add flush, statfs, mkfs to device file system interface.

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@804 bbd45198-f89e-11dd-88c7-29a3b14d5316

components/dfs/filesystems/elmfat/dfs_elm.c

@@ -104,6 +104,63 @@ int dfs_elm_unmount(struct dfs_filesystem* fs)
 	return 0;
 }
 
+int dfs_elm_mkfs(const char* device_name)
+{
+	BYTE drv;
+	rt_device_t dev;
+	FRESULT result;
+
+	/* find device name */
+	for (drv = 0; drv < _DRIVES; drv ++)
+	{
+		dev = disk[drv];
+		if (rt_strncmp(dev->parent.name, device_name, RT_NAME_MAX) == 0)
+		{
+			/* 1: no partition table */
+			/* 0: auto selection of cluster size */
+			result = f_mkfs(drv, 1, 0);
+			if ( result != FR_OK)
+			{
+				rt_kprintf("format error\n");
+				return elm_result_to_dfs(result);
+			}
+
+			return DFS_STATUS_OK;
+		}
+	}
+
+	/* can't find device driver */
+	rt_kprintf("can not find device driver: %s\n", device_name);
+	return -DFS_STATUS_EIO;
+}
+
+int dfs_elm_statfs(struct dfs_filesystem* fs, struct dfs_statfs *buf)
+{
+	FATFS *f;
+	FRESULT res;
+	char driver[4];
+	DWORD fre_clust, fre_sect, tot_sect;
+
+	RT_ASSERT(fs != RT_NULL);
+	RT_ASSERT(buf != RT_NULL);
+
+	f = (FATFS*) fs->data;
+
+	rt_snprintf(driver, sizeof(driver), "%d:", f->drive);
+	res = f_getfree(driver, &fre_clust, &f);
+	if (res) return elm_result_to_dfs(res);
+	
+	/* Get total sectors and free sectors */
+	tot_sect = (f->max_clust - 2) * f->csize;
+	fre_sect = fre_clust * f->csize;
+
+	buf->f_bfree = fre_sect;
+	buf->f_blocks = tot_sect;
+	buf->f_bsize = 512;
+
+	return 0;
+}
+
 int dfs_elm_open(struct dfs_fd* file)
 {
 	FIL* fd;
@@ -292,6 +349,18 @@ int dfs_elm_write(struct dfs_fd* file, const void* buf, rt_size_t len)
 	return elm_result_to_dfs(result);
 }
 
+int dfs_elm_flush(struct dfs_fd* file)
+{
+	FIL* fd;
+	FRESULT result;
+
+	fd = (FIL*)(file->data);
+	RT_ASSERT(fd != RT_NULL);
+
+	result = f_sync(fd);
+	return elm_result_to_dfs(result);
+}
+
 int dfs_elm_lseek(struct dfs_fd* file, rt_off_t offset)
 {
 	FIL* fd;
@@ -491,24 +560,29 @@ int dfs_elm_stat(struct dfs_filesystem* fs, const char *path, struct dfs_stat *s
 	return elm_result_to_dfs(result);
 }
 
-static struct dfs_filesystem_operation dfs_elm;
-int elm_init(void)
+static const struct dfs_filesystem_operation dfs_elm = 
 {
-	rt_strncpy(dfs_elm.name, "elm", DFS_FS_NAME_MAX);
-
-	dfs_elm.mount 	= dfs_elm_mount;
-	dfs_elm.unmount = dfs_elm_unmount;
-	dfs_elm.open	= dfs_elm_open;
-	dfs_elm.close 	= dfs_elm_close;
-	dfs_elm.ioctl 	= dfs_elm_ioctl;
-	dfs_elm.read	= dfs_elm_read;
-	dfs_elm.write 	= dfs_elm_write;
-	dfs_elm.lseek 	= dfs_elm_lseek;
-	dfs_elm.getdents= dfs_elm_getdents;
-	dfs_elm.unlink 	= dfs_elm_unlink;
-	dfs_elm.stat	= dfs_elm_stat;
-	dfs_elm.rename 	= dfs_elm_rename;
+	"elm",
+	dfs_elm_mount,
+	dfs_elm_unmount,
+	dfs_elm_mkfs,
+	dfs_elm_statfs,
+
+	dfs_elm_open,
+	dfs_elm_close,
+	dfs_elm_ioctl,
+	dfs_elm_read,
+	dfs_elm_write,
+	dfs_elm_flush,
+	dfs_elm_lseek,
+	dfs_elm_getdents,
+	dfs_elm_unlink,
+	dfs_elm_stat,
+	dfs_elm_rename,
+};
 
