Driver Installation Internals

PadForge v3 deals with three drivers/services and a legacy v2 cleanup path:

HIDMaestro is the user-mode UMDF2 driver that publishes every virtual gamepad except Keyboard+Mouse. It is not installed by DriverInstaller. The driver binaries, INF, profiles, and signing tools all ship inside HIDMaestro.Core.dll; HMContext.InstallDriver() (called from the engine on startup) registers them with Windows.
HidHide is the kernel-mode driver that hides physical controllers from games. Embedded as a WiX Burn bootstrapper EXE, install/uninstall via msiexec.
Windows MIDI Services is downloaded on demand from GitHub releases (the installer is ~210 MB, too large to embed) and run with /install /quiet /norestart.
Legacy v2 driver cleanup offers to uninstall ViGEmBus and vJoy on first v3 launch when either is detected. v2 used those two drivers as PadForge's virtual-controller backends. v3 replaces both with HIDMaestro.

Driver-side code lives in two files:

PadForge.App/Common/DriverInstaller.cs (PadForge.Common) handles HidHide + Windows MIDI Services install/uninstall, plus the legacy v2 ViGEmBus and vJoy uninstall paths.
PadForge.App/Common/Input/InputManager.Step5.VirtualDevices.cs owns EnsureHMaestroContext(), which calls into the HM SDK to register the HIDMaestro driver with Windows.

Architecture Overview

graph TD
    subgraph Engine["InputManager.Step5"]
        HM["EnsureHMaestroContext()<br/>HMContext.InstallDriver()"]
    end

    subgraph DriverInstaller["DriverInstaller (static class)"]
        direction TB
        HH["HidHide<br/>Embedded EXE bootstrapper"]
        MS["Windows MIDI Services<br/>GitHub releases API download"]
        LC["Legacy v2 cleanup<br/>(detect + uninstall ViGEmBus, vJoy if present)"]
    end

    HM -->|"InstallDriver() inside HIDMaestro.Core.dll"| HM_DRV["HIDMaestro UMDF2 driver<br/>(225+ profiles bundled in the SDK)"]
    HH -->|"embedded HidHide_1.5.230_x64.exe<br/>/extract -> msiexec /i HidHide.msi"| HH_DRV["HidHide kernel driver"]
    MS -->|"GitHub /releases -> SDK Runtime x64 EXE -> /install"| MS_SVC["Windows MIDI Services<br/>(Win11 24H2+)"]
    LC -.->|"msiexec /x ViGEm,<br/>cmd script for vJoy<br/>(pnputil /remove-device, sc, reg, rmdir)"| OLD["ViGEmBus / vJoy<br/>(only if detected)"]

    HM -.-> ELEV["PadForge process<br/>(elevated via app.manifest)"]
    HH -.-> ELEV
    MS -.-> ELEV
    LC -.-> ELEV

app.manifest declares <requestedExecutionLevel level="requireAdministrator" uiAccess="false"/>, so Windows shows the UAC shield on the icon and prompts once when the process starts. Every install/uninstall path runs inside the already-elevated process. There are no further UAC prompts mid-session.

The OpenXInput shim (xinput1_4.dll under Resources/OpenXInput/x64/) is not managed by DriverInstaller. It ships embedded inside PadForge.exe as a <Content> item bundled by IncludeNativeLibrariesForSelfExtract. App.xaml.cs calls SetDllDirectory on the single-file extract directory so the loader resolves PadForge's copy ahead of C:\Windows\System32\xinput1_4.dll. Nothing to install or uninstall, the shim is removed when you delete the PadForge folder.

devobj.dll is deliberately not shipped with the EXE. OpenXInput's source tree contains a stub devobj.dll (every export returns 0xCDCDCDCD) only to satisfy xinput1_4.dll's static-link import at compile time. Shipping it would let SetDllDirectory pre-empt C:\Windows\System32\devobj.dll for the entire process, including setupapi.dll's own DevObj* imports. setupapi then crashes during HID class enumeration. See PadForge #69. The system devobj.dll resolves from System32 unaided.

