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fix(windows): use GetTickCount64 to prevent overflow after 49.7 days (#76)
GetTickCount returns a DWORD (32-bit) that wraps at 2^32 ms (~49.7 days of uptime). After wrapping, the idle time calculation would produce incorrect values (either negative or huge numbers). Switch to GetTickCount64 which returns a 64-bit value with no practical overflow limit. Also handle the 32-bit wraparound of dwTime from GetLastInputInfo (which always returns DWORD per the Windows API). Fixes #16
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Lines changed: 23 additions & 7 deletions

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‎aw_watcher_afk/windows.py‎

Lines changed: 23 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,10 @@
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import ctypes
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import time
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from ctypes import POINTER, WINFUNCTYPE, Structure # type: ignore
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from ctypes import POINTER, WINFUNCTYPE, Structure, c_ulonglong # type: ignore
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from ctypes.wintypes import BOOL, DWORD, UINT
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ULONGLONG = c_ulonglong
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class LastInputInfo(Structure):
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_fields_ = [("cbSize", UINT), ("dwTime", DWORD)]
@@ -19,16 +21,30 @@ def _getLastInputTick() -> int:
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return lastinput.dwTime
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def _getTickCount() -> int:
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prototype = WINFUNCTYPE(DWORD)
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def _getTickCount64() -> int:
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"""Use GetTickCount64 to avoid 32-bit overflow after ~49.7 days of uptime."""
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prototype = WINFUNCTYPE(ULONGLONG)
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paramflags = ()
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c_GetTickCount = prototype(("GetTickCount", ctypes.windll.kernel32), paramflags) # type: ignore
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return c_GetTickCount()
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c_GetTickCount64 = prototype(("GetTickCount64", ctypes.windll.kernel32), paramflags) # type: ignore
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return c_GetTickCount64()
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def seconds_since_last_input():
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seconds_since_input = (_getTickCount() - _getLastInputTick()) / 1000
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return seconds_since_input
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tick_count = _getTickCount64()
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last_input_tick = _getLastInputTick() # 32-bit DWORD from GetLastInputInfo
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# GetLastInputInfo returns a 32-bit DWORD tick count that wraps at 2^32 ms.
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# GetTickCount64 returns 64-bit. To compute the difference correctly, we
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# compare only the lower 32 bits when the values are close (normal case),
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# and handle the wraparound when dwTime > lower 32 bits of tick_count.
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tick_lower32 = tick_count & 0xFFFFFFFF
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if tick_lower32 >= last_input_tick:
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diff_ms = tick_lower32 - last_input_tick
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else:
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# 32-bit wraparound: tick_count's lower bits wrapped past dwTime
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diff_ms = (0x100000000 - last_input_tick) + tick_lower32
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return diff_ms / 1000
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if __name__ == "__main__":

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