Source file src/os/exec_posix.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 windows
  
  package os
  
  import (
  	"syscall"
  )
  
  // The only signal values guaranteed to be present on all systems
  // are Interrupt (send the process an interrupt) and Kill (force
  // the process to exit).
  var (
  	Interrupt Signal = syscall.SIGINT
  	Kill      Signal = syscall.SIGKILL
  )
  
  func startProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
  	// If there is no SysProcAttr (ie. no Chroot or changed
  	// UID/GID), double-check existence of the directory we want
  	// to chdir into. We can make the error clearer this way.
  	if attr != nil && attr.Sys == nil && attr.Dir != "" {
  		if _, err := Stat(attr.Dir); err != nil {
  			pe := err.(*PathError)
  			pe.Op = "chdir"
  			return nil, pe
  		}
  	}
  
  	sysattr := &syscall.ProcAttr{
  		Dir: attr.Dir,
  		Env: attr.Env,
  		Sys: attr.Sys,
  	}
  	if sysattr.Env == nil {
  		sysattr.Env = Environ()
  	}
  	for _, f := range attr.Files {
  		sysattr.Files = append(sysattr.Files, f.Fd())
  	}
  
  	pid, h, e := syscall.StartProcess(name, argv, sysattr)
  	if e != nil {
  		return nil, &PathError{"fork/exec", name, e}
  	}
  	return newProcess(pid, h), nil
  }
  
  func (p *Process) kill() error {
  	return p.Signal(Kill)
  }
  
  // ProcessState stores information about a process, as reported by Wait.
  type ProcessState struct {
  	pid    int                // The process's id.
  	status syscall.WaitStatus // System-dependent status info.
  	rusage *syscall.Rusage
  }
  
  // Pid returns the process id of the exited process.
  func (p *ProcessState) Pid() int {
  	return p.pid
  }
  
  func (p *ProcessState) exited() bool {
  	return p.status.Exited()
  }
  
  func (p *ProcessState) success() bool {
  	return p.status.ExitStatus() == 0
  }
  
  func (p *ProcessState) sys() interface{} {
  	return p.status
  }
  
  func (p *ProcessState) sysUsage() interface{} {
  	return p.rusage
  }
  
  func (p *ProcessState) String() string {
  	if p == nil {
  		return "<nil>"
  	}
  	status := p.Sys().(syscall.WaitStatus)
  	res := ""
  	switch {
  	case status.Exited():
  		res = "exit status " + itoa(status.ExitStatus())
  	case status.Signaled():
  		res = "signal: " + status.Signal().String()
  	case status.Stopped():
  		res = "stop signal: " + status.StopSignal().String()
  		if status.StopSignal() == syscall.SIGTRAP && status.TrapCause() != 0 {
  			res += " (trap " + itoa(status.TrapCause()) + ")"
  		}
  	case status.Continued():
  		res = "continued"
  	}
  	if status.CoreDump() {
  		res += " (core dumped)"
  	}
  	return res
  }
  

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