+int elm_init(void)
+{
     /* register fatfs file system */
     dfs_register(&dfs_elm);
 
@@ -577,6 +651,7 @@ DRESULT disk_ioctl (BYTE drv, BYTE ctrl, void *buff)
 		rt_device_control(device, RT_DEVICE_CTRL_BLK_GETGEOME, &geometry);
 
 		*(DWORD*)buff = geometry.sector_count;
+		if (geometry.sector_count == 0) return RES_ERROR;
 	}
 	else if (ctrl == GET_SECTOR_SIZE)
 	{

components/dfs/filesystems/elmfat/ff.c

@@ -2772,7 +2772,7 @@ FRESULT f_forward (
 /* Create File System on the Drive                                       */
 /*-----------------------------------------------------------------------*/
 #define N_ROOTDIR	512			/* Multiple of 32 and <= 2048 */
-#define N_FATS		2			/* 1 or 2 */  //	my edit
+#define N_FATS		2			/* 1 or 2 */
 #define MAX_SECTOR	131072000UL	/* Maximum partition size */
 #define MIN_SECTOR	2000UL		/* Minimum partition size */
 

components/dfs/filesystems/nfs/dfs_nfs.c

@@ -1017,24 +1017,28 @@ int nfs_getdents(struct dfs_fd* file, struct dfs_dirent* dirp, rt_uint32_t count
 	return index * sizeof(struct dfs_dirent);
 }
 
-static struct dfs_filesystem_operation _nfs;
-int nfs_init(void)
+static const struct dfs_filesystem_operation _nfs = 
 {
-	rt_strncpy(_nfs.name, "nfs", DFS_FS_NAME_MAX);
-
-	_nfs.mount 		= nfs_mount;
-	_nfs.unmount	= nfs_unmount;
-	_nfs.open		= nfs_open;
-	_nfs.close 		= nfs_close;
-	_nfs.ioctl 		= nfs_ioctl;
-	_nfs.read		= nfs_read;
-	_nfs.write 		= nfs_write;
-	_nfs.lseek 		= nfs_lseek;
-	_nfs.getdents	= nfs_getdents;
-	_nfs.unlink 	= nfs_unlink;
-	_nfs.stat		= nfs_stat;
-	_nfs.rename 	= nfs_rename;
+	"nfs", 
+	nfs_mount,
+	nfs_unmount,
+	RT_NULL, /* mkfs */
+	RT_NULL, /* statfs */
+	nfs_open,
+	nfs_close,
+	nfs_ioctl,
+	nfs_read,
+	nfs_write,
+	RT_NULL, /* flush */
+	nfs_lseek,
+	nfs_getdents,
+	nfs_unlink, 
+	nfs_stat,
+	nfs_rename,
+};
 
+int nfs_init(void)
+{
 	/* register fatfs file system */
 	dfs_register(&_nfs);
 

components/dfs/include/dfs.h

+/*
+ * File      : dfs.h
+ * This file is part of Device File System in RT-Thread RTOS
+ * COPYRIGHT (C) 2004-2010, RT-Thread Development Team
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rt-thread.org/license/LICENSE.
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2005-02-22     Bernard      The first version.
+ */
+
+#ifndef __DFS_H__
+#define __DFS_H__
+
+#include <string.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+char* dfs_normalize_path(const char* directory, const char* filename);
+const char* dfs_subdir(const char* directory, const char* filename);
+
+/* FD APIs */
+int fd_new(void);
+struct dfs_fd* fd_get(int fd);
+void fd_put(struct dfs_fd* fd);
+int fd_is_open(const char* pathname);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

