fix(evdev): skip pointer-motion devices in keyboard discovery (#902)
* fix(evdev): skip pointer-motion devices in keyboard discovery find_keyboard_devices() treated any device with a nonzero EV_KEY bitmap as a keyboard, which includes Logitech mice (G502, MX Master 3) whose button interfaces report key bits. The hub then grabbed them (EVIOCGRAB) and re-emitted every event, including EV_REL pointer motion, through a paired uinput clone — piping all cursor movement through the reader thread and showing up as periodic cursor stutter. Discovery now excludes devices that report pointer motion (REL_X+REL_Y or ABS_X+ABS_Y) in both the /proc/bus/input/devices parser and the evdev.list_devices() fallback. Wheel-only devices (REL_WHEEL) and real keyboards are unaffected, and a mouse's separate keyboard interface node keeps working for shortcuts. Fixes #900 * test(evdev): annotate new device-discovery tests * chore: drop accidentally committed pr_body.md --------- Co-authored-by: Jatin K Malik <jatinkrmalik@gmail.com>
This commit is contained in:
devin-ai-integration[bot]
co-authored by
Jatin K Malik
Jatin K Malik
parent
758f640787
commit
af1029dc60
@@ -25,7 +25,7 @@ import select
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import threading
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import time
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import weakref
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from typing import Any, Optional, Sequence, TextIO
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from typing import Any, Mapping, Optional, Sequence, TextIO
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# Try to import evdev
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try:
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@@ -253,6 +253,10 @@ def find_keyboard_devices() -> list[str]:
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"""
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Find all keyboard input devices.
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Devices that emit pointer motion (REL_X/Y or ABS_X/Y) are excluded:
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a mouse is not a keyboard, and monitoring one proxies all cursor
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movement through the reader thread (cursor stutter, #900).
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Prefers /proc/bus/input/devices (host installs). Falls back to
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``evdev.list_devices()`` when that path cannot be read (common under snap
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confinement: raw-input grants /dev/input/event*, while hardware-observe
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@@ -277,34 +281,107 @@ def find_keyboard_devices() -> list[str]:
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return fallback
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# Bits 0 and 1 of a REL or ABS capability bitmap: REL_X|REL_Y or
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# ABS_X|ABS_Y — pointer motion. A keyboard never reports both; devices
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# that do are mice, trackpads or tablets, and monitoring one meant
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# grabbing it and piping all cursor movement through the reader thread,
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# which showed up as periodic cursor stutter (#900).
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_POINTER_AXIS_BITS = 0x3
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def _bitmap_has_any_bit(hex_bitmap: str) -> bool:
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"""True when any word of a /proc capability bitmap has a bit set."""
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try:
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return any(int(word, 16) for word in hex_bitmap.split())
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except ValueError:
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return False
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def _bitmap_low_bits(hex_bitmap: str) -> int:
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"""Low word (bits 0-63) of a /proc capability bitmap, or 0.
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Bitmaps print most-significant word first, so axis bits 0..63 live in
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the last word on the line.
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"""
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words = hex_bitmap.split()
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if not words:
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return 0
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try:
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return int(words[-1], 16)
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except ValueError:
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return 0
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def _proc_block_has_pointer_axes(device: dict[str, Any]) -> bool:
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"""True when a parsed /proc device block reports pointer motion axes."""
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return (
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_bitmap_low_bits(device.get("rel", "")) & _POINTER_AXIS_BITS == _POINTER_AXIS_BITS
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or _bitmap_low_bits(device.get("abs", "")) & _POINTER_AXIS_BITS == _POINTER_AXIS_BITS
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)
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def _parse_keyboard_devices_from_proc(proc_file: TextIO) -> list[str]:
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"""Parse an open /proc/bus/input/devices stream for event KEY devices."""
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"""Parse an open /proc/bus/input/devices stream for event KEY devices.
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Devices that emit pointer motion (REL_X/Y or ABS_X/Y) are skipped:
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mice and tablets report EV_KEY bits for their buttons, but grabbing
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them proxies every cursor movement through this reader.