Embedded Resources

Resource	Type	Approximate size	Purpose
`HIDMaestro.Core.dll` (referenced via `HintPath`, not embedded)	Managed assembly	varies by version	HIDMaestro SDK and bundled UMDF2 driver. Loaded by the CLR; `HMContext.InstallDriver()` registers the driver with Windows on first engine start.
`Resources\HidHide_1.5.230_x64.exe`	EXE (WiX Burn bootstrapper)	~3 MB	HidHide kernel driver. Bundled MSI extracted and run silently.
`Resources\OpenXInput\x64\xinput1_4.dll`	DLL (Content)	~150 KB	OpenXInput shim. Not an installer. Bundled into the single-file EXE via `IncludeNativeLibrariesForSelfExtract` and loaded via `SetDllDirectory` on the extract directory at runtime.

Windows MIDI Services is not embedded. It is downloaded on demand from api.github.com/repos/microsoft/MIDI/releases (~210 MB). The download path is ephemeral. Nothing is bundled with PadForge.

Declared in PadForge.App.csproj:

<Reference Include="HIDMaestro.Core">
  <HintPath>Resources\HIDMaestro\HIDMaestro.Core.dll</HintPath>
</Reference>
<EmbeddedResource Include="Resources\HidHide_1.5.230_x64.exe" />
<Content Include="Resources\OpenXInput\x64\xinput1_4.dll" Link="xinput1_4.dll" />

HIDMaestro.Core.dll is a <Reference>, not a <ProjectReference>. Using a project reference would build from source and pull in unstable in-progress work from the HIDMaestro repo. Updates happen by copying the Release build of HIDMaestro.Core.dll from the HIDMaestro repo into Resources\HIDMaestro\ after a tag is cut there. PadForge currently ships HIDMaestro 1.3.12.

Shared Helpers

Private methods reused across HidHide and the MIDI Services flows.

Method	Signature	Behavior
`ExtractEmbeddedResource`	`(string resourceFileName, string tempDir)`	Finds resource via case-insensitive `IndexOf` on `GetManifestResourceNames()`, streams to `{tempDir}\{resourceFileName}`. Throws `FileNotFoundException` (listing all resource names) if not found.
`ExtractInstallerBundle`	`(string exePath, string tempDir)`	Runs the WiX bootstrapper with `/extract` to unpack its MSI into `{tempDir}\Extracted\`. Recreates the directory if it exists. 60s timeout.
`FindMsi`	`(string extractDir, string primaryName, string fallbackPattern)`	Searches recursively for an MSI: exact name first, then glob fallback. Throws `FileNotFoundException` if neither matches.
`RunElevated`	`(string fileName, string arguments)`	Launches a child process with `Verb = "runas"`, hidden window, 180s timeout. PadForge is already elevated via `app.manifest`, so Windows does not show a UAC prompt when launching the child. Used by HidHide install/uninstall and the legacy vJoy uninstall script.
`RunMsiElevated`	`(string arguments)`	Wrapper: `RunElevated("msiexec.exe", arguments)`.
`CleanupTempDir`	`(string tempDir)`	Recursive delete, swallows all exceptions. Called in `finally` blocks.
`FindUninstallProductCode`	`(string displayNameSubstring)`	Scans `HKLM\...\Uninstall` (Registry64 + Registry32) for a `DisplayName` containing the substring. Returns the subkey name (the MSI ProductCode GUID `{XXXXXXXX-...}`) or `null`. Used for ViGEmBus uninstall, where PadForge does not embed the MSI.

HIDMaestro

PadForge does not ship a separate HIDMaestro installer EXE or MSI, and DriverInstaller has no InstallHIDMaestro / UninstallHIDMaestro methods. The HM SDK assembly (HIDMaestro.Core.dll) bundles the UMDF2 driver binaries, INF, signing tools, and 225+ device profiles. Driver registration happens at engine-start time via the SDK.

