/*
 * supervise-daemon
 * This is an experimental supervisor for daemons.
 * It will start a deamon and make sure it restarts if it crashes.
 */

/*
 * Copyright (c) 2016 The OpenRC Authors.
 * See the Authors file at the top-level directory of this distribution and
 * https://github.com/OpenRC/openrc/blob/master/AUTHORS
 *
 * This file is part of OpenRC. It is subject to the license terms in
 * the LICENSE file found in the top-level directory of this
 * distribution and at https://github.com/OpenRC/openrc/blob/master/LICENSE
 * This file may not be copied, modified, propagated, or distributed
 *    except according to the terms contained in the LICENSE file.
 */

/* nano seconds */
#define POLL_INTERVAL   20000000
#define WAIT_PIDFILE   500000000
#define ONE_SECOND    1000000000
#define ONE_MS           1000000

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <termios.h>
#include <sys/time.h>
#include <sys/wait.h>

#ifdef __linux__
#include <sys/syscall.h> /* For io priority */
#endif

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <limits.h>
#include <grp.h>
#include <pwd.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <unistd.h>

#ifdef HAVE_PAM
#include <security/pam_appl.h>

/* We are not supporting authentication conversations */
static struct pam_conv conv = { NULL, NULL};
#endif

#include "einfo.h"
#include "queue.h"
#include "rc.h"
#include "rc-misc.h"
#include "_usage.h"
#include "helpers.h"

const char *applet = NULL;
const char *extraopts = NULL;
const char *getoptstring = "D:d:e:g:I:Kk:m:N:p:r:Su:1:2:" \
	getoptstring_COMMON;
const struct option longopts[] = {
	{ "respawn-delay",        1, NULL, 'D'},
	{ "chdir",        1, NULL, 'd'},
	{ "env",          1, NULL, 'e'},
	{ "group",        1, NULL, 'g'},
	{ "ionice",       1, NULL, 'I'},
	{ "stop",         0, NULL, 'K'},
	{ "umask",        1, NULL, 'k'},
	{ "respawn-max",    1, NULL, 'm'},
	{ "nicelevel",    1, NULL, 'N'},
	{ "pidfile",      1, NULL, 'p'},
	{ "respawn-period",        1, NULL, 'P'},
	{ "chroot",       1, NULL, 'r'},
	{ "start",        0, NULL, 'S'},
	{ "user",         1, NULL, 'u'},
	{ "stdout",       1, NULL, '1'},
	{ "stderr",       1, NULL, '2'},
	longopts_COMMON
};
const char * const longopts_help[] = {
	"Set a respawn delay",
	"Change the PWD",
	"Set an environment string",
	"Change the process group",
	"Set an ionice class:data when starting",
	"Stop daemon",
	"Set the umask for the daemon",
	"set maximum number of respawn attempts",
	"Set a nicelevel when starting",
	"Match pid found in this file",
	"Set respawn time period",
	"Chroot to this directory",
	"Start daemon",
	"Change the process user",
	"Redirect stdout to file",
	"Redirect stderr to file",
	longopts_help_COMMON
};
const char *usagestring = NULL;

static int nicelevel = 0;
static int ionicec = -1;
static int ioniced = 0;
static char *changeuser, *ch_root, *ch_dir;
static uid_t uid = 0;
static gid_t gid = 0;
static int devnull_fd = -1;
static int stdin_fd;
static int stdout_fd;
static int stderr_fd;
static char *redirect_stderr = NULL;
static char *redirect_stdout = NULL;
static bool exiting = false;
#ifdef TIOCNOTTY
static int tty_fd = -1;
#endif

extern char **environ;

