Gamemode/daemon/gamemoded.c

/*

Copyright (c) 2017-2019, Feral Interactive
All rights reserved.

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modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright
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   documentation and/or other materials provided with the distribution.
 * Neither the name of Feral Interactive nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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 */

/**
 * Simple daemon to allow user space programs to control the CPU governors
 *
 * The main process is responsible for bootstrapping the D-BUS daemon, caching
 * the initial governor settings, and then responding to requests over D-BUS.
 *
 * Clients register their pid(s) with the service, which are routinely checked
 * to see if they've expired. Once we reach our first actively registered client
 * we put the system into "game mode", i.e. move the CPU governor into a performance
 * mode.
 *
 * Upon exit, or when all clients have stopped running, we put the system back
 * into the default governor policy, which is invariably powersave or similar
 * on laptops. This ensures that the system is obtaining the maximum performance
 * whilst gaming, and allowed to sanely return to idle once the workload is
 * complete.
 */

#define _GNU_SOURCE

#include "gamemode.h"
#include "common-logging.h"
#include "gamemode-config.h"

#include "gamemode_client.h"

#include "build-config.h"

#include <fcntl.h>
#include <getopt.h>
#include <signal.h>
#include <sys/stat.h>
#include <systemd/sd-daemon.h> /* TODO: Move usage to gamemode-dbus.c */
#include <unistd.h>

#define USAGE_TEXT                                                                                 \
	"Usage: %s [-d] [-l] [-r] [-t] [-h] [-v]\n\n"                                                  \
	"  -r[PID], --request=[PID] Toggle gamemode for process\n"                                     \
	"                           When no PID given, requests gamemode and pauses\n"                 \
	"  -s[PID], --status=[PID]  Query the status of gamemode for process\n"                        \
	"                           When no PID given, queries the status globally\n"                  \
	"  -d, --daemonize          Daemonize self after launch\n"                                     \
	"  -l, --log-to-syslog      Log to syslog\n"                                                   \
	"  -t, --test               Run tests\n"                                                       \
	"  -h, --help               Print this help\n"                                                 \
	"  -v, --version            Print version\n"                                                   \
	"\n"                                                                                           \
	"See man page for more information.\n"

#define VERSION_TEXT "gamemode version: v" GAMEMODE_VERSION "\n"

static void sigint_handler(__attribute__((unused)) int signo)
{
	LOG_MSG("Quitting by request...\n");
	sd_notify(0, "STATUS=GameMode is quitting by request...\n");

	/* Clean up nicely */
	game_mode_context_destroy(game_mode_context_instance());

	_Exit(EXIT_SUCCESS);
}

static void sigint_handler_noexit(__attribute__((unused)) int signo)
{
	LOG_MSG("Quitting by request...\n");
}

/**
 * Helper to perform standard UNIX daemonization
 */
static void daemonize(const char *name)
{
	/* Initial fork */
	pid_t pid = fork();
	if (pid < 0) {
		FATAL_ERRORNO("Failed to fork");
	}

	if (pid != 0) {
		LOG_MSG("Daemon launched as %s...\n", name);
		exit(EXIT_SUCCESS);
	}

	/* Fork a second time */
	pid = fork();
	if (pid < 0) {
		FATAL_ERRORNO("Failed to fork");
	} else if (pid > 0) {
		exit(EXIT_SUCCESS);
	}

	/* Now continue execution */
	umask(0022);
	if (setsid() < 0) {
		FATAL_ERRORNO("Failed to create process group\n");
	}
	if (chdir("/") < 0) {
		FATAL_ERRORNO("Failed to change to root directory\n");
	}

	/* replace standard file descriptors by /dev/null */
	int devnull_r = open("/dev/null", O_RDONLY);
	int devnull_w = open("/dev/null", O_WRONLY);

	if (devnull_r == -1 || devnull_w == -1)
	{
		LOG_ERROR("Failed to redirect standard input and output to /dev/null\n");
	}
	else
	{
		dup2(devnull_r, STDIN_FILENO);
		dup2(devnull_w, STDOUT_FILENO);
		dup2(devnull_w, STDERR_FILENO);
		close(devnull_r);
		close(devnull_w);
	}
}

/**
 * Main bootstrap entry into gamemoded
 */
int main(int argc, char *argv[])
{
	GameModeContext *context = NULL;

	/* Gather command line options */
	bool daemon = false;
	bool use_syslog = false;
	int opt = 0;

	/* Options struct for getopt_long */
	static struct option long_options[] = {
		{ "daemonize", no_argument, 0, 'd' },     { "log-to-syslog", no_argument, 0, 'l' },
		{ "request", optional_argument, 0, 'r' }, { "test", no_argument, 0, 't' },
		{ "status", optional_argument, 0, 's' },  { "help", no_argument, 0, 'h' },
		{ "version", no_argument, 0, 'v' },       { NULL, 0, NULL, 0 },
	};
	static const char *short_options = "dls::r::tvh";

	while ((opt = getopt_long(argc, argv, short_options, long_options, 0)) != -1) {
		switch (opt) {
		case 'd':
			daemon = true;
			break;
		case 'l':
			use_syslog = true;
			break;