EnsureHMaestroContext()

InputManager.Step5.VirtualDevices.cs owns the HM lifecycle:

private void EnsureHMaestroContext()
{
    if (_hmaestroContext != null || _hmaestroContextFailed) return;
    lock (_hmaestroContextLock)
    {
        if (_hmaestroContext != null || _hmaestroContextFailed) return;
        try
        {
            // Preflight: sweep leftover HM virtuals from prior sessions
            // (crash / forced kill / ungraceful exit). Without this,
            // InstallDriver's RemoveOldDriverPackages step fails with
            // "device using INF" because stale device nodes still
            // reference the old driver package.
            try { HMContext.RemoveAllVirtualControllers(); } catch { }

            var ctx = new HMContext();
            int n = ctx.LoadDefaultProfiles();
            ctx.InstallDriver();
            _hmaestroContext = ctx;
            // ... ProcessExit hook to purge VCs on ungraceful shutdown
        }
        catch (Exception ex)
        {
            _hmaestroContextFailed = true;
            RaiseError("Failed to initialize HIDMaestro.", ex);
        }
    }
}

InstallDriver() is idempotent and safe to call every Start(). Elevation is required, supplied by app.manifest.

Settings page surface

SettingsPage.xaml shows a fixed green "Installed" dot for HIDMaestro and the SDK assembly version (read once at startup):

private static string GetEmbeddedHidMaestroVersion()
{
    var asm = typeof(HIDMaestro.HMContext).Assembly;
    var v = asm.GetName().Version;
    return v != null ? $"v{v.Major}.{v.Minor}.{v.Build}" : string.Empty;
}

There are no Install or Uninstall buttons. The card is informational only because the SDK assembly is always present in the publish output. Comment in MainWindow.xaml.cs (line 1593) documents this:

// HIDMaestro is always available (embedded in HIDMaestro.Core.dll), so the
// Xbox / PlayStation / Extended categories are always enabled. MIDI still
// depends on Windows MIDI Services.

Cleanup

HMContext.RemoveAllVirtualControllers() is called in three places:

Site	When	Purpose
`EnsureHMaestroContext` preflight	Before each `InstallDriver()`	Purge stragglers from a prior crash so the install can succeed.
`ProcessExit` hook	Process teardown	Safety net for ungraceful exits where `HMController.Destroy()` did not run. Skipped when `_cleanShutdownPerformed` is set by the normal Stop path.
`App.xaml.cs` final shutdown	App close	Mirrors the `ProcessExit` hook for graceful exits.

PadForge does not expose a "remove HIDMaestro driver" path, and HIDMaestro is not designed to be removed like an ordinary user-mode driver. Removing it through Device Manager or pnputil /delete-driver is not supported and may leave the system in an inconsistent state. Deleting the PadForge folder leaves HM registered but inert. It only services PadForge's virtual-device creation requests, so an unused driver is effectively dormant.

HidHide

InstallHidHide()

public static void InstallHidHide()

Extract embedded HidHide_1.5.230_x64.exe to %TEMP%\PadForge_HidHide\, run /extract to unpack the MSI, locate HidHide.msi (with HidHide*.msi glob fallback), then run msiexec /i "{msiPath}" /qb /norestart via RunMsiElevated. Temp cleanup in finally.

UninstallHidHide()

public static void UninstallHidHide()

Same extraction flow as install, then msiexec /x "{msiPath}" /qb /norestart via RunMsiElevated. Temp cleanup in finally.

Detection: IsHidHideInstalled() / GetHidHideVersion()

public static bool IsHidHideInstalled()
public static string GetHidHideVersion()

Both delegate to TryGetHidHideMsiInfo(out displayVersion, out productCode), which scans Uninstall keys (Registry64 + Registry32) for "HidHide" or "HID Hide" in DisplayName (case-insensitive). Returns DisplayVersion and the subkey name (the MSI ProductCode GUID) when matched. GetHidHideVersion() falls back to "Installed" when DisplayVersion is null/empty.

