Enhance ways that upsd/upsmon can send signals to their running siblings

clients/upsmon.c

@@ -1279,7 +1279,7 @@ static int parse_conf_arg(size_t numargs, char **arg)
 	}
 
 	/* RUN_AS_USER <userid> */
- 	if (!strcmp(arg[0], "RUN_AS_USER")) {
+	if (!strcmp(arg[0], "RUN_AS_USER")) {
 		free(run_as_user);
 		run_as_user = xstrdup(arg[1]);
 		return 1;
@@ -1393,6 +1393,13 @@ static void loadconfig(void)
 		fatalx(EXIT_FAILURE, "%s", ctx.errmsg);
 	}
 
+	if (reload_flag == 1) {
+		/* if upsmon.conf added or changed
+		 * (or commented away) the debug_min
+		 * setting, detect that */
+		nut_debug_level_global = -1;
+	}
+
 	while (pconf_file_next(&ctx)) {
 		if (pconf_parse_error(&ctx)) {
 			upslogx(LOG_ERR, "Parse error: %s:%d: %s",
@@ -1419,6 +1426,15 @@ static void loadconfig(void)
 		}
 	}
 
+	if (reload_flag == 1) {
+		if (nut_debug_level_global > -1) {
+			upslogx(LOG_INFO,
+				"Applying debug_min=%d from upsmon.conf",
+				nut_debug_level_global);
+			nut_debug_level = nut_debug_level_global;
+		}
+	}
+
 	pconf_finish(&ctx);
 }
 
@@ -1809,6 +1825,7 @@ static void help(const char *arg_progname)
 	printf("		 - fsd: shutdown all primary-mode UPSes (use with caution)\n");
 	printf("		 - reload: reread configuration\n");
 	printf("		 - stop: stop monitoring and exit\n");
+	printf("  -P <pid>	send the signal above to specified PID (bypassing PID file)\n");
 	printf("  -D		raise debugging level (and stay foreground by default)\n");
 	printf("  -F		stay foregrounded even if no debugging is enabled\n");
 	printf("  -B		stay backgrounded even if debugging is bumped\n");
@@ -2042,7 +2059,8 @@ static void check_parent(void)
 int main(int argc, char *argv[])
 {
 	const char	*prog = xbasename(argv[0]);
-	int	i, cmd = 0, checking_flag = 0, foreground = -1;
+	int	i, cmd = 0, cmdret = -1, checking_flag = 0, foreground = -1;
+	pid_t	oldpid = -1;
 
 	printf("Network UPS Tools %s %s\n", prog, UPS_VERSION);
 
@@ -2053,7 +2071,7 @@ int main(int argc, char *argv[])
 
 	run_as_user = xstrdup(RUN_AS_USER);
 
-	while ((i = getopt(argc, argv, "+DFBhic:f:pu:VK46")) != -1) {
+	while ((i = getopt(argc, argv, "+DFBhic:P:f:pu:VK46")) != -1) {
 		switch (i) {
 			case 'c':
 				if (!strncmp(optarg, "fsd", strlen(optarg)))
@@ -2067,6 +2085,12 @@ int main(int argc, char *argv[])
 				if (cmd == 0)
 					help(argv[0]);
 				break;
+
+			case 'P':
+				if ((oldpid = parsepid(optarg)) < 0)
+					help(argv[0]);
+				break;
+
 			case 'D':
 				nut_debug_level++;
 				break;
@@ -2121,17 +2145,41 @@ int main(int argc, char *argv[])
 	}
 
 	if (cmd) {
-		sendsignal(prog, cmd);
-		exit(EXIT_SUCCESS);
+		if (oldpid < 0) {
+			cmdret = sendsignal(prog, cmd);
+		} else {
+			cmdret = sendsignalpid(oldpid, cmd);
+		}
+		/* exit(EXIT_SUCCESS); */
+		exit((cmdret == 0)?EXIT_SUCCESS:EXIT_FAILURE);
 	}
 
 	/* otherwise, we are being asked to start.
 	 * so check if a previous instance is running by sending signal '0'
 	 * (Ie 'kill <pid> 0') */
-	if (sendsignal(prog, 0) == 0) {
+	if (oldpid < 0) {
+		cmdret = sendsignal(prog, 0);
+	} else {
+		cmdret = sendsignalpid(oldpid, 0);
+	}
+	switch (cmdret) {
+	case 0:
 		printf("Fatal error: A previous upsmon instance is already running!\n");
 		printf("Either stop the previous instance first, or use the 'reload' command.\n");
 		exit(EXIT_FAILURE);
+
+	case -3:
+	case -2:
+		upslogx(LOG_WARNING, "Could not %s PID file "
+			"to see if previous upsmon instance is "
+			"already running!\n",
+			(cmdret == -3 ? "find" : "parse"));
+		break;
+
+	case -1:
+	default:
+		/* Just failed to send signal, no competitor running */
+		break;
 	}
 
 	argc -= optind;

common/common.c

@@ -293,7 +293,9 @@ void writepid(const char *name)
 	pidf = fopen(fn, "w");
 
 	if (pidf) {
-		fprintf(pidf, "%d\n", (int) getpid());
+		intmax_t pid = (intmax_t)getpid();
+		upsdebugx(1, "Saving PID %jd into %s", pid, fn);
+		fprintf(pidf, "%jd\n", pid);
 		fclose(pidf);
 	} else {
 		upslog_with_errno(LOG_NOTICE, "writepid: fopen %s", fn);
@@ -302,61 +304,97 @@ void writepid(const char *name)
 	umask(mask);
 }
 
