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Source file src/os/exec.go

Documentation: os

  // 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"
  	"sync"
  	"sync/atomic"
  	"syscall"
  	"time"
  )
  
  // Process stores the information about a process created by StartProcess.
  type Process struct {
  	Pid    int
  	handle uintptr      // handle is accessed atomically on Windows
  	isdone uint32       // process has been successfully waited on, non zero if true
  	sigMu  sync.RWMutex // avoid race between wait and signal
  }
  
  func newProcess(pid int, handle uintptr) *Process {
  	p := &Process{Pid: pid, handle: handle}
  	runtime.SetFinalizer(p, (*Process).Release)
  	return p
  }
  
  func (p *Process) setDone() {
  	atomic.StoreUint32(&p.isdone, 1)
  }
  
  func (p *Process) done() bool {
  	return atomic.LoadUint32(&p.isdone) > 0
  }
  
  // ProcAttr holds the attributes that will be applied to a new process
  // started by StartProcess.
  type ProcAttr struct {
  	// If Dir is non-empty, the child changes into the directory before
  	// creating the process.
  	Dir string
  	// If Env is non-nil, it gives the environment variables for the
  	// new process in the form returned by Environ.
  	// If it is nil, the result of Environ will be used.
  	Env []string
  	// Files specifies the open files inherited by the new process. The
  	// first three entries correspond to standard input, standard output, and
  	// standard error. An implementation may support additional entries,
  	// depending on the underlying operating system. A nil entry corresponds
  	// to that file being closed when the process starts.
  	Files []*File
  
  	// Operating system-specific process creation attributes.
  	// Note that setting this field means that your program
  	// may not execute properly or even compile on some
  	// operating systems.
  	Sys *syscall.SysProcAttr
  }
  
  // A Signal represents an operating system signal.
  // The usual underlying implementation is operating system-dependent:
  // on Unix it is syscall.Signal.
  type Signal interface {
  	String() string
  	Signal() // to distinguish from other Stringers
  }
  
  // Getpid returns the process id of the caller.
  func Getpid() int { return syscall.Getpid() }
  
  // Getppid returns the process id of the caller's parent.
  func Getppid() int { return syscall.Getppid() }
  
  // 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.
  //
  // On Unix systems, FindProcess always succeeds and returns a Process
  // for the given pid, regardless of whether the process exists.
  func FindProcess(pid int) (*Process, error) {
  	return findProcess(pid)
  }
  
  // StartProcess starts a new process with the program, arguments and attributes
  // specified by name, argv and attr.
  //
  // StartProcess is a low-level interface. The os/exec package provides
  // higher-level interfaces.
  //
  // If there is an error, it will be of type *PathError.
  func StartProcess(name string, argv []string, attr *ProcAttr) (*Process, error) {
  	return startProcess(name, argv, attr)
  }
  
  // Release releases any resources associated with the Process p,
  // rendering it unusable in the future.
  // Release only needs to be called if Wait is not.
  func (p *Process) Release() error {
  	return p.release()
  }
  
  // Kill causes the Process to exit immediately.
  func (p *Process) Kill() error {
  	return p.kill()
  }
  
  // Wait waits for the Process to exit, and then returns a
  // ProcessState describing its status and an error, if any.
  // Wait releases any resources associated with the Process.
  // On most operating systems, the Process must be a child
  // of the current process or an error will be returned.
  func (p *Process) Wait() (*ProcessState, error) {
  	return p.wait()
  }
  
  // Signal sends a signal to the Process.
  // Sending Interrupt on Windows is not implemented.
  func (p *Process) Signal(sig Signal) error {
  	return p.signal(sig)
  }
  
  // UserTime returns the user CPU time of the exited process and its children.
  func (p *ProcessState) UserTime() time.Duration {
  	return p.userTime()
  }
  
  // SystemTime returns the system CPU time of the exited process and its children.
  func (p *ProcessState) SystemTime() time.Duration {
  	return p.systemTime()
  }
  
  // Exited reports whether the program has exited.
  func (p *ProcessState) Exited() bool {
  	return p.exited()
  }
  
  // Success reports whether the program exited successfully,
  // such as with exit status 0 on Unix.
  func (p *ProcessState) Success() bool {
  	return p.success()
  }
  
  // Sys returns system-dependent exit information about
  // the process. Convert it to the appropriate underlying
  // type, such as syscall.WaitStatus on Unix, to access its contents.
  func (p *ProcessState) Sys() interface{} {
  	return p.sys()
  }
  
  // SysUsage returns system-dependent resource usage information about
  // the exited process. Convert it to the appropriate underlying
  // type, such as *syscall.Rusage on Unix, to access its contents.
  // (On Unix, *syscall.Rusage matches struct rusage as defined in the
  // getrusage(2) manual page.)
  func (p *ProcessState) SysUsage() interface{} {
  	return p.sysUsage()
  }
  

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