Re: [PATCH v1] test-drop-caches: simplify delay loading of NtSetSystemInformation

[Johannes Sixt <j6t@kdbg.org>]

Am 30.04.2018 um 16:26 schrieb Ben Peart:
> @@ -82,8 +83,6 @@ static int cmd_dropcaches(void)
>   {
>   	HANDLE hProcess = GetCurrentProcess();
>   	HANDLE hToken;
> -	HMODULE ntdll;
> -	DWORD(WINAPI *NtSetSystemInformation)(INT, PVOID, ULONG);
>   	SYSTEM_MEMORY_LIST_COMMAND command;
>   	int status;
>   
> @@ -95,14 +94,9 @@ static int cmd_dropcaches(void)
>   
>   	CloseHandle(hToken);
>   
> -	ntdll = LoadLibrary("ntdll.dll");
> -	if (!ntdll)
> -		return error("Can't load ntdll.dll, wrong Windows version?");
> -
> -	NtSetSystemInformation =
> -		(DWORD(WINAPI *)(INT, PVOID, ULONG))GetProcAddress(ntdll, "NtSetSystemInformation");
> -	if (!NtSetSystemInformation)
> -		return error("Can't get function addresses, wrong Windows version?");
> +	DECLARE_PROC_ADDR(ntdll.dll, DWORD, NtSetSystemInformation, INT, PVOID, ULONG);

This is a declaration-after-statement. Even though this is not in 
generic code, it is all too easy to trigger a warning from GCC if a 
corresponding warning is turned on.

> +	if (!INIT_PROC_ADDR(NtSetSystemInformation))
> +		return error("Could not find NtSetSystemInformation() function");
>   
>   	command = MemoryPurgeStandbyList;
>   	status = NtSetSystemInformation(
> @@ -115,8 +109,6 @@ static int cmd_dropcaches(void)
>   	else if (status != STATUS_SUCCESS)
>   		error("Unable to execute the memory list command %d", status);
>   
> -	FreeLibrary(ntdll);
> -
>   	return status;
>   }

-- Hannes