'ls' command for mounted FUSE filesystem keeps outputting ls: cannot access '/dfs': Input/output error

Question

I am building a FUSE file system using my Ubuntu22 virtual machine on a macbook. I have implemented the getattr function below and compiled using gcc fuse-fs.c -o testfs `pkg-config fuse --cflags --libs` which outputs no errors. However, when I mount using sudo ./testfs -d /dfs try to test it by running sudo ls /dfs, I get the following output:

ls: cannot access '/dfs': Input/output error

I'm not sure why this is happening, as my code looks correct based on the FUSE documentation. I have added the related functions to help.

struct filetype *dfs_tree_root = &(struct filetype){ .path="/" };

// Function to traverse the DFS tree and locate a file/directory by path
static struct filetype* get_filetype_from_path(struct filetype* root, const char* path) {
    if (root == NULL) {
        return NULL;
    }

    if (path == NULL || strlen(path) == 0) {
        return root; // Return root for empty path (refers to root directory)
    }

    // Split the path into components (separated by '/')
    char* path_copy = strdup(path); // Avoid modifying the original path
    char* component = strtok(path_copy, "/");
    struct filetype* current = root;

    while (component) {
    // Search for child with matching name in current directory
    int found = 0;
    for (int i = 0; i < current->num_children; i++) {
        if (strcmp(current->children[i]->path, component) == 0) {
        current = current->children[i];
        found = 1;
        break;
        }
    }

    // If not found in current directory, return NULL
    if (!found) {
        free(path_copy);
        return NULL;
    }

    component = strtok(NULL, "/"); // Get next path component
    }

    free(path_copy);
    return current;
}

// getattr operation for retrieving file attributes
static int dfs_getattr(const char *path, struct stat *stbuf) {
    printf( "Called [getattr]\n" );
    printf( "\tAttributes of %s requested\n", path );

    char *pathname = malloc(strlen(path) + 2);
    if (pathname == NULL) {
        return -ENOMEM; // Out of memory
    }

    strcpy(pathname, path);

    printf("GETATTR %s\n", pathname);

    filetype * file_node = get_filetype_from_path(dfs_tree_root, pathname);
    if(file_node == NULL)
        return -ENOENT;

    stbuf->st_uid = file_node -> user_id; // The owner of the file/directory is the user who mounted the filesystem
    stbuf->st_gid = file_node -> group_id; // The group of the file/directory is the same as the group of the user who mounted the filesystem
    stbuf->st_atime = file_node -> a_time; // The last "a"ccess of the file/directory is right now
    stbuf->st_mtime = file_node -> m_time; // The last "m"odification of the file/directory is right now
    stbuf->st_ctime = file_node -> c_time;
    stbuf->st_mode = file_node -> permissions;
    stbuf->st_nlink = file_node -> num_links + file_node -> num_children;
    stbuf->st_size = file_node -> size;

    free(pathname);
    return 0;
}