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These are currently empty structs but they will be used to pass some function and object pointers from bitcoin application code to IPC hooks that run, for example, when a remote object is created or destroyed, or a new process is created.
78 lines
3.4 KiB
C++
78 lines
3.4 KiB
C++
// Copyright (c) 2021 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_INTERFACES_IPC_H
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#define BITCOIN_INTERFACES_IPC_H
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#include <functional>
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#include <memory>
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#include <typeindex>
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namespace ipc {
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struct Context;
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} // namespace ipc
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namespace interfaces {
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class Init;
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//! Interface providing access to interprocess-communication (IPC)
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//! functionality. The IPC implementation is responsible for establishing
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//! connections between a controlling process and a process being controlled.
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//! When a connection is established, the process being controlled returns an
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//! interfaces::Init pointer to the controlling process, which the controlling
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//! process can use to get access to other interfaces and functionality.
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//!
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//! When spawning a new process, the steps are:
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//!
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//! 1. The controlling process calls interfaces::Ipc::spawnProcess(), which
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//! calls ipc::Process::spawn(), which spawns a new process and returns a
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//! socketpair file descriptor for communicating with it.
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//! interfaces::Ipc::spawnProcess() then calls ipc::Protocol::connect()
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//! passing the socketpair descriptor, which returns a local proxy
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//! interfaces::Init implementation calling remote interfaces::Init methods.
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//! 2. The spawned process calls interfaces::Ipc::startSpawnProcess(), which
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//! calls ipc::Process::checkSpawned() to read command line arguments and
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//! determine whether it is a spawned process and what socketpair file
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//! descriptor it should use. It then calls ipc::Protocol::serve() to handle
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//! incoming requests from the socketpair and invoke interfaces::Init
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//! interface methods, and exit when the socket is closed.
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//! 3. The controlling process calls local proxy interfaces::Init object methods
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//! to make other proxy objects calling other remote interfaces. It can also
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//! destroy the initial interfaces::Init object to close the connection and
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//! shut down the spawned process.
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class Ipc
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{
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public:
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virtual ~Ipc() = default;
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//! Spawn a child process returning pointer to its Init interface.
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virtual std::unique_ptr<Init> spawnProcess(const char* exe_name) = 0;
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//! If this is a spawned process, block and handle requests from the parent
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//! process by forwarding them to this process's Init interface, then return
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//! true. If this is not a spawned child process, return false.
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virtual bool startSpawnedProcess(int argc, char* argv[], int& exit_status) = 0;
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//! Add cleanup callback to remote interface that will run when the
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//! interface is deleted.
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template<typename Interface>
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void addCleanup(Interface& iface, std::function<void()> cleanup)
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{
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addCleanup(typeid(Interface), &iface, std::move(cleanup));
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}
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//! IPC context struct accessor (see struct definition for more description).
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virtual ipc::Context& context() = 0;
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protected:
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//! Internal implementation of public addCleanup method (above) as a
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//! type-erased virtual function, since template functions can't be virtual.
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virtual void addCleanup(std::type_index type, void* iface, std::function<void()> cleanup) = 0;
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};
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//! Return implementation of Ipc interface.
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std::unique_ptr<Ipc> MakeIpc(const char* exe_name, const char* process_argv0, Init& init);
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} // namespace interfaces
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#endif // BITCOIN_INTERFACES_IPC_H
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