Windows MIDI Services

The installer is ~210 MB so it is not embedded. It is downloaded from the GitHub API at install time.

InstallMidiServicesAsync()

public static async Task InstallMidiServicesAsync()

flowchart TD
    A[Create %TEMP%\PadForge_MidiServices\] --> B
    B["HttpClient with UserAgent='PadForge'<br/>Timeout = 10 minutes"] --> C
    C["GET https://api.github.com/repos/<br/>microsoft/MIDI/releases<br/>(full releases list, not /latest)"] --> D
    D["FindMidiServicesDownloadUrl<br/>Parse JSON for SDK.Runtime x64 .exe"] --> E
    E["Download installer (~210 MB)<br/>Stream to MidiServicesSdkRuntime.exe"] --> F
    F["Run installer directly (no runas)<br/>/install /quiet /norestart<br/>Wait up to 5 minutes"] --> G
    G["MidiVirtualController.ResetAvailability()<br/>Clear cached SDK check"] --> H
    H[Cleanup temp directory]

Why /releases not /releases/latest: the microsoft/MIDI repo only publishes pre-releases. /releases/latest returns 404 without a stable release; /releases returns all releases (first = most recent).

Why no runas: PadForge is already elevated via app.manifest. Using Verb = "runas" when already elevated throws Win32Exception on some systems, so MIDI uses a direct Process.Start.

Post-install: calls MidiVirtualController.ResetAvailability() so the cached SDK availability check re-evaluates.

FindMidiServicesDownloadUrl()

private static async Task<string> FindMidiServicesDownloadUrl(HttpClient http)

Parses the GitHub releases JSON to find the SDK Runtime x64 installer URL. Uses simple string search (no JSON library): finds "browser_download_url" occurrences, extracts URLs, matches on "SDK.Runtime" + "x64" + .exe (case-insensitive). Returns the first match. Throws InvalidOperationException if none found.

Asset pattern: Windows.MIDI.Services.SDK.Runtime.and.Tools.*-x64.exe

UninstallMidiServices()

public static void UninstallMidiServices()

Calls FindMidiServicesUninstallString() to retrieve the registry UninstallString. Parses quoted/unquoted exe paths and any preserved arguments, appends /quiet /norestart, launches hidden via Process.Start, waits up to 5 minutes. Throws InvalidOperationException if no uninstall entry is found.

FindMidiServicesUninstallString()

private static string FindMidiServicesUninstallString()

Scans Uninstall keys (Registry64 + Registry32) for DisplayName exactly matching "Windows MIDI Services Runtime and Tools" (case-insensitive). Returns UninstallString, or null if not found.

IsMidiServicesInstalled()

public static bool IsMidiServicesInstalled()

Returns true if FindMidiServicesUninstallString() is non-null. Checks the registry for the WiX Burn bootstrapper entry, not SDK runtime availability (that lives in MidiVirtualController.IsAvailable()).

Legacy v2 driver cleanup

PadForge v2 used ViGEmBus (Xbox / DS4 virtuals) and vJoy (everything else) as separate drivers. v3 replaces both with HIDMaestro. To keep upgrading users from carrying around dead drivers, MainWindow.xaml.cs::MaybeOfferLegacyDriverCleanup() runs once on first v3 launch.

First-launch dialog

The dialog only fires when both:

_viewModel.Settings.LegacyDriverCleanupOffered is false (per-user once-only flag persisted in PadForge.xml), and
At least one of DriverInstaller.IsExtendedInstalled() (vJoy) or DriverInstaller.GetViGEmVersion() != null (ViGEmBus) returns truthy.

