问如何在C++中使用SFTP和libssh从服务器下载文件夹或文件？

EN

int AutoUpdator::sftp_read_sync(ssh_session session, sftp_session sftp, std::string path)
{
    ans_info("start sftp_read_sync");
    std::cout << path << std::endl;
    int access_type;
    sftp_file file;
    char buffer[MAX_XFER_BUF_SIZE];
    int nbytes, nwritten, rc;
    int fd;
    access_type = O_RDONLY;
    file = sftp_open(sftp, path.c_str(), access_type, 0);
    if (file == NULL) {
        fprintf(stderr, "Can't open file for reading: %s\n", ssh_get_error(session));
        return SSH_ERROR;
    }

    /* open a file for writing... */
    fd = open("/home/writing_test.txt",O_WRONLY|O_CREAT, 0700);
    if (fd < 0) {
        fprintf(stderr, "Can't open file for writing: %s\n", strerror(errno));
        return SSH_ERROR;
    }

    for (;;) {
        nbytes = sftp_read(file, buffer, sizeof(buffer));
        if (nbytes > 0) {
            std::cout << "nbytes :" << nbytes << std::endl;
            std::cout << "buffer :" << buffer << std::endl;
            server_version_ = buffer;
            ans_info("server_version : " + server_version_);
        }
        else if (nbytes == 0) {
            ans_info("EOF");
            break; // EOF
        }
        else if (nbytes < 0) {
            fprintf(stderr, "Error while reading file: %s\n", ssh_get_error(session));
            sftp_close(file);
            return SSH_ERROR;
        }
        nwritten = write(fd, buffer, nbytes);
        if (nwritten != nbytes) {
            fprintf(stderr, "Error writing: %s\n", strerror(errno));
            sftp_close(file);
            return SSH_ERROR;
        }
    }
    
    rc = sftp_close(file);
    if (rc != SSH_OK) {
        fprintf(stderr, "Can't close the read file: %s\n", ssh_get_error(session));
        return rc;
    }
    return SSH_OK;
}