-/* open pidfn, get the pid, then send it sig */
-int sendsignalfn(const char *pidfn, int sig)
+/* send sig to pid, returns -1 for error, or
+ * zero for a successfully sent signal
+ */
+int sendsignalpid(pid_t pid, int sig)
 {
-	char	buf[SMALLBUF];
-	FILE	*pidf;
-	pid_t	pid = -1;
 	int	ret;
 
-	pidf = fopen(pidfn, "r");
-	if (!pidf) {
-		upslog_with_errno(LOG_NOTICE, "fopen %s", pidfn);
+	if (pid < 2 || pid > get_max_pid_t()) {
+		upslogx(LOG_NOTICE,
+			"Ignoring invalid pid number %" PRIdMAX,
+			(intmax_t) pid);
 		return -1;
 	}
 
-	if (fgets(buf, sizeof(buf), pidf) == NULL) {
-		upslogx(LOG_NOTICE, "Failed to read pid from %s", pidfn);
-		fclose(pidf);
+	/* see if this is going to work first */
+	ret = kill(pid, 0);
+
+	if (ret < 0) {
+		perror("kill");
 		return -1;
 	}
 
-	{ /* scoping */
-		intmax_t _pid = strtol(buf, (char **)NULL, 10); /* assuming 10 digits for a long */
-		if (_pid <= get_max_pid_t()) {
-			pid = (pid_t)_pid;
-		} else {
-			upslogx(LOG_NOTICE, "Received a pid number too big for a pid_t: %" PRIdMAX, _pid);
+	if (sig != 0) {
+		/* now actually send it */
+		ret = kill(pid, sig);
+
+		if (ret < 0) {
+			perror("kill");
+			return -1;
 		}
 	}
 
-	if (pid < 2) {
-		upslogx(LOG_NOTICE, "Ignoring invalid pid number %" PRIdMAX, (intmax_t) pid);
-		fclose(pidf);
-		return -1;
+	return 0;
+}
+
+/* parses string buffer into a pid_t if it passes
+ * a few sanity checks; returns -1 on error
+ */
+pid_t parsepid(const char *buf)
+{
+	pid_t	pid = -1;
+
+	/* assuming 10 digits for a long */
+	intmax_t _pid = strtol(buf, (char **)NULL, 10);
+	if (_pid <= get_max_pid_t()) {
+		pid = (pid_t)_pid;
+	} else {
+		upslogx(LOG_NOTICE, "Received a pid number too big for a pid_t: %" PRIdMAX, _pid);
 	}
 
-	/* see if this is going to work first */
-	ret = kill(pid, 0);
+	return pid;
+}
 
-	if (ret < 0) {
-		perror("kill");
+/* open pidfn, get the pid, then send it sig
+ * returns negative codes for errors, or
+ * zero for a successfully sent signal
+ */
+int sendsignalfn(const char *pidfn, int sig)
+{
+	char	buf[SMALLBUF];
+	FILE	*pidf;
+	pid_t	pid = -1;
+	int	ret = -1;
+
+	pidf = fopen(pidfn, "r");
+	if (!pidf) {
+		upslog_with_errno(LOG_NOTICE, "fopen %s", pidfn);
+		return -3;
+	}
+
+	if (fgets(buf, sizeof(buf), pidf) == NULL) {
+		upslogx(LOG_NOTICE, "Failed to read pid from %s", pidfn);
 		fclose(pidf);
-		return -1;
+		return -2;
 	}
+	/* TOTHINK: Original code only closed pidf before
+	 * exiting the method, on error or "normally".
+	 * Why not here? Do we want an (exclusive?) hold
+	 * on it while being active in the method?
+	 */
 
-	/* now actually send it */
-	ret = kill(pid, sig);
+	/* this method actively reports errors, if any */
+	pid = parsepid(buf);
 
-	if (ret < 0) {
-		perror("kill");
-		fclose(pidf);
-		return -1;
+	if (pid >= 0) {
+		/* this method actively reports errors, if any */
+		ret = sendsignalpid(pid, sig);
 	}
 
 	fclose(pidf);
-	return 0;
+	return ret;
 }
 
 int snprintfcat(char *dst, size_t size, const char *fmt, ...)

