Windows / refactoring: utility functions for LoadLibraryA and GetProcAddress (#1417)

Windows / refactoring: add utility functions for LoadLibraryA and GetProcAddress. Centralize logic in one place.

6 files changed, 121 insertions, 213 deletions

diff --git a/make.bat b/make.bat
index 43000535..d47eaecc 100644
--- a/make.bat
+++ b/make.bat
@@ -20,8 +20,13 @@ rem      set PYTHON=C:\Python34\python.exe & set TSCRIPT=foo.py & make.bat test
 rem ==========================================================================
 
 if "%PYTHON%" == "" (
-    set PYTHON=C:\Python27\python.exe
+    if exist "C:\Python37\python.exe" (
+        set PYTHON=C:\Python37\python.exe
+    ) else (
+        set PYTHON=C:\Python27\python.exe
+    )
 )
+
 if "%TSCRIPT%" == "" (
     set TSCRIPT=psutil\tests\__main__.py
 )
diff --git a/psutil/_psutil_windows.c b/psutil/_psutil_windows.c
index b5b5a8f5..55a1cb22 100644
--- a/psutil/_psutil_windows.c
+++ b/psutil/_psutil_windows.c
@@ -205,15 +205,12 @@ psutil_get_num_cpus(int fail_on_err) {
     unsigned int ncpus = 0;
     SYSTEM_INFO sysinfo;
     static DWORD(CALLBACK *_GetActiveProcessorCount)(WORD) = NULL;
-    HINSTANCE hKernel32;
 
     // GetActiveProcessorCount is available only on 64 bit versions
     // of Windows from Windows 7 onward.
-    // Windows Vista 64 bit and Windows XP doesn't have it.
-    hKernel32 = GetModuleHandleW(L"KERNEL32");
-    _GetActiveProcessorCount = (void*)GetProcAddress(
-        hKernel32, "GetActiveProcessorCount");
-
+    // Windows Vista 64 bit and Windows XP don't have it.
+    _GetActiveProcessorCount = \
+        psutil_GetProcAddress("kernel32", "GetActiveProcessorCount");
     if (_GetActiveProcessorCount != NULL) {
         ncpus = _GetActiveProcessorCount(ALL_PROCESSOR_GROUPS);
         if ((ncpus == 0) && (fail_on_err == 1)) {
@@ -261,11 +258,9 @@ psutil_boot_time(PyObject *self, PyObject *args) {
     time_t pt;
     FILETIME fileTime;
     long long ll;
-    HINSTANCE hKernel32;
-    psutil_GetTickCount64 = NULL;
+    psutil_GetTickCount64;
 
     GetSystemTimeAsFileTime(&fileTime);
-
     /*
     HUGE thanks to:
     http://johnstewien.spaces.live.com/blog/cns!E6885DB5CEBABBC8!831.entry
@@ -288,12 +283,11 @@ psutil_boot_time(PyObject *self, PyObject *args) {
     pt = (time_t)((ll - 116444736000000000ull) / 10000000ull);
 
     // GetTickCount64() is Windows Vista+ only. Dinamically load
-    // GetTickCount64() at runtime. We may have used
+    // it at runtime. We may have used
     // "#if (_WIN32_WINNT >= 0x0600)" pre-processor but that way
     // the produced exe/wheels cannot be used on Windows XP, see:
     // https://github.com/giampaolo/psutil/issues/811#issuecomment-230639178
-    hKernel32 = GetModuleHandleW(L"KERNEL32");
-    psutil_GetTickCount64 = (void*)GetProcAddress(hKernel32, "GetTickCount64");
+    psutil_GetTickCount64 = psutil_GetProcAddress("kernel32", "GetTickCount64");
     if (psutil_GetTickCount64 != NULL) {
         // Windows >= Vista
         uptime = psutil_GetTickCount64() / (ULONGLONG)1000.00f;
@@ -642,14 +636,10 @@ psutil_cpu_count_phys(PyObject *self, PyObject *args) {
     // it supports process groups, meaning this is able to report more
     // than 64 CPUs. See:
     // https://bugs.python.org/issue33166
-    _GetLogicalProcessorInformationEx = \
-        (PFN_GETLOGICALPROCESSORINFORMATIONEX)GetProcAddress(
-            GetModuleHandle(TEXT("kernel32")),
-                            "GetLogicalProcessorInformationEx");
-    if (_GetLogicalProcessorInformationEx == NULL) {
-        psutil_debug("failed loading GetLogicalProcessorInformationEx()");
-        goto return_none;
-    }
+    _GetLogicalProcessorInformationEx = psutil_GetProcAddressFromLib(
+        "kernel32", "GetLogicalProcessorInformationEx");
+    if (_GetLogicalProcessorInformationEx == NULL)
+        return NULL;
 
