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Source file src/syscall/pwd_plan9.go

Documentation: syscall

  // Copyright 2015 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.
  
  // The working directory in Plan 9 is effectively per P, so different
  // goroutines and even the same goroutine as it's rescheduled on
  // different Ps can see different working directories.
  //
  // Instead, track a Go process-wide intent of the current working directory,
  // and switch to it at important points.
  
  package syscall
  
  import "sync"
  
  var (
  	wdmu  sync.Mutex // guards following
  	wdSet bool
  	wdStr string
  )
  
  func Fixwd() {
  	wdmu.Lock()
  	defer wdmu.Unlock()
  	fixwdLocked()
  }
  
  func fixwdLocked() {
  	if !wdSet {
  		return
  	}
  	// always call chdir when getwd returns an error
  	wd, _ := getwd()
  	if wd == wdStr {
  		return
  	}
  	if err := chdir(wdStr); err != nil {
  		return
  	}
  }
  
  // goroutine-specific getwd
  func getwd() (wd string, err error) {
  	fd, err := open(".", O_RDONLY)
  	if err != nil {
  		return "", err
  	}
  	defer Close(fd)
  	return Fd2path(fd)
  }
  
  func Getwd() (wd string, err error) {
  	wdmu.Lock()
  	defer wdmu.Unlock()
  
  	if wdSet {
  		return wdStr, nil
  	}
  	wd, err = getwd()
  	if err != nil {
  		return
  	}
  	wdSet = true
  	wdStr = wd
  	return wd, nil
  }
  
  func Chdir(path string) error {
  	wdmu.Lock()
  	defer wdmu.Unlock()
  
  	if err := chdir(path); err != nil {
  		return err
  	}
  
  	wd, err := getwd()
  	if err != nil {
  		return err
  	}
  	wdSet = true
  	wdStr = wd
  	return nil
  }
  

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