Common: Add a PCAP writer module

Source/Core/Common/PcapFile.h

@@ -0,0 +1,44 @@
+// Copyright 2014 Dolphin Emulator Project
+// Licensed under GPLv2
+// Refer to the license.txt file included.
+
+// PCAP is a standard file format for network capture files. This also extends
+// to any capture of packetized intercommunication data. This file provides a
+// class called PCAP which is a very light wrapper around the file format,
+// allowing only creating a new PCAP capture file and appending packets to it.
+//
+// Example use:
+//   PCAP pcap(new IOFile("test.pcap", "wb"));
+//   pcap.AddPacket(pkt);  // pkt is automatically casted to u8*
+
+#pragma once
+
+#include <cstddef>
+#include <memory>
+
+#include "Common/CommonTypes.h"
+#include "Common/FileUtil.h"
+
+class PCAP final : public NonCopyable
+{
+public:
+	// Takes ownership of the file object. Assumes the file object is already
+	// opened in write mode.
+	explicit PCAP(File::IOFile* fp) : m_fp(fp)
+	{
+		AddHeader();
+	}
+
+	template <typename T>
+	void AddPacket(const T& obj)
+	{
+		AddPacket(reinterpret_cast<const u8*>(&obj), sizeof (obj));
+	}
+
+	void AddPacket(const u8* bytes, size_t size);
+
+private:
+	void AddHeader();
+
+	std::unique_ptr<File::IOFile> m_fp;
+};