Revert new experimental libev backend due to time constraints

Due to time constraints I had to revert the new libev backend to the
service, I/O and signals monitor.  Employed instead is the tried and
tested signals based service monitor, with a small extension for an
additional I/O monitor using poll() for the I/O plugins to use.

Tried restoring the startx finit.conf directive on top of the service
implementation. However, it's currently not usable to run /usr/bin/startx
for any other user than root. I recommend using the examples/finit.conf
and run /usr/sbin/gdm instead.

finit.c:
        New run_loop() function, replaces libev ev_run().

helpers.c:
        Refactor start_process() into svc_start().

plugin.c:
        Add fds[] array for use in the io_monitor() called by the
        new run_loop().

signal.c:
        Ignore SIGCHLD. Handled by waitpid() in svc_monitor() now,
        which is called by the new run_loop().

svc.c:
        svc_register(): Optional @username parsing for the command line.
        svc_monitor(): Replaced libev callback with waitpid()
        svc_start(): Refactored to use most of helpers.c:start_process()

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Makefile

@@ -42,7 +42,7 @@ CPPFLAGS   += -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_GNU_SOURCE
 CPPFLAGS   += -DVERSION=\"$(VERSION)\" -DWHOAMI=\"`whoami`@`hostname`\"
 CPPFLAGS   += -DPLUGIN_PATH=\"$(PLUGIN_DIR)\"
 LDFLAGS    += -rdynamic
-LDLIBS     += -ldl -lev
+LDLIBS     += -ldl
 
 prefix     ?= /usr/local
 sysconfdir ?= /etc

conf.c

@@ -122,9 +122,12 @@ void parse_finit_conf(char *file)
 				network = build_cmd(NULL, x, CMD_SIZE);
 				continue;
 			}
+			if (MATCH_CMD(line, "startx ", x)) {
+				svc_register(x, username);
+				continue;
+			}
 			if (MATCH_CMD(line, "service ", x)) {
-				if (svc_register(x))
-					_e("Failed, too many services to monitor.\n");
+				svc_register(x, NULL);
 				continue;
 			}
 		}

examples/finit.conf

@@ -1,6 +1,5 @@
 # Simple Debian finit.conf
 check /dev/vda1
-module tipc
 module evdev
 module loop
 module psmouse
@@ -10,4 +9,4 @@ network service networking start
 service /sbin/klogd -n -- Kernel logging server
 service /sbin/syslogd -n -- Syslog server
 service /usr/sbin/sshd -D -- OpenSSH server
-service /usr/bin/startx -- X Window System
+service /usr/sbin/gdm -- GNOME Display Manager

finit.c

@@ -22,10 +22,11 @@
  * THE SOFTWARE.
  */
 
-#include <ctype.h>
 #include <sys/mount.h>
+#include <ctype.h>
 #include <dirent.h>
 #include <linux/fs.h>
+#include <sys/stat.h>		/* umask(), mkdir() */
 
 #include "finit.h"
 #include "helpers.h"
@@ -60,10 +61,18 @@ static void parse_kernel_cmdline(void)
 	}
 }
 
+static int run_loop(void)
+{
+	while (1) {
+		svc_monitor();
+		io_monitor();
+	}
+
+	return 0;
+}
+
 int main(int UNUSED(args), char *argv[])
 {
-	struct ev_loop *loop = ev_default_loop(0);
-
 	/*
 	 * Initial setup of signals, ignore all until we're up.
 	 */
@@ -133,7 +142,7 @@ int main(int UNUSED(args), char *argv[])
 	 * Load plugins and run first level hooks.
 	 */
 	_d("Loading plugins ...");
-	load_plugins(loop, PLUGIN_PATH);
+	load_plugins(PLUGIN_PATH);
 
 	_d("Running first level hooks ...");
 	run_hooks(HOOK_BASEFS_UP);
@@ -183,9 +192,7 @@ int main(int UNUSED(args), char *argv[])
 	 * Enter main loop to monior /dev/initctl and services
 	 */
 	_d("Entering main loop ...");
-	ev_run(loop, 0);
-
-	return 0;
+	return run_loop();
 }
 
 /**

finit.h

@@ -29,6 +29,8 @@
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 #include <unistd.h>
 
