Function fuse_fs_read_buf 

pub unsafe extern "C" fn fuse_fs_read_buf(
    fs: *mut fuse_fs,
    path: *const c_char,
    bufp: *mut *mut fuse_bufvec,
    size: size_t,
    off: off_t,
    fi: *mut fuse_file_info,
) -> c_int