conf/upsd.conf.sample

@@ -155,3 +155,14 @@
 # running mode directly, and without need to edit init-scripts or service
 # unit definitions. Note that command-line option `-D` can only increase
 # this verbosity level.
+#
+# NOTE: if the running daemon receives a `reload` command, presence of the
+# `DEBUG_MIN NUMBER` value in the configuration file can be used to tune
+# debugging verbosity in the running service daemon (it is recommended to
+# comment it away or set the minimum to explicit zero when done, to avoid
+# huge journals and I/O system abuse). Keep in mind that for this run-time
+# tuning, the `DEBUG_MIN` value *present* in *reloaded* configuration files
+# is applied instantly and overrides any previously set value, from file
+# or CLI options, regardless of older logging level being higher or lower
+# than the newly found number; a missing (or commented away) value however
+# does not change the previously active logging verbosity.

conf/upsmon.conf.sample.in

@@ -440,3 +440,14 @@ FINALDELAY 5
 # running mode directly, and without need to edit init-scripts or service
 # unit definitions. Note that command-line option `-D` can only increase
 # this verbosity level.
+#
+# NOTE: if the running daemon receives a `reload` command, presence of the
+# `DEBUG_MIN NUMBER` value in the configuration file can be used to tune
+# debugging verbosity in the running service daemon (it is recommended to
+# comment it away or set the minimum to explicit zero when done, to avoid
+# huge journals and I/O system abuse). Keep in mind that for this run-time
+# tuning, the `DEBUG_MIN` value *present* in *reloaded* configuration files
+# is applied instantly and overrides any previously set value, from file
+# or CLI options, regardless of older logging level being higher or lower
+# than the newly found number; a missing (or commented away) value however
+# does not change the previously active logging verbosity.

docs/man/upsd.conf.txt

@@ -135,6 +135,17 @@ Optionally specify a minimum debug level for `upsd` data daemon, e.g. for
 troubleshooting a deployment, without impacting foreground or background
 running mode directly. Command-line option `-D` can only increase this
 verbosity level.
++
+NOTE: if the running daemon receives a `reload` command, presence of the
+`DEBUG_MIN NUMBER` value in the configuration file can be used to tune
+debugging verbosity in the running service daemon (it is recommended to
+comment it away or set the minimum to explicit zero when done, to avoid
+huge journals and I/O system abuse). Keep in mind that for this run-time
+tuning, the `DEBUG_MIN` value *present* in *reloaded* configuration files
+is applied instantly and overrides any previously set value, from file
+or CLI options, regardless of older logging level being higher or lower
+than the newly found number; a missing (or commented away) value however
+does not change the previously active logging verbosity.
 
 SEE ALSO
 --------

docs/man/upsd.txt

@@ -43,13 +43,20 @@ are:
 	*reload*;; reread configuration files
 	*stop*;; stop process and exit
 
+*-P* 'pid'::
+Send the command signal above using specified PID number, rather than
+consulting the PID file.  This can help define service units which
+start `upsd` as a foreground process so it does not create a PID file.
+See also `-FF` option as an alternative.
+
 *-D*::
 Raise the debugging level.  upsd will run in the foreground by default,
 and will print information on stdout about the monitoring process.
 Use this option multiple times for more details.
 
 *-F*::
 upsd will run in the foreground, regardless of debugging settings.
+Specify twice (`-FF` or `-F -F`) to save the PID file even in this mode.
 
 *-B*::
 upsd will run in the background, regardless of debugging settings.

docs/man/upsmon.conf.txt

@@ -399,6 +399,17 @@ Optionally specify a minimum debug level for `upsmon` daemon, e.g. for
 troubleshooting a deployment, without impacting foreground or background
 running mode directly. Command-line option `-D` can only increase this
 verbosity level.
++
+NOTE: if the running daemon receives a `reload` command, presence of the
+`DEBUG_MIN NUMBER` value in the configuration file can be used to tune
+debugging verbosity in the running service daemon (it is recommended to
+comment it away or set the minimum to explicit zero when done, to avoid
+huge journals and I/O system abuse). Keep in mind that for this run-time
+tuning, the `DEBUG_MIN` value *present* in *reloaded* configuration files
+is applied instantly and overrides any previously set value, from file
+or CLI options, regardless of older logging level being higher or lower
+than the newly found number; a missing (or commented away) value however
+does not change the previously active logging verbosity.
 
 SEE ALSO
 --------

docs/man/upsmon.txt

@@ -11,7 +11,7 @@ SYNOPSIS
 
 *upsmon* -h
 
-*upsmon* -c 'command'
+*upsmon* -c 'command' [-P 'pid']
 
 *upsmon* [-D] [-F | -B] [-K] [-p] [-u 'user']
 
@@ -44,6 +44,12 @@ commands are:
 *reload*;; reread linkman:upsmon.conf[5] configuration file.  See
 "reloading nuances" below if this doesn't work.
 
+*-P* 'pid'::
+Send the command signal above using specified PID number, rather than
+consulting the PID file.  This can help define service units which
+start main `upsmon` as a foreground process so it does not have to
+rely on a PID file.
+
 *-D*::
 Raise the debugging level.  upsmon will run in the foreground by default,
 and will print information on stdout about the monitoring process.