mangoapp: Use POSIX message queues

This allows multiple mangoapp instances to run on the same system.

src/mangoapp.cpp

@@ -1,6 +1,7 @@
 #include <sys/ipc.h>
 #include <unistd.h>
 #include <sys/msg.h>
+#include <mqueue.h>
 #include <cstring>
 
 #include "steamcompmgr.hpp"
@@ -9,8 +10,10 @@
 
 static bool inited = false;
 static int msgid = 0;
+static mqd_t mangoapp_mq = 0;
 extern bool g_bAppWantsHDRCached;
 extern uint32_t g_focusedBaseAppId;
+extern const char *g_sMangoappMqName;
 
 struct mangoapp_msg_header {
     long msg_type;  // Message queue ID, never change
@@ -36,8 +39,22 @@ struct mangoapp_msg_v1 {
 } __attribute__((packed)) mangoapp_msg_v1;
 
 void init_mangoapp(){
-    int key = ftok("mangoapp", 65);
+    // WARNING: "mangoapp" most likely isn't in the working directory so key will be -1 (0xffffffff)
+    // TODO: Deprecate SysV message queues
+    key_t key = ftok("mangoapp", 65);
     msgid = msgget(key, 0666 | IPC_CREAT);
+    struct mq_attr attrs = {
+        .mq_flags = O_NONBLOCK,
+        .mq_maxmsg = 4,
+        .mq_msgsize = sizeof( mangoapp_msg_v1 ),
+    };
+    if ( g_sMangoappMqName != nullptr ) {
+        mq_unlink( g_sMangoappMqName );
+        mangoapp_mq = mq_open( g_sMangoappMqName, O_CREAT | O_EXCL | O_WRONLY | O_NONBLOCK, S_IRUSR | S_IWUSR, &attrs );
+        if (mangoapp_mq == -1)
+            console_log.errorf("Failed to create mangoapp message queue at %s %d (%s)", g_sMangoappMqName, errno, strerror(errno));
+    }
+
     mangoapp_msg_v1.hdr.msg_type = 1;
     mangoapp_msg_v1.hdr.version = 1;
     mangoapp_msg_v1.fsrUpscale = 0;
@@ -60,6 +77,9 @@ void mangoapp_update( uint64_t visible_frametime, uint64_t app_frametime_ns, uin
     mangoapp_msg_v1.displayRefresh = (uint16_t) gamescope::ConvertmHzToHz( g_nOutputRefresh );
     mangoapp_msg_v1.bAppWantsHDR = g_bAppWantsHDRCached;
     mangoapp_msg_v1.bSteamFocused = g_focusedBaseAppId == 769;
+    if (mangoapp_mq > 0 && mq_send( mangoapp_mq, (const char *)&mangoapp_msg_v1, sizeof( struct mangoapp_msg_v1 ), 0 ) == -1 && errno != EAGAIN) {
+        console_log.errorf( "Failed to send message to mangoapp %d: %s", errno, strerror( errno ) );
+    }
     msgsnd(msgid, &mangoapp_msg_v1, sizeof(mangoapp_msg_v1) - sizeof(mangoapp_msg_v1.hdr.msg_type), IPC_NOWAIT);
 }
 

src/steamcompmgr.cpp

@@ -74,6 +74,7 @@
 #include <getopt.h>
 #include <spawn.h>
 #include <signal.h>
+#include <mqueue.h>
 #include <linux/input-event-codes.h>
 #include <X11/Xmu/CurUtil.h>
 #include "waitable.h"
@@ -164,6 +165,8 @@ uint32_t g_reshade_technique_idx = 0;
 bool g_bSteamIsActiveWindow = false;
 bool g_bForceInternal = false;
 
+const char *g_sMangoappMqName = nullptr;
+
 static std::vector< steamcompmgr_win_t* > GetGlobalPossibleFocusWindows();
 static bool
 pick_primary_focus_and_override(focus_t *out, Window focusControlWindow, const std::vector<steamcompmgr_win_t*>& vecPossibleFocusWindows, bool globalFocus, const std::vector<uint32_t>& ctxFocusControlAppIDs);
@@ -5900,6 +5903,9 @@ steamcompmgr_exit(void)
 {
 	g_ImageWaiter.Shutdown();
 
+	if ( g_sMangoappMqName != nullptr )
+		mq_unlink( g_sMangoappMqName );
+
 	// Clean up any commits.
 	{
 		gamescope_xwayland_server_t *server = NULL;
@@ -7384,6 +7390,11 @@ void LaunchNestedChildren( char **ppPrimaryChildArgv )
 
 	if ( g_bLaunchMangoapp )
 	{
+		char szMangoappMqName[ NAME_MAX ];
+		snprintf( szMangoappMqName, sizeof( szMangoappMqName ), "/gamescope-mangoapp-%d", getpid() );
+		setenv( "MANGOAPP_MQ_NAME", szMangoappMqName, 0 );
+		g_sMangoappMqName = getenv( "MANGOAPP_MQ_NAME" );
+
 		char *ppMangoappArgv[] = { (char *)"mangoapp", NULL };
 		gamescope::Process::SpawnProcessInWatchdog( ppMangoappArgv, true );
 	}