If neither legacy driver is detected, the flag is flipped to true and the offer is silently skipped. Otherwise PadForge raises a Wpf.Ui.Controls.MessageBox titled "Legacy Driver Cleanup", listing the detected legacy drivers, and offers Uninstall / Keep buttons. On Uninstall, both UninstallViGEmBus() and UninstallVJoy() run inline (try/catch wraps the pair so a failure in one still attempts the other, and any exception surfaces a follow-up "encountered an error" dialog). The flag is then flipped to true regardless of outcome to avoid re-prompting on every launch.

The whole entry point is wrapped in a top-level try/catch that swallows everything because it runs as async void from the dispatcher. An unhandled exception there would surface as a generic "unexpected error" dialog at startup. On detection failure, the flag is not flipped, so the next launch retries.

Detection

IsExtendedInstalled() (vJoy)

public static bool IsExtendedInstalled()

Two-path detection:

Path	Method	Detail
Primary	Check `C:\Program Files\vJoy\vjoy.sys`	File existence test. Catches v2 PadForge's minimal SetupAPI install.
Fallback	`GetVJoyVersionFromRegistry()`	Scans Uninstall keys (Registry64 + Registry32) for `"vJoy"` in `DisplayName`. Catches legacy Inno Setup installs.

GetViGEmVersion()

public static string GetViGEmVersion()

Scans Uninstall keys (Registry64 + Registry32) for "ViGEm" in DisplayName (case-insensitive). Returns DisplayVersion, or null if not found.

UninstallViGEmBus()

public static void UninstallViGEmBus()

Calls FindUninstallProductCode("ViGEm") to look up the MSI ProductCode GUID. If found, runs msiexec /x {ProductCode} /qb /norestart via RunMsiElevated. No-op if no ProductCode is found.

Registry-based lookup means PadForge does not have to embed the 6 MB ViGEmBus installer. The MSI is already on the user's machine via Windows Installer cache.

UninstallVJoy()

public static void UninstallVJoy()

Builds a .cmd script at %TEMP%\PadForge_vjoy_uninstall.cmd and runs it via RunElevated("cmd.exe", "/c \"{scriptPath}\""), then calls CleanExtendedRegistryArtifacts() in-process for the registry mop-up. Script deletion in finally.

The script is generated dynamically because the OEM .inf names are determined at runtime by FindExtendedOemInfs().

flowchart TD
    A[FindExtendedOemInfs<br/>detect OEM .inf files] --> B
    B[Generate PadForge_vjoy_uninstall.cmd] --> C
    C["RunElevated cmd.exe /c script<br/>(elevation inherited from PadForge)"]

    subgraph CMD["Batch Script Execution"]
        direction TB
        U1["pnputil /remove-device ROOT\\HIDCLASS\\NNNN /subtree<br/>for NNNN in 0000..0015"] --> U2
        U2["timeout /t 2"] --> U3
        U3["sc stop vjoy"] --> U4
        U4["timeout /t 2"] --> U5
        U5["sc delete vjoy"] --> U6
        U6["reg delete HKLM\\SYSTEM\\{CurrentControlSet,ControlSet001..003}\\Services\\vjoy /f<br/>(belt-and-braces if sc delete returned STOP_PENDING)"] --> U7
        U7["pnputil /delete-driver oemNN.inf /uninstall /force<br/>per stale OEM inf"] --> U8
        U8["rmdir /s /q C:\\Program Files\\vJoy<br/>del System32\\drivers\\vjoy.sys"] --> U9
        U9["powershell one-liner: scan HKLM Uninstall + WOW6432Node Uninstall<br/>for DisplayName -like '*vJoy*' and Remove-Item -Recurse -Force"]
    end

    C --> CMD
    CMD --> D[CleanExtendedRegistryArtifacts<br/>C# method, no further elevation needed]
    D --> E[Delete .cmd file]

Step ordering matters: device nodes are removed before sc stop so the driver can fully unload from the kernel. Stopping the service while devices are still attached leaves it in STOP_PENDING, which is irrecoverable without a reboot.

