 +516,11 @@ int fs_statvfs(const char *path, struct fs_statvfs *stat);
*
* Register file system with virtual file system.
*
* @param type Type of file system (ex: FS_FATFS)
* @param type Type of file system (ex: @c FS_FATFS)
* @param fs Pointer to File system
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 negative errno code on error.
*/
int fs_register(int type, const struct fs_file_system_t *fs);
@ -523,11 +529,11 @@ int fs_register(int type, const struct fs_file_system_t *fs);
*
* Unregister file system from virtual file system.
*
* @param type Type of file system (ex: FS_FATFS)
* @param type Type of file system (ex: @c FS_FATFS)
* @param fs Pointer to File system
*
* @retval 0 Success
* @retval -ERRNO errno code if error
* @retval 0 on success;
* @retval <0 negative errno code on error.
*/
int fs_unregister(int type, const struct fs_file_system_t *fs);