 #include <syslog.h>

helpers.c

@@ -174,37 +174,6 @@ int print_result(int fail)
 	return fail;
 }
 
-int start_process(char *cmd, char *args[], int console)
-{
-	pid_t pid;
-
-	if (sig_stopped())
-		return 0;
-
-	pid = fork();
-	if (!pid) {
-		int i;
-		struct sigaction sa;
-
-		/* Reset signal handlers that were set by the parent process */
-                for (i = 1; i < NSIG; i++)
-			DFLSIG(sa, i, 0);
-
-		if (console) {
-			int fd = open (CONSOLE, O_WRONLY | O_APPEND);
-			if (-1 != fd) {
-				dup2(STDOUT_FILENO, fd);
-				dup2(STDERR_FILENO, fd);
-			}
-		}
-
-		execvp(cmd, args);
-		exit(!console ? print_result(0) : 0);
-	}
-
-	return pid;
-}
-
 int run(char *cmd)
 {
 	int status, result, i = 0;
@@ -353,12 +322,14 @@ pid_t run_getty(char *cmd, char *argv[])
 		sigset_t nmask;
 		struct sigaction sa;
 
+		/* Detach from initial controlling TTY */
 		vhangup();
 
 		close(2);
 		close(1);
 		close(0);
 
+		/* Attach TTY to console */
 		if (open(CONSOLE, O_RDWR) != 0)
 			exit(1);
 
@@ -479,7 +450,7 @@ int getuser(char *s)
 {
 	struct passwd *usr;
 
-	if ((usr = getpwnam(s)) == NULL)
+	if (!s || (usr = getpwnam(s)) == NULL)
 		return -1;
 
 	return usr->pw_uid;

plugin.c

@@ -24,6 +24,7 @@
 #include <errno.h>
 #include <dlfcn.h>		/* dlopen() et al */
 #include <dirent.h>		/* readdir() et al */
+#include <poll.h>
 #include <string.h>
 #include <sys/queue.h>		/* BSD sys/queue.h API */
 
@@ -33,10 +34,16 @@
 #include "plugin.h"
 #include "svc.h"
 
+#define is_io_plugin(p) ((p)->io.cb && (p)->io.fd >= 0)
+
+static size_t        num_fds = 0;
+static struct pollfd fds[MAX_NUM_FDS];
 static LIST_HEAD(, plugin) plugins = LIST_HEAD_INITIALIZER();
 
 int plugin_register(plugin_t *plugin)
 {
+	int inuse = 0;
+
 	if (!plugin) {
 		errno = EINVAL;
 		return 1;
@@ -51,15 +58,29 @@ int plugin_register(plugin_t *plugin)
 			plugin->name = (char *)info.dli_fname;
 	}
 
+	if (is_io_plugin(plugin)) {
+		if (num_fds + 1 >= MAX_NUM_FDS) {
+			num_fds = MAX_NUM_SVC;
+			errno = ENOMEM;
+			return 1;
+		}
+		num_fds++;
+		inuse++;
+	}
+
 	if (plugin->svc.cb) {
 		svc_t *svc = svc_find_by_name(plugin->name);
 
-		if (!svc) {
-			_e("No service \"%s\" loaded, skipping plugin.", basename(plugin->name));
-			return 1;
+		if (svc) {
+			plugin->svc.id = svc_id(svc);
+			svc->plugin    = &plugin->svc;
+			inuse++;
 		}
-		plugin->svc.id = svc_id(svc);
-		svc->plugin    = &plugin->svc;
+	}
+
+	if (!inuse) {
+		_e("No service \"%s\" loaded, skipping plugin.", basename(plugin->name));
+		return 1;
 	}
 
 	LIST_INSERT_HEAD(&plugins, plugin, link);
@@ -71,6 +92,8 @@ int plugin_unregister(plugin_t *plugin)
 {
 	LIST_REMOVE(plugin, link);
 
+	/* XXX: Unfinished, add cleanup code here! */
+
 	return 0;
 }
 
@@ -100,44 +123,62 @@ void run_services(void)
 }
 
 /* Generic libev I/O callback, looks up correct plugin and calls its callback */
-static void generic_io_cb(struct ev_loop *loop, ev_io *w, int revents)
+static void generic_io_cb(int fd, int events)
 {
 	plugin_t *p;
 
-	ev_io_stop(loop, w);
-
 	/* Find matching plugin, pick first matching fd */
 	PLUGIN_ITERATOR(p) {
-		if (p->io.cb && p->io.fd == w->fd) {
-			p->io.cb(p->io.arg, w->fd, revents);
+		if (is_io_plugin(p) && p->io.fd == fd) {
+			_d("Calling I/O %s from runloop...", basename(p->name));
+			p->io.cb(p->io.arg, fd, events);
 			break;
 		}
 	}
+}
 
