nginx源码学习——命令行选项处理

static ngx_int_t ngx_get_options(int argc, char *const *argv);

if (ngx_get_options(argc, argv) != NGX_OK) {
     return 1;
}

static ngx_int_t
ngx_get_options(int argc, char *const *argv)
{
    u_char     *p;
    ngx_int_t   i;

	// 跳过argv[0]程序名处理后面的参数 
    for (i = 1; i < argc; i++) {

		// 处理每一个选项的指针p
        p = (u_char *) argv[i];

		// 每一个参数都必须以'-'开始
        if (*p++ != '-') {
            ngx_log_stderr(0, "invalid option: \"%s\"", argv[i]);
            return NGX_ERROR;
        }

		// 开始解析'-'符号后面的字符, 允许连续多个字符, 例如, -abc...
        while (*p) {

			// 根据选项设置各种标记变量
            switch (*p++) {

            case '?':
            case 'h':
                ngx_show_version = 1;
                ngx_show_help = 1;
                break;

            case 'v':
                ngx_show_version = 1;
                break;

            case 'V':
                ngx_show_version = 1;
                ngx_show_configure = 1;
                break;

            case 't':
                ngx_test_config = 1;
                break;

            case 'q':
                ngx_quiet_mode = 1;
                break;

            case 'p':
				// 字符p后面紧接着value, 即p后面没有空格
                if (*p) {
                    ngx_prefix = p;
                    goto next;
                }
				
				// 否则, p后面有空格, 即下一个参数作为p的value
                if (argv[++i]) {
                    ngx_prefix = (u_char *) argv[i];
                    goto next;
                }

                ngx_log_stderr(0, "option \"-p\" requires directory name");
                return NGX_ERROR;

            case 'c':
				// 同上
                if (*p) {
                    ngx_conf_file = p;
                    goto next;
                }

                if (argv[++i]) {
                    ngx_conf_file = (u_char *) argv[i];
                    goto next;
                }

                ngx_log_stderr(0, "option \"-c\" requires file name");
                return NGX_ERROR;

            case 'g':
				// 同上
                if (*p) {
                    ngx_conf_params = p;
                    goto next;
                }

                if (argv[++i]) {
                    ngx_conf_params = (u_char *) argv[i];
                    goto next;
                }

                ngx_log_stderr(0, "option \"-g\" requires parameter");
                return NGX_ERROR;

            case 's':
				// 同上
                if (*p) {
                    ngx_signal = (char *) p;

                } else if (argv[++i]) {
                    ngx_signal = argv[i];

                } else {
                    ngx_log_stderr(0, "option \"-s\" requires parameter");
                    return NGX_ERROR;
                }

                if (ngx_strcmp(ngx_signal, "stop") == 0
                    || ngx_strcmp(ngx_signal, "quit") == 0
                    || ngx_strcmp(ngx_signal, "reopen") == 0
                    || ngx_strcmp(ngx_signal, "reload") == 0)
                {
                    ngx_process = NGX_PROCESS_SIGNALLER;
                    goto next;
                }

                ngx_log_stderr(0, "invalid option: \"-s %s\"", ngx_signal);
                return NGX_ERROR;

            default:
                ngx_log_stderr(0, "invalid option: \"%c\"", *(p - 1));
                return NGX_ERROR;
            }
        }

    next:

        continue;
    }

    return NGX_OK;
}