Function in fuse linux in c

Question

I am new in linux, and i have an assignment about FUSE.

My FUSE need to be able open a file, edit, and rename it. Here is my full code

#include <fuse.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <errno.h>
#include <sys/statfs.h>
#include <stdlib.h>

static const char *dirpath  = "/home/cync48/Downloads";

static int xmp_getattr(const char *path, struct stat *stbuf)
{
    int res;
    char fpath[1000];
    sprintf(fpath, "%s%s", dirpath, path);
    res = lstat(fpath, stbuf);

    if(res == -1)
        return -errno;

        return 0;
}



static int xmp_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
               off_t offset, struct fuse_file_info *fi)
{
     char fpath[1000];
    if(strcmp(path,"/")==0)
    {
        path = dirpath;
        sprintf(fpath, "%s", path);
    }
    else
        sprintf(fpath, "%s%s", dirpath, path);

    DIR *dp;
    struct dirent *de;

    (void) offset;
    (void) fi;

    dp = opendir(fpath);
    if (dp == NULL)
        return -errno;

    while ((de = readdir(dp)) != NULL) {
        struct stat st;
        memset(&st, 0, sizeof(st));
        st.st_ino = de->d_ino;
        st.st_mode = de->d_type << 12;
        if (filler(buf, de->d_name, &st, 0))
            break;
    }

    closedir(dp);
    return 0;
}

static int xmp_mknod(const char *path, mode_t mode, dev_t rdev)
{
    int res;
    char fpath[1000];

    sprintf(fpath, "%s%s", dirpath, path);

    //On Linux this could just be 'mknod(path, mode, rdev)' but thisis more portable
    if (S_ISREG(mode)) {
        res = open(fpath, O_CREAT | O_EXCL | O_WRONLY, mode);
        if (res >= 0)
            res = close(res);
    } else if (S_ISFIFO(mode))
        res = mkfifo(fpath, mode);
    else
        res = mknod(fpath, mode, rdev);
    if (res == -1)
        return -errno;

    return 0;
}

static int xmp_mkdir(const char *path, mode_t mode)
{
    int res;
    char fpath[1000];

    sprintf(fpath, "%s%s", dirpath, path);
    res = mkdir(fpath, mode);
    if (res == -1)
        return -errno;

    return 0;
}

static int xmp_unlink(const char *path)
{
    int res;
    char fpath[1000];

    sprintf(fpath, "%s%s", dirpath, path);

    res = unlink(fpath);
    if (res == -1)
        return -errno;

    return 0;
}

static int xmp_rmdir(const char *path)
{
    int res;
    char fpath[1000];

    sprintf(fpath, "%s%s", dirpath, path);

    res = rmdir(fpath);
    if (res == -1)
        return -errno;

    return 0;
}

static int xmp_rename(const char *from, const char *to)
{
    int res;

    res = rename(from, to);
    if (res == -1)
        return -errno;

    return 0;
}

static int xmp_open(const char *path, struct fuse_file_info *fi)
{
    int res;
    char fpath[1000];

    sprintf(fpath, "%s%s", dirpath, path);
    //(void) fi;
    res = open(fpath, fi->flags);
    if (res == -1)
        return -errno;

    close(res);
    return 0;
}

static int xmp_read(const char *path, char *buf, size_t size, off_t offset,
            struct fuse_file_info *fi)
{
    int fd;
    int res;
    char fpath[1000];

    sprintf(fpath, "%s%s", dirpath, path);

    (void) fi;
    fd = open(path, O_RDONLY);
    if (fd == -1)
        return -errno;

    res = pread(fd, buf, size, offset);
    if (res == -1)
        res = -errno;

    close(fd);
    return res;
}

static int xmp_write(const char *path, const char *buf, size_t size,
             off_t offset, struct fuse_file_info *fi)
{
    int fd;
    int res;
     char fpath[1000];

    sprintf(fpath, "%s%s", dirpath, path);

    (void) fi;
    fd = open(fpath, O_WRONLY);
    if (fd == -1)
        return -errno;

    res = pwrite(fd, buf, size, offset);
    if (res == -1)
        res = -errno;

    close(fd);
    return res;
}

static int xmp_release(const char *path, struct fuse_file_info *fi)
{
    //Just a stub.   This method is optional and can safely be left unimplemented
    char fpath[1000];

    sprintf(fpath, "%s%s", dirpath, path);
    (void) fpath;
    (void) fi;
    return 0;
}

static struct fuse_operations xmp_oper = {
    .getattr    = xmp_getattr,
    .mknod      = xmp_mknod,
    .mkdir      = xmp_mkdir,
    .readdir     = xmp_readdir,
    .unlink     = xmp_unlink,
    .rmdir      = xmp_rmdir,
    .rename     = xmp_rename,
    .open       = xmp_open,
    .read       = xmp_read,
    .write      = xmp_write,
    .release    = xmp_release,
};

int main(int argc, char *argv[])
{
    umask(0);
    return fuse_main(argc, argv, &xmp_oper, NULL);
}

1. I still cannot open a file, the error is "Too many open files ins system"
2. I still cannot rename a file, i write the exact syntax to rename a file ( mv name new_name ) but it said about moving a file.

Does my code incorrect?