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// 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.
package os
import (
"runtime"
"syscall"
)
// StartProcess starts a new process with the program, arguments and attributes
// specified by name, argv and attr.
func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
sysattr := &syscall.ProcAttr{
Dir: attr.Dir,
Env: attr.Env,
Sys: attr.Sys,
}
// Create array of integer (system) fds.
intfd := make([]int, len(attr.Files))
for i, f := range attr.Files {
if f == nil {
intfd[i] = -1
} else {
intfd[i] = f.Fd()
}
}
sysattr.Files = intfd
pid, h, e := syscall.StartProcess(name, argv, sysattr)
if iserror(e) {
return nil, &PathError{"fork/exec", name, e}
}
return newProcess(pid, h), nil
}
// Plan9Note implements the Signal interface on Plan 9.
type Plan9Note string
func (note Plan9Note) String() string {
return string(note)
}
func (p *Process) Signal(sig Signal) error {
if p.done {
return NewError("os: process already finished")
}
f, e := OpenFile("/proc/"+itoa(p.Pid)+"/note", O_WRONLY, 0)
if iserror(e) {
return NewSyscallError("signal", e)
}
defer f.Close()
_, e = f.Write([]byte(sig.String()))
return e
}
// Kill causes the Process to exit immediately.
func (p *Process) Kill() error {
f, e := OpenFile("/proc/"+itoa(p.Pid)+"/ctl", O_WRONLY, 0)
if iserror(e) {
return NewSyscallError("kill", e)
}
defer f.Close()
_, e = f.Write([]byte("kill"))
return e
}
// Exec replaces the current process with an execution of the
// named binary, with arguments argv and environment envv.
// If successful, Exec never returns. If it fails, it returns an error.
// ForkExec is almost always a better way to execute a program.
func Exec(name string, argv []string, envv []string) error {
e := syscall.Exec(name, argv, envv)
if iserror(e) {
return &PathError{"exec", name, e}
}
return nil
}
// Waitmsg stores the information about an exited process as reported by Wait.
type Waitmsg struct {
syscall.Waitmsg
}
// Wait waits for the Process to exit or stop, and then returns a
// Waitmsg describing its status and an error, if any. The options
// (WNOHANG etc.) affect the behavior of the Wait call.
func (p *Process) Wait(options int) (w *Waitmsg, err error) {
var waitmsg syscall.Waitmsg
if p.Pid == -1 {
return nil, EINVAL
}
for true {
err = syscall.Await(&waitmsg)
if iserror(err) {
return nil, NewSyscallError("wait", err)
}
if waitmsg.Pid == p.Pid {
p.done = true
break
}
}
return &Waitmsg{waitmsg}, nil
}
// Wait waits for process pid to exit or stop, and then returns a
// Waitmsg describing its status and an error, if any. The options
// (WNOHANG etc.) affect the behavior of the Wait call.
// Wait is equivalent to calling FindProcess and then Wait
// and Release on the result.
func Wait(pid int, options int) (w *Waitmsg, err error) {
p, e := FindProcess(pid)
if e != nil {
return nil, e
}
defer p.Release()
return p.Wait(options)
}
// Release releases any resources associated with the Process.
func (p *Process) Release() error {
// NOOP for Plan 9.
p.Pid = -1
// no need for a finalizer anymore
runtime.SetFinalizer(p, nil)
return nil
}
// FindProcess looks for a running process by its pid.
// The Process it returns can be used to obtain information
// about the underlying operating system process.
func FindProcess(pid int) (p *Process, err error) {
// NOOP for Plan 9.
return newProcess(pid, 0), nil
}
func (w *Waitmsg) String() string {
if w == nil {
return "<nil>"
}
return "exit status: " + w.Msg
}
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