From e9a20e764f5f5e144673392eaf72e0631e36014a Mon Sep 17 00:00:00 2001
From: Colin Kinloch <colin.kinloch@collabora.com>
Date: Mon, 16 Dec 2024 11:43:26 +0000
Subject: [PATCH] mangoapp: Select unique SysV message queue

This allows multiple mangoapp instances to run on the same system.
---
 src/mangoapp.cpp     |  9 ++++++++-
 src/steamcompmgr.cpp | 27 +++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/mangoapp.cpp b/src/mangoapp.cpp
index 91e01bc275..7ff94b895b 100644
--- a/src/mangoapp.cpp
+++ b/src/mangoapp.cpp
@@ -11,6 +11,7 @@ static bool inited = false;
 static int msgid = 0;
 extern bool g_bAppWantsHDRCached;
 extern uint32_t g_focusedBaseAppId;
+extern int g_sMangoappMqId;
 
 struct mangoapp_msg_header {
     long msg_type;  // Message queue ID, never change
@@ -36,8 +37,11 @@ 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: Stop using message queues
+    key_t key = ftok("mangoapp", 65);
     msgid = msgget(key, 0666 | IPC_CREAT);
+
     mangoapp_msg_v1.hdr.msg_type = 1;
     mangoapp_msg_v1.hdr.version = 1;
     mangoapp_msg_v1.fsrUpscale = 0;
@@ -60,7 +64,10 @@ 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;
+
     msgsnd(msgid, &mangoapp_msg_v1, sizeof(mangoapp_msg_v1) - sizeof(mangoapp_msg_v1.hdr.msg_type), IPC_NOWAIT);
+    if (g_sMangoappMqId > 0)
+      msgsnd(g_sMangoappMqId, &mangoapp_msg_v1, sizeof(mangoapp_msg_v1) - sizeof(mangoapp_msg_v1.hdr.msg_type), IPC_NOWAIT);
 }
 
 extern uint64_t g_uCurrentBasePlaneCommitID;
diff --git a/src/steamcompmgr.cpp b/src/steamcompmgr.cpp
index 18be94d19c..7aadbf02cf 100644
--- a/src/steamcompmgr.cpp
+++ b/src/steamcompmgr.cpp
@@ -69,6 +69,7 @@
 #endif
 #include <sys/socket.h>
 #include <sys/resource.h>
+#include <sys/msg.h>
 #include <time.h>
 #include <unistd.h>
 #include <getopt.h>
@@ -164,6 +165,8 @@ uint32_t g_reshade_technique_idx = 0;
 bool g_bSteamIsActiveWindow = false;
 bool g_bForceInternal = false;
 
+int g_sMangoappMqId = -1;
+
 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_sMangoappMqId > 0 )
+		msgctl( g_sMangoappMqId, IPC_RMID, NULL);
+
 	// Clean up any commits.
 	{
 		gamescope_xwayland_server_t *server = NULL;
@@ -7390,6 +7396,27 @@ void LaunchNestedChildren( char **ppPrimaryChildArgv )
 
 	if ( g_bLaunchMangoapp )
 	{
+		char szMangoappMqKey[ NAME_MAX ];
+		// Attempt to find a fresh message queue id
+		for ( int i = 0; i < 255; i++ ) {
+			key_t key = ftok( ".", i );
+			int res = msgget( key, 0666 | IPC_CREAT | IPC_EXCL );
+			if ( res == -1 ) {
+				switch ( errno ) {
+					case EEXIST:
+						continue;
+					default:
+						break;
+				}
+			}
+
+			// Success
+			g_sMangoappMqId = res;
+			snprintf( szMangoappMqKey, sizeof( szMangoappMqKey ), "%d", key );
+			setenv( "MANGOAPP_MQ_KEY", szMangoappMqKey, 0 );
+			break;
+		}
+
 		char *ppMangoappArgv[] = { (char *)"mangoapp", NULL };
 		gamescope::Process::SpawnProcessInWatchdog( ppMangoappArgv, true );
 	}