Launch elevated instances via shell:AppFolder

Fixes microsoft#14501

This uses `shell:AppsFolder` to launch elevated instances of the app via
`ShellExecuteEx` and `runas` in elevate-shim.exe. The app to launch is
discovered via the `GetCurrentApplicationUserModelId` API.

e.g. `shell:AppsFolder\WindowsTerminalDev_8wekyb3d8bbwe!App`

This will fallback to launching `WindowsTerminal.exe` if it fails to
discover the app user model id to launch.

This also fixes an innocuous bug in elevate-shim where the first
argument of WinMain was lost (e.g. `new-tab`).

src/cascadia/ElevateShim/elevate-shim.cpp

@@ -25,15 +25,64 @@
 // process can successfully elevate.
 
 #pragma warning(suppress : 26461) // we can't change the signature of wWinMain
-int __stdcall wWinMain(HINSTANCE, HINSTANCE, LPWSTR pCmdLine, int)
+int __stdcall wWinMain(HINSTANCE, HINSTANCE, LPWSTR, int)
 {
-    // All of the args passed to us (something like `new-tab -p {guid}`) are in
-    // pCmdLine
+    // This supports being invoked in two possible ways. See GH#14501
+    //
+    // #1 Invoke the AppX package using shell:AppsFolder\app!id. The callers passes
+    // the cmd as the first argument in the form of shell:AppsFolder\app!id. We parse
+    // this out of the command line as the cmd and pass the remainder as the cmdline
+    //      `shell:AppsFolder\WindowsTerminalDev_8wekyb3d8bbwe!App new-tab -p {guid}`
+    //
+    // #2 in this scenario we find and execute WindowsTerminal.exe and pass the
+    // cmdline args as-is.
+    //      `new-tab -p {guid}`
+    //
 
-    // Get the path to WindowsTerminal.exe, which should live next to us.
-    std::filesystem::path module{ wil::GetModuleFileNameW<std::wstring>(nullptr) };
-    // Swap elevate-shim.exe for WindowsTerminal.exe
-    module.replace_filename(L"WindowsTerminal.exe");
+    DebugBreak();
+
+    // The cmdline argument in WinMain is stripping the first argument.
+    // Using GetCommandLine() and __wargv instead.
+    int argc = __argc;
+    LPWSTR* argv = __wargv;
+    if (argv == nullptr)
+    {
+        OutputDebugString(L"elevate-shim: no arguments found, argv == nullptr");
+        LOG_LAST_ERROR_IF_NULL(argv);
+        return -1;
+    }
+    if (argc == 0)
+    {
+        OutputDebugString(L"elevate-shim: no arguments found, argc == 0");
+        return -1;
+    }
+
+    std::wstring cmdLine = GetCommandLine();
+    std::wstring cmd = {};
+    std::wstring args = {};
+
+    std::wstring arg0 = argv[0];
+    if (arg0.starts_with(L"shell:AppsFolder"))
+    {
+        // scenario #1
+        cmd = arg0;
+
+        // We don't want to reconstruct the args with proper quoting and escaping.
+        // Let's remove the first arg instead. This assumes it was not unescaped
+        // when processed to __wargv. We might leave a pair of empty quotes if it
+        // was quoted.
+        args = cmdLine.replace(cmdLine.find(arg0), arg0.length(), L"");
+    }
+    else
+    {
+        // scenario #2
+        // Get the path to WindowsTerminal.exe, which should live next to us.
+        std::filesystem::path module{ wil::GetModuleFileNameW<std::wstring>(nullptr) };
+        // Swap elevate-shim.exe for WindowsTerminal.exe
+        module.replace_filename(L"WindowsTerminal.exe");
+        cmd = module;
+        args = GetCommandLine(); // args as-is
+    }
 
     // Go!
 
@@ -46,8 +95,10 @@ int __stdcall wWinMain(HINSTANCE, HINSTANCE, LPWSTR pCmdLine, int)
     seInfo.cbSize = sizeof(seInfo);
     seInfo.fMask = SEE_MASK_DEFAULT;
     seInfo.lpVerb = L"runas"; // This asks the shell to elevate the process
-    seInfo.lpFile = module.c_str(); // This is `...\WindowsTerminal.exe`
-    seInfo.lpParameters = pCmdLine; // This is `new-tab -p {guid}`
+    seInfo.lpFile = cmd.c_str(); // This is `shell:AppsFolder\...` or `...\WindowsTerminal.exe`
+    seInfo.lpParameters = args.c_str(); // This is `new-tab -p {guid}`
     seInfo.nShow = SW_SHOWNORMAL;
     LOG_IF_WIN32_BOOL_FALSE(ShellExecuteExW(&seInfo));
+
+    return 0;
 }

src/cascadia/TerminalApp/AppLogic.cpp

@@ -11,6 +11,7 @@
 #include <LibraryResources.h>
 #include <WtExeUtils.h>
 #include <wil/token_helpers.h>
+#include <appmodel.h>
 
