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

[Johannes Sixt]

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