Add support for terminal handoff

binding.gyp

@@ -21,7 +21,11 @@
               'AdditionalOptions': [
                 '/guard:cf'
               ]
-            }
+            },
+            'VCMIDLTool': {
+              'OutputDirectory': '<(INTERMEDIATE_DIR)',
+              'HeaderFileName': '<(RULE_INPUT_ROOT).h',
+            },
           },
       }],
     ],
@@ -33,7 +37,13 @@
           'target_name': 'conpty',
           'sources' : [
             'src/win/conpty.cc',
-            'src/win/path_util.cc'
+            'src/win/path_util.cc',
+            'src/win/ITerminalHandoff.idl'
+          ],
+          'include_dirs' : [
+            'deps/wil/include',
+            # To allow including "ITerminalHandoff.h"
+            '<(INTERMEDIATE_DIR)',
           ],
           'libraries': [
             'shlwapi.lib'

src/win/ITerminalHandoff.idl

@@ -0,0 +1,82 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+import "unknwn.idl";
+
+typedef struct _TERMINAL_STARTUP_INFO
+{
+    // In STARTUPINFO
+    BSTR pszTitle;
+
+    // Also wanted
+    BSTR pszIconPath;
+    LONG iconIndex;
+
+    // The rest of STARTUPINFO
+    DWORD dwX;
+    DWORD dwY;
+    DWORD dwXSize;
+    DWORD dwYSize;
+    DWORD dwXCountChars;
+    DWORD dwYCountChars;
+    DWORD dwFillAttribute;
+    DWORD dwFlags;
+    WORD wShowWindow;
+} TERMINAL_STARTUP_INFO;
+
+// LOAD BEARING!
+//
+// There is only ever one OpenConsoleProxy.dll loaded by COM for _ALL_ terminal
+// instances, across Dev, Preview, Stable, whatever. So we have to keep all old
+// versions of interfaces in the file here, even if the old version is no longer
+// in use.
+
+// This was the original prototype. The reasons for changes to it are explained below.
+[
+    object,
+    uuid(59D55CCE-FC8A-48B4-ACE8-0A9286C6557F)
+] interface ITerminalHandoff : IUnknown
+{
+    // DEPRECATED!
+    HRESULT EstablishPtyHandoff([in, system_handle(sh_pipe)] HANDLE in,
+                                [in, system_handle(sh_pipe)] HANDLE out,
+                                [in, system_handle(sh_pipe)] HANDLE signal,
+                                [in, system_handle(sh_file)] HANDLE ref,
+                                [in, system_handle(sh_process)] HANDLE server,
+                                [in, system_handle(sh_process)] HANDLE client);
+};
+
+// We didn't consider the need for TERMINAL_STARTUP_INFO, because Windows Terminal never had support for launching
+// .lnk files in the first place. They aren't executables after all, but rather a shell thing.
+// Its need quickly became apparent right after releasing ITerminalHandoff, which is why it was very short-lived.
+[
+    object,
+    uuid(AA6B364F-4A50-4176-9002-0AE755E7B5EF)
+] interface ITerminalHandoff2 : IUnknown
+{
+    HRESULT EstablishPtyHandoff([in, system_handle(sh_pipe)] HANDLE in,
+                                [in, system_handle(sh_pipe)] HANDLE out,
+                                [in, system_handle(sh_pipe)] HANDLE signal,
+                                [in, system_handle(sh_file)] HANDLE ref,
+                                [in, system_handle(sh_process)] HANDLE server,
+                                [in, system_handle(sh_process)] HANDLE client,
+                                [in] TERMINAL_STARTUP_INFO startupInfo);
+};
+
+// Quite a while later, we realized that passing the in/out handles as [in] instead of [out] has always been flawed.
+// It prevents the terminal from making choices over the pipe buffer size and whether to use overlapped IO or not.
+// The other handles remain [in] parameters because they have always been created internally by ConPTY.
+// Additionally, passing TERMINAL_STARTUP_INFO by-value was unusual under COM as structs are usually given by-ref.
+[
+    object,
+    uuid(6F23DA90-15C5-4203-9DB0-64E73F1B1B00)
+] interface ITerminalHandoff3 : IUnknown
+{
+    HRESULT EstablishPtyHandoff([out, system_handle(sh_pipe)] HANDLE* in,
+                                [out, system_handle(sh_pipe)] HANDLE* out,
+                                [in, system_handle(sh_pipe)] HANDLE signal,
+                                [in, system_handle(sh_file)] HANDLE reference,
+                                [in, system_handle(sh_process)] HANDLE server,
+                                [in, system_handle(sh_process)] HANDLE client,
+                                [in] const TERMINAL_STARTUP_INFO* startupInfo);
+};

