core: use pthread_setschedparam on OpenBSD

OpenBSD don't have support for sched_getparam(), sched_setparam(), or
sched_setscheduler() functions (yet). In this case, we need use
pthead-equivalents for real-time sched for picom. Theses changes add
this support.

Authored-by: Jose Maldonado aka Yukiteru <josemald89@gmail.com>
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/meson.build

@@ -86,6 +86,10 @@ elif (host_system == 'freebsd' or host_system == 'netbsd' or
 	cflags += ['-DHAS_KQUEUE']
 endif
 
+if host_system == 'openbsd'
+	deps += [dependency('threads', required: true)]
+endif
+
 subdir('backend')
 
 picom = executable('picom', srcs, c_args: cflags,

src/picom.c

@@ -35,6 +35,9 @@
 #include <xcb/render.h>
 #include <xcb/sync.h>
 #include <xcb/xfixes.h>
+#ifdef __OpenBSD__
+#include <pthread.h>
+#endif
 
 #include <ev.h>
 #include <test.h>
@@ -2588,17 +2591,30 @@ void set_rr_scheduling(void) {
 	int ret;
 	struct sched_param param;
 
+#ifndef __OpenBSD__
 	ret = sched_getparam(0, &param);
+#else
+	int old_policy;
+	ret = pthread_getschedparam(pthread_self(), &old_policy, &param);
+#endif
+
 	if (ret != 0) {
 		log_debug("Failed to get old scheduling priority");
 		return;
 	}
 
 	param.sched_priority = priority;
+
+#ifndef __OpenBSD__
 	ret = sched_setscheduler(0, SCHED_RR, &param);
+#else
+	ret = pthread_setschedparam(pthread_self(), SCHED_RR, &param);
+#endif
+
 	if (ret != 0) {
 		log_info("Failed to set real-time scheduling priority to %d. Consider "
-		         "giving picom the CAP_SYS_NICE capability",
+		         "giving picom the CAP_SYS_NICE capability or equivalent "
+		         "support.",
 		         priority);
 		return;
 	}