     while (1) {
         rc = _GetLogicalProcessorInformationEx(
@@ -765,7 +755,7 @@ psutil_proc_exe(PyObject *self, PyObject *args) {
     HANDLE hProcess;
     wchar_t exe[MAX_PATH];
 #if (_WIN32_WINNT >= 0x0600)  // >= Vista
-    PDWORD size = MAX_PATH;
+    unsigned int size = sizeof(exe);
 #endif
 
     if (! PyArg_ParseTuple(args, "l", &pid))
@@ -1057,7 +1047,6 @@ psutil_per_cpu_times(PyObject *self, PyObject *args) {
     // NtQuerySystemInformation stuff
     typedef DWORD (_stdcall * NTQSI_PROC) (int, PVOID, ULONG, PULONG);
     NTQSI_PROC NtQuerySystemInformation;
-    HINSTANCE hNtDll;
 
     double idle, kernel, systemt, user, interrupt, dpc;
     NTSTATUS status;
@@ -1069,19 +1058,10 @@ psutil_per_cpu_times(PyObject *self, PyObject *args) {
 
     if (py_retlist == NULL)
         return NULL;
-
-    // obtain NtQuerySystemInformation
-    hNtDll = LoadLibrary(TEXT("ntdll.dll"));
-    if (hNtDll == NULL) {
-        PyErr_SetFromWindowsErr(0);
+    NtQuerySystemInformation = \
+        psutil_GetProcAddressFromLib("ntdll.dll", "NtQuerySystemInformation");
+    if (NtQuerySystemInformation == NULL)
         goto error;
-    }
-    NtQuerySystemInformation = (NTQSI_PROC)GetProcAddress(
-        hNtDll, "NtQuerySystemInformation");
-    if (NtQuerySystemInformation == NULL) {
-        PyErr_SetFromWindowsErr(0);
-        goto error;
-    }
 
     // retrieves number of processors
     ncpus = psutil_get_num_cpus(1);
@@ -1144,7 +1124,6 @@ psutil_per_cpu_times(PyObject *self, PyObject *args) {
     }
 
     free(sppi);
-    FreeLibrary(hNtDll);
     return py_retlist;
 
 error:
@@ -1152,8 +1131,6 @@ error:
     Py_DECREF(py_retlist);
     if (sppi)
         free(sppi);
-    if (hNtDll)
-        FreeLibrary(hNtDll);
     return NULL;
 }
 
@@ -1672,11 +1649,26 @@ psutil_net_connections(PyObject *self, PyObject *args) {
     PyObject *_SOCK_STREAM = PyLong_FromLong((long)SOCK_STREAM);
     PyObject *_SOCK_DGRAM = PyLong_FromLong((long)SOCK_DGRAM);
 