CleanExtendedRegistryArtifacts()

private static void CleanExtendedRegistryArtifacts()

Removes registry keys that can cause a reinstall of vJoy to hang. Best-effort (throwOnMissingSubKey: false, per-key try/catch).

HKLM paths deleted:

Registry Path	Purpose
`SYSTEM\CurrentControlSet\Services\vjoy`	Service entry (current)
`SYSTEM\ControlSet001\Services\vjoy`	Service entry (ControlSet001)
`SYSTEM\ControlSet002\Services\vjoy`	Service entry (ControlSet002)
`SYSTEM\ControlSet003\Services\vjoy`	Service entry (ControlSet003)
`SYSTEM\CurrentControlSet\Control\MediaProperties\PrivateProperties\Joystick\OEM\VID_1234&PID_BEAD`	Joystick OEM properties
`SYSTEM\ControlSet001\Services\EventLog\System\vjoy`	Event log registration
`SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\PnpLockdownFiles\%SystemRoot%/System32/drivers/hidkmdf.sys`	PnP lockdown entry
`SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\PnpLockdownFiles\%SystemRoot%/System32/drivers/vjoy.sys`	PnP lockdown entry
`SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Setup\PnpLockdownFiles\%SystemRoot%/System32/drivers/hidkmdf.sys`	Same under WOW6432Node
`SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Setup\PnpLockdownFiles\%SystemRoot%/System32/drivers/vjoy.sys`	Same under WOW6432Node

HKCU path deleted:

Registry Path	Purpose
`System\CurrentControlSet\Control\MediaProperties\PrivateProperties\Joystick\OEM\VID_1234&PID_BEAD`	User-level joystick OEM properties

After the path list, calls CleanExtendedDeviceClassEntries().

CleanExtendedDeviceClassEntries()

private static void CleanExtendedDeviceClassEntries()

Enumerates subkeys under HKLM\SYSTEM\ControlSet001\Control\Class\{781ef630-72b2-11d2-b852-00c04fad5101} (the shared HID device class key) and deletes any whose Class value equals "vjoy" (case-insensitive). Best-effort. Exceptions caught silently.

FindExtendedOemInfs()

private static string[] FindExtendedOemInfs()

Runs pnputil.exe /enum-drivers (30s timeout, output captured), then walks the output line-by-line tracking the most recent Published Name : oemXX.inf and watching each block for "shaul" or "vjoy" (case-insensitive). Returns matching oem*.inf names; returns an empty array on any error. Used by UninstallVJoy() to know which pnputil /delete-driver lines to emit.

HidHide Runtime API (HidHideController)

File: PadForge.App/Common/HidHideController.cs Namespace: PadForge.Common

Runtime device management (blacklisting, whitelisting, cloaking) communicates directly with the HidHide control device (\\.\HidHide) via P/Invoke IOCTLs.

IOCTL Codes

IOCTL	Code	Direction	Purpose
`GET_WHITELIST`	`0x80016000`	Read	Get whitelisted application paths
`SET_WHITELIST`	`0x80016004`	Write	Replace whitelisted application paths
`GET_BLACKLIST`	`0x80016008`	Read	Get blacklisted device instance IDs
`SET_BLACKLIST`	`0x8001600C`	Write	Replace blacklisted device instance IDs
`GET_ACTIVE`	`0x80016010`	Read	Get cloaking active state (1 byte)
`SET_ACTIVE`	`0x80016014`	Write	Enable/disable cloaking (1 byte)

Buffer Format

GET/SET list operations use Multi-SZ format: null-separated UTF-16 strings with double-null terminator. SET replaces the entire list (not append).