#if !defined(SYS_ioprio_set) && defined(__NR_ioprio_set)
# define SYS_ioprio_set __NR_ioprio_set
#endif
#if !defined(__DragonFly__)
static inline int ioprio_set(int which _unused, int who _unused,
			     int ioprio _unused)
{
#ifdef SYS_ioprio_set
	return syscall(SYS_ioprio_set, which, who, ioprio);
#else
	return 0;
#endif
}
#endif

static void cleanup(void)
{
	free(changeuser);
}

static pid_t get_pid(const char *pidfile)
{
	FILE *fp;
	pid_t pid;

	if (! pidfile)
		return -1;

	if ((fp = fopen(pidfile, "r")) == NULL) {
		ewarnv("%s: fopen `%s': %s", applet, pidfile, strerror(errno));
		return -1;
	}

	if (fscanf(fp, "%d", &pid) != 1) {
		ewarnv("%s: no pid found in `%s'", applet, pidfile);
		fclose(fp);
		return -1;
	}

	fclose(fp);

	return pid;
}

static void child_process(char *exec, char **argv, char *svcname,
		int start_count)
{
	RC_STRINGLIST *env_list;
	RC_STRING *env;
	int i;
	char *p;
	char *token;
	size_t len;
	char *newpath;
	char *np;
	char **c;
	char cmdline[PATH_MAX];
	time_t start_time;
	char start_count_string[20];
	char start_time_string[20];

#ifdef HAVE_PAM
	pam_handle_t *pamh = NULL;
	int pamr;
	const char *const *pamenv = NULL;
#endif

	setsid();

	if (svcname) {
start_time = time(NULL);
from_time_t(start_time_string, start_time);
		rc_service_value_set(svcname, "start_time", start_time_string);
sprintf(start_count_string, "%i", start_count);
		rc_service_value_set(svcname, "start_count", start_count_string);
	}

	if (nicelevel) {
		if (setpriority(PRIO_PROCESS, getpid(), nicelevel) == -1)
			eerrorx("%s: setpriority %d: %s", applet, nicelevel,
					strerror(errno));
	}

	if (ionicec != -1 && ioprio_set(1, getpid(), ionicec | ioniced) == -1)
		eerrorx("%s: ioprio_set %d %d: %s", applet, ionicec, ioniced,
				strerror(errno));

	if (ch_root && chroot(ch_root) < 0)
		eerrorx("%s: chroot `%s': %s", applet, ch_root, strerror(errno));

	if (ch_dir && chdir(ch_dir) < 0)
		eerrorx("%s: chdir `%s': %s", applet, ch_dir, strerror(errno));

#ifdef HAVE_PAM
	if (changeuser != NULL) {
		pamr = pam_start("supervise-daemon",
		    changeuser, &conv, &pamh);

		if (pamr == PAM_SUCCESS)
			pamr = pam_acct_mgmt(pamh, PAM_SILENT);
		if (pamr == PAM_SUCCESS)
			pamr = pam_open_session(pamh, PAM_SILENT);
		if (pamr != PAM_SUCCESS)
			eerrorx("%s: pam error: %s", applet, pam_strerror(pamh, pamr));
	}
#endif

	if (gid && setgid(gid))
		eerrorx("%s: unable to set groupid to %d", applet, gid);
	if (changeuser && initgroups(changeuser, gid))
		eerrorx("%s: initgroups (%s, %d)", applet, changeuser, gid);
	if (uid && setuid(uid))
		eerrorx ("%s: unable to set userid to %d", applet, uid);

	/* Close any fd's to the passwd database */
	endpwent();

	/* remove the controlling tty */
#ifdef TIOCNOTTY
	ioctl(tty_fd, TIOCNOTTY, 0);
	close(tty_fd);
#endif

	/* Clean the environment of any RC_ variables */
	env_list = rc_stringlist_new();
	i = 0;
	while (environ[i])
		rc_stringlist_add(env_list, environ[i++]);

#ifdef HAVE_PAM
	if (changeuser != NULL) {
		pamenv = (const char *const *)pam_getenvlist(pamh);
		if (pamenv) {
			while (*pamenv) {
				/* Don't add strings unless they set a var */
				if (strchr(*pamenv, '='))
					putenv(xstrdup(*pamenv));
				else
					unsetenv(*pamenv);
				pamenv++;
			}
		}
	}
#endif