+    // Import some functions.
+    rtlIpv4AddressToStringA = psutil_GetProcAddressFromLib(
+        "ntdll.dll", "RtlIpv4AddressToStringA");
+    if (rtlIpv4AddressToStringA == NULL)
+        goto error;
+    rtlIpv6AddressToStringA = psutil_GetProcAddressFromLib(
+        "ntdll.dll", "RtlIpv6AddressToStringA");
+    if (rtlIpv6AddressToStringA == NULL)
+        goto error;
+    getExtendedTcpTable = psutil_GetProcAddressFromLib(
+        "iphlpapi.dll", "GetExtendedTcpTable");
+    if (getExtendedTcpTable == NULL)
+        goto error;
+    getExtendedUdpTable = psutil_GetProcAddressFromLib(
+        "iphlpapi.dll", "GetExtendedUdpTable");
+    if (getExtendedUdpTable == NULL)
+        goto error;
+
     if (! PyArg_ParseTuple(args, "lOO", &pid, &py_af_filter, &py_type_filter))
-    {
-        _psutil_conn_decref_objs();
-        return NULL;
-    }
+        goto error;
 
     if (!PySequence_Check(py_af_filter) || !PySequence_Check(py_type_filter)) {
         _psutil_conn_decref_objs();
@@ -1696,27 +1688,6 @@ psutil_net_connections(PyObject *self, PyObject *args) {
         }
     }
 
-    // Import some functions.
-    {
-        HMODULE ntdll;
-        HMODULE iphlpapi;
-
-        ntdll = LoadLibrary(TEXT("ntdll.dll"));
-        rtlIpv4AddressToStringA = (_RtlIpv4AddressToStringA)GetProcAddress(
-                                   ntdll, "RtlIpv4AddressToStringA");
-        rtlIpv6AddressToStringA = (_RtlIpv6AddressToStringA)GetProcAddress(
-                                   ntdll, "RtlIpv6AddressToStringA");
-        /* TODO: Check these two function pointers */
-
-        iphlpapi = LoadLibrary(TEXT("iphlpapi.dll"));
-        getExtendedTcpTable = (_GetExtendedTcpTable)GetProcAddress(iphlpapi,
-                              "GetExtendedTcpTable");
-        getExtendedUdpTable = (_GetExtendedUdpTable)GetProcAddress(iphlpapi,
-                              "GetExtendedUdpTable");
-        FreeLibrary(ntdll);
-        FreeLibrary(iphlpapi);
-    }
-
     if ((getExtendedTcpTable == NULL) || (getExtendedUdpTable == NULL)) {
         PyErr_SetString(PyExc_NotImplementedError,
                         "feature not supported on this Windows version");
@@ -2152,11 +2123,12 @@ psutil_proc_io_priority_get(PyObject *self, PyObject *args) {
     long pid;
     HANDLE hProcess;
     DWORD IoPriority;
+    _NtQueryInformationProcess NtQueryInformationProcess;
 
-    _NtQueryInformationProcess NtQueryInformationProcess =
-        (_NtQueryInformationProcess)GetProcAddress(
-            GetModuleHandleA("ntdll.dll"), "NtQueryInformationProcess");
-
+    NtQueryInformationProcess = \
+        psutil_GetProcAddress("ntdll.dll", "NtQueryInformationProcess");
+    if (NtQueryInformationProcess == NULL)
+        return NULL;
     if (! PyArg_ParseTuple(args, "l", &pid))
         return NULL;
     hProcess = psutil_handle_from_pid(pid, PROCESS_QUERY_LIMITED_INFORMATION);
@@ -2184,17 +2156,12 @@ psutil_proc_io_priority_set(PyObject *self, PyObject *args) {
     DWORD prio;
     HANDLE hProcess;
     DWORD access = PROCESS_QUERY_INFORMATION | PROCESS_SET_INFORMATION;
+    _NtSetInformationProcess NtSetInformationProcess;
 