Public API

static bool IsAvailable()                                   // Can open \\.\HidHide
static List<string> GetBlacklist()                          // Device instance IDs
static void SetBlacklist(List<string> ids)                  // Replace entire blacklist
static List<string> GetWhitelist()                          // DOS device paths
static void SetWhitelist(List<string> paths)                // Replace entire whitelist
static bool GetActive()                                     // Cloaking enabled?
static void SetActive(bool active)                          // Enable/disable cloaking
static void RemoveManagedDevices()                          // Remove only PadForge's entries
static void SyncManagedDevices(HashSet<string> desiredIds)  // Atomic diff-based blacklist sync
static void ClearAll()                                      // Clear blacklist + disable cloaking
static List<string> FindInstanceIdsByVidPid(ushort, ushort) // Enumerate HID devices by VID/PID (USB + BLE formats)
static string DevicePathToInstanceId(string p)              // \\?\HID#... -> HID\VID_...\...
static string ToDosDevicePathPublic(string filePath)        // C:\... -> \Device\HarddiskVolumeN\...

Managed Device Tracking

_managedDeviceIds (HashSet<string>) tracks device IDs PadForge added to the blacklist. RemoveManagedDevices() removes only these entries, leaving entries from other tools untouched.

Removed methods: AddToBlacklist(string) and RemoveFromBlacklist(string) were removed. All blacklist management now goes through SyncManagedDevices(HashSet<string>), which performs an atomic diff-based sync (add missing, remove excess) in a single operation.

Merge-based cache: ApplyDeviceHiding uses a merge-based approach for its resolved instance ID cache. New IDs are added but previously cached IDs are never discarded. This ensures offline devices that were resolved in a prior cycle remain in the blacklist even if they are not currently enumerable.

VID/PID Format Matching

FindInstanceIdsByVidPid() matches device instance IDs in two formats:

USB HID: HID\VID_045E&PID_0B13\.... Standard VID_XXXX&PID_XXXX pattern
Bluetooth LE (HID-over-GATT): HID\VID&0202D0&PID&0101\.... Uses VID&02XXXX (USB-assigned) or VID&01XXXX (Bluetooth SIG-assigned) paired with PID&XXXX

This dual matching ensures Bluetooth LE controllers (e.g., Xbox Series X via Bluetooth) are fully hidden. Both the HID child and BTHLEDEVICE parent nodes.

DOS Device Path Conversion

Whitelist requires DOS device paths (\Device\HarddiskVolumeN\...), not regular paths (C:\...). ToDosDevicePath() converts via QueryDosDeviceW.

Device Instance ID Conversion

DevicePathToInstanceId() converts device paths (\\?\HID#VID_054C&PID_0CE6#...{guid}) to PnP instance IDs (HID\VID_054C&PID_0CE6\...): strip \\?\ prefix, remove trailing GUID {...}, replace # with \.

Uninstall Guards

The Settings page disables uninstall buttons when a driver/service is in use, preventing removal while virtual controllers depend on it.

Driver	Guard Condition	Delegate
HidHide	Any device has HidHide hiding enabled	`HasAnyHidHideDevices`
MIDI Services	Any created slot uses MIDI	`HasAnyMidiSlots`

Guards are Func<bool> delegates on SettingsViewModel, injected by MainWindow.xaml.cs. RefreshDriverGuards() re-evaluates CanExecute on the uninstall commands after slot creation, deletion, or type changes.

HIDMaestro has no Install or Uninstall command in v3 (the SDK assembly is always available), so there is no guard to enforce. The legacy v2 cleanup dialog is single-shot and does not appear on the Settings page, so it has no guard either.

Elevation Strategy

PadForge requires elevation unconditionally. app.manifest declares:

<requestedExecutionLevel level="requireAdministrator" uiAccess="false"/>

Windows shows the UAC shield on the icon and prompts once when the process starts. The previous v2 approach of relaunching mid-session via Verb = "runas" (and the conditional auto-elevation tied to vJoy presence) is gone. Every code path that needs admin runs inside the already-elevated process.

