[doc] SIGUSR1 doc and lighttpd-angel SIGUSR1

lighttpd-angel:
  add paranoid check to avoid sending kill(-1, <signal>) as root

doc/initscripts.txt

@@ -1,9 +1,12 @@
 * lighttpd responds to the following signals:
 
-SIGINT  - shut down gracefully  (finish serving existing connections and exit)
-SIGTERM - shut down immediately (terminate existing connections and exit)
+SIGTERM - shut down immediately (terminate existing connections, then exit)
+SIGINT  - shut down gracefully  (serve existing connections, then exit)
+SIGUSR1 - reload gracefully     (serve existing connections, then reload config)
 SIGHUP  - re-open log files     (NOTE: does not reload lighttpd configuration)
 
+(Note: SIGUSR1 behavior is available in lighttpd 1.4.46 and later)
+
 
 * lighttpd graceful restart
 
@@ -11,6 +14,10 @@ https://blog.lighttpd.net/articles/2005/09/02/graceful-restart/
 The current recommended way to reload lighttpd config is to gracefully stop
 and then to restart lighttpd.
 
+With lighttpd 1.4.46 and later, SIGUSR1 is the recommended method to gracefully
+handle configuration reloads and log rotation, though a graceful stop and then
+restart of lighttpd is still required for lighttpd configurations which chroot.
+
 
 * lighttpd initscripts
 
@@ -36,5 +43,7 @@ https://gitweb.gentoo.org/repo/gentoo.git/tree/www-servers/lighttpd/files
 openSUSE:
 https://build.opensuse.org/package/show/server:http/lighttpd
 
+sample systemd unit script: doc/systemd/lighttpd.service
+
 Additional, updated information may be found at
 https://redmine.lighttpd.net/projects/lighttpd/wiki/InstallFromSource

doc/lighttpd-angel.8

@@ -11,15 +11,18 @@ lighttpd-angel \- monitor/supervise lighttpd daemon
 lighttpd-angel will restart lighttpd if lighttpd exits for any reason, other
 than by signals sent by lighttpd-angel.
 .PP
+Send lighttpd-angel SIGTERM to initiate immediate shutdown of lighttpd.
+.PP
 Send lighttpd-angel SIGINT to initiate graceful shutdown of lighttpd.
 .PP
-Send lighttpd-angel SIGTERM to initiate shutdown of lighttpd.
+Send lighttpd-angel SIGHUP to initiate graceful restart of lighttpd.
 .PP
-Send lighttpd-angel SIGHUP to initiate restart of lighttpd, reloading config.
+Send lighttpd-angel SIGUSR1 to initiate graceful reload of lighttpd config.
 .
 .SH SEE ALSO
 Online Documentation:
 
+https://redmine.lighttpd.net/projects/lighttpd/wiki/InstallFromSource
 https://blog.lighttpd.net/articles/2007/09/02/there-is-an-angel-for-lighty/
 .
 .SH AUTHOR

doc/systemd/lighttpd.service

@@ -4,8 +4,10 @@ After=network.target
 
 [Service]
 Type=simple
+PIDFile=/var/run/lighttpd.pid
 ExecStartPre=/usr/sbin/lighttpd -tt -f /etc/lighttpd/lighttpd.conf
 ExecStart=/usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf
+ExecReload=/bin/kill -USR1 $MAINPID
 Restart=on-failure
 
 [Install]

src/lighttpd-angel.c

@@ -38,12 +38,15 @@ static void sigaction_handler(int sig, siginfo_t *si, void *context) {
 	switch (sig) {
 	case SIGINT: 
 	case SIGTERM:
+	case SIGUSR1:
+		if (pid <= 0) break;
 		memcpy(&last_sigterm_info, si, sizeof(*si));
 
 		/** forward the sig to the child */
 		kill(pid, sig);
 		break;
 	case SIGHUP: /** do a graceful restart */
+		if (pid <= 0) break;
 		memcpy(&last_sighup_info, si, sizeof(*si));
 
 		/** do a graceful shutdown on the main process and start a new child */
@@ -81,6 +84,7 @@ int main(int argc, char **argv) {
 
 	sigaction(SIGINT,  &act, NULL);
 	sigaction(SIGTERM, &act, NULL);
+	sigaction(SIGUSR1, &act, NULL);
 	sigaction(SIGHUP,  &act, NULL);
 	sigaction(SIGALRM, &act, NULL);
 	sigaction(SIGCHLD, &act, NULL);