-    _NtSetInformationProcess NtSetInformationProcess =
-        (_NtSetInformationProcess)GetProcAddress(
-            GetModuleHandleA("ntdll.dll"), "NtSetInformationProcess");
-
-    if (NtSetInformationProcess == NULL) {
-        PyErr_SetString(PyExc_RuntimeError,
-                        "couldn't get NtSetInformationProcess syscall");
+    NtSetInformationProcess = \
+        psutil_GetProcAddress("ntdll.dll", "NtSetInformationProcess");
+    if (NtSetInformationProcess == NULL)
         return NULL;
-    }
-
     if (! PyArg_ParseTuple(args, "li", &pid, &prio))
         return NULL;
     hProcess = psutil_handle_from_pid(pid, access);
@@ -2797,23 +2764,21 @@ psutil_users(PyObject *self, PyObject *args) {
     PWTS_CLIENT_ADDRESS address;
     char address_str[50];
     long long unix_time;
-
     PWINSTATIONQUERYINFORMATIONW WinStationQueryInformationW;
     WINSTATION_INFO station_info;
-    HINSTANCE hInstWinSta = NULL;
     ULONG returnLen;
-
-    PyObject *py_retlist = PyList_New(0);
     PyObject *py_tuple = NULL;
     PyObject *py_address = NULL;
     PyObject *py_username = NULL;
+    PyObject *py_retlist = PyList_New(0);
 
     if (py_retlist == NULL)
         return NULL;
 
-    hInstWinSta = LoadLibraryA("winsta.dll");
-    WinStationQueryInformationW = (PWINSTATIONQUERYINFORMATIONW) \
-        GetProcAddress(hInstWinSta, "WinStationQueryInformationW");
+    WinStationQueryInformationW = psutil_GetProcAddressFromLib(
+        "winsta.dll", "WinStationQueryInformationW");
+    if (WinStationQueryInformationW == NULL)
+        goto error;
 
     if (WTSEnumerateSessions(hServer, 0, 1, &sessions, &count) == 0) {
         PyErr_SetFromWindowsErr(0);
@@ -2902,7 +2867,6 @@ psutil_users(PyObject *self, PyObject *args) {
     WTSFreeMemory(sessions);
     WTSFreeMemory(buffer_user);
     WTSFreeMemory(buffer_addr);
-    FreeLibrary(hInstWinSta);
     return py_retlist;
 
 error:
@@ -2911,8 +2875,6 @@ error:
     Py_XDECREF(py_address);
     Py_DECREF(py_retlist);
 
-    if (hInstWinSta != NULL)
-        FreeLibrary(hInstWinSta);
     if (sessions != NULL)
         WTSFreeMemory(sessions);
     if (buffer_user != NULL)
@@ -3100,7 +3062,6 @@ psutil_proc_memory_maps(PyObject *self, PyObject *args) {
     GetSystemInfo(&system_info);
     maxAddr = system_info.lpMaximumApplicationAddress;
     baseAddress = NULL;
-    previousAllocationBase = NULL;
 
     while (VirtualQueryEx(hProcess, baseAddress, &basicInfo,
                           sizeof(MEMORY_BASIC_INFORMATION)))
@@ -3135,7 +3096,7 @@ psutil_proc_memory_maps(PyObject *self, PyObject *args) {
             Py_DECREF(py_tuple);
             Py_DECREF(py_str);
         }
-        previousAllocationBase = basicInfo.AllocationBase;
+        previousAllocationBase = (ULONGLONG)basicInfo.AllocationBase;
         baseAddress = (PCHAR)baseAddress + basicInfo.RegionSize;
     }
 
@@ -3517,11 +3478,8 @@ error:
  */
 static PyObject *
 psutil_cpu_stats(PyObject *self, PyObject *args) {
-    // NtQuerySystemInformation stuff
     typedef DWORD (_stdcall * NTQSI_PROC) (int, PVOID, ULONG, PULONG);
     NTQSI_PROC NtQuerySystemInformation;
-    HINSTANCE hNtDll;
-
     NTSTATUS status;
     _SYSTEM_PERFORMANCE_INFORMATION *spi = NULL;
     _SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION *sppi = NULL;
@@ -3531,18 +3489,10 @@ psutil_cpu_stats(PyObject *self, PyObject *args) {
     ULONG64 dpcs = 0;
     ULONG interrupts = 0;
 