components/dfs/include/dfs_file.h

+/*
++------------------------------------------------------------------------------
+| Project   : Device Filesystem
++------------------------------------------------------------------------------
+| Copyright 2004, 2005  www.fayfayspace.org.
+| All rights reserved.
+|------------------------------------------------------------------------------
+| File      : dfs_raw.h, the raw APIs of Device FileSystem
+|------------------------------------------------------------------------------
+| Chang Logs:
+| Date           Author       Notes
+| 2005-01-26     ffxz		  The first version
++------------------------------------------------------------------------------
+*/
+
+#ifndef __DFS_RAW_H__
+#define __DFS_RAW_H__
+
+#include <dfs_def.h>
+#include <dfs.h>
+#include <dfs_fs.h>
+
+int dfs_file_open(struct dfs_fd* fd, const char *path, int flags);
+int dfs_file_close(struct dfs_fd* fd);
+int dfs_file_ioctl(struct dfs_fd* fd, int cmd, void *args);
+int dfs_file_read(struct dfs_fd* fd, void *buf, rt_size_t len);
+int dfs_file_getdents(struct dfs_fd* fd, struct dfs_dirent* dirp, rt_size_t nbytes);
+int dfs_file_unlink(const char *path);
+int dfs_file_write(struct dfs_fd* fd, const void *buf, rt_size_t len);
+int dfs_file_lseek(struct dfs_fd* fd, rt_off_t offset);
+int dfs_file_stat(const char *path, struct dfs_stat *buf);
+int dfs_file_rename(const char* oldpath, const char* newpath);
+
+#endif
+

