Re: move udev-rules parsing into the daemon

[Kay Sievers <kay.sievers@vrfy.org>]

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On Sun, Jul 31, 2005 at 02:42:27AM +0200, Kay Sievers wrote:
> Here we move the parsed rules into the udev daemon, which will no longer
> execute the udev binary. This saves us the rule parsing, cause the
> parsed rules will be inherited from the daemon process, which will
> fork() a child which imediately becomes the event process without doing
> an exec(). It's basically a retry of this old patch:
>   http://marc.theaimsgroup.com/?l=linux-hotplug-devel&m=109814301613236&w=2
> 
> Changes to /etc/udev/rules.d/* will automatically recognized and will cause
> a reload of the rules, also the usual -HUP should work.
> 
> Would be nice if someone brave enough can give it a try, we want to put
> that upstream if it works as expected. The patch applies on top of v064.

New patch with a few fixes on top of the current git tree.

Thanks,
Kay

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diff --git a/udevcontrol.c b/udevcontrol.c
--- a/udevcontrol.c
+++ b/udevcontrol.c
@@ -97,7 +97,9 @@ int main(int argc, char *argv[], char *e
 		usend_msg.type = UDEVD_SET_MAX_CHILDS;
 		*intval = atoi(val);
 		info("send max_childs=%i", *intval);
-	} else {
+	} else if (!strcmp(argv[1], "reload_rules"))
+		usend_msg.type = UDEVD_RELOAD_RULES;
+	else {
 		err("error parsing command\n");
 		goto exit;
 	}
diff --git a/udevd.c b/udevd.c
--- a/udevd.c
+++ b/udevd.c
@@ -45,6 +45,7 @@
 #include "udev_libc_wrapper.h"
 #include "udev.h"
 #include "udev_version.h"
+#include "udev_rules.h"
 #include "udev_utils.h"
 #include "udevd.h"
 #include "logging.h"
@@ -54,6 +55,7 @@
 #endif
 
 /* global variables*/
+struct udev_rules rules;
 static int udevd_sock;
 static int uevent_netlink_sock;
 static pid_t sid;
@@ -65,6 +67,7 @@ static volatile int sig_flag;
 static int init_phase = 1;
 static int run_exec_q;
 static int stop_exec_q;
+static int reload_config;
 
 static LIST_HEAD(msg_list);
 static LIST_HEAD(exec_list);
@@ -75,12 +78,13 @@ static void msg_queue_manager(void);
 static void user_sighandler(void);
 static void reap_sigchilds(void);
 
-static char *udev_bin;
 static unsigned long long expected_seqnum;
 static int event_timeout;
 static int max_childs;
 static int max_childs_running;
 
+static char log[32];
+
 
 #ifdef USE_LOG
 void log_message (int priority, const char *format, ...)
@@ -167,10 +171,58 @@ static void msg_queue_insert(struct ueve
 	return;
 }
 
+static void asmlinkage udev_event_sig_handler(int signum)
+{
+	if (signum == SIGALRM)
+		exit(1);
+}
+
+static int udev_event_process(struct uevent_msg *msg)
+{
+	struct sigaction act;
+	struct udevice udev;
+	struct name_entry *name_loop;
+	int i;
+	int retval;
+
+	logging_init("udevd-event");
+
+	/* set signal handlers */
+	memset(&act, 0x00, sizeof(act));
+	act.sa_handler = (void (*)(int)) udev_event_sig_handler;
+	sigemptyset (&act.sa_mask);
+	act.sa_flags = 0;
+	sigaction(SIGALRM, &act, NULL);
+
+	/* trigger timeout to prevent hanging processes */
+	alarm(UDEV_ALARM_TIMEOUT);
+
+	/* reconstruct env from message */
+	for (i = 0; msg->envp[i]; i++)
+		putenv(msg->envp[i]);
+
+	udev_init_device(&udev, msg->devpath, msg->subsystem, msg->action);
+	retval = udev_process_event(&rules, &udev);
+
+	/* run programs collected by RUN-key*/
+	if (!retval) {
+		list_for_each_entry(name_loop, &udev.run_list, node) {
+			if (strncmp(name_loop->name, "socket:", strlen("socket:")) == 0)
+				pass_env_to_socket(&name_loop->name[strlen("socket:")], msg->devpath, msg->action);
+			else
+				execute_program(name_loop->name, udev.subsystem, NULL, 0, NULL);
+		}
+	}
+
+	udev_cleanup_device(&udev);
+	logging_close();
+
+	return 0;
+}
+
 /* forks event and removes event from run queue when finished */
 static void udev_event_fork(struct uevent_msg *msg)
 {
-	char *const argv[] = { "udev", msg->subsystem, NULL };
 	pid_t pid;
 	struct sysinfo info;
 