-    // obtain NtQuerySystemInformation
-    hNtDll = LoadLibrary(TEXT("ntdll.dll"));
-    if (hNtDll == NULL) {
-        PyErr_SetFromWindowsErr(0);
-        goto error;
-    }
-    NtQuerySystemInformation = (NTQSI_PROC)GetProcAddress(
-        hNtDll, "NtQuerySystemInformation");
-    if (NtQuerySystemInformation == NULL) {
-        PyErr_SetFromWindowsErr(0);
-        goto error;
-    }
+    NtQuerySystemInformation = \
+        psutil_GetProcAddressFromLib("ntdll.dll", "NtQuerySystemInformation");
+    if (NtQuerySystemInformation == NULL)
+        return NULL;
 
     // retrieves number of processors
     ncpus = psutil_get_num_cpus(1);
@@ -3613,7 +3563,6 @@ psutil_cpu_stats(PyObject *self, PyObject *args) {
     free(spi);
     free(InterruptInformation);
     free(sppi);
-    FreeLibrary(hNtDll);
     return Py_BuildValue(
         "kkkk",
         spi->ContextSwitches,
@@ -3629,8 +3578,6 @@ error:
         free(InterruptInformation);
     if (sppi)
         free(sppi);
-    if (hNtDll)
-        FreeLibrary(hNtDll);
     return NULL;
 }
 
diff --git a/psutil/arch/windows/inet_ntop.h b/psutil/arch/windows/inet_ntop.h
index 70573a36..0dbf28bf 100644
--- a/psutil/arch/windows/inet_ntop.h
+++ b/psutil/arch/windows/inet_ntop.h
@@ -9,7 +9,7 @@
 PCSTR WSAAPI
 inet_ntop(
     __in                                INT             Family,
-    __in                                PVOID           pAddr,
+    __in                                const VOID *    pAddr,
     __out_ecount(StringBufSize)         PSTR            pStringBuf,
     __in                                size_t          StringBufSize
 );
diff --git a/psutil/arch/windows/process_handles.c b/psutil/arch/windows/process_handles.c
index 356e2368..4ac02b91 100644
--- a/psutil/arch/windows/process_handles.c
+++ b/psutil/arch/windows/process_handles.c
@@ -5,6 +5,7 @@
  *
  */
 #include "process_handles.h"
+#include "process_info.h"
 #include "../../_psutil_common.h"
 
 static _NtQuerySystemInformation __NtQuerySystemInformation = NULL;
@@ -22,12 +23,6 @@ ULONG g_dwSize = 0;
 ULONG g_dwLength = 0;
 
 
-PVOID
-GetLibraryProcAddress(PSTR LibraryName, PSTR ProcName) {
-    return GetProcAddress(GetModuleHandleA(LibraryName), ProcName);
-}
-
-
 PyObject *
 psutil_get_open_files(long dwPid, HANDLE hProcess) {
     OSVERSIONINFO osvi;
@@ -50,9 +45,10 @@ psutil_get_open_files_init(BOOL threaded) {
         return;
 
     // Resolve the Windows API calls
-    __NtQuerySystemInformation =
-        GetLibraryProcAddress("ntdll.dll", "NtQuerySystemInformation");
-    __NtQueryObject = GetLibraryProcAddress("ntdll.dll", "NtQueryObject");
+    __NtQuerySystemInformation = psutil_GetProcAddressFromLib(
+        "ntdll.dll", "NtQuerySystemInformation");
+    __NtQueryObject = psutil_GetProcAddressFromLib(
+        "ntdll.dll", "NtQueryObject");
 
     // Create events for signalling work between threads
     if (threaded == TRUE) {
diff --git a/psutil/arch/windows/process_info.c b/psutil/arch/windows/process_info.c
index 6f877342..9001ab14 100644
--- a/psutil/arch/windows/process_info.c
+++ b/psutil/arch/windows/process_info.c
@@ -161,70 +161,42 @@ typedef struct {
 const int STATUS_INFO_LENGTH_MISMATCH = 0xC0000004;
 const int STATUS_BUFFER_TOO_SMALL = 0xC0000023L;
 
