multiprocess: Add Ipc interface implementation

1 files changed, 61 insertions, 0 deletions

diff --git a/src/ipc/process.cpp b/src/ipc/process.cpp
new file mode 100644
index 0000000000..43ed1f1bae
--- /dev/null
+++ b/src/ipc/process.cpp
@@ -0,0 +1,61 @@
+// Copyright (c) 2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <fs.h>
+#include <ipc/process.h>
+#include <ipc/protocol.h>
+#include <mp/util.h>
+#include <tinyformat.h>
+#include <util/strencodings.h>
+
+#include <cstdint>
+#include <exception>
+#include <iostream>
+#include <stdexcept>
+#include <stdlib.h>
+#include <string.h>
+#include <system_error>
+#include <unistd.h>
+#include <utility>
+#include <vector>
+
+namespace ipc {
+namespace {
+class ProcessImpl : public Process
+{
+public:
+    int spawn(const std::string& new_exe_name, const fs::path& argv0_path, int& pid) override
+    {
+        return mp::SpawnProcess(pid, [&](int fd) {
+            fs::path path = argv0_path;
+            path.remove_filename();
+            path.append(new_exe_name);
+            return std::vector<std::string>{path.string(), "-ipcfd", strprintf("%i", fd)};
+        });
+    }
+    int waitSpawned(int pid) override { return mp::WaitProcess(pid); }
+    bool checkSpawned(int argc, char* argv[], int& fd) override
+    {
+        // If this process was not started with a single -ipcfd argument, it is
+        // not a process spawned by the spawn() call above, so return false and
+        // do not try to serve requests.
+        if (argc != 3 || strcmp(argv[1], "-ipcfd") != 0) {
+            return false;
+        }
+        // If a single -ipcfd argument was provided, return true and get the
+        // file descriptor so Protocol::serve() can be called to handle
+        // requests from the parent process. The -ipcfd argument is not valid
+        // in combination with other arguments because the parent process
+        // should be able to control the child process through the IPC protocol
+        // without passing information out of band.
+        if (!ParseInt32(argv[2], &fd)) {
+            throw std::runtime_error(strprintf("Invalid -ipcfd number '%s'", argv[2]));
+        }
+        return true;
+    }
+};
+} // namespace
+
+std::unique_ptr<Process> MakeProcess() { return std::make_unique<ProcessImpl>(); }
+} // namespace ipc