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// Copyright (c) 2012 VMware, Inc.
// +build darwin freebsd netbsd openbsd
// Go interface to BSD kqueue process events.
package psnotify
import (
"syscall"
)
const (
// Flags (from <sys/event.h>)
PROC_EVENT_FORK = syscall.NOTE_FORK // fork() events
PROC_EVENT_EXEC = syscall.NOTE_EXEC // exec() events
PROC_EVENT_EXIT = syscall.NOTE_EXIT // exit() events
// Watch for all process events
PROC_EVENT_ALL = PROC_EVENT_FORK | PROC_EVENT_EXEC | PROC_EVENT_EXIT
)
type kqueueListener struct {
kq int // The syscall.Kqueue() file descriptor
buf [1]syscall.Kevent_t // An event buffer for Add/Remove watch
}
// Initialize bsd implementation of the eventListener interface
func createListener() (eventListener, error) {
listener := &kqueueListener{}
kq, err := syscall.Kqueue()
listener.kq = kq
return listener, err
}
// Initialize Kevent_t fields and propagate changelist for the given pid
func (w *Watcher) kevent(pid int, fflags uint32, flags int) error {
listener, _ := w.listener.(*kqueueListener)
event := &listener.buf[0]
syscall.SetKevent(event, pid, syscall.EVFILT_PROC, flags)
event.Fflags = fflags
_, err := syscall.Kevent(listener.kq, listener.buf[:], nil, nil)
return err
}
// Delete filter for given pid from the queue
func (w *Watcher) unregister(pid int) error {
return w.kevent(pid, 0, syscall.EV_DELETE)
}
// Add and enable filter for given pid in the queue
func (w *Watcher) register(pid int, flags uint32) error {
return w.kevent(pid, flags, syscall.EV_ADD|syscall.EV_ENABLE)
}
// Poll the kqueue file descriptor and dispatch to the Event channels
func (w *Watcher) readEvents() {
listener, _ := w.listener.(*kqueueListener)
events := make([]syscall.Kevent_t, 10)
for {
if w.isDone() {
return
}
n, err := syscall.Kevent(listener.kq, nil, events, nil)
if err != nil {
w.Error <- err
continue
}
for _, ev := range events[:n] {
pid := int(ev.Ident)
switch ev.Fflags {
case syscall.NOTE_FORK:
w.Fork <- &ProcEventFork{ParentPid: pid}
case syscall.NOTE_EXEC:
w.Exec <- &ProcEventExec{Pid: pid}
case syscall.NOTE_EXIT:
w.RemoveWatch(pid)
w.Exit <- &ProcEventExit{Pid: pid}
}
}
}
}
// Close our kqueue file descriptor; deletes any remaining filters
func (listener *kqueueListener) close() error {
return syscall.Close(listener.kq)
}
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