-#define WINDOWS_UNINITIALIZED 0
-#define WINDOWS_XP 51
-#define WINDOWS_VISTA 60
-#define WINDOWS_7 61
-#define WINDOWS_8 62
-#define WINDOWS_81 63
-#define WINDOWS_10 100
-
-
-int get_windows_version() {
-    OSVERSIONINFO ver_info;
-    BOOL result;
-    DWORD dwMajorVersion;
-    DWORD dwMinorVersion;
-    DWORD dwBuildNumber;
-    static int windows_version = WINDOWS_UNINITIALIZED;
-    // windows_version is static
-    // and equal to WINDOWS_UNINITIALIZED only on first call
-    if (windows_version == WINDOWS_UNINITIALIZED) {
-        memset(&ver_info, 0, sizeof(ver_info));
-        ver_info.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
-        result = GetVersionEx(&ver_info);
-        if (result != FALSE) {
-            dwMajorVersion = ver_info.dwMajorVersion;
-            dwMinorVersion = ver_info.dwMinorVersion;
-            dwBuildNumber = ver_info.dwBuildNumber;
-            // Windows XP, Windows server 2003
-            if (dwMajorVersion == 5 && dwMinorVersion == 1) {
-                windows_version = WINDOWS_XP;
-            }
-            // Windows Vista
-            else if (dwMajorVersion == 6 && dwMinorVersion == 0) {
-                windows_version = WINDOWS_VISTA;
-            }
-            // Windows 7, Windows Server 2008 R2
-            else if (dwMajorVersion == 6 && dwMinorVersion == 1) {
-                windows_version = WINDOWS_7;
-            }
-            // Windows 8, Windows Server 2012
-            else if (dwMajorVersion == 6 && dwMinorVersion == 2) {
-                windows_version = WINDOWS_8;
-            }
-            // Windows 8.1, Windows Server 2012 R2
-            else if (dwMajorVersion == 6 && dwMinorVersion == 3)
-            {
-                windows_version = WINDOWS_81;
-            }
-            // Windows 10, Windows Server 2016
-            else if (dwMajorVersion == 10) {
-                windows_version = WINDOWS_10;
-            }
-        }
+
+// A wrapper around GetModuleHandle and GetProcAddress.
+PVOID
+psutil_GetProcAddress(LPCSTR libname, LPCSTR procname) {
+    HMODULE mod;
+    FARPROC addr;
+
+    if ((mod = GetModuleHandleA(libname)) == NULL) {
+        PyErr_SetFromWindowsErrWithFilename(0, libname);
+        return NULL;
+    }
+    if ((addr = GetProcAddress(mod, procname)) == NULL) {
+        PyErr_SetFromWindowsErrWithFilename(0, procname);
+        return NULL;
     }
-    return windows_version;
+    return addr;
 }
 
 
-_NtQueryInformationProcess psutil_NtQueryInformationProcess() {
-    static _NtQueryInformationProcess NtQueryInformationProcess = NULL;
-    if (NtQueryInformationProcess == NULL) {
-        NtQueryInformationProcess = (_NtQueryInformationProcess)GetProcAddress(
-            GetModuleHandleA("ntdll.dll"), "NtQueryInformationProcess");
+// A wrapper around LoadLibrary and GetProcAddress.
+PVOID
+psutil_GetProcAddressFromLib(LPCSTR libname, LPCSTR procname) {
+    HMODULE mod;
+    FARPROC addr;
+
+    if ((mod = LoadLibraryA(libname)) == NULL) {
+        PyErr_SetFromWindowsErrWithFilename(0, libname);
+        return NULL;
+    }
+    if ((addr = GetProcAddress(mod, procname)) == NULL) {
+        PyErr_SetFromWindowsErrWithFilename(0, procname);
+        FreeLibrary(mod);
+        return NULL;
     }
-    return NtQueryInformationProcess;
+    FreeLibrary(mod);
+    return addr;
 }
 