src/win/conpty.cc

@@ -21,6 +21,8 @@
 #include <vector>
 #include <Windows.h>
 #include <strsafe.h>
+#include <wrl.h>
+#include "ITerminalHandoff.h"
 #include "path_util.h"
 #include "conpty.h"
 
@@ -542,16 +544,71 @@ static Napi::Value PtyKill(const Napi::CallbackInfo& info) {
   return env.Undefined();
 }
 
+class TerminalHandoff
+  : public Microsoft::WRL::RuntimeClass<
+  Microsoft::WRL::RuntimeClassFlags<Microsoft::WRL::ClassicCom>,
+  ITerminalHandoff2>
+{
+public:
+  virtual HRESULT STDMETHODCALLTYPE EstablishPtyHandoff(
+    /* [system_handle][in] */ HANDLE in,
+    /* [system_handle][in] */ HANDLE out,
+    /* [system_handle][in] */ HANDLE signal,
+    /* [system_handle][in] */ HANDLE ref,
+    /* [system_handle][in] */ HANDLE server,
+    /* [system_handle][in] */ HANDLE client,
+    /* [in] */ TERMINAL_STARTUP_INFO startupInfo) override
+  {
+    MessageBoxW(nullptr, L"EstablishPtyHandoff", L"", 0);
+    return E_NOTIMPL;
+  }
+};
+
+static DWORD g_cTerminalHandoffRegistration = 0;
+
+static Napi::Value PtyRegisterHandoff(const Napi::CallbackInfo& info) {
+  Napi::Env env(info.Env());
+  Napi::HandleScope scope(env);
+
+  if (info.Length() != 2 ||
+    !info[0].IsString() ||
+    !info[1].IsFunction()) {
+    throw Napi::Error::New(env, "Usage: pty.registerHandoff(clsid, callback)");
+  }
+
+  const std::wstring clsidStr(path_util::to_wstring(info[0].As<Napi::String>()));
+  Napi::Function callback = info[1].As<Napi::Function>();
+
+  using namespace Microsoft::WRL;
+
+  const auto classFactory = Make<SimpleClassFactory<TerminalHandoff>>();
+
+  ComPtr<IUnknown> unk;
+  HRESULT hr = classFactory.As(&unk);
+
+  CLSID clsid;
+  hr = CLSIDFromString(clsidStr.c_str(), &clsid);
+
+  hr = CoRegisterClassObject(clsid, unk.Get(), CLSCTX_LOCAL_SERVER, REGCLS_MULTIPLEUSE, &g_cTerminalHandoffRegistration);
+
+  CoAddRefServerProcess();
+
+  return env.Undefined();
+}
+
 /**
 * Init
 */
 
 Napi::Object init(Napi::Env env, Napi::Object exports) {
+  MessageBoxW(nullptr, L"", L"", 0); // debug
+
   exports.Set("startProcess", Napi::Function::New(env, PtyStartProcess));
   exports.Set("connect", Napi::Function::New(env, PtyConnect));
   exports.Set("resize", Napi::Function::New(env, PtyResize));
   exports.Set("clear", Napi::Function::New(env, PtyClear));
   exports.Set("kill", Napi::Function::New(env, PtyKill));
+  exports.Set("registerHandoff", Napi::Function::New(env, PtyRegisterHandoff));
   return exports;
 };