Move /src to /subprojects

This will facilitate breaking up Nix into multiple packages for each
component with Meson.

subprojects/libstore/worker-protocol-connection.hh

@@ -0,0 +1,171 @@
+#pragma once
+///@file
+
+#include "worker-protocol.hh"
+#include "store-api.hh"
+
+namespace nix {
+
+struct WorkerProto::BasicConnection
+{
+    /**
+     * Send with this.
+     */
+    FdSink to;
+
+    /**
+     * Receive with this.
+     */
+    FdSource from;
+
+    /**
+     * The protocol version agreed by both sides.
+     */
+    WorkerProto::Version protoVersion;
+
+    /**
+     * The set of features that both sides support.
+     */
+    std::set<Feature> features;
+
+    /**
+     * Coercion to `WorkerProto::ReadConn`. This makes it easy to use the
+     * factored out serve protocol serializers with a
+     * `LegacySSHStore::Connection`.
+     *
+     * The serve protocol connection types are unidirectional, unlike
+     * this type.
+     */
+    operator WorkerProto::ReadConn()
+    {
+        return WorkerProto::ReadConn{
+            .from = from,
+            .version = protoVersion,
+        };
+    }
+
+    /**
+     * Coercion to `WorkerProto::WriteConn`. This makes it easy to use the
+     * factored out serve protocol serializers with a
+     * `LegacySSHStore::Connection`.
+     *
+     * The serve protocol connection types are unidirectional, unlike
+     * this type.
+     */
+    operator WorkerProto::WriteConn()
+    {
+        return WorkerProto::WriteConn{
+            .to = to,
+            .version = protoVersion,
+        };
+    }
+};
+
+struct WorkerProto::BasicClientConnection : WorkerProto::BasicConnection
+{
+    /**
+     * Flush to direction
+     */
+    virtual ~BasicClientConnection();
+
+    virtual void closeWrite() = 0;
+
+    std::exception_ptr processStderrReturn(Sink * sink = 0, Source * source = 0, bool flush = true, bool block = true);
+
+    void
+    processStderr(bool * daemonException, Sink * sink = 0, Source * source = 0, bool flush = true, bool block = true);
+
+    /**
+     * Establishes connection, negotiating version.
+     *
+     * @return the minimum version supported by both sides and the set
+     * of protocol features supported by both sides.
+     *
+     * @param to Taken by reference to allow for various error handling
+     * mechanisms.
+     *
+     * @param from Taken by reference to allow for various error
+     * handling mechanisms.
+     *
+     * @param localVersion Our version which is sent over
+     *
+     * @param features The protocol features that we support
+     */
+    // FIXME: this should probably be a constructor.
+    static std::tuple<Version, std::set<Feature>> handshake(
+        BufferedSink & to,
+        Source & from,
+        WorkerProto::Version localVersion,
+        const std::set<Feature> & supportedFeatures);
+
+    /**
+     * After calling handshake, must call this to exchange some basic
+     * information abou the connection.
+     */
+    ClientHandshakeInfo postHandshake(const StoreDirConfig & store);
+
+    void addTempRoot(const StoreDirConfig & remoteStore, bool * daemonException, const StorePath & path);
+
+    StorePathSet queryValidPaths(
+        const StoreDirConfig & remoteStore,
+        bool * daemonException,
+        const StorePathSet & paths,
+        SubstituteFlag maybeSubstitute);
+
+    UnkeyedValidPathInfo queryPathInfo(const StoreDirConfig & store, bool * daemonException, const StorePath & path);
+
+    void putBuildDerivationRequest(
+        const StoreDirConfig & store,
+        bool * daemonException,
+        const StorePath & drvPath,
+        const BasicDerivation & drv,
+        BuildMode buildMode);
+
+    /**
+     * Get the response, must be paired with
+     * `putBuildDerivationRequest`.
+     */
+    BuildResult getBuildDerivationResponse(const StoreDirConfig & store, bool * daemonException);
+
+    void narFromPath(
+        const StoreDirConfig & store,
+        bool * daemonException,
+        const StorePath & path,
+        std::function<void(Source &)> fun);
+
+    void importPaths(const StoreDirConfig & store, bool * daemonException, Source & source);
+};
+
+struct WorkerProto::BasicServerConnection : WorkerProto::BasicConnection
+{
+    /**
+     * Establishes connection, negotiating version.
+     *
+     * @return the version provided by the other side of the
+     * connection.
+     *
+     * @param to Taken by reference to allow for various error handling
+     * mechanisms.
+     *
+     * @param from Taken by reference to allow for various error
+     * handling mechanisms.
+     *
+     * @param localVersion Our version which is sent over
+     *
+     * @param features The protocol features that we support
+     */
+    // FIXME: this should probably be a constructor.
+    static std::tuple<Version, std::set<Feature>> handshake(
+        BufferedSink & to,
+        Source & from,
+        WorkerProto::Version localVersion,
+        const std::set<Feature> & supportedFeatures);
+
+    /**
+     * After calling handshake, must call this to exchange some basic
+     * information abou the connection.
+     */
+    void postHandshake(const StoreDirConfig & store, const ClientHandshakeInfo & info);
+};
+
+}