components/dfs/src/dfs.c

+/*
+ * File      : dfs.c
+ * This file is part of Device File System in RT-Thread RTOS
+ * COPYRIGHT (C) 2004-2010, RT-Thread Development Team
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rt-thread.org/license/LICENSE.
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2005-02-22     Bernard      The first version.
+ * 2010-07-16
+ */
+
+#include <dfs.h>
+#include <dfs_fs.h>
+#include <dfs_config.h>
+#include <dfs_file.h>
+
+/* Global variables */
+const struct dfs_filesystem_operation* filesystem_operation_table[DFS_FILESYSTEM_TYPES_MAX];
+struct dfs_filesystem filesystem_table[DFS_FILESYSTEMS_MAX];
+
+/* device filesystem lock */
+static struct rt_mutex fslock;
+
+#ifdef DFS_USING_WORKDIR
+char working_directory[DFS_PATH_MAX];
+#endif
+
+#ifdef DFS_USING_STDIO
+struct dfs_fd fd_table[3 + DFS_FD_MAX];
+#else
+struct dfs_fd fd_table[DFS_FD_MAX];
+#endif
+
+/**
+ * this function will initialize device file system.
+ */
+void dfs_init()
+{
+	/* clear filesystem operations table */
+	rt_memset(filesystem_operation_table, 0, sizeof(filesystem_operation_table));
+	/* clear filesystem table */
+	rt_memset(filesystem_table, 0, sizeof(filesystem_table));
+	/* clean fd table */
+	rt_memset(fd_table, 0, sizeof(fd_table));
+
+	/* create device filesystem lock */
+	rt_mutex_init(&fslock, "fslock", RT_IPC_FLAG_FIFO);
+
+#ifdef DFS_USING_WORKDIR
+	/* set current working directory */
+	rt_memset(working_directory, 0, sizeof(working_directory));
+	working_directory[0] = '/';
+#endif
+}
+
+/**
+ * this function will lock device file system.
+ *
+ * note: please don't invoke it on ISR.
+ */
+void dfs_lock()
+{
+	rt_err_t result;
+
+	result = rt_mutex_take(&fslock, RT_WAITING_FOREVER);
+	RT_ASSERT(result == RT_EOK);
+}
+
+/**
+ * this function will lock device file system.
+ *
+ * note: please don't invoke it on ISR.
+ */
+void dfs_unlock()
+{
+	rt_mutex_release(&fslock);
+}
+
+/**
+ * this function will allocate a file descriptor.
+ *
+ * @return -1 on failed or the allocated file descriptor.
+ */
+int fd_new(void)
+{
+	struct dfs_fd* d;
+	int idx;
+
+	/* lock filesystem */
+	dfs_lock();
+
+	/* find an empty fd entry */
+#ifdef DFS_USING_STDIO
+	for (idx = 3; idx < DFS_FD_MAX + 3 && fd_table[idx].ref_count > 0; idx++);
+#else
+	for (idx = 0; idx < DFS_FD_MAX && fd_table[idx].ref_count > 0; idx++);
+#endif
+
+	/* can't find an empty fd entry */
+#ifdef DFS_USING_STDIO
+	if (idx == DFS_FD_MAX + 3)
+#else
+	if (idx == DFS_FD_MAX)
+#endif
+	{
+		idx = -1;
+		goto __result;
+	}
+
+	d = &(fd_table[idx]);
+	d->ref_count = 1;
+
+__result:
+	dfs_unlock();
+	return idx;
+}
+
+/**
+ * this function will return a file descriptor structure according to file 
+ * descriptor.
+ *
+ * @return NULL on on this file descriptor or the file descriptor structure
+ * pointer.
+ */
+struct dfs_fd* fd_get(int fd)
+{
+	struct dfs_fd* d;
+
+#ifdef DFS_USING_STDIO
+	if ( fd < 3 || fd > DFS_FD_MAX + 3) return RT_NULL;
+#else
+	if ( fd < 0 || fd > DFS_FD_MAX ) return RT_NULL;
+#endif
+
+	dfs_lock();
+	d = &fd_table[fd];
+
+	/* increase the reference count */
+	d->ref_count ++;
+	dfs_unlock();
+
+	return d;
+}
+
+/**
+ * this function will put the file descriptor.
+ */
+void fd_put(struct dfs_fd* fd)
+{
+	dfs_lock();
+	fd->ref_count --;
+
+	/* clear this fd entry */
+	if ( fd->ref_count == 0 )
+	{
+		rt_memset(fd, 0, sizeof(struct dfs_fd));
+	}
+	dfs_unlock();
+};
+
+/** 
+ * this function will return whether this file has been opend.
+ * 
