notify parent using SIGUSR2

src/http/server.c

@@ -50,6 +50,7 @@
 #include "../tools.h"
 #include "../threading.h"
 #include "../logging.h"
+#include "../process.h"
 #include "../picture.h"
 #include "../encoder.h"
 #include "../stream.h"
@@ -176,6 +177,9 @@ int http_server_listen(struct http_server_t *server) {
 	EXPOSED(expose_begin_ts) = get_now_monotonic();
 	EXPOSED(expose_cmp_ts) = EXPOSED(expose_begin_ts);
 	EXPOSED(expose_end_ts) = EXPOSED(expose_begin_ts);
+	// See _http_exposed_refresh()
+	EXPOSED(notify_last_width) = EXPOSED(picture->width);
+	EXPOSED(notify_last_height) = EXPOSED(picture->height);
 #	undef EXPOSED
 
 	{
@@ -791,6 +795,25 @@ static void _http_exposed_refresh(UNUSED int fd, UNUSED short what, void *v_serv
 #	undef UNLOCK_STREAM
 
 	_http_queue_send_stream(server, stream_updated, picture_updated);
+
+#	define EXPOSED(_next) server->run->exposed->_next
+
+	if (
+		picture_updated
+		&& server->notify_parent
+		&& (
+			EXPOSED(notify_last_online) != EXPOSED(online)
+			|| EXPOSED(notify_last_width) != EXPOSED(picture->width)
+			|| EXPOSED(notify_last_height) != EXPOSED(picture->height)
+		)
+	) {
+		EXPOSED(notify_last_online) = EXPOSED(online);
+		EXPOSED(notify_last_width) = EXPOSED(picture->width);
+		EXPOSED(notify_last_height) = EXPOSED(picture->height);
+		process_notify_parent();
+	}
+
+#	undef EXPOSED
 }
 
 static bool _expose_new_picture_unsafe(struct http_server_t *server) {

src/http/server.h

@@ -65,6 +65,10 @@ struct exposed_t {
 	long double			expose_cmp_ts;
 	long double			expose_end_ts;
 	long double			last_as_blank_ts;
+
+	bool		notify_last_online;
+	unsigned	notify_last_width;
+	unsigned	notify_last_height;
 };
 
 struct http_server_runtime_t {
@@ -100,6 +104,8 @@ struct http_server_t {
 	unsigned	fake_width;
 	unsigned	fake_height;
 
+	bool		notify_parent;
+
 	struct http_server_runtime_t *run;
 };
 

src/options.c

@@ -110,6 +110,7 @@ enum _OPT_VALUES {
 #ifdef WITH_SETPROCTITLE
 	_O_PROCESS_NAME_PREFIX,
 #endif
+	_O_NOTIFY_PARENT,
 
 	_O_LOG_LEVEL,
 	_O_PERF,
@@ -180,6 +181,7 @@ static const struct option _LONG_OPTS[] = {
 #ifdef WITH_SETPROCTITLE
 	{"process-name-prefix",		required_argument,	NULL,	_O_PROCESS_NAME_PREFIX},
 #endif
+	{"notify-parent",			no_argument,		NULL,	_O_NOTIFY_PARENT},
 
 	{"log-level",				required_argument,	NULL,	_O_LOG_LEVEL},
 	{"perf",					no_argument,		NULL,	_O_PERF},
@@ -396,6 +398,7 @@ int options_parse(struct options_t *options, struct device_t *dev, struct encode
 #			ifdef WITH_SETPROCTITLE
 			case _O_PROCESS_NAME_PREFIX:	OPT_SET(process_name_prefix, optarg);
 #			endif
+			case _O_NOTIFY_PARENT:			OPT_SET(server->notify_parent, true);
 
 			case _O_LOG_LEVEL:			OPT_NUMBER("--log-level", log_level, LOG_LEVEL_INFO, LOG_LEVEL_DEBUG, 0);
 			case _O_PERF:				OPT_SET(log_level, LOG_LEVEL_PERF);
@@ -633,6 +636,8 @@ static void _help(struct device_t *dev, struct encoder_t *encoder, struct http_s
 #ifdef WITH_SETPROCTITLE
 	printf("    --process-name-prefix <str>  ── Set process name prefix which will be displayed in the process list\n");
 	printf("                                    like '<str>: ustreamer --blah-blah-blah'. Default: disabled.\n\n");
+	printf("    --notify-parent  ────────────── Send SIGUSR2 to the parent process when the stream parameters are changed.\n");
+	printf("                                    Checking changes is performed for the online flag and image resolution.\n\n");
 #endif
 	printf("Logging options:\n");
 	printf("════════════════\n");

src/process.h

@@ -22,6 +22,12 @@
 
 #pragma once
 
+#include <signal.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+
+
 #if defined(__linux__)
 #	define HAS_PDEATHSIG
 #elif defined(__FreeBSD__)
@@ -32,19 +38,14 @@
 #endif
 
 
-#ifdef HAS_PDEATHSIG
-#	include <signal.h>
-#	include <unistd.h>
-#endif
 #ifdef WITH_SETPROCTITLE
 #	include <stdlib.h>
 #	include <string.h>
 #	if defined(__linux__)
 #		include <bsd/unistd.h>
-#		include <sys/types.h>
 #	elif (defined(__FreeBSD__) || defined(__DragonFly__))
-#		include <unistd.h>
-#		include <sys/types.h>
+//#		include <unistd.h>
+//#		include <sys/types.h>
 #	elif (defined(__NetBSD__) || defined(__OpenBSD__)) // setproctitle() placed in stdlib.h
 #	else
 #		error setproctitle() not implemented, you can disable it using WITH_SETPROCTITLE=0
@@ -72,6 +73,7 @@ extern char **environ;
 
 #ifdef HAS_PDEATHSIG
 INLINE int process_track_parent_death(void) {
+	pid_t parent = getppid();
 	int signum = SIGTERM;
 #	if defined(__linux__)
 	int retval = prctl(PR_SET_PDEATHSIG, signum);
@@ -85,8 +87,8 @@ INLINE int process_track_parent_death(void) {
 		return -1;
 	}
 
-	if (kill(getppid(), 0) < 0) {
-		LOG_PERROR("The parent process is already dead");
+	if (kill(parent, 0) < 0) {
+		LOG_PERROR("The parent process %d is already dead", parent);
 		return -1;
 	}
 
@@ -128,3 +130,11 @@ INLINE void process_set_name_prefix(int argc, char *argv[], const char *prefix)
 	free(cmdline);
 }
 #endif
+
+INLINE void process_notify_parent(void) {
+	pid_t parent = getppid();
+
+	if (kill(parent, SIGUSR2) < 0) {
+		LOG_PERROR("Can't send SIGUSR2 to the parent process %d", parent);
+	}
+}