-	ev_io_start(loop, w);
+void io_monitor(void)
+{
+	int ret;
+	size_t i;
+
+	while ((ret = poll(fds, num_fds, 500))) {
+		if (-1 == ret) {
+			if (EINTR == errno)
+				continue;
+
+			_e("Failed polling I/O plugin descriptors, error %d: %s",
+			   errno, strerror(errno));
+			break;
+		}
+
+		/* Traverse all I/O fds and run callbacks */
+		for (i = 0; i < num_fds; i++) {
+			if (fds[i].revents)
+				generic_io_cb(fds[i].fd, fds[i].revents);
+		}
+
+		break;
+	}
 }
 
 /* Setup any I/O callbacks for plugins that use them */
-static void init_plugins(struct ev_loop *loop)
+static void init_plugins(void)
 {
+	int i = 0;
 	plugin_t *p;
 
 	PLUGIN_ITERATOR(p) {
-		if (p->io.cb && p->io.fd >= 0) {
-			ev_io *w = calloc(1, sizeof(ev_io));
-
+		if (is_io_plugin(p)) {
 			_d("Initializing plugin %s for I/O", basename(p->name));
-			if (!w) {
-				_e("Failed setting up plugin %s: Out of memory", basename(p->name));
-				continue;
-			}
-			ev_io_init(w, generic_io_cb, p->io.fd, p->io.flags);
-			ev_io_start(loop, w);
+			fds[i].revents    = 0;
+			fds[i].events     = p->io.flags;
+			fds[num_fds++].fd = p->io.fd;
 		}
 	}
 }
 
-int load_plugins(struct ev_loop *loop, char *path)
+int load_plugins(char *path)
 {
 	DIR *dp = opendir(path);
 	struct dirent *entry;
@@ -167,7 +208,7 @@ int load_plugins(struct ev_loop *loop, char *path)
 	}
 
 	closedir(dp);
-	init_plugins(loop);
+	init_plugins();
 
 	return 0;
 }

plugin.h

@@ -24,11 +24,11 @@
 #ifndef FINIT_PLUGIN_H_
 #define FINIT_PLUGIN_H_
 
-#include <ev.h>
+#include <poll.h>
 #include <sys/queue.h>		/* BSD sys/queue.h API */
 
-#define PLUGIN_IO_READ  EV_READ
-#define PLUGIN_IO_WRITE EV_READ
+#define PLUGIN_IO_READ  POLLIN
+#define PLUGIN_IO_WRITE POLLOUT
 
 #define PLUGIN_INIT(x) static void __attribute__ ((constructor)) x(void)
 #define PLUGIN_EXIT(x) static void __attribute__ ((destructor))  x(void)

plugins/initctl.c

@@ -77,6 +77,8 @@ static void read_initctl(void *UNUSED(arg), int fd, int UNUSED(events))
 				_d("Unsupported runlevel: %d", request.runlevel);
 				break;
 			}
+		} else {
+			_d("Unsupported cmd: %d", request.cmd);
 		}
 	}
 }

private.h

@@ -30,7 +30,8 @@
 /* plugin.c */
 void run_hooks        (hook_point_t no);
 void run_services     (void);
-int  load_plugins     (struct ev_loop *loop, char *path);
+int  load_plugins     (char *path);
+void io_monitor       (void);
 
 #endif /* FINIT_PRIVATE_H_ */
 

signal.c

@@ -98,13 +98,7 @@ static void shutdown_handler(int sig, siginfo_t *info, void *UNUSED(ctx))
  */
 static void chld_handler(int UNUSED(sig), siginfo_t *UNUSED(info), void *UNUSED(ctx))
 {
-	int status;
-
-//	_d("Child %d died due to signal %d, harvesting.", info->si_pid, sig);
-	while (waitpid(-1, &status, WNOHANG) != 0) {
-		if (errno == ECHILD)
-			break;
-	}
+	/* Do nothing, the svc_monitor() is the designated child reaper. */
 }
 
 /*

svc.c

@@ -23,6 +23,7 @@
  */
 
 #include <string.h>
+#include <sys/wait.h>
 
 #include "finit.h"
 #include "helpers.h"
@@ -35,7 +36,7 @@
  * liveness state of all daemons that should run. */
 static int svc_counter = 0;		/* Number of registered services to monitor. */
 static svc_t *services = NULL;          /* List of registered services, in shared memory. */
-static ev_child watchers[MAX_NUM_SVC];
+
 
 /* Connect to/create shared memory area of registered servies */
 static void __connect_shm(void)
@@ -138,28 +139,61 @@ svc_t *svc_iterator(int restart)
 
