rem: static int sshfs_async_read(struct sshfs_file *sf, struct read_chunk *chunk)
add: static int sshfs_async_read(struct sshfs_file *sf, char *rbuf, size_t size, off_t offset)
context: static int sshfs_async_read(struct sshfs_file *sf, struct read_chunk *chunk){    int err;    struct buffer buf;    struct buffer *handle = &sf->handle;    buf_init(&buf, 0);    buf_add_buf(&buf, handle);    buf_add_uint64(&buf, chunk->offset);    buf_add_uint32(&buf, chunk->size);    err = sftp_request_async(SSH_FXP_READ, &buf, sshfs_read_begin,                             sshfs_read_end, chunk);    buf_free(&buf);    return err;    }