LibIPC: Allow transporting a SharedCircularQueue over IPC

Author: https://github.com/kleinesfilmroellchen
Commit: https://github.com/SerenityOS/serenity/commit/fc7d231b00
Pull-request: https://github.com/SerenityOS/serenity/pull/12102
Issue: https://github.com/SerenityOS/serenity/issues/11882
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/bgianfo
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibIPC/Decoder.h

@@ -11,7 +11,10 @@
 #include <AK/NumericLimits.h>
 #include <AK/StdLibExtras.h>
 #include <AK/String.h>
+#include <AK/Try.h>
+#include <LibCore/SharedCircularQueue.h>
 #include <LibCore/Stream.h>
+#include <LibIPC/File.h>
 #include <LibIPC/Forward.h>
 #include <LibIPC/Message.h>
 
@@ -117,6 +120,18 @@ public:
         return {};
     }
 
+    template<typename T, size_t Size>
+    ErrorOr<void> decode(Core::SharedSingleProducerCircularQueue<T, Size>& queue)
+    {
+        // FIXME: We don't support decoding into valid queues.
+        VERIFY(!queue.is_valid());
+
+        IPC::File anon_file;
+        TRY(decode(anon_file));
+        queue = TRY((Core::SharedSingleProducerCircularQueue<T, Size>::try_create(anon_file.take_fd())));
+        return {};
+    }
+
     template<typename T>
     ErrorOr<void> decode(Optional<T>& optional)
     {

Userland/Libraries/LibIPC/Encoder.h

@@ -8,6 +8,7 @@
 
 #include <AK/Concepts.h>
 #include <AK/StdLibExtras.h>
+#include <LibCore/SharedCircularQueue.h>
 #include <LibIPC/Forward.h>
 #include <LibIPC/Message.h>
 
@@ -77,6 +78,13 @@ public:
         return *this;
     }
 
+    template<typename T, size_t Size>
+    Encoder& operator<<(Core::SharedSingleProducerCircularQueue<T, Size> const& queue)
+    {
+        *this << IPC::File(queue.fd());
+        return *this;
+    }
+
     template<Enum T>
     Encoder& operator<<(T const& enum_value)
     {