	TAILQ_FOREACH(env, env_list, entries) {
		if ((strncmp(env->value, "RC_", 3) == 0 &&
			strncmp(env->value, "RC_SERVICE=", 10) != 0 &&
			strncmp(env->value, "RC_SVCNAME=", 10) != 0) ||
		    strncmp(env->value, "SSD_NICELEVEL=", 14) == 0)
		{
			p = strchr(env->value, '=');
			*p = '\0';
			unsetenv(env->value);
			continue;
		}
	}
	rc_stringlist_free(env_list);

	/* For the path, remove the rcscript bin dir from it */
	if ((token = getenv("PATH"))) {
		len = strlen(token);
		newpath = np = xmalloc(len + 1);
		while (token && *token) {
			p = strchr(token, ':');
			if (p) {
				*p++ = '\0';
				while (*p == ':')
					p++;
			}
			if (strcmp(token, RC_LIBEXECDIR "/bin") != 0 &&
			    strcmp(token, RC_LIBEXECDIR "/sbin") != 0)
			{
				len = strlen(token);
				if (np != newpath)
					*np++ = ':';
				memcpy(np, token, len);
				np += len;
				}
			token = p;
		}
		*np = '\0';
		unsetenv("PATH");
		setenv("PATH", newpath, 1);
	}

	stdin_fd = devnull_fd;
	stdout_fd = devnull_fd;
	stderr_fd = devnull_fd;
	if (redirect_stdout) {
		if ((stdout_fd = open(redirect_stdout,
			    O_WRONLY | O_CREAT | O_APPEND,
			    S_IRUSR | S_IWUSR)) == -1)
			eerrorx("%s: unable to open the logfile"
				    " for stdout `%s': %s",
				    applet, redirect_stdout, strerror(errno));
	}
	if (redirect_stderr) {
		if ((stderr_fd = open(redirect_stderr,
			    O_WRONLY | O_CREAT | O_APPEND,
			    S_IRUSR | S_IWUSR)) == -1)
			eerrorx("%s: unable to open the logfile"
			    " for stderr `%s': %s",
			    applet, redirect_stderr, strerror(errno));
	}

	dup2(stdin_fd, STDIN_FILENO);
	if (redirect_stdout || rc_yesno(getenv("EINFO_QUIET")))
		dup2(stdout_fd, STDOUT_FILENO);
	if (redirect_stderr || rc_yesno(getenv("EINFO_QUIET")))
		dup2(stderr_fd, STDERR_FILENO);

	for (i = getdtablesize() - 1; i >= 3; --i)
		fcntl(i, F_SETFD, FD_CLOEXEC);

	*cmdline = '\0';
	c = argv;
	while (*c) {
		strcat(cmdline, *c);
		strcat(cmdline, " ");
		c++;
	}
	syslog(LOG_INFO, "Running command line: %s", cmdline);
	execvp(exec, argv);

#ifdef HAVE_PAM
	if (changeuser != NULL && pamr == PAM_SUCCESS)
		pam_close_session(pamh, PAM_SILENT);
#endif
	eerrorx("%s: failed to exec `%s': %s", applet, exec,strerror(errno));
}

static void handle_signal(int sig)
{
	int serrno = errno;
	char signame[10] = { '\0' };

	switch (sig) {
	case SIGINT:
		snprintf(signame, sizeof(signame), "SIGINT");
		break;
	case SIGTERM:
		snprintf(signame, sizeof(signame), "SIGTERM");
		break;
	case SIGQUIT:
		snprintf(signame, sizeof(signame), "SIGQUIT");
		break;
	}

	if (*signame != 0) {
		syslog(LOG_INFO, "%s: caught signal %s, exiting", applet, signame);
		exiting = true;
	} else
		syslog(LOG_INFO, "%s: caught unknown signal %d", applet, sig);