+ * @param pathname the file path name.
+ *
+ * @return 0 on file has been open, -1 on not open.
+ */
+int fd_is_open(const char* pathname)
+{
+	char *fullpath;
+	unsigned int index;
+	struct dfs_filesystem* fs;
+	struct dfs_fd* fd;
+
+	fullpath = dfs_normalize_path(RT_NULL, pathname);
+	if (fullpath != RT_NULL)
+	{
+		char *mountpath;
+		fs = dfs_filesystem_lookup(fullpath);
+		if (fs == RT_NULL)
+		{
+			/* can't find mounted file system */
+			rt_free(fullpath);
+			return -1;
+		}
+
+		/* get file path name under mounted file system */
+		if (fs->path[0] == '/' && fs->path[1] == '\0')
+			mountpath = fullpath;
+		else mountpath = fullpath + strlen(fs->path);
+
+		dfs_lock();
+		for (index = 0; index < DFS_FD_MAX; index++)
+		{
+			fd = &(fd_table[index]);
+			if (fd->fs == RT_NULL) continue;
+
+			if (fd->fs == fs &&
+				strcmp(fd->path, mountpath) == 0)
+			{
+				/* found file in file descriptor table */
+				rt_free(fullpath);
+				dfs_unlock();
+				return 0;
+			}
+		}
+		dfs_unlock();
+
+		rt_free(fullpath);
+	}
+
+	return -1;
+}
+
+/**
+ * this function will return a sub-path name under directory.
+ *
+ * @param directory the parent directory.
+ * @param filename the filename.
+ *
+ * @return the subdir pointer in filename
+ */
+const char* dfs_subdir(const char* directory, const char* filename)
+{
+	const char* dir;
+
+	dir = filename + strlen(directory);
+	if ((*dir != '/') && (dir != filename))
+	{
+		dir --;
+	}
+	return dir;
+}
+
+/** 
+ * this function will normalize a path according to specified parent directory and file name.
+ *
+ * @param directory the parent path
+ * @param filename the file name
+ *
+ * @return the built full file path (absoluted path)
+ */
+char* dfs_normalize_path(const char* directory, const char* filename)
+{
+	char *fullpath;
+	char *dst0, *dst, *src;
+
+	/* check parameters */
+	RT_ASSERT(filename != RT_NULL);
+
+#ifdef DFS_USING_WORKDIR
+	if (directory == NULL) /* shall use working directory */
+		directory = &working_directory[0];
+#else
+	if ((directory == NULL) && (filename[0] != '/'))
+	{
+		return RT_NULL;
+	}
+#endif
+
+	if (filename[0] != '/') /* it's a absolute path, use it directly */
+	{
+		fullpath = rt_malloc(strlen(directory) + strlen(filename) + 2);
+
+		/* join path and file name */
+		rt_snprintf(fullpath, strlen(directory) + strlen(filename) + 2, 
+			"%s/%s", directory, filename);
+	}
+	else
+	{
+		fullpath = rt_strdup(filename); /* copy string */
+	}
+
+	src = fullpath;
+	dst = fullpath;
+	while (1)
+	{
+		char c = *src;
+
+		 if (c == '.')
+		 {
+			 if (!src[1]) src ++; /* '.' and ends */
+			 else if (src[1] == '/')
+			 {
+				 /* './' case */
+				 src += 2;
+
+				 while ((*src == '/') && (*src != '\0')) src ++;
+				 continue;
+			 }
+			 else if (src[1] == '.')
+			 {
+				 if (!src[2])
+				 {
+					/* '..' and ends case */
+					 src += 2;
+					 goto up_one;
+				 }
+				 else if (src[2] == '/')
+				 {
+					/* '../' case */
+					 src += 3;
+
+					 while ((*src == '/') && (*src != '\0')) src ++;
+					 goto up_one;
+				 }
+			 }
+		 }
+
+		 /* copy up the next '/' and erase all '/' */
+		 while ((c = *src++) != '\0' && c != '/') *dst ++ = c;
+
+		 if (c == '/')
+		 {
+			 *dst ++ = '/';
+			 while (c == '/') c = *src++;
+
+			 src --;
+		 }
+		 else if (!c) break;
+
+		 continue;
+
+up_one:
+		dst --;
+		if (dst < dst0) { rt_free(fullpath); return NULL;}
+		while (dst0 < dst && dst[-1] != '/') dst --;
+	}
+
+	*dst = '\0';
+	return fullpath;
+}

