Implement Snap and Flathub compatibility on Linux

Author: ungive

src/connection_unix.cpp

@@ -26,6 +26,14 @@ static int MsgFlags = MSG_NOSIGNAL;
 static int MsgFlags = 0;
 #endif
 
+// Directories where the discord-ipc socket might live
+// https://github.com/flathub/com.discordapp.Discord/wiki/Rich-Precense-(discord-rpc)
+static const char* DiscordIpcSocketDirs[] = {
+  "",                           // Default
+  "snap.discord",               // https://snapcraft.io/discord
+  "app/com.discordapp.Discord", // https://flathub.org/apps/com.discordapp.Discord
+};
+
 static const char* GetTempPath()
 {
     const char* temp = getenv("XDG_RUNTIME_DIR");
@@ -63,13 +71,21 @@ bool BaseConnection::Open()
     setsockopt(self->sock, SOL_SOCKET, SO_NOSIGPIPE, &optval, sizeof(optval));
 #endif
 
-    for (int pipeNum = 0; pipeNum < 10; ++pipeNum) {
-        snprintf(
-          PipeAddr.sun_path, sizeof(PipeAddr.sun_path), "%s/discord-ipc-%d", tempPath, pipeNum);
-        int err = connect(self->sock, (const sockaddr*)&PipeAddr, sizeof(PipeAddr));
-        if (err == 0) {
-            self->isOpen = true;
-            return true;
+    for (const char* dir : DiscordIpcSocketDirs) {
+        const char* dir_prefix = dir ? "/" : "";
+        for (int pipeNum = 0; pipeNum < 10; ++pipeNum) {
+            snprintf(PipeAddr.sun_path,
+                     sizeof(PipeAddr.sun_path),
+                     "%s%s%s/discord-ipc-%d",
+                     tempPath,
+                     dir_prefix,
+                     dir,
+                     pipeNum);
+            int err = connect(self->sock, (const sockaddr*)&PipeAddr, sizeof(PipeAddr));
+            if (err == 0) {
+                self->isOpen = true;
+                return true;
+            }
         }
     }
     self->Close();