	/* Restore errno */
	errno = serrno;
}

static char * expand_home(const char *home, const char *path)
{
	char *opath, *ppath, *p, *nh;
	size_t len;
	struct passwd *pw;

	if (!path || *path != '~')
		return xstrdup(path);

	opath = ppath = xstrdup(path);
	if (ppath[1] != '/' && ppath[1] != '\0') {
		p = strchr(ppath + 1, '/');
		if (p)
			*p = '\0';
		pw = getpwnam(ppath + 1);
		if (pw) {
			home = pw->pw_dir;
			ppath = p;
			if (ppath)
				*ppath = '/';
		} else
			home = NULL;
	} else
		ppath++;

	if (!home) {
	free(opath);
		return xstrdup(path);
	}
	if (!ppath) {
		free(opath);
		return xstrdup(home);
	}

	len = strlen(ppath) + strlen(home) + 1;
	nh = xmalloc(len);
	snprintf(nh, len, "%s%s", home, ppath);
	free(opath);
	return nh;
}

int main(int argc, char **argv)
{
	int opt;
	bool start = false;
	bool stop = false;
	char *exec = NULL;
	char *pidfile = NULL;
	char *home = NULL;
	int tid = 0;
	pid_t child_pid, pid;
	char *svcname = getenv("RC_SVCNAME");
	char *tmp;
	char *p;
	char *token;
	int i;
	int n;
	char exec_file[PATH_MAX];
	int respawn_count = 0;
	int respawn_delay = 0;
	int respawn_max = 10;
	int respawn_period = 5;
	time_t respawn_now= 0;
	time_t first_spawn= 0;
	struct passwd *pw;
	struct group *gr;
	FILE *fp;
	mode_t numask = 022;

	applet = basename_c(argv[0]);
	atexit(cleanup);

	signal_setup(SIGINT, handle_signal);
	signal_setup(SIGQUIT, handle_signal);
	signal_setup(SIGTERM, handle_signal);
	openlog(applet, LOG_PID, LOG_DAEMON);

	if ((tmp = getenv("SSD_NICELEVEL")))
		if (sscanf(tmp, "%d", &nicelevel) != 1)
			eerror("%s: invalid nice level `%s' (SSD_NICELEVEL)",
			    applet, tmp);

	/* Get our user name and initial dir */
	p = getenv("USER");
	home = getenv("HOME");
	if (home == NULL || p == NULL) {
		pw = getpwuid(getuid());
		if (pw != NULL) {
			if (p == NULL)
				setenv("USER", pw->pw_name, 1);
			if (home == NULL) {
				setenv("HOME", pw->pw_dir, 1);
				home = pw->pw_dir;
			}
		}
	}

	while ((opt = getopt_long(argc, argv, getoptstring, longopts,
		    (int *) 0)) != -1)
		switch (opt) {
		case 'D':  /* --respawn-delay time */
			n = sscanf(optarg, "%d", &respawn_delay);
			if (n	!= 1 || respawn_delay < 1)
				eerrorx("Invalid respawn-delay value '%s'", optarg);
			break;

		case 'I': /* --ionice */
			if (sscanf(optarg, "%d:%d", &ionicec, &ioniced) == 0)
				eerrorx("%s: invalid ionice `%s'",
				    applet, optarg);
			if (ionicec == 0)
				ioniced = 0;
			else if (ionicec == 3)
				ioniced = 7;
			ionicec <<= 13; /* class shift */
			break;

		case 'K':  /* --stop */
			stop = true;
			break;

		case 'N':  /* --nice */
			if (sscanf(optarg, "%d", &nicelevel) != 1)
				eerrorx("%s: invalid nice level `%s'",
				    applet, optarg);
			break;

		case 'P':  /* --respawn-period time */
			n = sscanf(optarg, "%d", &respawn_period);
			if (n	!= 1 || respawn_delay < 1)
				eerrorx("Invalid respawn-delay value '%s'", optarg);
			break;

		case 'S':  /* --start */
			start = true;
			break;

		case 'd':  /* --chdir /new/dir */
			ch_dir = optarg;
			break;

		case 'e': /* --env */
			putenv(optarg);
			break;

		case 'g':  /* --group <group>|<gid> */
			if (sscanf(optarg, "%d", &tid) != 1)
				gr = getgrnam(optarg);
			else
				gr = getgrgid((gid_t)tid);
			if (gr == NULL)
				eerrorx("%s: group `%s' not found",
				    applet, optarg);
			gid = gr->gr_gid;
			break;