 /**
  * svc_register - Register a non-backgrounding service to be monitored
- * @line: A complete command line with -- separated description text
+ * @line:     A complete command line with -- separated description text
+ * @username: Optional username to run service as, or %NULL to run as root
+ *
+ * Actually, the @line can optionally start with a username, denoted by
+ * an @ character. Like this:
+ *
+ *   "service [@username] /path/to/daemon -- Description text"
+ *
+ * The [] brackets means the argument is optional. If the username is
+ * left out the daemon is started as root.
  *
  * Returns:
  * POSIX OK(0) on success, or non-zero errno exit status on failure.
  */
-int svc_register(char *line)
+int svc_register(char *line, char *username)
 {
 	int i = 0;
 	char *cmd, *descr;
-	svc_t *svc = svc_new();
+	svc_t *svc;
 
-	if (!svc || !line) {
-		return -EINVAL;
+	if (!line) {
+		_e("Invalid input argument.");
+		return errno = EINVAL;
 	}
 
 	descr = strstr(line, "-- ");
-	if (descr) {
+	if (descr)
 		*descr = 0;
-		strlcpy(svc->descr, descr + 3, sizeof(svc->descr));
-	}
 
 	cmd = strtok(line, " ");
+	if (!cmd) {
+	incomplete:
+		_e("Incomplete service, cannot register.");
+		return errno = ENOENT;
+	}
+
+	if (cmd[0] == '@') {	/* @username */
+		username = &cmd[1];
+
+		/* Check if valid command follows... */
+		cmd = strtok(NULL, " ");
+		if (!cmd)
+			goto incomplete;
+	}
+
+	svc = svc_new();
+	if (!svc) {
+		_e("Out of memorym, cannot register service %s", cmd);
+		return errno = ENOMEM;
+	}
+
+	if (descr)
+		strlcpy(svc->descr, descr + 3, sizeof(svc->descr));
+	if (username)
+		strlcpy(svc->username, username, sizeof(svc->username));
 	strlcpy(svc->cmd, cmd, sizeof(svc->cmd));
 	strlcpy(svc->args[i++], cmd, sizeof(svc->args[0]));
 
@@ -206,27 +240,14 @@ static int is_norespawn(void)
 		fexist("/tmp/norespawn");
 }
 
-/* Used to cleanup any lingering or semi-restarting tasks before respawning. */
-static int kill_service(svc_t *svc, int signo)
+void svc_monitor(void)
 {
-	char *name = basename(svc->cmd);
-
-	_d("Sending signal %d to all processes named %s", signo, name);
-	kill_procname(name, signo);
-
-	/* Don't restart immediately, some throttling necessary.
-	 * Also it's good form to let the application terminate properly. */
-	sleep(1);
-
-	return 0;
-}
-
-static void svc_monitor(EV_P_ ev_child *w, int UNUSED(revents))
-{
-	pid_t lost = w->rpid;
+	pid_t lost;
 	svc_t *svc;
 
-	ev_child_stop(EV_A_ w);
+	lost = waitpid(-1, NULL, WNOHANG);
+	if (lost < 1)
+		return;
 
 	if (fexist(SYNC_SHUTDOWN) || lost <= 1)
 		return;
@@ -236,16 +257,20 @@ static void svc_monitor(EV_P_ ev_child *w, int UNUSED(revents))
 		return;
 
 	for (svc = svc_iterator(1); svc; svc = svc_iterator(0)) {
+		char *name = basename(svc->cmd);
+
 		if (lost != svc->pid)
 			continue;
 
+		_d("Ouch, lost pid %d - %s(%d)", lost, name, svc->pid);
 		if (sig_stopped()) {
 			_e("Stopped, not respawning killed processes.");
 			break;
 		}
 
-		_d("Ouch, lost pid %d - %s(%d)", lost, svc->cmd, svc->pid);
-		kill_service(svc, SIGTERM);
+		/* Cleanup any lingering or semi-restarting tasks before respawning */
+		_d("Sending SIGTERM to service group %s", name);
+		kill_procname(name, SIGTERM);
 
 		/* Restarting lost service. */
 		if (svc_enabled(svc, 0))
@@ -257,36 +282,56 @@ static void svc_monitor(EV_P_ ev_child *w, int UNUSED(revents))
 
 int svc_start(svc_t *svc)
 {
+	int respawn = svc->pid != 0;
+	pid_t pid;
 	char *args[MAX_NUM_SVC_ARGS];
-	int i = 0, restart = 0;
-	ev_child *cw = &watchers[svc->id];
 
 	/* Ignore if finit is SIGSTOP'ed */
 	if (is_norespawn())
 		return 0;
 
