podman

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#include <windows.h>
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#include <MsiQuery.h>
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BOOL isWSLEnabled();
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LPCWSTR boolToNStr(BOOL bool);
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/**
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 * CheckWSL is a custom action loaded by the Podman Windows installer
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 * to determine whether the system already has WSL installed.
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 *
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 * The intention is that this action is compiled for x86_64, which
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 * can be ran on both Intel and Arm based systems (the latter through
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 * emulation). While the code should build fine on MSVC and clang, the
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 * intended usage is MingW-W64 (cross-compiling gcc targeting Windows).
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 *
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 * Previously this was implemented as a Golang c-shared cgo library,
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 * however, the WoW x86_64 emulation layer struggled with dynamic
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 * hot-loaded transformation of the goruntime into an existing process
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 * (required by MSI custom actions). In the future this could be
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 * converted back, should the emulation issue be resolved.
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 */
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 __declspec(dllexport) UINT __cdecl CheckWSL(MSIHANDLE hInstall) {
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	BOOL hasWSL = isWSLEnabled();
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	// Set a property with the WSL state for the installer to operate on
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	MsiSetPropertyW(hInstall, L"HAS_WSLFEATURE", boolToNStr(hasWSL));
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	return 0;
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}
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LPCWSTR boolToNStr(BOOL bool) {
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	return bool ? L"1" : L"0";
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}
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BOOL isWSLEnabled() {
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	/*
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	 * The simplest, and most reliable check across all variants and versions
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	 * of WSL appears to be changing the default version to WSL 2 and check
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	 * for errors, which we need to do anyway.
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	 */
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	STARTUPINFOW startup;
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	PROCESS_INFORMATION process;
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	ZeroMemory(&startup, sizeof(STARTUPINFOW));
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	startup.cb = sizeof(STARTUPINFOW);
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	// These settings hide the console window, so there is no annoying flash
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	startup.dwFlags = STARTF_USESHOWWINDOW;
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	startup.wShowWindow = SW_HIDE;
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	// CreateProcessW requires lpCommandLine to be mutable
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	wchar_t cmd[] = L"wsl --set-default-version 2";
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	if (! CreateProcessW(NULL, cmd, NULL, NULL, FALSE, CREATE_NEW_CONSOLE,
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					     NULL, NULL, &startup, &process)) {
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		return FALSE;
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	}
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	DWORD exitCode;
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	WaitForSingleObject(process.hProcess, INFINITE);
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	if (! GetExitCodeProcess(process.hProcess, &exitCode)) {
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		return FALSE;
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	}
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	return exitCode == 0;
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}
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