@@ -183,9 +235,9 @@ static void udev_event_fork(struct ueven
 		close(udevd_sock);
 		logging_close();
 		setpriority(PRIO_PROCESS, 0, UDEV_PRIORITY);
-		execve(udev_bin, argv, msg->envp);
-		err("exec of child failed");
-		_exit(1);
+
+		udev_event_process(msg);
+		exit(0);
 	case -1:
 		err("fork of child failed");
 		msg_queue_delete(msg);
@@ -574,12 +626,19 @@ static struct uevent_msg *get_udevd_msg(
 		intval = (int *) usend_msg.envbuf;
 		info("udevd message (SET_LOG_PRIORITY) received, udev_log_priority=%i", *intval);
 		udev_log_priority = *intval;
+		sprintf(log, "UDEV_LOG=%i", udev_log_priority);
+		putenv(log);
 		break;
 	case UDEVD_SET_MAX_CHILDS:
 		intval = (int *) usend_msg.envbuf;
 		info("udevd message (UDEVD_SET_MAX_CHILDS) received, max_childs=%i", *intval);
 		max_childs = *intval;
 		break;
+	case UDEVD_RELOAD_RULES:
+		info("udevd message (RELOAD_RULES) received");
+		udev_rules_close(&rules);
+		udev_rules_init(&rules, 1);
+		break;
 	default:
 		dbg("unknown message type");
 	}
@@ -650,16 +709,17 @@ static void asmlinkage sig_handler(int s
 		case SIGALRM:
 			/* set flag, then write to pipe if needed */
 			run_msg_q = 1;
-			goto do_write;
 			break;
 		case SIGCHLD:
 			/* set flag, then write to pipe if needed */
 			sigchilds_waiting = 1;
-			goto do_write;
+			break;
+		case SIGHUP:
+		case SIGIO:
+			reload_config = 1;
 			break;
 	}
 
-do_write:
 	/* if pipe is empty, write to pipe to force select to return
 	 * immediately when it gets called
 	 */
@@ -787,6 +847,24 @@ static int init_uevent_netlink_sock(void
 	return 0;
 }
 
+static int watch_directory(const char *dir)
+{
+	int fd;
+
+	fd = open(dir, O_RDONLY);
+	if (fd < 0) {
+		err("could not open '%s' to watch it", dir);
+		return -1;
+	}
+	if (fcntl(fd, F_NOTIFY, DN_MODIFY | DN_CREATE | DN_DELETE | DN_MULTISHOT) == -1) {
+		err("could not set dnotify on '%s'", dir);
+		return -1;
+		close(fd);
+	}
+
+	return 0;
+}
+
 int main(int argc, char *argv[], char *envp[])
 {
 	int maxsockplus;
@@ -891,6 +969,11 @@ int main(int argc, char *argv[], char *e
 	sigaction(SIGTERM, &act, NULL);
 	sigaction(SIGALRM, &act, NULL);
 	sigaction(SIGCHLD, &act, NULL);
+	sigaction(SIGHUP, &act, NULL);
+	sigaction(SIGIO, &act, NULL);
+
+	udev_rules_init(&rules, 1);
+	watch_directory(udev_rules_filename);
 
 	if (init_uevent_netlink_sock() < 0) {
 		dbg("uevent socket not available");
@@ -905,13 +988,6 @@ int main(int argc, char *argv[], char *e
 		goto exit;
 	}
 
-	/* override of forked udev binary, used for testing */
-	udev_bin = getenv("UDEV_BIN");
-	if (udev_bin != NULL)
-		info("udev binary is set to '%s'", udev_bin);
-	else
-		udev_bin = UDEV_BIN;
-
 	/* init of expected_seqnum value */
 	value = getenv("UDEVD_EXPECTED_SEQNUM");
 	if (value) {
@@ -943,6 +1019,13 @@ int main(int argc, char *argv[], char *e
 		max_childs_running = UDEVD_MAX_CHILDS_RUNNING;
 	info("initialize max_childs_running to %u", max_childs_running);
 
+	/* clear environment for forked event processes */
+	clearenv();
+
+	/* export log_priority , as called programs may want to do the same as udev */
+	sprintf(log, "UDEV_LOG=%i", udev_log_priority);
+	putenv(log);
+
 	FD_ZERO(&readfds);
 	FD_SET(udevd_sock, &readfds);
 	if (uevent_netlink_sock != -1)
@@ -1010,6 +1093,12 @@ int main(int argc, char *argv[], char *e
 			if (!stop_exec_q)
 				exec_queue_manager();
 		}
+
+		if (reload_config) {
+			reload_config = 0;
+			udev_rules_close(&rules);
+			udev_rules_init(&rules, 1);
+		}
 	}
 
 exit:
diff --git a/udevd.h b/udevd.h
--- a/udevd.h
+++ b/udevd.h
@@ -54,6 +54,7 @@ enum udevd_msg_type {
 	UDEVD_START_EXEC_QUEUE,
 	UDEVD_SET_LOG_LEVEL,
 	UDEVD_SET_MAX_CHILDS,
+	UDEVD_RELOAD_RULES,
 };