 #include "../../types/inc/utils.hpp"
 
@@ -219,6 +220,43 @@ namespace winrt::TerminalApp::implementation
         return _isUwp;
     }
 
+    // Method Description:
+    // - Called by _OpenElevatedWT to determine the app name to invoke with shell:AppFolder
+    // Arguments:
+    // - <none>
+    // Return Value:
+    // - Empty if inaccessible; an invocable shell appfolder path otherwise e.g. WindowsTerminalDev_8wekyb3d8bbwe!App
+    winrt::hstring AppLogic::GetApplicationUserModelId()
+    {
+        winrt::hstring _applicationUserModelId = {};
+        UINT32 length = 0;
+        LONG rc = GetCurrentApplicationUserModelId(&length, NULL);
+        switch (rc)
+        {
+        case ERROR_INSUFFICIENT_BUFFER:
+            break; // expected
+        case APPMODEL_ERROR_NO_PACKAGE:
+            return _applicationUserModelId;
+        default: // unexpected
+            return _applicationUserModelId;
+        }
+
+        wchar_t* packageId = new wchar_t[length];
+        if (packageId == nullptr)
+        {
+            return _applicationUserModelId; // doh
+        }
+
+        rc = GetCurrentApplicationUserModelId(&length, packageId);
+        if (rc != ERROR_SUCCESS)
+        {
+            return _applicationUserModelId;
+        }
+        _applicationUserModelId = packageId;
+        delete[] packageId;
+        return _applicationUserModelId;
+    }
+
     // Method Description:
     // - Called around the codebase to discover if Terminal is running elevated
     // Arguments:

src/cascadia/TerminalApp/AppLogic.h

@@ -64,6 +64,8 @@ namespace winrt::TerminalApp::implementation
         bool IsElevated() const noexcept;
         void ReloadSettings();
 
+        winrt::hstring GetApplicationUserModelId();
+
         [[nodiscard]] Microsoft::Terminal::Settings::Model::CascadiaSettings GetSettings() const noexcept;
 
         void Quit();

src/cascadia/TerminalApp/AppLogic.idl

@@ -50,6 +50,8 @@ namespace TerminalApp
         void RunAsUwp();
         Boolean IsElevated();
 
+        String GetApplicationUserModelId();
+
         Boolean HasCommandlineArguments();
         Boolean HasSettingsStartupActions();
         Int32 SetStartupCommandline(String[] commands);
@@ -68,7 +70,7 @@ namespace TerminalApp
 
         Boolean FocusMode { get; };
         Boolean Fullscreen { get; };
-        void Maximized(Boolean newMaximized); 
+        void Maximized(Boolean newMaximized);
         Boolean AlwaysOnTop { get; };
         Boolean AutoHideWindow { get; };
 

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -4114,9 +4114,22 @@ namespace winrt::TerminalApp::implementation
         std::filesystem::path exePath = wil::GetModuleFileNameW<std::wstring>(nullptr);
         exePath.replace_filename(L"elevate-shim.exe");
 
+        std::wstring shellCommand = {};
+
+        auto appUserModelId = ::winrt::Windows::UI::Xaml::Application::Current().as<::winrt::TerminalApp::App>().Logic().GetApplicationUserModelId();
+        if (appUserModelId.length() > 0)
+        {
+            // See GH#14501 for background. If you quote this string, you'll have
+            // to update elevate-shim to strip the quotes when constructing the arguments.
+            shellCommand = fmt::format(L"shell:AppsFolder\\{}", appUserModelId);
+        }
+        // else leave shellCommand empty; fallback to invoking WindowsTerminal.exe
+
         // Build the commandline to pass to wt for this set of NewTerminalArgs
+        // The shellCommand argument is used if we're using shell:AppsFolder to launch the app;
+        // else, leave it empty.
         auto cmdline{
-            fmt::format(L"new-tab {}", newTerminalArgs.ToCommandline().c_str())
+            fmt::format(L"{} new-tab {}", shellCommand, newTerminalArgs.ToCommandline().c_str())
         };
 
         wil::unique_process_information pi;