Source file src/os/exec_unix.go

  // Copyright 2009 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
  
  package os
  
  import (
  	"errors"
  	"runtime"
  	"syscall"
  	"time"
  )
  
  func (p *Process) wait() (ps *ProcessState, err error) {
  	if p.Pid == -1 {
  		return nil, syscall.EINVAL
  	}
  
  	// If we can block until Wait4 will succeed immediately, do so.
  	ready, err := p.blockUntilWaitable()
  	if err != nil {
  		return nil, err
  	}
  	if ready {
  		// Mark the process done now, before the call to Wait4,
  		// so that Process.signal will not send a signal.
  		p.setDone()
  		// Acquire a write lock on sigMu to wait for any
  		// active call to the signal method to complete.
  		p.sigMu.Lock()
  		p.sigMu.Unlock()
  	}
  
  	var status syscall.WaitStatus
  	var rusage syscall.Rusage
  	pid1, e := syscall.Wait4(p.Pid, &status, 0, &rusage)
  	if e != nil {
  		return nil, NewSyscallError("wait", e)
  	}
  	if pid1 != 0 {
  		p.setDone()
  	}
  	ps = &ProcessState{
  		pid:    pid1,
  		status: status,
  		rusage: &rusage,
  	}
  	return ps, nil
  }
  
  var errFinished = errors.New("os: process already finished")
  
  func (p *Process) signal(sig Signal) error {
  	if p.Pid == -1 {
  		return errors.New("os: process already released")
  	}
  	if p.Pid == 0 {
  		return errors.New("os: process not initialized")
  	}
  	p.sigMu.RLock()
  	defer p.sigMu.RUnlock()
  	if p.done() {
  		return errFinished
  	}
  	s, ok := sig.(syscall.Signal)
  	if !ok {
  		return errors.New("os: unsupported signal type")
  	}
  	if e := syscall.Kill(p.Pid, s); e != nil {
  		if e == syscall.ESRCH {
  			return errFinished
  		}
  		return e
  	}
  	return nil
  }
  
  func (p *Process) release() error {
  	// NOOP for unix.
  	p.Pid = -1
  	// no need for a finalizer anymore
  	runtime.SetFinalizer(p, nil)
  	return nil
  }
  
  func findProcess(pid int) (p *Process, err error) {
  	// NOOP for unix.
  	return newProcess(pid, 0), nil
  }
  
  func (p *ProcessState) userTime() time.Duration {
  	return time.Duration(p.rusage.Utime.Nano()) * time.Nanosecond
  }
  
  func (p *ProcessState) systemTime() time.Duration {
  	return time.Duration(p.rusage.Stime.Nano()) * time.Nanosecond
  }
  

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