-	restart = svc->pid != 0;
-	if (!restart) print_descr("Starting ", svc->descr);
+	if (!respawn)
+		print_descr("Starting ", svc->descr);
 
-	/* Serve copy of args to process in case it modifies them. */
-	while (svc->args[i][0] != 0 && i < MAX_NUM_SVC_ARGS) {
-		args[i] = svc->args[i];
-		i++;
+	pid = fork();
+	if (pid == 0) {
+		int i = 0;
+		int uid = getuser(svc->username);
+		struct sigaction sa;
+
+		/* Reset signal handlers that were set by the parent process */
+                for (i = 1; i < NSIG; i++)
+			DFLSIG(sa, i, 0);
+
+		/* Set desired user */
+		if (uid >= 0)
+			setuid(uid);
+
+		/* Serve copy of args to process in case it modifies them. */
+		for (i = 0; svc->args[i][0] != 0 && i < MAX_NUM_SVC_ARGS; i++)
+			args[i] = svc->args[i];
+		args[i] = NULL;
+
+		if (debug) {
+			int fd = open (CONSOLE, O_WRONLY | O_APPEND);
+			if (-1 != fd) {
+				dup2(STDOUT_FILENO, fd);
+				dup2(STDERR_FILENO, fd);
+			}
+
+			_e("%starting %s ", respawn ? "Res" : "S", svc->cmd);
+			for (i = 0; args[i] && i < MAX_NUM_SVC_ARGS; i++)
+				_e("%s ", args[i]);
+			_e("");
+		}
+
+		execvp(svc->cmd, args);
+		exit(0);
 	}
-	args[i] = NULL;
+	svc->pid = pid;
 
-	if (debug) {
-		_e("(re)starting %s ", svc->cmd);
-		for (i = 0; args[i] && i < MAX_NUM_SVC_ARGS; i++)
-			_e("%s ", args[i]);
-		_e("");
-	}
-
-	svc->pid = start_process(svc->cmd, args, debug);
-	ev_child_init (cw, svc_monitor, svc->pid, 0);
-	ev_child_start (EV_DEFAULT_ cw);
-
-	if (!restart) print_result(0);
+	if (!respawn)
+		print_result(svc->pid > 1 ? 0 : 1);
 
 	return 0;
 }
@@ -304,7 +349,6 @@ int svc_start_by_name(char *name)
 int svc_stop(svc_t *svc)
 {
 	int res = 1;
-	ev_child *cw = &watchers[svc->id];
 
 	if (!svc) {
 		_e("Failed, no svc pointer.");
@@ -319,7 +363,6 @@ int svc_stop(svc_t *svc)
 
 	print_descr("Stopping ", svc->descr);
 	_d("Sending SIGTERM to pid:%d name:'%s'", svc->pid, get_pidname(svc->pid, NULL, 0));
-	ev_child_stop(ev_default_loop(0), cw);
 	res = kill(svc->pid, SIGTERM);
 	print_result(res);
 	svc->pid = 0;

svc.h

@@ -42,6 +42,8 @@ typedef enum {
 #define FINIT_SHM_ID     0x494E4954  /* "INIT", see ascii(7) */
 #define MAX_ARG_LEN      64
 #define MAX_STR_LEN      64
+#define MAX_USER_LEN     16
+#define MAX_NUM_FDS      64	     /* Max number of I/O plugins */
 #define MAX_NUM_SVC      64	     /* Enough? */
 #define MAX_NUM_SVC_ARGS 16
 
@@ -55,6 +57,7 @@ typedef struct svc {
 	char	       cmd[MAX_ARG_LEN];
 	char	       args[MAX_NUM_SVC_ARGS][MAX_ARG_LEN];
 	char	       descr[MAX_STR_LEN];
+	char           username[MAX_USER_LEN];
 	/* Public */
 	int	       delayed_reload; /* For external service plugin. */
 	plugin_svc_t  *plugin;
@@ -94,7 +97,7 @@ svc_t    *svc_find_by_id    (int id);
 svc_t    *svc_find_by_name  (char *name);
 svc_t    *svc_iterator      (int restart);
 
-int       svc_register      (char *line);
+int       svc_register      (char *line, char *username);
 int       svc_id_by_name    (char *name);
 svc_cmd_t svc_enabled	    (svc_t *svc, int dynamic);
 int       svc_start         (svc_t *svc);
@@ -102,6 +105,7 @@ int       svc_start_by_name (char *name);
 int       svc_stop          (svc_t *svc);
 int       svc_reload        (svc_t *svc);
 void      svc_start_all     (void);
+void      svc_monitor       (void);
 
 #endif	/* FINIT_SVC_H_ */