components/dfs/src/dfs_file.c

+/*
+ * File      : dfs_file.c
+ * This file is part of Device File System in RT-Thread RTOS
+ * COPYRIGHT (C) 2004-2010, RT-Thread Development Team
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rt-thread.org/license/LICENSE.
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2005-02-22     Bernard      The first version.
+ */
+#include <dfs.h>
+#include <dfs_file.h>
+
+#define NO_WORKING_DIR	"system does not support working dir\n"
+
+/**
+ * this function will open a file which specified by path with specified flags.
+ *
+ * @param fd the file descriptor pointer to return the corresponding result.
+ * @param path the spaciefied file path.
+ * @param flags the flags for open operator.
+ *
+ * @return 0 on successful, -1 on failed.
+ */
+int dfs_file_open(struct dfs_fd* fd, const char *path, int flags)
+{
+	struct dfs_filesystem* fs;
+	char *fullpath;
+	int result;
+
+	/* parameter check */
+	if ( fd == RT_NULL ) return -DFS_STATUS_EINVAL;
+
+	/* make sure we have an absolute path */
+	fullpath = dfs_normalize_path(RT_NULL, path);
+	if (fullpath == RT_NULL)
+	{
+		rt_kprintf(NO_WORKING_DIR);
+		return -1;
+	}
+
+	dfs_log(DFS_DEBUG_INFO, ("open file:%s", fullpath));
+
+	/* find filesystem */
+	fs = dfs_filesystem_lookup(fullpath);
+	if ( fs == RT_NULL )
+	{
+		rt_free(fullpath); /* release path */
+		return -DFS_STATUS_ENOENT;
+	}
+
+	dfs_log(DFS_DEBUG_INFO, ("open in filesystem:%s", fs->ops->name));
+	fd->fs = fs;
+
+	/* initilize the fd item */
+	fd->type = FT_REGULAR;
+	fd->flags = flags;
+	fd->size = 0;
+	fd->pos = 0;
+
+	fd->path = rt_strdup(dfs_subdir(fs->path, fullpath));
+	rt_free(fullpath);
+	dfs_log(DFS_DEBUG_INFO, ("actul file path: %s\n", fd->path));
+
+	/* specific file system open routine */
+	if (fs->ops->open == RT_NULL)
+	{
+		/* clear fd */
+		rt_free(fd->path);		
+		rt_memset(fd, 0, sizeof(*fd));
+
+		return -DFS_STATUS_ENOSYS;
+	}
+
+	if ((result = fs->ops->open(fd)) < 0)
+	{
+		/* clear fd */
+		rt_free(fd->path);
+		rt_memset(fd, 0, sizeof(*fd));
+
+		dfs_log(DFS_DEBUG_INFO, ("open failed"));
+
+		return result;
+	}
+
+	fd->flags |= DFS_F_OPEN;
+	if ( flags & DFS_O_DIRECTORY )
+	{
+		fd->type = FT_DIRECTORY;
+		fd->flags |= DFS_F_DIRECTORY;
+	}
+
+	dfs_log(DFS_DEBUG_INFO, ("open successful"));
+	return 0;
+}
+
+/**
+ * this function will close a file descriptor.
+ * 
+ * @param fd the file descriptor to be closed.
+ *
+ * @return 0 on successful, -1 on failed.
+ */
+int dfs_file_close(struct dfs_fd* fd)
+{
+	int result = 0;
+
+	if (fd != RT_NULL && fd->fs->ops->close != RT_NULL) result = fd->fs->ops->close(fd);
+
+	/* close fd error, return */
+	if ( result < 0 ) return result; 
+
+	rt_free(fd->path);
+	rt_memset(fd, 0, sizeof(struct dfs_fd));
+
+	return result;
+}
+
+/**
+ * this function will perform a io control on a file descriptor.
+ * 
+ * @param fd the file descriptor.
+ * @param cmd the command to send to file descriptor.
+ * @param args the argument to send to file descriptor.
+ *
+ * @return 0 on successful, -1 on failed.
+ */
+int dfs_file_ioctl(struct dfs_fd* fd, int cmd, void *args)
+{
+	struct dfs_filesystem* fs;
+
+	if (fd == RT_NULL || fd->type != FT_REGULAR) return -DFS_STATUS_EINVAL;
+
+	fs = fd->fs;
+	if (fs->ops->ioctl != RT_NULL) return fs->ops->ioctl(fd, cmd, args);
+
+	return -DFS_STATUS_ENOSYS;
+}
+
+/**
+ * this function will read specified length data from a file descriptor to a buffer.
+ *
+ * @param fd the file descriptor.
+ * @param buf the buffer to save the read data.
+ * @param len the length of data buffer to be read.
+ *
+ * @return the actual read data bytes or 0 on end of file or failed.
+ */
+int dfs_file_read(struct dfs_fd* fd, void *buf, rt_size_t len)
+{
+	struct dfs_filesystem* fs;
+	int result = 0;
+
+	if (fd == RT_NULL) return -DFS_STATUS_EINVAL;
+	
+	fs = (struct dfs_filesystem*) fd->fs;
+	if (fs->ops->read == RT_NULL) return -DFS_STATUS_ENOSYS;
+
+	if ( (result = fs->ops->read(fd, buf, len)) < 0 ) fd->flags |= DFS_F_EOF;
+
+	return result;
+}