		case 'k':
			if (parse_mode(&numask, optarg))
				eerrorx("%s: invalid mode `%s'",
				    applet, optarg);
			break;

		case 'm':  /* --respawn-max count */
			n = sscanf(optarg, "%d", &respawn_max);
			if (n	!= 1 || respawn_max < 1)
				eerrorx("Invalid respawn-max value '%s'", optarg);
			break;

		case 'p':  /* --pidfile <pid-file> */
			pidfile = optarg;
			break;

		case 'r':  /* --chroot /new/root */
			ch_root = optarg;
			break;

		case 'u':  /* --user <username>|<uid> */
		{
			p = optarg;
			tmp = strsep(&p, ":");
			changeuser = xstrdup(tmp);
			if (sscanf(tmp, "%d", &tid) != 1)
				pw = getpwnam(tmp);
			else
				pw = getpwuid((uid_t)tid);

			if (pw == NULL)
				eerrorx("%s: user `%s' not found",
				    applet, tmp);
			uid = pw->pw_uid;
			home = pw->pw_dir;
			unsetenv("HOME");
			if (pw->pw_dir)
				setenv("HOME", pw->pw_dir, 1);
			unsetenv("USER");
			if (pw->pw_name)
				setenv("USER", pw->pw_name, 1);
			if (gid == 0)
				gid = pw->pw_gid;

			if (p) {
				tmp = strsep (&p, ":");
				if (sscanf(tmp, "%d", &tid) != 1)
					gr = getgrnam(tmp);
				else
					gr = getgrgid((gid_t) tid);

				if (gr == NULL)
					eerrorx("%s: group `%s'"
					    " not found",
					    applet, tmp);
				gid = gr->gr_gid;
			}
		}
		break;

		case '1':   /* --stdout /path/to/stdout.lgfile */
			redirect_stdout = optarg;
			break;

		case '2':  /* --stderr /path/to/stderr.logfile */
			redirect_stderr = optarg;
			break;

		case_RC_COMMON_GETOPT
		}

	if (!pidfile)
		eerrorx("%s: --pidfile must be specified", applet);

	endpwent();
	argc -= optind;
	argv += optind;
	exec = *argv;

	if (start) {
		if (!exec)
			eerrorx("%s: nothing to start", applet);
		if (respawn_delay * respawn_max > respawn_period) {
			ewarn("%s: Please increase the value of --respawn-period to more "
				"than %d to avoid infinite respawning", applet, 
				respawn_delay * respawn_max);
		}
	}

	/* Expand ~ */
	if (ch_dir && *ch_dir == '~')
		ch_dir = expand_home(home, ch_dir);
	if (ch_root && *ch_root == '~')
		ch_root = expand_home(home, ch_root);
	if (exec) {
		if (*exec == '~')
			exec = expand_home(home, exec);

		/* Validate that the binary exists if we are starting */
		if (*exec == '/' || *exec == '.') {
			/* Full or relative path */
			if (ch_root)
				snprintf(exec_file, sizeof(exec_file),
				    "%s/%s", ch_root, exec);
			else
				snprintf(exec_file, sizeof(exec_file),
				    "%s", exec);
		} else {
			/* Something in $PATH */
			p = tmp = xstrdup(getenv("PATH"));
			*exec_file = '\0';
			while ((token = strsep(&p, ":"))) {
				if (ch_root)
					snprintf(exec_file, sizeof(exec_file),
					    "%s/%s/%s",
					    ch_root, token, exec);
				else
					snprintf(exec_file, sizeof(exec_file),
					    "%s/%s", token, exec);
				if (exists(exec_file))
					break;
				*exec_file = '\0';
			}
			free(tmp);
		}
	}
	if (start && !exists(exec_file))
		eerrorx("%s: %s does not exist", applet,
		    *exec_file ? exec_file : exec);

	if (stop) {
		pid = get_pid(pidfile);
		if (pid == -1)
			i = pid;
		else
			i = kill(pid, SIGTERM);
		if (i != 0)
			/* We failed to stop something */
			exit(EXIT_FAILURE);

