Device Virtual File System

Collaboration diagram for Device Virtual File System:

Modules
	File Descriptor
	File System API
	File API
	File POSIX API

Functions
int	dfs_init (void)
struct dfs_fdtable *	dfs_fdtable_get (void)
int	dfs_fdtable_dup (struct dfs_fdtable *fdt_dst, struct dfs_fdtable *fdt_src, int fd_src)
int	dfs_fdtable_drop_fd (struct dfs_fdtable *fdt, int fd)
int	dfs_dup_to (int oldfd, struct dfs_fdtable *fdtab)
int	dfs_dup_from (int oldfd, struct dfs_fdtable *fdtab)
const char *	dfs_subdir (const char *directory, const char *filename)
char *	dfs_normalize_path (const char *directory, const char *filename)

Detailed Description

DFS is a virtual file system in RT-Thread RTOS.

The DFS (Device Virtual File System) is a vfs file system of RT-Thread RTOS, which is focused on embedded device. VFS is an abstraction layer on top of a more concrete file system. The purpose of a VFS is to allow client applications to access different types of concrete file systems in a uniform way.

Figure 4: Device Virtual File System Architecture

The DFS specifies an interface between the kernel and a concrete file system. Therefore, it is easy to add support for new file system types to the kernel simply by fulfilling the interface.

Function Documentation

dfs_init()

int dfs_init

(

void

)

this function will initialize device file system.

dfs_fdtable_get()

struct dfs_fdtable* dfs_fdtable_get

(

void

)

This function will get the file descriptor table of current process.

dfs_fdtable_dup()

int dfs_fdtable_dup	(	struct dfs_fdtable *	fdt_dst,
		struct dfs_fdtable *	fdt_src,
		int	fd_src
	)

Dup the specified fd_src from fdt_src to fdt_dst.

Parameters

fdt_dst	is the fd table for destination, if empty, use global (_fdtab).
fdt_src	is the fd table for source, if empty, use global (_fdtab).
fd_src	is the fd in the designate fdt_src table.

Returns

-1 on failed or the allocated file descriptor.

dfs_fdtable_drop_fd()

int dfs_fdtable_drop_fd	(	struct dfs_fdtable *	fdt,
		int	fd
	)

drop fd from the fd table.

Parameters

fdt	is the fd table, if empty, use global (_fdtab).
fd	is the fd in the designate fd table.

Returns

-1 on failed the drop file descriptor.

dfs_dup_to()

int dfs_dup_to	(	int	oldfd,
		struct dfs_fdtable *	fdtab
	)

The fd in the current process dup to designate fd table.

Parameters

oldfd	is the fd in current process.
fdtab	is the fd table to dup, if empty, use global (_fdtab).

Returns

-1 on failed or the allocated file descriptor.

dfs_dup_from()

int dfs_dup_from	(	int	oldfd,
		struct dfs_fdtable *	fdtab
	)

The fd in the designate fd table dup to current process.

Parameters

oldfd	is the fd in the designate fd table.
fdtab	is the fd table for oldfd, if empty, use global (_fdtab).

Returns

-1 on failed or the allocated file descriptor.

dfs_subdir()

const char* dfs_subdir	(	const char *	directory,
		const char *	filename
	)

this function will return a sub-path name under directory.

Parameters

directory	the parent directory.
filename	the filename.

Returns

the subdir pointer in filename

dfs_normalize_path()

char* dfs_normalize_path	(	const char *	directory,
		const char *	filename
	)

this function will normalize a path according to specified parent directory and file name.

Parameters

directory	the parent path
filename	the file name

Returns

the built full file path (absolute path)