+
+/**
+ * this function will fetch directory entries from a directory descriptor.
+ *
+ * @param fd the directory decriptor.
+ * @param dirp the dirent buffer to save result.
+ * @param nbytes the aviable room in the buffer.
+ *
+ * @return the read dirent, others on failed.
+ */
+int dfs_file_getdents(struct dfs_fd* fd, struct dfs_dirent* dirp, rt_size_t nbytes)
+{
+	struct dfs_filesystem* fs;
+
+	/* parameter check */
+	if (fd == RT_NULL || fd->type != FT_DIRECTORY) return -DFS_STATUS_EINVAL;
+
+	fs = (struct dfs_filesystem*) fd->fs;
+	if (fs->ops->getdents != RT_NULL) return fs->ops->getdents(fd, dirp, nbytes);
+
+	return -DFS_STATUS_ENOSYS;
+}
+
+/**
+ * this function will unlink (remove) a specified path file from file system.
+ *
+ * @param path the specified path file to be unlinked.
+ *
+ * @return 0 on successful, -1 on failed.
+ */
+int dfs_file_unlink(const char *path)
+{
+	int result;
+	char *fullpath;
+	struct dfs_filesystem* fs;
+
+	result = DFS_STATUS_OK;
+
+	/* Make sure we have an absolute path */
+	fullpath = dfs_normalize_path(RT_NULL, path);
+	if ( fullpath == RT_NULL)
+	{
+		rt_kprintf(NO_WORKING_DIR);
+		return -DFS_STATUS_EINVAL;
+	}
+
+	/* get filesystem */
+	if ( (fs = dfs_filesystem_lookup(fullpath)) == RT_NULL)
+	{
+		result = -DFS_STATUS_ENOENT;
+		goto __exit;
+	}
+
+	/* Check whether file is already open */
+	if (fd_is_open(fullpath) == 0)
+	{
+		result = -DFS_STATUS_EBUSY;
+		goto __exit;
+	}
+
+	if (fs->ops->unlink != RT_NULL) 
+		result = fs->ops->unlink(fs, dfs_subdir(fs->path, fullpath));
+	else result = -DFS_STATUS_ENOSYS;
+
+__exit:
+	rt_free(fullpath);
+	return result;
+}
+
+/**
+ * this function will write some specified length data to file system.
+ * 
+ * @param fd the file descriptor.
+ * @param buf the data buffer to be written.
+ * @param len the data buffer length
+ *
+ * @return the actual written data length.
+ */
+int dfs_file_write(struct dfs_fd* fd, const void *buf, rt_size_t len)
+{
+	struct dfs_filesystem* fs;
+
+	if (fd == RT_NULL) return -DFS_STATUS_EINVAL;
+
+	fs = fd->fs;
+	if (fs->ops->write == RT_NULL) return -DFS_STATUS_ENOSYS;
+
+	return fs->ops->write(fd, buf, len);
+}
+
+/**
+ * this function will flush buffer on a file descriptor.
+ *
+ * @param fd the file descriptor.
+ *
+ * @return 0 on successful, -1 on failed.
+ */
+int dfs_file_flush(struct dfs_fd* fd)
+{
+	struct dfs_filesystem* fs;
+
+	if (fd == RT_NULL) return -DFS_STATUS_EINVAL;
+
+	fs = fd->fs;
+	if (fs->ops->flush == RT_NULL) return -DFS_STATUS_ENOSYS;
+
+	return fs->ops->flush(fd);
+}
+
+/**
+ * this function will seek the offset for specified file descriptor.
+ *
+ * @param fd the file descriptor.
+ * @param offset the offset to be seeked.
+ *
+ * @return the current position after seek.
+ */
+int dfs_file_lseek(struct dfs_fd* fd, rt_off_t offset)
+{
+	struct dfs_filesystem* fs = fd->fs;
+
+	if (fd == RT_NULL) return -DFS_STATUS_EINVAL;
+	if (fs->ops->lseek == RT_NULL) return -DFS_STATUS_ENOSYS;
+
+	return fs->ops->lseek(fd, offset);
+}
+
+/**
+ * this function will get file information.
+ *
+ * @param path the file path.
+ * @param buf the data buffer to save stat description.
+ *
+ * @return 0 on successful, -1 on failed.
+ */
+int dfs_file_stat(const char *path, struct dfs_stat *buf)
+{
+	int result;
+	char* fullpath;
+	struct dfs_filesystem* fs;
+
+	fullpath = dfs_normalize_path(RT_NULL, path);
+	if ( fullpath == RT_NULL )
+	{
+		rt_kprintf(NO_WORKING_DIR);
+		return -1;
+	}
+
+	if ((fs = dfs_filesystem_lookup(fullpath)) == RT_NULL)
+	{
+		dfs_log(DFS_DEBUG_ERROR, ("can't find mounted filesystem on this path:%s", fullpath));
+		rt_free(fullpath);
+		return -DFS_STATUS_ENOENT;
+	}
+
+	if (fullpath[0] == '/' && fullpath[1] == '\0')
+	{
+		/* it's the root directory */
+		buf->st_dev   = 0;
+
+		buf->st_mode = DFS_S_IRUSR | DFS_S_IRGRP | DFS_S_IROTH |
+			DFS_S_IWUSR | DFS_S_IWGRP | DFS_S_IWOTH;
+		buf->st_mode |= DFS_S_IFDIR | DFS_S_IXUSR | DFS_S_IXGRP | DFS_S_IXOTH;
+
+		buf->st_size  = 0;
+		buf->st_mtime = 0;
