feat: add IsWindows8OrGreater() and GetCurrentPackageFullName() APIs

[halildurmus]

I have a concrete use-case at YehudaKremer/msix#292: Determining if your app is running with package identity:

#include <windows.h>
#include <appmodel.h>
#include <atlbase.h>
#include <VersionHelpers.h>

std::optional<bool> NativePlugin::checkIdentity() {
  if (!IsWindows8OrGreater()) return false;
  uint32_t length = 0;
  auto error = GetCurrentPackageFullName(&length, nullptr);
  if (error == APPMODEL_ERROR_NO_PACKAGE) {
    return false;
  } else if (error != ERROR_INSUFFICIENT_BUFFER) {
    return std::nullopt;
  }
  std::vector<wchar_t> fullName(length);
  error = GetCurrentPackageFullName(&length, fullName.data());
  if (error != ERROR_SUCCESS) return std::nullopt;
  return true;
}

Seems this package doesn't include <appmodel.h>, so I can't use IsWindows8OrGreater() or GetCurrentPackageFullName().

Originally posted by @Levi-Lesches in #819 (comment)

[Levi-Lesches]

I was trying this myself, and ran into an issue. IsWindows8OrGreater is inline, and the function it calls, IsWindowsVersionOrGreater, is also inline! How can I call these in Dart without re-implementing them? I checked the kernel32.dll and sure enough, they're not even in there. Should I just translate the function to Dart FFI directly?

[halildurmus]

I was trying this myself, and ran into an issue. IsWindows8OrGreater is inline, and the function it calls, IsWindowsVersionOrGreater, is also inline! How can I call these in Dart without re-implementing them?

You need to implement inline functions yourself, you can't wrap them with FFI. See packages/win32/lib/src/inline.dart file which implements several inline functions:

win32/packages/win32/lib/src/inline.dart

Line 103 in 249459b

int IsWindowsVersionOrGreater(

Here's the implementation of the IsWindows8OrGreater:

const _WIN32_WINNT_WIN8 = 0x0602;

/// Indicates if the current OS version matches, or is greater than, the
/// Windows 8 version.
///
/// {@category version}
int IsWindows8OrGreater() => IsWindowsVersionOrGreater(
      HIBYTE(_WIN32_WINNT_WIN8),
      LOBYTE(_WIN32_WINNT_WIN8),
      0,
    );

And GetCurrentPackageFullName:

final _kernel32 = DynamicLibrary.open('kernel32.dll');

/// Gets the package full name for the calling process.
///
/// ```c
/// LONG GetCurrentPackageFullName(
///   UINT32 *packageFullNameLength,
///   PWSTR  packageFullName
/// );
/// ```
/// {@category kernel32}
int GetCurrentPackageFullName(Pointer<Uint32> packageFullNameLength,
        Pointer<Utf16> packageFullName) =>
    _GetCurrentPackageFullName(packageFullNameLength, packageFullName);

final _GetCurrentPackageFullName = _kernel32.lookupFunction<
    Uint32 Function(
        Pointer<Uint32> packageFullNameLength, Pointer<Utf16> packageFullName),
    int Function(Pointer<Uint32> packageFullNameLength,
        Pointer<Utf16> packageFullName)>('GetCurrentPackageFullName');

I'll probably add these to the package tomorrow.

I didn't test it but this should work:

import 'dart:ffi';

import 'package:ffi/ffi.dart';
import 'package:win32/win32.dart';

bool checkIdentity() {
  if (IsWindows8OrGreater() == FALSE) return false;
  final length = calloc<Uint32>();
  try {
    var error = GetCurrentPackageFullName(length, nullptr);
    if (error == WIN32_ERROR.APPMODEL_ERROR_NO_PACKAGE) {
      return false;
    } else if (error != WIN32_ERROR.ERROR_INSUFFICIENT_BUFFER) {
      return false;
    }
    final packageFullName = wsalloc(length.value);
    error = GetCurrentPackageFullName(length, packageFullName);
    free(packageFullName);
    return error == WIN32_ERROR.ERROR_SUCCESS;
  } finally {
    free(length);
  }
}

void main() {
  if (checkIdentity()) {
    print('This is a Windows 8+ Store App');
  } else {
    print('This is not a Windows 8+ Store App');
  }
}

[Levi-Lesches]

It works, thanks!

[Levi-Lesches]

Thanks again!