 
@@ -523,11 +495,8 @@ psutil_get_process_region_size64(HANDLE hProcess,
     MEMORY_BASIC_INFORMATION64 info64;
 
     if (NtWow64QueryVirtualMemory64 == NULL) {
-        NtWow64QueryVirtualMemory64 =
-            (_NtWow64QueryVirtualMemory64)GetProcAddress(
-                    GetModuleHandleA("ntdll.dll"),
-                    "NtWow64QueryVirtualMemory64");
-
+        NtWow64QueryVirtualMemory64 = psutil_GetProcAddressFromLib(
+            "ntdll.dll", "NtWow64QueryVirtualMemory64");
         if (NtWow64QueryVirtualMemory64 == NULL) {
             PyErr_SetString(PyExc_NotImplementedError,
                     "NtWow64QueryVirtualMemory64 missing");
@@ -611,12 +580,15 @@ psutil_get_process_data(long pid,
 #endif
     DWORD access = PROCESS_QUERY_INFORMATION | PROCESS_VM_READ;
 
+    NtQueryInformationProcess = \
+        psutil_GetProcAddress("ntdll.dll", "NtQueryInformationProcess");
+    if (NtQueryInformationProcess == NULL)
+        return -1;
+
     hProcess = psutil_handle_from_pid(pid, access);
     if (hProcess == NULL)
         return -1;
 
-    NtQueryInformationProcess = psutil_NtQueryInformationProcess();
-
 #ifdef _WIN64
     /* 64 bit case.  Check if the target is a 32 bit process running in WoW64
      * mode. */
@@ -679,11 +651,9 @@ psutil_get_process_data(long pid,
         RTL_USER_PROCESS_PARAMETERS64 procParameters64;
 
         if (NtWow64QueryInformationProcess64 == NULL) {
-            NtWow64QueryInformationProcess64 =
-                (_NtQueryInformationProcess)GetProcAddress(
-                        GetModuleHandleA("ntdll.dll"),
-                        "NtWow64QueryInformationProcess64");
-
+            NtWow64QueryInformationProcess64 = \
+                psutil_GetProcAddressFromLib(
+                    "ntdll.dll", "NtWow64QueryInformationProcess64");
             if (NtWow64QueryInformationProcess64 == NULL) {
                 PyErr_SetString(PyExc_NotImplementedError,
                                 "NtWow64QueryInformationProcess64 missing");
@@ -703,11 +673,9 @@ psutil_get_process_data(long pid,
 
         // read peb
         if (NtWow64ReadVirtualMemory64 == NULL) {
-            NtWow64ReadVirtualMemory64 =
-                (_NtWow64ReadVirtualMemory64)GetProcAddress(
-                        GetModuleHandleA("ntdll.dll"),
-                        "NtWow64ReadVirtualMemory64");
-
+            NtWow64ReadVirtualMemory64 = \
+                psutil_GetProcAddressFromLib(
+                    "ntdll.dll", "NtWow64ReadVirtualMemory64");
             if (NtWow64ReadVirtualMemory64 == NULL) {
                 PyErr_SetString(PyExc_NotImplementedError,
                                 "NtWow64ReadVirtualMemory64 missing");
@@ -870,13 +838,12 @@ psutil_get_cmdline_data(long pid, WCHAR **pdata, SIZE_T *psize) {
     WCHAR * cmdline_buffer_wchar = NULL;
     PUNICODE_STRING tmp = NULL;
     DWORD string_size;
-    _NtQueryInformationProcess NtQueryInformationProcess = NULL;
+    _NtQueryInformationProcess NtQueryInformationProcess;
 
-    NtQueryInformationProcess = psutil_NtQueryInformationProcess();
-    if (NtQueryInformationProcess == NULL) {
-        PyErr_SetFromWindowsErr(0);
+    NtQueryInformationProcess = \
+        psutil_GetProcAddress("ntdll.dll", "NtQueryInformationProcess");
+    if (NtQueryInformationProcess == NULL)
         goto error;
-    }
 
     cmdline_buffer = calloc(ret_length, 1);
     if (cmdline_buffer == NULL) {
@@ -885,10 +852,8 @@ psutil_get_cmdline_data(long pid, WCHAR **pdata, SIZE_T *psize) {
     }
 
     hProcess = psutil_handle_from_pid(pid, PROCESS_QUERY_LIMITED_INFORMATION);
-    if (hProcess == NULL) {
-        PyErr_SetFromWindowsErr(0);
+    if (hProcess == NULL)
         goto error;
-    }
     status = NtQueryInformationProcess(
         hProcess,
         60, // ProcessCommandLineInformation
@@ -939,10 +904,8 @@ psutil_get_cmdline(long pid, int use_peb) {
     PyObject *py_unicode = NULL;
     LPWSTR *szArglist = NULL;
     int nArgs, i;
-    int windows_version;
     int func_ret;
 
