95 lines
2.4 KiB
Go
95 lines
2.4 KiB
Go
//go:build linux
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package evidence
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import (
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"context"
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"log"
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"github.com/jezek/xgb/xproto"
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"github.com/jezek/xgbutil"
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"github.com/jezek/xgbutil/ewmh"
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"github.com/jezek/xgbutil/icccm"
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"github.com/jezek/xgbutil/xevent"
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"github.com/jezek/xgbutil/xprop"
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"github.com/jezek/xgbutil/xwindow"
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)
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// NewSource returns the real X11 active-window sensor.
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func NewSource() Source { return &x11Source{} }
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type x11Source struct{}
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// Watch opens one long-lived X connection, subscribes to _NET_ACTIVE_WINDOW
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// changes on the root window, and emits a snapshot immediately plus on every
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// change. Any failure degrades to an Unavailable snapshot; it never panics the
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// daemon.
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func (s *x11Source) Watch(ctx context.Context, onChange func(WindowSnapshot)) {
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X, err := xgbutil.NewConn()
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if err != nil {
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onChange(unavailable("cannot connect to X server: " + err.Error()))
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<-ctx.Done()
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return
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}
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defer X.Conn().Close()
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root := X.RootWin()
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activeAtom, err := xprop.Atm(X, "_NET_ACTIVE_WINDOW")
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if err != nil {
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onChange(unavailable("no _NET_ACTIVE_WINDOW atom: " + err.Error()))
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<-ctx.Done()
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return
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}
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// Listen for property changes on the root window.
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if err := xwindow.New(X, root).Listen(xproto.EventMaskPropertyChange); err != nil {
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onChange(unavailable("cannot listen on root window: " + err.Error()))
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<-ctx.Done()
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return
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}
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emit := func() { onChange(snapshot(X)) }
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emit() // immediate current window
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xevent.PropertyNotifyFun(func(_ *xgbutil.XUtil, ev xevent.PropertyNotifyEvent) {
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if ev.Atom == activeAtom {
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emit()
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}
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}).Connect(X, root)
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// Run the event loop until ctx is cancelled.
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go func() {
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<-ctx.Done()
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xevent.Quit(X)
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}()
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xevent.Main(X)
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}
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func snapshot(X *xgbutil.XUtil) WindowSnapshot {
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active, err := ewmh.ActiveWindowGet(X)
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if err != nil || active == 0 {
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return unavailable("no active window")
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}
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title, err := ewmh.WmNameGet(X, active)
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if err != nil || title == "" {
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// Fall back to ICCCM WM_NAME.
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if t, e := icccm.WmNameGet(X, active); e == nil {
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title = t
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}
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}
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var class string
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if wmClass, err := icccm.WmClassGet(X, active); err == nil && wmClass != nil {
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class = wmClass.Class
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}
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return WindowSnapshot{
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Title: title,
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Class: class,
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Health: EvidenceHealth{Available: true},
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}
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}
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func unavailable(reason string) WindowSnapshot {
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log.Printf("evidence: %s", reason)
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return WindowSnapshot{Health: EvidenceHealth{Available: false, Reason: reason}}
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}
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