github.com/zebozhuang/go@v0.0.0-20200207033046-f8a98f6f5c5d/src/os/exec_unix.go (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
     6  
     7  package os
     8  
     9  import (
    10  	"errors"
    11  	"runtime"
    12  	"syscall"
    13  	"time"
    14  )
    15  
    16  func (p *Process) wait() (ps *ProcessState, err error) {
    17  	if p.Pid == -1 {
    18  		return nil, syscall.EINVAL
    19  	}
    20  
    21  	// If we can block until Wait4 will succeed immediately, do so.
    22  	ready, err := p.blockUntilWaitable()
    23  	if err != nil {
    24  		return nil, err
    25  	}
    26  	if ready {
    27  		// Mark the process done now, before the call to Wait4,
    28  		// so that Process.signal will not send a signal.
    29  		p.setDone()
    30  		// Acquire a write lock on sigMu to wait for any
    31  		// active call to the signal method to complete.
    32  		p.sigMu.Lock()
    33  		p.sigMu.Unlock()
    34  	}
    35  
    36  	var status syscall.WaitStatus
    37  	var rusage syscall.Rusage
    38  	pid1, e := syscall.Wait4(p.Pid, &status, 0, &rusage)
    39  	if e != nil {
    40  		return nil, NewSyscallError("wait", e)
    41  	}
    42  	if pid1 != 0 {
    43  		p.setDone()
    44  	}
    45  	ps = &ProcessState{
    46  		pid:    pid1,
    47  		status: status,
    48  		rusage: &rusage,
    49  	}
    50  	return ps, nil
    51  }
    52  
    53  var errFinished = errors.New("os: process already finished")
    54  
    55  func (p *Process) signal(sig Signal) error {
    56  	if p.Pid == -1 {
    57  		return errors.New("os: process already released")
    58  	}
    59  	if p.Pid == 0 {
    60  		return errors.New("os: process not initialized")
    61  	}
    62  	p.sigMu.RLock()
    63  	defer p.sigMu.RUnlock()
    64  	if p.done() {
    65  		return errFinished
    66  	}
    67  	s, ok := sig.(syscall.Signal)
    68  	if !ok {
    69  		return errors.New("os: unsupported signal type")
    70  	}
    71  	if e := syscall.Kill(p.Pid, s); e != nil {
    72  		if e == syscall.ESRCH {
    73  			return errFinished
    74  		}
    75  		return e
    76  	}
    77  	return nil
    78  }
    79  
    80  func (p *Process) release() error {
    81  	// NOOP for unix.
    82  	p.Pid = -1
    83  	// no need for a finalizer anymore
    84  	runtime.SetFinalizer(p, nil)
    85  	return nil
    86  }
    87  
    88  func findProcess(pid int) (p *Process, err error) {
    89  	// NOOP for unix.
    90  	return newProcess(pid, 0), nil
    91  }
    92  
    93  func (p *ProcessState) userTime() time.Duration {
    94  	return time.Duration(p.rusage.Utime.Nano()) * time.Nanosecond
    95  }
    96  
    97  func (p *ProcessState) systemTime() time.Duration {
    98  	return time.Duration(p.rusage.Stime.Nano()) * time.Nanosecond
    99  }