		case 's':
			if (optarg != NULL) {
				pid_t pid = atoi(optarg);
				switch (gamemode_query_status_for(pid)) {
				case 0: /* inactive */
					LOG_MSG("gamemode is inactive\n");
					break;
				case 1: /* active not not registered */
					LOG_MSG("gamemode is active but [%d] not registered\n", pid);
					break;
				case 2: /* active for client */
					LOG_MSG("gamemode is active and [%d] registered\n", pid);
					break;
				case -1:
					LOG_ERROR("gamemode_query_status_for(%d) failed: %s\n",
					          pid,
					          gamemode_error_string());
					exit(EXIT_FAILURE);
				default:
					LOG_ERROR("gamemode_query_status returned unexpected value 2\n");
					exit(EXIT_FAILURE);
				}
			} else {
				int ret = 0;
				switch ((ret = gamemode_query_status())) {
				case 0: /* inactive */
					LOG_MSG("gamemode is inactive\n");
					break;
				case 1: /* active */
					LOG_MSG("gamemode is active\n");
					break;
				case -1: /* error */
					LOG_ERROR("gamemode status request failed: %s\n", gamemode_error_string());
					exit(EXIT_FAILURE);
				default: /* unexpected value eg. 2 */
					LOG_ERROR("gamemode_query_status returned unexpected value %d\n", ret);
					exit(EXIT_FAILURE);
				}
			}

			exit(EXIT_SUCCESS);

		case 'r':

			if (optarg != NULL) {
				pid_t pid = atoi(optarg);

				/* toggle gamemode for the process */
				switch (gamemode_query_status_for(pid)) {
				case 0: /* inactive */
				case 1: /* active not not registered */
					LOG_MSG("gamemode not active for client, requesting start for %d...\n", pid);
					if (gamemode_request_start_for(pid) < 0) {
						LOG_ERROR("gamemode_request_start_for(%d) failed: %s\n",
						          pid,
						          gamemode_error_string());
						exit(EXIT_FAILURE);
					}
					LOG_MSG("request succeeded\n");
					break;
				case 2: /* active for client */
					LOG_MSG("gamemode active for client, requesting end for %d...\n", pid);
					if (gamemode_request_end_for(pid) < 0) {
						LOG_ERROR("gamemode_request_end_for(%d) failed: %s\n",
						          pid,
						          gamemode_error_string());
						exit(EXIT_FAILURE);
					}
					LOG_MSG("request succeeded\n");
					break;
				case -1: /* error */
					LOG_ERROR("gamemode_query_status_for(%d) failed: %s\n",
					          pid,
					          gamemode_error_string());
					exit(EXIT_FAILURE);
				}

			} else {
				/* Request gamemode for this process */
				if (gamemode_request_start() < 0) {
					LOG_ERROR("gamemode request failed: %s\n", gamemode_error_string());
					exit(EXIT_FAILURE);
				}

				/* Request and report on the status */
				switch (gamemode_query_status()) {
				case 2: /* active for this client */
					LOG_MSG("gamemode request succeeded and is active\n");
					break;
				case 1: /* active */
					LOG_ERROR("gamemode request succeeded and is active but registration failed\n");
					exit(EXIT_FAILURE);
				case 0: /* inactive */
					LOG_ERROR("gamemode request succeeded but is not active\n");
					exit(EXIT_FAILURE);
				case -1: /* error */
					LOG_ERROR("gamemode_query_status failed: %s\n", gamemode_error_string());
					exit(EXIT_FAILURE);
				}

				/* Simply pause and wait a SIGINT */
				if (signal(SIGINT, sigint_handler_noexit) == SIG_ERR) {
					FATAL_ERRORNO("Could not catch SIGINT");
				}
				pause();

				/* Explicitly clean up */
				if (gamemode_request_end() < 0) {
					LOG_ERROR("gamemode request failed: %s\n", gamemode_error_string());
					exit(EXIT_FAILURE);
				}
			}

			exit(EXIT_SUCCESS);

		case 't': {
			int status = game_mode_run_client_tests();
			exit(status);
		}
		case 'v':
			LOG_MSG(VERSION_TEXT);
			exit(EXIT_SUCCESS);
		case 'h':
			LOG_MSG(USAGE_TEXT, argv[0]);
			exit(EXIT_SUCCESS);
		default:
			fprintf(stderr, USAGE_TEXT, argv[0]);
			exit(EXIT_FAILURE);
		}
	}

	/* If syslog is requested, set it up with our process name */
	if (use_syslog) {
		set_use_syslog(argv[0]);
	}

	/* Daemonize ourselves first if asked */
	if (daemon) {
		daemonize(argv[0]);
	}

	/* Log a version message on startup */
	LOG_MSG("v%s\n", GAMEMODE_VERSION);

	/* Set up the game mode context */
	context = game_mode_context_instance();
	game_mode_context_init(context);

	/* Handle quits cleanly */
	if (signal(SIGINT, sigint_handler) == SIG_ERR) {
		FATAL_ERRORNO("Could not catch SIGINT");
	}
	if (signal(SIGTERM, sigint_handler) == SIG_ERR) {
		FATAL_ERRORNO("Could not catch SIGTERM");
	}

	/* Run the main dbus message loop */
	game_mode_context_loop(context);

	game_mode_context_destroy(context);

	/* Log we're finished */
	LOG_MSG("Quitting naturally...\n");
	sd_notify(0, "STATUS=GameMode is quitting naturally...\n");
}