Consider splitting up WaylandBackend.cpp

src/Backends/wayland/CreateShmBuffer.cpp

@@ -0,0 +1,36 @@
+#include "Utils/Defer.h"
+#include "Utils/TempFiles.h"
+
+#include <cstdint>
+#include <cstring>
+#include <sys/mman.h>
+#include <unistd.h>
+
+namespace gamescope {
+
+int CreateShmBuffer(uint32_t uSize, void* pData) {
+	char szShmBufferPath[PATH_MAX];
+	int nFd = MakeTempFile(szShmBufferPath, k_szGamescopeTempShmTemplate);
+	if (nFd < 0)
+		return -1;
+
+	if (ftruncate(nFd, uSize) < 0) {
+		close(nFd);
+		return -1;
+	}
+
+	if (pData) {
+		void* pMappedData = mmap(nullptr, uSize, PROT_READ | PROT_WRITE, MAP_SHARED, nFd, 0);
+		if (pMappedData == MAP_FAILED) {
+			close(nFd);
+			return -1;
+		}
+		defer(munmap(pMappedData, uSize));
+
+		memcpy(pMappedData, pData, uSize);
+	}
+
+	return nFd;
+}
+
+} // namespace gamescope

src/Backends/wayland/CreateShmBuffer.hpp

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <cstdint>
+
+namespace gamescope {
+
+int CreateShmBuffer(uint32_t uSize, void* pData);
+
+}