用FUSE写简单的文件系统

[lym1108csu]

问下CSDN里面的大牛们点问题。。
我们作业要写个简易的file system用到FUSE。我大概看明白了hello.c这个文件。。。可以实现在mount 的文件夹下建立一个hello文件,，但是我不会在mount的文件夹下先建立一个文件夹，然后再在文件夹里面建立hello 文件
最后的效果应该可以这样访问
cat mountfile/folderIcreate/hello
以下是代码，跟hello.c差不多：

#define FUSE_USE_VERSION 30

#include <fuse.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>

static const char *hello_str = "Hello World!\n";
static const char *add_path = "/add";
static const char *div_path = "/div";
static const char *hello_path = "/hello";

static int hello_getattr(const char *path, struct stat *stbuf)
{
	int res = 0;
	
	printf("%s", path);

	memset(stbuf, 0, sizeof(struct stat));
	if (strcmp(path, "/") == 0) 
	{
		stbuf->st_mode = S_IFDIR | 0755;
		stbuf->st_nlink = 2;
	} 
	else if (strcmp(path, hello_path) == 0) 
	{
		stbuf->st_mode = S_IFREG | 0444;
		stbuf->st_nlink = 1;
		stbuf->st_size = strlen(hello_str);
	}
	else if (strcmp(path, add_path) == 0) 
	{
		stbuf->st_mode = S_IFDIR | 0755;
		stbuf->st_nlink = 3;
		if (strcmp(path, add_path1) == 0) 
	{
		stbuf->st_mode = S_IFREG | 0444;
		stbuf->st_nlink = 1;
		stbuf->st_size = strlen(hello_str);
	}
	}
	else if(strcmp(path, div_path) == 0)
	{
		stbuf->st_mode = S_IFDIR | 0755;
		stbuf->st_nlink = 3;
	} 
	else if(strcmp(path, div_path) == 0)
	{
		stbuf->st_mode = S_IFDIR | 0755;
		stbuf->st_nlink = 3;
	} 
	else
		res = -ENOENT;

	return res;
}

static int hello_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
			 off_t offset, struct fuse_file_info *fi)
{
	printf("%s", path);
	(void) offset;
	(void) fi;

	if (strcmp(path, "/") != 0)
		return -ENOENT;

	filler(buf, ".", NULL, 0);
	filler(buf, "..", NULL, 0);
	filler(buf, hello_path + 1, NULL, 0);
	filler(buf, add_path + 1, NULL, 0);
	filler(buf, div_path + 1, NULL, 0);

	return 0;
}

static int hello_open(const char *path, struct fuse_file_info *fi)
{
	printf("%s", path);
	if (strcmp(path, hello_path) != 0)
		return -ENOENT;

	if ((fi->flags & 3) != O_RDONLY)
		return -EACCES;

	return 0;
}

static int hello_read(const char *path, char *buf, size_t size, off_t offset,
		      struct fuse_file_info *fi)
{
	printf("%s", path);
	size_t len;
	(void) fi;
	if(strcmp(path, hello_path) != 0)
		return -ENOENT;

	len = strlen(hello_str);
	if (offset < len) {
		if (offset + size > len)
			size = len - offset;
		memcpy(buf, hello_str + offset, size);
	} else
		size = 0;

	return size;
}

static struct fuse_operations hello_oper = {
	.getattr	= hello_getattr,
	.readdir	= hello_readdir,
	.open		= hello_open,
	.read		= hello_read,
};

int main(int argc, char *argv[])
{
	return fuse_main(argc, argv, &hello_oper, NULL);
}

尽量不要修改struct fuse_operation.
希望大牛们不吝赐教。。因为感觉网上有关FUSE的资源确实太少。要么就是千篇一律的用hello.c，要么就是开源的文件系统，太过高深，不太适合我们学习。。拜谢，如果方便的话，提供下简单的例子，如果不太方便的话，提供下思路，以及需要修改的函数的片段。谢谢！！！