1 files changed, 127 insertions, 0 deletions
diff --git a/include/libcamera/internal/shared_mem_object.h b/include/libcamera/internal/shared_mem_object.h
new file mode 100644
index 00000000..9b1d9393
--- /dev/null
+++ b/include/libcamera/internal/shared_mem_object.h
@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2023 Raspberry Pi Ltd
+ * Copyright (C) 2024 Andrei Konovalov
+ * Copyright (C) 2024 Dennis Bonke
+ *
+ * shared_mem_object.h - Helpers for shared memory allocations
+ */
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string>
+#include <sys/mman.h>
+#include <type_traits>
+#include <utility>
+
+#include <libcamera/base/class.h>
+#include <libcamera/base/shared_fd.h>
+#include <libcamera/base/span.h>
+
+namespace libcamera {
+
+class SharedMem
+{
+public:
+	SharedMem();
+
+	SharedMem(const std::string &name, std::size_t size);
+	SharedMem(SharedMem &&rhs);
+
+	virtual ~SharedMem();
+
+	SharedMem &operator=(SharedMem &&rhs);
+
+	const SharedFD &fd() const
+	{
+		return fd_;
+	}
+
+	Span<uint8_t> mem() const
+	{
+		return mem_;
+	}
+
+	explicit operator bool() const
+	{
+		return !mem_.empty();
+	}
+
+private:
+	LIBCAMERA_DISABLE_COPY(SharedMem)
+
+	SharedFD fd_;
+
+	Span<uint8_t> mem_;
+};
+
+template<class T, typename = std::enable_if_t<std::is_standard_layout<T>::value>>
+class SharedMemObject : public SharedMem
+{
+public:
+	static constexpr std::size_t kSize = sizeof(T);
+
+	SharedMemObject()
+		: SharedMem(), obj_(nullptr)
+	{
+	}
+
+	template<class... Args>
+	SharedMemObject(const std::string &name, Args &&...args)
+		: SharedMem(name, kSize), obj_(nullptr)
+	{
+		if (mem().empty())
+			return;
+
+		obj_ = new (mem().data()) T(std::forward<Args>(args)...);
+	}
+
+	SharedMemObject(SharedMemObject<T> &&rhs)
+		: SharedMem(std::move(rhs))
+	{
+		this->obj_ = rhs.obj_;
+		rhs.obj_ = nullptr;
+	}
+
+	~SharedMemObject()
+	{
+		if (obj_)
+			obj_->~T();
+	}
+
+	SharedMemObject<T> &operator=(SharedMemObject<T> &&rhs)
+	{
+		SharedMem::operator=(std::move(rhs));
+		this->obj_ = rhs.obj_;
+		rhs.obj_ = nullptr;
+		return *this;
+	}
+
+	T *operator->()
+	{
+		return obj_;
+	}
+
+	const T *operator->() const
+	{
+		return obj_;
+	}
+
+	T &operator*()
+	{
+		return *obj_;
+	}
+
+	const T &operator*() const
+	{
+		return *obj_;
+	}
+
+private:
+	LIBCAMERA_DISABLE_COPY(SharedMemObject)
+
+	T *obj_;
+};
+
+} /* namespace libcamera */