-    windows_version = get_windows_version();
     /*
     By defaut, still use PEB (if command line params have been patched in
     the PEB, we will get the actual ones). Reading the PEB to get the
@@ -1058,14 +1021,13 @@ psutil_get_proc_info(DWORD pid, PSYSTEM_PROCESS_INFORMATION *retProcess,
     PVOID buffer;
     ULONG bufferSize;
     PSYSTEM_PROCESS_INFORMATION process;
-
-    // get NtQuerySystemInformation
     typedef DWORD (_stdcall * NTQSI_PROC) (int, PVOID, ULONG, PULONG);
     NTQSI_PROC NtQuerySystemInformation;
-    HINSTANCE hNtDll;
-    hNtDll = LoadLibrary(TEXT("ntdll.dll"));
-    NtQuerySystemInformation = (NTQSI_PROC)GetProcAddress(
-        hNtDll, "NtQuerySystemInformation");
+
+    NtQuerySystemInformation = \
+        psutil_GetProcAddressFromLib("ntdll.dll", "NtQuerySystemInformation");
+    if (NtQuerySystemInformation == NULL)
+        goto error;
 
     bufferSize = initialBufferSize;
     buffer = malloc(bufferSize);
@@ -1077,7 +1039,6 @@ psutil_get_proc_info(DWORD pid, PSYSTEM_PROCESS_INFORMATION *retProcess,
     while (TRUE) {
         status = NtQuerySystemInformation(SystemProcessInformation, buffer,
                                           bufferSize, &bufferSize);
-
         if (status == STATUS_BUFFER_TOO_SMALL ||
                 status == STATUS_INFO_LENGTH_MISMATCH)
         {
@@ -1115,7 +1076,6 @@ psutil_get_proc_info(DWORD pid, PSYSTEM_PROCESS_INFORMATION *retProcess,
     goto error;
 
 error:
-    FreeLibrary(hNtDll);
     if (buffer != NULL)
         free(buffer);
     return 0;
diff --git a/psutil/arch/windows/process_info.h b/psutil/arch/windows/process_info.h
index f85c1efd..d2e60b7c 100644
--- a/psutil/arch/windows/process_info.h
+++ b/psutil/arch/windows/process_info.h
@@ -15,7 +15,6 @@
 #define HANDLE_TO_PYNUM(handle) PyLong_FromUnsignedLong((unsigned long) handle)
 #define PYNUM_TO_HANDLE(obj) ((HANDLE)PyLong_AsUnsignedLong(obj))
 
-
 DWORD* psutil_get_pids(DWORD *numberOfReturnedPIDs);
 HANDLE psutil_handle_from_pid(DWORD pid, DWORD dwDesiredAccess);
 int psutil_pid_is_running(DWORD pid);
@@ -24,9 +23,10 @@ int psutil_get_proc_info(DWORD pid, PSYSTEM_PROCESS_INFORMATION *retProcess,
 
 int psutil_assert_pid_exists(DWORD pid, char *err);
 int psutil_assert_pid_not_exists(DWORD pid, char *err);
+PVOID psutil_GetProcAddress(LPCSTR libname, LPCSTR procname);
+PVOID psutil_GetProcAddressFromLib(LPCSTR libname, LPCSTR procname);
 
-
-PyObject* psutil_get_cmdline(long pid);
+PyObject* psutil_get_cmdline(long pid, int use_peb);
 PyObject* psutil_get_cwd(long pid);
 PyObject* psutil_get_environ(long pid);