#1379 - Windows: suspend / resume process by using native APIs

HISTORY.rst

@@ -7,6 +7,9 @@ XXXX-XX-XX
 
 **Enhancements**
 
+- 1379_: [Windows] Process suspend() and resume() now use NtSuspendProcess
+  and NtResumeProcess instead of stopping/resuming all threads of a process.
+  This is faster and more reliable (aka this is what ProcessHacker does).
 - 1420_: [Windows] in case of exception disk_usage() now also shows the path
   name.
 - 1422_: [Windows] Windows APIs requiring to be dynamically loaded from DLL

psutil/_psutil_windows.c

@@ -1019,93 +1019,31 @@ psutil_proc_cwd(PyObject *self, PyObject *args) {
 /*
  * Resume or suspends a process
  */
-int
-psutil_proc_suspend_or_resume(DWORD pid, int suspend) {
-    // a huge thanks to http://www.codeproject.com/KB/threads/pausep.aspx
-    HANDLE hThreadSnap = NULL;
-    HANDLE hThread;
-    THREADENTRY32  te32 = {0};
-
-    if (pid == 0) {
-        AccessDenied("");
-        return FALSE;
-    }
-
-    hThreadSnap = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0);
-    if (hThreadSnap == INVALID_HANDLE_VALUE) {
-        PyErr_SetFromOSErrnoWithSyscall("CreateToolhelp32Snapshot");
-        return FALSE;
-    }
-
-    // Fill in the size of the structure before using it
-    te32.dwSize = sizeof(THREADENTRY32);
-
-    if (! Thread32First(hThreadSnap, &te32)) {
-        PyErr_SetFromOSErrnoWithSyscall("Thread32First");
-        CloseHandle(hThreadSnap);
-        return FALSE;
-    }
-
-    // Walk the thread snapshot to find all threads of the process.
-    // If the thread belongs to the process, add its information
-    // to the display list.
-    do {
-        if (te32.th32OwnerProcessID == pid) {
-            hThread = OpenThread(THREAD_SUSPEND_RESUME, FALSE,
-                                 te32.th32ThreadID);
-            if (hThread == NULL) {
-                PyErr_SetFromOSErrnoWithSyscall("OpenThread");
-                CloseHandle(hThread);
-                CloseHandle(hThreadSnap);
-                return FALSE;
-            }
-            if (suspend == 1) {
-                if (SuspendThread(hThread) == (DWORD) - 1) {
-                    PyErr_SetFromOSErrnoWithSyscall("SuspendThread");
-                    CloseHandle(hThread);
-                    CloseHandle(hThreadSnap);
-                    return FALSE;
-                }
-            }
-            else {
-                if (ResumeThread(hThread) == (DWORD) - 1) {
-                    PyErr_SetFromOSErrnoWithSyscall("ResumeThread");
-                    CloseHandle(hThread);
-                    CloseHandle(hThreadSnap);
-                    return FALSE;
-                }
-            }
-            CloseHandle(hThread);
-        }
-    } while (Thread32Next(hThreadSnap, &te32));
-
-    CloseHandle(hThreadSnap);
-    return TRUE;
-}
-
-
 static PyObject *
-psutil_proc_suspend(PyObject *self, PyObject *args) {
+psutil_proc_suspend_or_resume(PyObject *self, PyObject *args) {
     long pid;
-    int suspend = 1;
+    int ret;
+    HANDLE hProcess;
+    PyObject* suspend;
 
-    if (! PyArg_ParseTuple(args, "l", &pid))
+    if (! PyArg_ParseTuple(args, "lO", &pid, &suspend))
         return NULL;
-    if (! psutil_proc_suspend_or_resume(pid, suspend))
-        return NULL;
-    Py_RETURN_NONE;
-}
 
+    hProcess = psutil_handle_from_pid(pid, PROCESS_SUSPEND_RESUME);
+    if (hProcess == NULL)
+        return NULL;
 
-static PyObject *
-psutil_proc_resume(PyObject *self, PyObject *args) {
-    long pid;
-    int suspend = 0;
+    if (PyObject_IsTrue(suspend))
+        ret = psutil_NtSuspendProcess(hProcess);
+    else
+        ret = psutil_NtResumeProcess(hProcess);
 
-    if (! PyArg_ParseTuple(args, "l", &pid))
-        return NULL;
-    if (! psutil_proc_suspend_or_resume(pid, suspend))
+    if (ret != 0) {
+        PyErr_SetFromWindowsErr(0);
+        CloseHandle(hProcess);
         return NULL;
+    }
+    CloseHandle(hProcess);
     Py_RETURN_NONE;
 }
 
@@ -2060,8 +1998,7 @@ psutil_proc_cpu_affinity_set(PyObject *self, PyObject *args) {
 
