refactor code to use a common utility functionwin-time-precision

4 files changed, 47 insertions, 29 deletions

diff --git a/psutil/_psutil_common.c b/psutil/_psutil_common.c
index 028e48e0..07578eda 100644
--- a/psutil/_psutil_common.c
+++ b/psutil/_psutil_common.c
@@ -352,6 +352,7 @@ psutil_set_winver() {
     return 0;
 }
 
+
 int
 psutil_load_globals() {
     if (psutil_loadlibs() != 0)
@@ -362,4 +363,41 @@ psutil_load_globals() {
     InitializeCriticalSection(&PSUTIL_CRITICAL_SECTION);
     return 0;
 }
+
+
+/*
+ * Convert the hi and lo parts of a FILETIME structure or a LARGE_INTEGER
+ * to a UNIX time.
+ * A FILETIME contains a 64-bit value representing the number of
+ * 100-nanosecond intervals since January 1, 1601 (UTC).
+ * A UNIX time is the number of seconds that have elapsed since the
+ * UNIX epoch, that is the time 00:00:00 UTC on 1 January 1970.
+ */
+static double
+_to_unix_time(ULONGLONG hiPart, ULONGLONG loPart) {
+    ULONGLONG ret;
+
+    // 100 nanosecond intervals since January 1, 1601.
+    ret = hiPart << 32;
+    ret += loPart;
+    // Change starting time to the Epoch (00:00:00 UTC, January 1, 1970).
+    ret -= 116444736000000000ull;
+    // Convert nano secs to secs.
+    return (double) ret / 10000000ull;
+}
+
+
+double
+psutil_FiletimeToUnixTime(FILETIME ft) {
+    return _to_unix_time((ULONGLONG)ft.dwHighDateTime,
+                         (ULONGLONG)ft.dwLowDateTime);
+
+}
+
+
+double
+psutil_LargeIntegerToUnixTime(LARGE_INTEGER li) {
+    return _to_unix_time((ULONGLONG)li.HighPart,
+                         (ULONGLONG)li.LowPart);
+}
 #endif  // PSUTIL_WINDOWS
diff --git a/psutil/_psutil_common.h b/psutil/_psutil_common.h
index 9e1ef887..65defdac 100644
--- a/psutil/_psutil_common.h
+++ b/psutil/_psutil_common.h
@@ -137,4 +137,6 @@ int psutil_setup(void);
     PVOID psutil_GetProcAddress(LPCSTR libname, LPCSTR procname);
     PVOID psutil_GetProcAddressFromLib(LPCSTR libname, LPCSTR procname);
     PVOID psutil_SetFromNTStatusErr(NTSTATUS Status, const char *syscall);
+    double psutil_FiletimeToUnixTime(FILETIME ft);
+    double psutil_LargeIntegerToUnixTime(LARGE_INTEGER li);
 #endif
diff --git a/psutil/_psutil_windows.c b/psutil/_psutil_windows.c
index 6b4d2e59..64592103 100644
--- a/psutil/_psutil_windows.c
+++ b/psutil/_psutil_windows.c
@@ -45,27 +45,6 @@ static PyObject *TimeoutAbandoned;
 
 
 /*
- * Convert a FILETIME structure to a UNIX time.
- * A FILETIME contains a 64-bit value representing the number of
- * 100-nanosecond intervals since January 1, 1601 (UTC).
- * A UNIX time is the number of seconds that have elapsed since the
- * UNIX epoch, that is the time 00:00:00 UTC on 1 January 1970
- */
-double
-psutil_FileTimeToUnixTime(FILETIME ft) {
-    ULONGLONG ull;
-
-    // 100 nanosecond intervals since January 1, 1601
-    ull = (ULONGLONG)ft.dwHighDateTime << 32;
-    ull += (ULONGLONG)ft.dwLowDateTime;
-    // change starting time to the Epoch (00:00:00 UTC, January 1, 1970)
-    ull -= 116444736000000000ull;
-    // convert nano secs to secs
-    return (double) ull / 10000000ull;
-}
-
-
-/*
  * Return the number of logical, active CPUs. Return 0 if undetermined.
  * See discussion at: https://bugs.python.org/issue33166#msg314631
  */
@@ -106,7 +85,7 @@ psutil_boot_time(PyObject *self, PyObject *args) {
     GetSystemTimeAsFileTime(&fileTime);
     // Number of milliseconds that have elapsed since the system was started.
     upTime = GetTickCount64() / 1000ull;
-    return Py_BuildValue("d", psutil_FileTimeToUnixTime(fileTime) - upTime);
+    return Py_BuildValue("d", psutil_FiletimeToUnixTime(fileTime) - upTime);
 }
 
 
@@ -366,7 +345,7 @@ psutil_proc_create_time(PyObject *self, PyObject *args) {
     }
 
     CloseHandle(hProcess);
-    return Py_BuildValue("d", psutil_FileTimeToUnixTime(ftCreate));
+    return Py_BuildValue("d", psutil_FiletimeToUnixTime(ftCreate));
 }
 
 
diff --git a/psutil/arch/windows/process_info.c b/psutil/arch/windows/process_info.c
index d8104c81..73a69912 100644
--- a/psutil/arch/windows/process_info.c
+++ b/psutil/arch/windows/process_info.c
@@ -578,7 +578,8 @@ out:
  * fills the structure with various process information in one shot
  * by using NtQuerySystemInformation.
  * We use this as a fallback when faster functions fail with access
- * denied. This is slower because it iterates over all processes.
+ * denied. This is slower because it iterates over all processes
+ * but it doesn't require any privilege (also work for PID 0).
  * On success return 1, else 0 with Python exception already set.
  */
 int
@@ -669,7 +670,7 @@ psutil_proc_info(PyObject *self, PyObject *args) {
     ULONG ctx_switches = 0;
     double user_time;
     double kernel_time;
-    long long create_time;
+    double create_time;
     PyObject *py_retlist;
 
     if (! PyArg_ParseTuple(args, _Py_PARSE_PID, &pid))
@@ -692,9 +693,7 @@ psutil_proc_info(PyObject *self, PyObject *args) {
         create_time = 0;
     }
     else {
-        create_time = ((LONGLONG)process->CreateTime.HighPart) << 32;
-        create_time += process->CreateTime.LowPart - 116444736000000000LL;
-        create_time /= 10000000;
+        create_time = psutil_LargeIntegerToUnixTime(process->CreateTime);
     }
 
     py_retlist = Py_BuildValue(
@@ -707,7 +706,7 @@ psutil_proc_info(PyObject *self, PyObject *args) {
         ctx_switches,                           // num ctx switches
         user_time,                              // cpu user time
         kernel_time,                            // cpu kernel time
-        (double)create_time,                    // create time
+        create_time,                            // create time
         (int)process->NumberOfThreads,          // num threads
         // IO counters
         process->ReadOperationCount.QuadPart,   // io rcount