		/* Even if we have not actually killed anything, we should
		 * remove information about it as it may have unexpectedly
		 * crashed out. We should also return success as the end
		 * result would be the same. */
		if (pidfile && exists(pidfile))
			unlink(pidfile);
		if (svcname) {
			rc_service_daemon_set(svcname, exec,
			    (const char *const *)argv,
			    pidfile, false);
			rc_service_mark(svcname, RC_SERVICE_STOPPED);
		}
		exit(EXIT_SUCCESS);
	}

	pid = get_pid(pidfile);
	if (pid != -1)
		if (kill(pid, 0) == 0)
			eerrorx("%s: %s is already running", applet, exec);

	einfov("Detaching to start `%s'", exec);
	eindentv();

	/* Remove existing pidfile */
	if (pidfile)
		unlink(pidfile);

	/*
	 * Make sure we can write a pid file
	 */
	fp = fopen(pidfile, "w");
	if (! fp)
		eerrorx("%s: fopen `%s': %s", applet, pidfile, strerror(errno));
	fclose(fp);

	child_pid = fork();
	if (child_pid == -1)
		eerrorx("%s: fork: %s", applet, strerror(errno));

	/* first parent process, do nothing. */
	if (child_pid != 0)
		exit(EXIT_SUCCESS);

#ifdef TIOCNOTTY
	tty_fd = open("/dev/tty", O_RDWR);
#endif
	devnull_fd = open("/dev/null", O_RDWR);
	child_pid = fork();
	if (child_pid == -1)
		eerrorx("%s: fork: %s", applet, strerror(errno));

	if (child_pid != 0) {
		/* this is the supervisor */
		umask(numask);

		fp = fopen(pidfile, "w");
		if (! fp)
			eerrorx("%s: fopen `%s': %s", applet, pidfile, strerror(errno));
		fprintf(fp, "%d\n", getpid());
		fclose(fp);

		if (svcname)
			rc_service_daemon_set(svcname, exec,
									(const char * const *) argv, pidfile, true);

	/* remove the controlling tty */
#ifdef TIOCNOTTY
		ioctl(tty_fd, TIOCNOTTY, 0);
		close(tty_fd);
#endif

		/*
		 * Supervisor main loop
		 */
		i = 0;
		while (!exiting) {
			wait(&i);
			if (exiting) {
				syslog(LOG_INFO, "stopping %s, pid %d", exec, child_pid);
				kill(child_pid, SIGTERM);
			} else {
				sleep(respawn_delay);
				if (respawn_max > 0 && respawn_period > 0) {
					respawn_now = time(NULL);
					if (first_spawn == 0)
						first_spawn = respawn_now;
					if (respawn_now - first_spawn > respawn_period) {
						respawn_count = 0;
						first_spawn = 0;
					} else
						respawn_count++;
					if (respawn_count >= respawn_max) {
						syslog(LOG_INFO, "respawned \"%s\" too many times, "
								"exiting", exec);
						exiting = true;
						continue;
					}
				}
				if (WIFEXITED(i))
					syslog(LOG_INFO, "%s, pid %d, exited with return code %d",
							exec, child_pid, WEXITSTATUS(i));
				else if (WIFSIGNALED(i))
					syslog(LOG_INFO, "%s, pid %d, terminated by signal %d",
							exec, child_pid, WTERMSIG(i));
				child_pid = fork();
				if (child_pid == -1)
					eerrorx("%s: fork: %s", applet, strerror(errno));
				if (child_pid == 0)
					child_process(exec, argv, svcname, respawn_count);
			}
		}

		if (pidfile && exists(pidfile))
			unlink(pidfile);
		if (svcname) {
			rc_service_daemon_set(svcname, exec,
			    (const char *const *)argv,
			    pidfile, false);
			rc_service_mark(svcname, RC_SERVICE_STOPPED);
		}
		exit(EXIT_SUCCESS);
	} else if (child_pid == 0)
		child_process(exec, argv, svcname, respawn_count);
}