Implement service event log

Store global and per-service event changes in the runtime dir under events.
Stores runlevel changes in the global log, service state changes in per-service log

Author: axtloss

src/librc/librc.c

@@ -1061,6 +1061,10 @@ rc_service_mark(const char *service, const RC_SERVICE state)
 			closedir(dp);
 		}
 	}
+
+	/* Log the service state change to the eventlog */
+	rc_eventlog_service(service, state);
+
 	free(init);
 	return true;
 }

src/librc/librc.h

@@ -77,4 +77,30 @@ static const char *const dirnames[RC_DIR_SYS_MAX] =
 RC_STRINGLIST *config_list(int dirfd, const char *pathname);
 void clear_dirfds(void);
 
+/*
+ * Log an event for a specific service.
+ * Events are logged to <RC_DIR_SVCDIR>/events/services/<service>
+ *
+ * @param service name of the service
+ * @param state new state of the service
+ */
+void rc_eventlog_service(const char *service, RC_SERVICE state);
+
+/*
+ * Log a global system event.
+ * Events are logged to <RC_DIR_SVCDIR>/events/global
+ *
+ * @param event_type type of event (e.g., "runlevel", "boot", "shutdown")
+ * @param message event message with details
+ */
+void rc_eventlog_global(const char *event_type, const char *message);
+
+/*
+ * Initialize the eventlog system.
+ * Creates necessary directories under <RC_DIR_SVCDIR>/events/
+ *
+ * @return 0 on success, -1 on failure
+ */
+int rc_eventlog_init(void);
+
 #endif

src/librc/meson.build

@@ -11,6 +11,7 @@ librc_sources = [
   'librc-depend.c',
   'librc-misc.c',
   'librc-stringlist.c',
+  'rc-eventlog.c',
 ]
 
 rc_h = configure_file(input : 'rc.h.in', output : 'rc.h',

src/librc/rc-eventlog.c

@@ -0,0 +1,166 @@
+/*
+ * rc-eventlog.c
+ * Event logging for OpenRC services and system events
+ */
+
+/*
+ * Copyright (c) 2024 The OpenRC Authors.
+ * See the Authors file at the top-level directory of this distribution and
+ * https://github.com/OpenRC/openrc/blob/HEAD/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/HEAD/LICENSE
+ * This file may not be copied, modified, propagated, or distributed
+ *    except according to the terms contained in the LICENSE file.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "librc.h"
+
+#define RC_EVENTLOG_DIR		"events"
+#define RC_EVENTLOG_SERVICES	"events/"
+#define RC_EVENTLOG_GLOBAL	"events/rc"
+
+/*
+ * Get the name of a service state.
+ */
+static const char *rc_service_state_name(RC_SERVICE state)
+{
+	int i;
+
+	for (i = 0; rc_service_state_names[i].name; i++) {
+		if (rc_service_state_names[i].state == state)
+			return rc_service_state_names[i].name;
+	}
+
+	return "unknown";
+}
+
+/*
+ * Format the current time as an ISO 8601 timestamp with milliseconds.
+ * Returns a dynamically allocated string that must be freed by the caller.
+ */
+static char *format_timestamp(void)
+{
+	time_t now;
+	struct tm *tm;
+	char timebuf[32];
+	char *result;
+	int ms;
+
+	clock_gettime(CLOCK_REALTIME, &ts);
+	tm = localtime(&ts.tv_sec);
+	ms = (int)(ts.tv_nsec / 1000000);
+
+	strftime(timebuf, sizeof(timebuf), "%Y-%m-%dT%H:%M:%S", tm);
+	xasprintf(&result, "%s.%03d%+03ld%02ld", timebuf, ms,
+		tm->tm_gmtoff / 3600, (labs(tm->tm_gmtoff) % 3600) / 60);
+
+	return result;
+}
+
+/*
+ * Initialize the eventlog system.
+ * Creates necessary directories under <RC_DIR_SVCDIR>/events/
+ */
+int rc_eventlog_init(void)
+{
+	int svcfd = rc_dirfd(RC_DIR_SVCDIR);
+
+	if (svcfd < 0)
+		return -1;
+
+	if (mkdirat(svcfd, RC_EVENTLOG_DIR, 0755) == -1 && errno != EEXIST)
+		return -1;
+
+	if (mkdirat(svcfd, RC_EVENTLOG_SERVICES, 0755) == -1 && errno != EEXIST)
+		return -1;
+
+	return 0;
+}
+
+/*
+ * Log an event for a specific service.
+ */
+void rc_eventlog_service(const char *service, RC_SERVICE state)
+{
+	int svcfd;
+	int eventsfd;
+	char *timestamp;
+	FILE *fp;
+	const char *state_name;
+
+	if (!service)
+		return;
+
+	svcfd = rc_dirfd(RC_DIR_SVCDIR);
+	if (svcfd < 0)
+		return;
+
+	if (rc_eventlog_init() != 0)
+		return;
+
+	eventsfd = openat(svcfd, RC_EVENTLOG_SERVICES, O_RDONLY | O_DIRECTORY);
+	if (eventsfd < 0)
+		return;
+
+	service = basename_c(service);
+
+	timestamp = format_timestamp();
+
+	state_name = rc_service_state_name(state);
+
+	fp = do_fopenat(eventsfd, service, O_WRONLY | O_CREAT | O_APPEND);
+	close(eventsfd);
+
+	if (!fp) {
+		free(timestamp);
+		return;
+	}
+
+	fprintf(fp, "%s %s\n", timestamp, state_name);
+	fclose(fp);
+	free(timestamp);
+}
+
+/*
+ * Log a global system event.
+ */
+void rc_eventlog_global(const char *event_type, const char *message)
+{
+	int svcfd;
+	char *timestamp;
+	FILE *fp;
+
+	if (!event_type || !message)
+		return;
+
+	svcfd = rc_dirfd(RC_DIR_SVCDIR);
+	if (svcfd < 0)
+		return;
+
+	if (rc_eventlog_init() != 0)
+		return;
+
+	timestamp = format_timestamp();
+
+	fp = do_fopenat(svcfd, RC_EVENTLOG_GLOBAL, O_WRONLY | O_CREAT | O_APPEND);
+	if (!fp) {
+		free(timestamp);
+		return;
+	}
+
+	fprintf(fp, "%s %s %s\n", timestamp, event_type, message);
+	fclose(fp);
+	free(timestamp);
+}

src/openrc/rc.c

@@ -906,6 +906,7 @@ int main(int argc, char **argv)
 		if (access(RC_KRUNLEVEL, F_OK) != 0)
 			set_krunlevel(runlevel);
 		rc_runlevel_set(newlevel);
+		rc_eventlog_global("runlevel", newlevel);
 		setenv("RC_RUNLEVEL", newlevel, 1);
 		setenv("RC_GOINGDOWN", "YES", 1);
 	} else {
@@ -1059,6 +1060,7 @@ int main(int argc, char **argv)
 	/* Store the new runlevel */
 	if (newlevel) {
 		rc_runlevel_set(newlevel);
+		rc_eventlog_global("runlevel", newlevel);
 		free(runlevel);
 		runlevel = xstrdup(newlevel);
 		setenv("RC_RUNLEVEL", runlevel, 1);