G4.1: sandbox plugin host (plugin_host.exe) PoC — Nexus runs in child process, GUI + audio via SHM, crash isolation verified

2026-08-16 10:36:01 +07:00
parent 700f612674
commit 7de00955d8
4 changed files with 265 additions and 0 deletions
@@ -0,0 +1,133 @@
+// native_bridge/src/plugin_host_main.cpp - G4.1 sandbox VST3 host (child process).
+// Proof-of-concept (NOT shipped): runs ONE VST3 out-of-process. The plugin's
+// own crash can only kill this process, never the DAW/bridge. Audio + MIDI +
+// heartbeat travel over a child-owned SHM mapping reusing the SharedAudioBufferIPC
+// layout, so the bridge can later adopt the same struct without layout churn.
+//
+// argv: --shm <name> --path <vst3> [--sr <rate>] [--block <n>] [--parent <pid>]
+#include "Vst3Instrument.h"
+#include "SharedMemoryIPC.h"
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+#include <chrono>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <string>
+#include <thread>
+
+static bool parent_alive(uint32_t pid) {
+#ifdef _WIN32
+    HANDLE h = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE, pid);
+    if (!h) return false;
+    CloseHandle(h);
+    return true;
+#else
+    return pid == 0 || (kill(pid, 0) == 0);
+#endif
+}
+
+int main(int argc, char* argv[]) {
+    std::string shmName, path;
+    double sr = 44100.0;
+    uint32_t block = AUDIO_BLOCK_SIZE;
+    uint32_t parentPid = 0;
+    for (int i = 1; i < argc; ++i) {
+        if (strcmp(argv[i], "--shm") == 0 && i + 1 < argc) shmName = argv[++i];
+        else if (strcmp(argv[i], "--path") == 0 && i + 1 < argc) path = argv[++i];
+        else if (strcmp(argv[i], "--sr") == 0 && i + 1 < argc) sr = atof(argv[++i]);
+        else if (strcmp(argv[i], "--block") == 0 && i + 1 < argc) block = (uint32_t)atoi(argv[++i]);
+        else if (strcmp(argv[i], "--parent") == 0 && i + 1 < argc) parentPid = (uint32_t)strtoul(argv[++i], nullptr, 0);
+    }
+    if (shmName.empty() || path.empty()) {
+        printf("usage: plugin_host --shm <name> --path <vst3> [--sr rate] [--block n] [--parent pid]\n");
+        return 2;
+    }
+
+#ifdef _WIN32
+    CoInitializeEx(nullptr, COINIT_APARTMENTTHREADED);
+#endif
+    printf("[plugin_host] pid=%lu shm=%s path=%s sr=%.0f block=%u\n",
+           (unsigned long)GetCurrentProcessId(), shmName.c_str(), path.c_str(), sr, block);
+    fflush(stdout);
+
+    // PoC: the child owns the mapping. Bridge adoption (G4.2) opens instead.
+    ShmHandle* shm = shm_create(shmName.c_str());
+    if (!shm) {
+        printf("[plugin_host] FAILED shm_create %s\n", shmName.c_str());
+        return 3;
+    }
+    SharedAudioBufferIPC* ipc = shm_ptr(shm);
+
+    Vst3Instrument inst;
+    inst.init(sr, block);  // sets sampleRate_/maxBlockSize_ used by setupProcessing
+    if (!inst.loadPlugin(path, sr)) {
+        printf("[plugin_host] loadPlugin failed\n");
+        return 4;
+    }
+
+    // GUI on the main thread (editorhost pattern: attach then pump below).
+    HWND hwnd = nullptr;
+    {
+        WNDCLASSEX wc = {};
+        wc.cbSize = sizeof(wc);
+        wc.lpfnWndProc = DefWindowProc;
+        wc.hInstance = GetModuleHandle(nullptr);
+        wc.lpszClassName = "PluginHostClass";
+        RegisterClassEx(&wc);
+        hwnd = CreateWindowEx(0, "PluginHostClass", "PluginHost", WS_OVERLAPPEDWINDOW,
+                              0, 0, 800, 600, nullptr, nullptr, wc.hInstance, nullptr);
+    }
+    printf("[plugin_host] ownHwnd=%p openGUI...\n", (void*)hwnd);
+    fflush(stdout);
+    bool gui = inst.openGUI(hwnd);
+    printf("[plugin_host] openGUI=%d\n", gui ? 1 : 0);
+    fflush(stdout);
+
+    // Heartbeat ~10Hz, independent of the audio loop (G3.1 pattern).
+    std::thread([ipc]() {
+        for (;;) {
+            Sleep(100);
+            ipc->heartbeat++;
+        }
+    }).detach();
+
+    for (;;) {
+        MSG msg;
+        while (PeekMessageW(&msg, nullptr, 0, 0, PM_REMOVE)) {
+            TranslateMessage(&msg);
+            DispatchMessageW(&msg);
+        }
+        uint32_t n = ipc->midiQueueCount > 64 ? 64 : ipc->midiQueueCount;
+        for (uint32_t i = 0; i < n; ++i) {
+            const SharedAudioBufferIPC::MidiEventIPC& e = ipc->midiQueue[i];
+            switch (e.command) {
+                case 0x9:
+                    if (e.velocity > 0) inst.noteOn(e.channel, e.pitch, e.velocity / 127.0f, 0);
+                    else inst.noteOff(e.channel, e.pitch, 0);
+                    break;
+                case 0x8: inst.noteOff(e.channel, e.pitch, 0); break;
+                case 0xB: inst.controlChange(e.channel, e.pitch, e.data2); break;
+                case 0xC: inst.programChange(e.channel, e.data2); break;
+                case 0xE: inst.pitchBend(e.channel, e.data2 | (uint32_t(e.data3) << 7)); break;
+                default: break;
+            }
+        }
+        ipc->midiQueueCount = 0;
+        inst.processAudioBlock(ipc->masterLeft, ipc->masterRight, block);
+        ipc->bridgeWriteIndex++;
+        if (parentPid && !parent_alive(parentPid)) {
+            printf("[plugin_host] parent gone - exiting\n");
+            break;
+        }
+        Sleep(1);
+    }
+    inst.closeGUI();
+#ifdef _WIN32
+    CoUninitialize();
+#endif
+    shm_close(shm);
+    return 0;
+}