Writting a simple filesystem in C using FUSE

[Yimeng]

I've learned the hello.c using FUSE. It can create a hello file under mountfile. But I've no idea about how to create a folder under the mountfile and then create hello under mountfile/folderIcreate. then I can use cat mountfile/folderIcreate/hello the code is similar to the simple hello.c.

#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);
}

can someone give a simple example about how to revise the code above without changing the strcut fuse_operations. Thank you!

[iamthwee]

Check the documentation, as with any question regarding a specific library you are unlikely to get an answer unless someone here has used that library before or has the time to install and test it.

Most folk don't have the time or inclination.

[Yimeng]

I've solved it.