114 lines
4.6 KiB
Bash
Executable File
114 lines
4.6 KiB
Bash
Executable File
#!/bin/bash
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# Webcam presence detection daemon.
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# Checks for motion at an adaptive interval (20s normally, backed off to 120s
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# under heavy system load) and shares caffeine's systemd-inhibit idle lock
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# while the user is detected, so hypridle never fires during an active session.
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#
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# Camera selection: set PRESENCE_DETECT_CAMERA env var or write
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# CAMERA=<id> to ~/.config/presence-detect.conf
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#
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# Exit codes from python helper: 0=motion, 1=no motion, 2=camera error (busy/unavailable)
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# On camera error the daemon silently skips the tick and leaves the inhibit
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# state exactly as it was on the previous run.
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# Resolve the script's real directory so the Python helper path stays valid
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# even when invoked via a symlink or from a different cwd.
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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PYTHON_DETECT="$SCRIPT_DIR/python/presence_detect.py"
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# Shared with caffeine.sh: both the manual toggle and this daemon drive the
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# same systemd-inhibit lock, so caffeine-status.sh reflects either source.
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PID_FILE="/tmp/caffeine-inhibit.pid"
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# Marks that *this daemon* (not the manual caffeine toggle) currently holds
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# the lock, so a "no motion" tick never releases a manually-started session.
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OWNED_FLAG="/tmp/presence-inhibit-owned"
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PRESENCE_CFG="${XDG_CONFIG_HOME:-$HOME/.config}/presence-detect.conf"
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INTERVAL_IDLE=20 # seconds between checks under normal load
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INTERVAL_BUSY=120 # seconds between checks when CPU or RAM is >= LOAD_THRESHOLD
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LOAD_THRESHOLD=0.70
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NPROC="$(nproc)"
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# Resolve camera ID: env var takes highest priority, then config file, then default 0.
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_camera_id() {
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if [[ -n "$PRESENCE_DETECT_CAMERA" ]]; then
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echo "$PRESENCE_DETECT_CAMERA"
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elif [[ -f "$PRESENCE_CFG" ]]; then
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# -oP 'CAMERA=\K[0-9]+': Perl-style look-behind strips "CAMERA=" prefix.
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grep -oP 'CAMERA=\K[0-9]+' "$PRESENCE_CFG" 2>/dev/null || echo 0
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else
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echo 0
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fi
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}
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# True if 1-minute load average (normalized by core count) or RAM usage is
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# at/above LOAD_THRESHOLD. Load average is a cheap, sampling-free proxy for
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# "CPU busy" — avoids adding an extra measurement delay to every tick.
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_system_busy() {
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local load1 cpu_busy mem_frac mem_busy
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load1="$(awk '{print $1}' /proc/loadavg)"
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cpu_busy="$(awk -v l="$load1" -v n="$NPROC" -v t="$LOAD_THRESHOLD" \
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'BEGIN{print (l/n >= t) ? 1 : 0}')"
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[[ "$cpu_busy" == "1" ]] && return 0
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mem_frac="$(free | awk '/^Mem:/ {print $3/$2}')"
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mem_busy="$(awk -v m="$mem_frac" -v t="$LOAD_THRESHOLD" 'BEGIN{print (m >= t) ? 1 : 0}')"
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[[ "$mem_busy" == "1" ]]
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}
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_next_interval() {
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if _system_busy; then echo "$INTERVAL_BUSY"; else echo "$INTERVAL_IDLE"; fi
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}
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# Returns true if the inhibitor sentinel process is still alive.
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_inhibit_running() {
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[[ -f "$PID_FILE" ]] && kill -0 "$(cat "$PID_FILE")" 2>/dev/null
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}
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_start_inhibit() {
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# Guard: don't start a second inhibitor if one is already active — whether
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# it's ours from a previous tick or a manually-started caffeine session.
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_inhibit_running && return
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# --what=idle: target the logind idle-inhibit lock that hypridle polls.
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# "sleep infinity" is the sentinel; its PID is saved so we can kill it later.
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systemd-inhibit --what=idle --who="presence-detect" \
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--why="User presence detected" --mode=block \
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sleep infinity &
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echo $! > "$PID_FILE"
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touch "$OWNED_FLAG"
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# logger writes to the system journal — visible via `journalctl -t presence-detect`.
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logger -t presence-detect "Motion detected — idle inhibited"
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}
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_stop_inhibit() {
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_inhibit_running || return
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# Never release a lock we didn't start — that would be a manual caffeine
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# session, which must persist regardless of presence.
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[[ -f "$OWNED_FLAG" ]] || return
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# Killing the sleep process releases the systemd-inhibit lock automatically.
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kill "$(cat "$PID_FILE")" 2>/dev/null
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rm -f "$PID_FILE" "$OWNED_FLAG"
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logger -t presence-detect "No motion — idle inhibit released"
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}
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_cleanup() {
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# On daemon stop (systemd unit stop, user logout, etc.), release the lock
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# cleanly, but only if we're the one holding it.
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_stop_inhibit
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exit 0
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}
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# Intercept termination signals to ensure the inhibitor PID is never orphaned.
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trap _cleanup SIGTERM SIGINT SIGHUP
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while true; do
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CAMERA="$(_camera_id)"
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# Run the OpenCV motion detector; stderr suppressed to keep the journal clean.
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python3 "$PYTHON_DETECT" "$CAMERA" 2>/dev/null
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rc=$?
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case $rc in
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0) _start_inhibit ;;
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1) _stop_inhibit ;;
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# rc=2 = camera busy/unavailable — silently skip, state unchanged
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esac
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sleep "$(_next_interval)"
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done
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