Kernel: Split the Plan9FileSystem.{cpp,h} file into smaller components

Kernel/FileSystem/Plan9FS/Message.h

@@ -0,0 +1,189 @@
+/*
+ * Copyright (c) 2020, Sergey Bugaev <bugaevc@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <Kernel/FileSystem/Plan9FS/Definitions.h>
+#include <Kernel/KBuffer.h>
+#include <Kernel/KBufferBuilder.h>
+
+namespace Kernel {
+
+class Plan9FS;
+class Plan9FSInode;
+
+class Plan9FSMessage {
+    friend class Plan9FS;
+    friend class Plan9FSInode;
+
+public:
+    enum class Type : u8 {
+        // 9P2000.L
+        Tlerror = 6,
+        Rlerror = 7,
+        Tstatfs = 8,
+        Rstatfs = 9,
+
+        Tlopen = 12,
+        Rlopen = 13,
+        Tlcreate = 14,
+        Rlcreate = 15,
+        Tsymlink = 16,
+        Rsymlink = 17,
+        Tmknod = 18,
+        Rmknod = 19,
+        Trename = 20,
+        Rrename = 21,
+        Treadlink = 22,
+        Rreadlink = 23,
+        Tgetattr = 24,
+        Rgetattr = 25,
+        Tsetattr = 26,
+        Rsetattr = 27,
+
+        Txattrwalk = 30,
+        Rxattrwalk = 31,
+        Txattrcreate = 32,
+        Rxattrcreate = 33,
+
+        Treaddir = 40,
+        Rreaddir = 41,
+
+        Tfsync = 50,
+        Rfsync = 51,
+        Tlock = 52,
+        Rlock = 53,
+        Tgetlock = 54,
+        Rgetlock = 55,
+
+        Tlink = 70,
+        Rlink = 71,
+        Tmkdir = 72,
+        Rmkdir = 73,
+        Trenameat = 74,
+        Rrenameat = 75,
+        Tunlinkat = 76,
+        Runlinkat = 77,
+
+        // 9P2000
+        Tversion = 100,
+        Rversion = 101,
+        Tauth = 102,
+        Rauth = 103,
+        Tattach = 104,
+        Rattach = 105,
+        Terror = 106,
+        Rerror = 107,
+        Tflush = 108,
+        Rflush = 109,
+        Twalk = 110,
+        Rwalk = 111,
+        Topen = 112,
+        Ropen = 113,
+        Tcreate = 114,
+        Rcreate = 115,
+        Tread = 116,
+        Rread = 117,
+        Twrite = 118,
+        Rwrite = 119,
+        Tclunk = 120,
+        Rclunk = 121,
+        Tremove = 122,
+        Rremove = 123,
+        Tstat = 124,
+        Rstat = 125,
+        Twstat = 126,
+        Rwstat = 127
+    };
+
+    class Decoder {
+    public:
+        explicit Decoder(StringView data)
+            : m_data(data)
+        {
+        }
+
+        Decoder& operator>>(u8&);
+        Decoder& operator>>(u16&);
+        Decoder& operator>>(u32&);
+        Decoder& operator>>(u64&);
+        Decoder& operator>>(StringView&);
+        Decoder& operator>>(Plan9FSQIdentifier&);
+        StringView read_data();
+
+        bool has_more_data() const { return !m_data.is_empty(); }
+
+    private:
+        StringView m_data;
+
+        template<typename N>
+        Decoder& read_number(N& number)
+        {
+            VERIFY(sizeof(number) <= m_data.length());
+            memcpy(&number, m_data.characters_without_null_termination(), sizeof(number));
+            m_data = m_data.substring_view(sizeof(number), m_data.length() - sizeof(number));
+            return *this;
+        }
+    };
+
+    Plan9FSMessage& operator<<(u8);
+    Plan9FSMessage& operator<<(u16);
+    Plan9FSMessage& operator<<(u32);
+    Plan9FSMessage& operator<<(u64);
+    Plan9FSMessage& operator<<(StringView);
+    void append_data(StringView);
+
+    template<typename T>
+    Plan9FSMessage& operator>>(T& t)
+    {
+        VERIFY(m_have_been_built);
+        m_built.decoder >> t;
+        return *this;
+    }
+
+    StringView read_data()
+    {
+        VERIFY(m_have_been_built);
+        return m_built.decoder.read_data();
+    }
+
+    Type type() const { return m_type; }
+    u16 tag() const { return m_tag; }
+
+    Plan9FSMessage(Plan9FS&, Type);
+    Plan9FSMessage(NonnullOwnPtr<KBuffer>&&);
+    ~Plan9FSMessage();
+    Plan9FSMessage& operator=(Plan9FSMessage&&);
+
+    KBuffer const& build();
+
+    static constexpr size_t max_header_size = 24;
+
+private:
+    template<typename N>
+    Plan9FSMessage& append_number(N number)
+    {
+        VERIFY(!m_have_been_built);
+        // FIXME: Handle append failure.
+        (void)m_builder.append(reinterpret_cast<char const*>(&number), sizeof(number));
+        return *this;
+    }
+
+    union {
+        KBufferBuilder m_builder;
+        struct {
+            NonnullOwnPtr<KBuffer> buffer;
+            Decoder decoder;
+        } m_built;
+    };
+
+    u16 m_tag { 0 };
+    Type m_type { 0 };
+    bool m_have_been_built { false };
+};
+
+}