+		buf->st_blksize = 512;
+
+		/* release full path */
+		rt_free(fullpath);
+
+		return DFS_STATUS_OK;
+	}
+	
+	/* get the real file path */
+	
+	if (fs->ops->stat == RT_NULL)
+	{
+		rt_free(fullpath);
+		dfs_log(DFS_DEBUG_ERROR, ("the filesystem didn't implement this function"));
+		return -DFS_STATUS_ENOSYS;
+	}
+
+	result = fs->ops->stat(fs, fullpath, buf);
+	rt_free(fullpath);
+
+	return result;
+}
+
+/**
+ * this funciton will rename an old path name to a new path name.
+ *
+ * @param oldpath the old path name.
+ * @param newpath the new path name.
+ *
+ * @return 0 on successful, -1 on failed.
+ */
+int dfs_file_rename(const char* oldpath, const char* newpath)
+{
+	int result;
+	struct dfs_filesystem *oldfs, *newfs;
+	char *oldfullpath, *newfullpath;
+
+	result = DFS_STATUS_OK;
+
+	oldfullpath = dfs_normalize_path(RT_NULL, oldpath);
+	if ( oldfullpath == RT_NULL )
+	{
+		rt_kprintf(NO_WORKING_DIR);
+		result = -DFS_STATUS_ENOENT;
+		goto __exit;
+	}
+
+	newfullpath = dfs_normalize_path(RT_NULL, newpath);
+	if ( newfullpath == RT_NULL )
+	{
+		rt_kprintf(NO_WORKING_DIR);
+		result = -DFS_STATUS_ENOENT;
+		goto __exit;
+	}
+
+	if ( (oldfs = dfs_filesystem_lookup(oldfullpath)) == RT_NULL )
+	{
+		result = -DFS_STATUS_ENOENT;
+		goto __exit;
+	}
+
+	if ( (newfs = dfs_filesystem_lookup(newfullpath)) == RT_NULL )
+	{
+		result = -DFS_STATUS_ENOENT;
+		goto __exit;
+	}
+
+	if ( oldfs == newfs )
+	{
+		if ( oldfs->ops->rename == RT_NULL )
+		{
+			result = -DFS_STATUS_ENOSYS;
+			goto __exit;
+		}
+
+		result = oldfs->ops->rename(oldfs, oldfullpath, newfullpath);
+		goto __exit;
+	}
+
+	result = -DFS_STATUS_EXDEV;
+
+__exit:
+	rt_free(oldfullpath);
+	rt_free(newfullpath);
+
+	/* not at same file system, return EXDEV */
+	return result;
+}
+
+#ifdef RT_USING_FINSH
+#include <finsh.h>
+
+static struct dfs_fd fd;
+static struct dfs_dirent dirent;
+void ls(const char* pathname)
+{
+	struct dfs_stat stat;
+	int length;
+	char* fullpath;
+
+	fullpath = rt_malloc(DFS_PATH_MAX + 1);
+	if (fullpath == RT_NULL) return; /* out of memory */
+	/* list directory */
+	if ( dfs_file_open(&fd, pathname, DFS_O_DIRECTORY) == 0 )
+	{
+		rt_kprintf("Directory %s:\n", pathname);
+		do
+		{
+			rt_memset(&dirent, 0, sizeof(struct dfs_dirent));
+			length = dfs_file_getdents(&fd, &dirent, sizeof(struct dfs_dirent));
+			if ( length > 0 ) 
+			{
+				rt_memset(&stat, 0, sizeof(struct dfs_stat));
+
+				/* build full path for each file */
+				if (pathname[strlen(pathname) - 1] != '/')
+					rt_snprintf(fullpath, DFS_PATH_MAX + 1, "%s%c%s", pathname, '/', dirent.d_name);
+				else
+					rt_snprintf(fullpath, DFS_PATH_MAX + 1, "%s%s", pathname, dirent.d_name);
+				
+				dfs_file_stat(fullpath, &stat);
+				if ( stat.st_mode & DFS_S_IFDIR )
+				{
+					rt_kprintf("%s\t\t<DIR>\n", dirent.d_name);
+				}
+				else
+				{
+					rt_kprintf("%s\t\t%lu\n", dirent.d_name, stat.st_size);
+				}
+			}
+		}while(length > 0);
+
+		dfs_file_close(&fd);
+	}
+	else
+	{
+		rt_kprintf("No such directory\n");
+	}
+	rt_free(fullpath);
+}
+FINSH_FUNCTION_EXPORT(ls, list directory contents)
+
+static void mkdir(const char* pathname)
+{
+	/* make a new directory */
+	if (dfs_file_open(&fd, pathname, DFS_O_DIRECTORY | DFS_O_CREAT) == 0)
+	{
+		dfs_file_close(&fd);
+	}
+	else rt_kprintf("Can't mkdir %s\n", pathname);
+}
+FINSH_FUNCTION_EXPORT(mkdir, make a directory)
+
+void rm(const char* filename)
+{
+	if (dfs_file_unlink(filename) < 0)
+	{
+		rt_kprintf("Delete %s failed\n", filename);
+	}
+}
+FINSH_FUNCTION_EXPORT(rm, remove files or directories)
+
+void cat(const char* filename)
+{
+	rt_uint32_t length;
+	char buffer[81];
+	
+	if (dfs_file_open(&fd, filename, DFS_O_RDONLY) < 0)
+	{
+		rt_kprintf("Open %s failed\n", filename);
+		return;
+	}
+	
+	do
+	{
+		rt_memset(buffer, 0, sizeof(buffer));
+		length = dfs_file_read(&fd, buffer, 81);
+		if (length > 0)
+		{
+			rt_kprintf("%s", buffer);
+		}
+	}while (length > 0);
+	
+	dfs_file_close(&fd);
+}
+FINSH_FUNCTION_EXPORT(cat, print file)
+
+#endif