 
 /*
- * Return True if one of the process threads is in a waiting or
- * suspended status.
+ * Return True if all process threads are in waiting/suspended state.
  */
 static PyObject *
 psutil_proc_is_suspended(PyObject *self, PyObject *args) {
@@ -2072,9 +2009,8 @@ psutil_proc_is_suspended(PyObject *self, PyObject *args) {
 
     if (! PyArg_ParseTuple(args, "l", &pid))
         return NULL;
-    if (! psutil_get_proc_info(pid, &process, &buffer)) {
+    if (! psutil_get_proc_info(pid, &process, &buffer))
         return NULL;
-    }
     for (i = 0; i < process->NumberOfThreads; i++) {
         if (process->Threads[i].ThreadState != Waiting ||
                 process->Threads[i].WaitReason != Suspended)
@@ -3430,7 +3366,8 @@ psutil_sensors_battery(PyObject *self, PyObject *args) {
 static PyMethodDef
 PsutilMethods[] = {
     // --- per-process functions
-    {"proc_cmdline", (PyCFunction)(void(*)(void))psutil_proc_cmdline, METH_VARARGS | METH_KEYWORDS,
+    {"proc_cmdline", (PyCFunction)(void(*)(void))psutil_proc_cmdline,
+        METH_VARARGS | METH_KEYWORDS,
      "Return process cmdline as a list of cmdline arguments"},
     {"proc_environ", psutil_proc_environ, METH_VARARGS,
      "Return process environment data"},
@@ -3451,10 +3388,8 @@ PsutilMethods[] = {
      "Return the USS of the process"},
     {"proc_cwd", psutil_proc_cwd, METH_VARARGS,
      "Return process current working directory"},
-    {"proc_suspend", psutil_proc_suspend, METH_VARARGS,
-     "Suspend a process"},
-    {"proc_resume", psutil_proc_resume, METH_VARARGS,
-     "Resume a process"},
+    {"proc_suspend_or_resume", psutil_proc_suspend_or_resume, METH_VARARGS,
+     "Suspend or resume a process"},
     {"proc_open_files", psutil_proc_open_files, METH_VARARGS,
      "Return files opened by process"},
     {"proc_username", psutil_proc_username, METH_VARARGS,

psutil/_pswindows.py

@@ -913,11 +913,11 @@ def cpu_times(self):
 
     @wrap_exceptions
     def suspend(self):
-        return cext.proc_suspend(self.pid)
+        cext.proc_suspend_or_resume(self.pid, True)
 
     @wrap_exceptions
     def resume(self):
-        return cext.proc_resume(self.pid)
+        cext.proc_suspend_or_resume(self.pid, False)
 
     @wrap_exceptions
     def cwd(self):

psutil/arch/windows/global.c

@@ -117,6 +117,16 @@ psutil_loadlibs() {
     if (! psutil_RtlGetVersion)
         return 1;
 
+    psutil_NtSuspendProcess = psutil_GetProcAddressFromLib(
+        "ntdll", "NtSuspendProcess");
+    if (! psutil_NtSuspendProcess)
+        return 1;
+
+    psutil_NtResumeProcess = psutil_GetProcAddressFromLib(
+        "ntdll", "NtResumeProcess");
+    if (! psutil_NtResumeProcess)
+        return 1;
+
     /*
      * Optional.
      */

psutil/arch/windows/global.h

@@ -62,3 +62,9 @@ _GetLogicalProcessorInformationEx \
 
 _RtlGetVersion \
     psutil_RtlGetVersion;
+
+_NtSuspendProcess \
+    psutil_NtSuspendProcess;
+
+_NtResumeProcess \
+    psutil_NtResumeProcess;

psutil/arch/windows/ntextapi.h

@@ -455,4 +455,12 @@ typedef NTSTATUS (WINAPI *_RtlGetVersion) (
     PRTL_OSVERSIONINFOW lpVersionInformation
 );
 
+typedef NTSTATUS (WINAPI *_NtResumeProcess) (
+    HANDLE hProcess
+);
+
+typedef NTSTATUS (WINAPI *_NtSuspendProcess) (
+    HANDLE hProcess
+);
+
 #endif // __NTEXTAPI_H__

psutil/arch/windows/process_info.c

@@ -222,17 +222,21 @@ psutil_is_phandle_running(HANDLE hProcess, DWORD pid) {
 HANDLE
 psutil_check_phandle(HANDLE hProcess, DWORD pid) {
     int ret = psutil_is_phandle_running(hProcess, pid);
-    if (ret == 1)
+    if (ret == 1) {
         return hProcess;
-    else if (ret == 0)
+    }
+    else if (ret == 0) {
         return NoSuchProcess("");
-    else if (ret == -1)
+    }
+    else if (ret == -1) {
         if (GetLastError() == ERROR_ACCESS_DENIED)
             return PyErr_SetFromWindowsErr(0);
         else
             return PyErr_SetFromOSErrnoWithSyscall("OpenProcess");
-    else  // -2
+    }
+    else {
         return NULL;
+    }
 }
 
 
@@ -244,15 +248,16 @@ psutil_check_phandle(HANDLE hProcess, DWORD pid) {
  * Return a process handle or NULL.
  */
 HANDLE
-psutil_handle_from_pid(DWORD pid, DWORD dwDesiredAccess) {
+psutil_handle_from_pid(DWORD pid, DWORD access) {
     HANDLE hProcess;
 
     if (pid == 0) {
         // otherwise we'd get NoSuchProcess
         return AccessDenied("");
     }
-
-    hProcess = OpenProcess(dwDesiredAccess, FALSE, pid);
+    // needed for GetExitCodeProcess
+    access |= PROCESS_QUERY_LIMITED_INFORMATION;
+    hProcess = OpenProcess(access, FALSE, pid);
     return psutil_check_phandle(hProcess, pid);
 }