Suppress MSI-initiated reboots during Store updates

When the WSL MSIX package is updated via the Microsoft Store, the
WslInstaller service automatically upgrades the MSI package by calling
MsiInstallProduct. This call was made with INSTALLUILEVEL_NONE (silent
install) but without setting the REBOOT=ReallySuppress property.

Per Windows Installer documentation, when a silent install encounters
files in use and REBOOT is not suppressed, the system reboots
automatically without any user prompt. This could cause unexpected
machine restarts after a Store update when WSL binaries (e.g.
wslservice.exe) were in use during the upgrade.

Every deployment script in the repo already passes /norestart to
msiexec (deploy-to-host.ps1, deploy-to-vm.ps1, install-latest-wsl.ps1,
test-setup.ps1), but the programmatic MsiInstallProduct path used by
the WslInstaller service lacked the equivalent property.

This change:
- Always appends REBOOT=ReallySuppress to MsiInstallProduct arguments
  in UpgradeViaMsi, preventing Windows Installer from ever initiating
  a system restart during install/upgrade.
- Switches UninstallViaMsi from MsiConfigureProduct to
  MsiConfigureProductEx so we can pass REBOOT=ReallySuppress during
  uninstall as well.
- Propagates ERROR_SUCCESS_REBOOT_REQUIRED (3010) to callers instead
  of swallowing it. User-facing paths (wsl --update, wsl --uninstall)
  print a reboot-needed message to stderr. The background WslInstaller
  service silently treats 3010 as success since it has no console.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Ben Hillis

src/windows/common/WslClient.cpp

@@ -1277,7 +1277,11 @@ int Uninstall()
 
     const auto exitCode = wsl::windows::common::install::UninstallViaMsi(logFile.c_str(), &wsl::windows::common::install::MsiMessageCallback);
 
-    if (exitCode != 0)
+    if (exitCode == ERROR_SUCCESS_REBOOT_REQUIRED)
+    {
+        wsl::windows::common::wslutil::PrintSystemError(ERROR_SUCCESS_REBOOT_REQUIRED);
+    }
+    else if (exitCode != 0)
     {
         clearLogs.release();
         THROW_HR_WITH_USER_ERROR(

src/windows/common/install.cpp

@@ -104,7 +104,11 @@ int UpdatePackageImpl(bool preRelease, bool repair)
 
         const auto exitCode = UpgradeViaMsi(downloadPath.c_str(), L"", logFile.c_str(), &MsiMessageCallback);
 
-        if (exitCode != 0)
+        if (exitCode == ERROR_SUCCESS_REBOOT_REQUIRED)
+        {
+            PrintSystemError(ERROR_SUCCESS_REBOOT_REQUIRED);
+        }
+        else if (exitCode != 0)
         {
             clearLogs.release();
             THROW_HR_WITH_USER_ERROR(
@@ -358,15 +362,20 @@ int wsl::windows::common::install::UpdatePackage(bool PreRelease, bool Repair)
 UINT wsl::windows::common::install::UpgradeViaMsi(
     _In_ LPCWSTR PackageLocation, _In_opt_ LPCWSTR ExtraArgs, _In_opt_ LPCWSTR LogFile, _In_ const std::function<void(INSTALLMESSAGE, LPCWSTR)>& Callback)
 {
-    WriteInstallLog(std::format("Upgrading via MSI package: {}. Args: {}", PackageLocation, ExtraArgs != nullptr ? ExtraArgs : L""));
+    // Always suppress MSI-initiated reboots. With INSTALLUILEVEL_NONE, Windows Installer
+    // will silently reboot the machine if files are in use and REBOOT is not suppressed.
+    std::wstring args = L"REBOOT=ReallySuppress";
+    if (ExtraArgs != nullptr && *ExtraArgs != L'\0')
+    {
+        args = std::wstring(ExtraArgs) + L" " + args;
+    }
+
+    WriteInstallLog(std::format("Upgrading via MSI package: {}. Args: {}", PackageLocation, args));
 
     ConfigureMsiLogging(LogFile, Callback);
 
-    auto result = MsiInstallProduct(PackageLocation, ExtraArgs);
-    WSL_LOG(
-        "MsiInstallResult",
-        TraceLoggingValue(result, "result"),
-        TraceLoggingValue(ExtraArgs != nullptr ? ExtraArgs : L"", "ExtraArgs"));
+    auto result = MsiInstallProduct(PackageLocation, args.c_str());
+    WSL_LOG("MsiInstallResult", TraceLoggingValue(result, "result"), TraceLoggingValue(args.c_str(), "ExtraArgs"));
 
     WriteInstallLog(std::format("MSI upgrade result: {}", result));
 
@@ -382,7 +391,7 @@ UINT wsl::windows::common::install::UninstallViaMsi(_In_opt_ LPCWSTR LogFile, _I
 
     ConfigureMsiLogging(LogFile, Callback);
 
-    auto result = MsiConfigureProduct(productCode.c_str(), 0, INSTALLSTATE_ABSENT);
+    auto result = MsiConfigureProductEx(productCode.c_str(), 0, INSTALLSTATE_ABSENT, L"REBOOT=ReallySuppress");
     WSL_LOG("MsiUninstallResult", TraceLoggingValue(result, "result"));
 
     WriteInstallLog(std::format("MSI package uninstall result: {}", result));

src/windows/wslinstaller/exe/WslInstaller.cpp

@@ -79,7 +79,20 @@ std::pair<UINT, std::wstring> InstallMsipackageImpl()
     auto result = wsl::windows::common::install::UpgradeViaMsi(
         GetMsiPackagePath().c_str(), L"SKIPMSIX=1", logFile.has_value() ? logFile->c_str() : nullptr, messageCallback);
 
-    WSL_LOG("MSIUpgradeResult", TraceLoggingValue(result, "result"), TraceLoggingValue(errors.c_str(), "errorMessage"));
+    // ERROR_SUCCESS_REBOOT_REQUIRED (3010) means the install succeeded but some files
+    // will be replaced on the next reboot. Treat as success since the service runs
+    // silently with no user-facing console.
+    const bool rebootRequired = (result == ERROR_SUCCESS_REBOOT_REQUIRED);
+    if (rebootRequired)
+    {
+        result = ERROR_SUCCESS;
+    }
+
+    WSL_LOG(
+        "MSIUpgradeResult",
+        TraceLoggingValue(result, "result"),
+        TraceLoggingValue(rebootRequired, "rebootRequired"),
+        TraceLoggingValue(errors.c_str(), "errorMessage"));
 
     return {result, errors};
 }