Scenario	Elevation Method	UAC Prompts
PadForge launch	`app.manifest` `requireAdministrator`	1 (per launch, if UAC is enabled)
`HMContext.InstallDriver()` (HM driver register)	App already elevated	0
HidHide install/uninstall	`msiexec` via `RunElevated` (child inherits PadForge's elevation)	0
MIDI Services install	Direct `Process.Start` (no `runas` to avoid `Win32Exception` on already-elevated processes)	0
Legacy ViGEmBus uninstall	`msiexec /x {ProductCode}` via `RunElevated`	0
Legacy vJoy uninstall	`cmd.exe /c {script}` via `RunElevated`	0
Driver runtime operations (HM device lifecycle, HidHide whitelist edits, etc.)	App already elevated	0

Temp Directories

Driver	Temp Directory
HidHide	`%TEMP%\PadForge_HidHide\`
MIDI Services	`%TEMP%\PadForge_MidiServices\`
Legacy vJoy uninstall script	`%TEMP%\PadForge_vjoy_uninstall.cmd`

All cleaned up after each operation via CleanupTempDir() or direct File.Delete() in finally blocks.

HIDMaestro has no temp directory because PadForge does not unpack any installer for it.

Error Handling and Rollback

General Strategy

All install/uninstall methods use try/finally for cleanup: temp directories always deleted, script files deleted after execution.

Per-driver

Path	Error Strategy
HIDMaestro `InstallDriver()`	Caught in `EnsureHMaestroContext`. On failure, sets `_hmaestroContextFailed = true` (sticky for the session) and calls `RaiseError("Failed to initialize HIDMaestro.", ex)`. The engine continues running for KB+M and (if installed) MIDI categories; HM-backed slot creation is gated on the context being non-null.
HidHide install/uninstall	MSI installer handles its own rollback. PadForge surfaces no specific error UI; failures bubble up as exceptions.
MIDI Services	WiX Burn bootstrapper handles rollback. PadForge surfaces no specific error UI; HTTP and process timeouts both throw.
Legacy ViGEmBus uninstall	No-op when no ProductCode found. Otherwise relies on MSI rollback.
Legacy vJoy uninstall	The `.cmd` script redirects every step's stderr to nul and continues regardless (`>nul 2>&1`). This is best-effort: a failed `pnputil` line should not prevent the next `sc delete`. The follow-up `CleanExtendedRegistryArtifacts()` is also per-key best-effort.

No Rollback

There is no explicit rollback machinery in DriverInstaller. On partial failure of a legacy vJoy uninstall, surviving residue (a stuck service, a stale OEM .inf) is harmless to v3 because v3 does not use vJoy at all. The next launch re-runs the legacy cleanup offer (the persisted flag only flips on successful dialog completion, not on failed Uninstall choice).

Driver Installation Internals

Driver Installation Internals

Contents

Architecture Overview

Embedded Resources

Shared Helpers

HIDMaestro

EnsureHMaestroContext()

Settings page surface

Cleanup

HidHide

InstallHidHide()

UninstallHidHide()

Detection: IsHidHideInstalled() / GetHidHideVersion()

Windows MIDI Services

InstallMidiServicesAsync()

FindMidiServicesDownloadUrl()

UninstallMidiServices()

FindMidiServicesUninstallString()

IsMidiServicesInstalled()

Legacy v2 driver cleanup

First-launch dialog

Detection

IsExtendedInstalled() (vJoy)

GetViGEmVersion()

UninstallViGEmBus()

UninstallVJoy()

CleanExtendedRegistryArtifacts()

CleanExtendedDeviceClassEntries()

FindExtendedOemInfs()

HidHide Runtime API (HidHideController)

IOCTL Codes

Buffer Format

Public API

Managed Device Tracking

VID/PID Format Matching

DOS Device Path Conversion

Device Instance ID Conversion

Uninstall Guards

Elevation Strategy

Temp Directories

Error Handling and Rollback

General Strategy

Per-driver

No Rollback

See Also

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