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"""
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keyboard_devices: list[str] = []
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current_device = None
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device: Optional[dict[str, Any]] = None
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def finish_device() -> None:
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nonlocal device
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if device is None:
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return
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if _bitmap_has_any_bit(device.get("key", "")):
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if _proc_block_has_pointer_axes(device):
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logger.debug(
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"Skipping pointer device during keyboard discovery: "
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f"{device.get('name', '?')} ({device.get('handlers', [])})"
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)
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else:
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for handler in device.get("handlers", []):
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if handler.startswith("event"):
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device_path = f"/dev/input/{handler}"
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if os.path.exists(device_path):
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keyboard_devices.append(device_path)
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device = None
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with proc_file as f:
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for line in f:
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line = line.rstrip("\n")
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if line.startswith("I: Bus="):
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current_device = {"handlers": []}
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elif line.startswith("H: Handlers=") and current_device is not None:
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handlers = line.split("=", 1)[1].strip()
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current_device["handlers"] = handlers.split()
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elif line.startswith("B: KEY=") and current_device is not None:
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# Check if this device has keyboard keys (bit 0 is set)
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key_bits = line.split("=", 1)[1].strip()
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# The first hex digit after KEY= contains keyboard capability
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# If it's not 0, 1, or ffffffffff, it has keyboard keys
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if key_bits and key_bits != "0":
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# Check if event handler exists
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for handler in current_device.get("handlers", []):
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if handler.startswith("event"):
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device_path = f"/dev/input/{handler}"
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if os.path.exists(device_path):
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keyboard_devices.append(device_path)
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current_device = None
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finish_device()
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device = {}
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elif device is not None:
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if line.startswith("N: Name="):
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device["name"] = line.split("=", 1)[1].strip().strip('"')
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elif line.startswith("H: Handlers="):
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device["handlers"] = line.split("=", 1)[1].strip().split()
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elif line.startswith("B: KEY="):
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device["key"] = line.split("=", 1)[1].strip()
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elif line.startswith("B: REL="):
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device["rel"] = line.split("=", 1)[1].strip()
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elif line.startswith("B: ABS="):
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device["abs"] = line.split("=", 1)[1].strip()
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finish_device()
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return keyboard_devices
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def _capabilities_have_pointer_axes(capabilities: Mapping[int, Sequence[int]]) -> bool:
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"""True when the device reports REL_X+REL_Y or ABS_X+ABS_Y pointer axes."""
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rel_codes = capabilities.get(ecodes.EV_REL, ())
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if ecodes.REL_X in rel_codes and ecodes.REL_Y in rel_codes:
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return True
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# capabilities() reports EV_ABS entries as (code, AbsInfo) pairs.
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abs_codes = {
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entry[0] if isinstance(entry, (tuple, list)) else entry
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for entry in capabilities.get(ecodes.EV_ABS, ())
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}
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return ecodes.ABS_X in abs_codes and ecodes.ABS_Y in abs_codes
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def _find_keyboard_devices_from_evdev() -> list[str]:
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"""Discover keyboards by opening devices from ``evdev.list_devices()``."""
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if not EVDEV_AVAILABLE:
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@@ -322,11 +399,18 @@ def _find_keyboard_devices_from_evdev() -> list[str]:
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device = InputDevice(path)
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try:
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capabilities = device.capabilities()
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device_name = str(getattr(device, "name", "") or "")
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finally:
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device.close()
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except (OSError, IOError, TypeError, ValueError):
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continue
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if capabilities and _capabilities_have_pointer_axes(capabilities):
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# Mice/tablets also report EV_KEY for their buttons; monitoring
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# a pointer pipes all cursor movement through this reader.
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logger.debug(f"Skipping pointer device during keyboard discovery: {device_name}")
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continue
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# Prefer devices that look like keyboards: EV_KEY with a common letter
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# or a modifier. This includes combo "Keyboard" nodes on mice/remotes.
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key_caps = capabilities.get(ecodes.EV_KEY, []) if capabilities else []
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