distcc源代码详解（1）

1、distcc分为server端和client端，其中client端，是在执行make命令编译的时候调用，而server端，是程序接受client端的请求，完成编译的任务

在dameon.c中可以找到main函数，是server函数的入口

/**
 * distcc daemon.  May run from inetd, or standalone.  Accepts
 * requests from clients to compile files.
 **/
int main(int argc, char *argv[])
{
    int ret;

    dcc_setup_startup_log();

    if (distccd_parse_options(argc, (const char **) argv))
        dcc_exit(EXIT_DISTCC_FAILED);

    /* check this before redirecting the logs, so that it's really obvious */
    if (!dcc_should_be_inetd())
        if (opt_allowed == NULL) {
            rs_log_error("--allow option is now mandatory; "
                         "you must specify which clients are allowed to connect");
            ret = EXIT_BAD_ARGUMENTS;
            goto out;
        }

    if ((ret = dcc_set_lifetime()) != 0)
        dcc_exit(ret);

    /* do this before giving away root */
    if (nice(opt_niceness) == -1) {
        rs_log_warning("nice %d failed: %s", opt_niceness,
                       strerror(errno));
        /* continue anyhow */
    }

    if ((ret = dcc_discard_root()) != 0)
        dcc_exit(ret);

    /* Discard privileges before opening log so that if it's created, it has
     * the right ownership. */
    dcc_setup_real_log();

    /* Do everything from $TMPDIR directory.  Allows start directory to be
     * unmounted. */
    if ((ret = dcc_get_tmp_top(&dcc_daemon_wd)))
        goto out;

    if (chdir(dcc_daemon_wd) == -1) {
        rs_log_error("failed to chdir to %s: %s",
                     dcc_daemon_wd, strerror(errno));
        ret = EXIT_IO_ERROR;
        goto out;
    } else {
        rs_trace("chdir to %s", dcc_daemon_wd);
    }

    if ((ret = dcc_setup_daemon_path()))
        goto out;

#ifdef HAVE_GSSAPI
    /* Obtain credentials if authentication is requested. */
    if (dcc_auth_enabled) {
        if ((ret = dcc_gssapi_acquire_credentials()) != 0) {
            goto out;
        }

        /* Read contents of list file into an array and apply qsort. */
        if (opt_blacklist_enabled || opt_whitelist_enabled) {
            if ((ret = dcc_gssapi_obtain_list((opt_blacklist_enabled) ? 1 : 0)) != 0) {
	            goto out;
	        }
        }
    }
#endif

    /* Initialize the distcc io timeout value */
    dcc_get_io_timeout();

    if (dcc_should_be_inetd())
        ret = dcc_inetd_server();
    else
        ret = dcc_standalone_server();

    out:
    dcc_exit(ret);
}

　　distccd_parse_options函数解析入参，dcc_discard_root()如果进程具有root权限，则换成一个低权限的运行，dcc_run_job这个函数接受client端的请求并完成编译，

 dcc_run_job中该函数dcc_r_request_header得到对端的版本信息。

 dcc_r_argv中获取client端发送的编译参数信息，即执行gcc时的参数信息，其中已经去除需要本地编译的参数必去-i,-I之类的