golang pwd_plan9 代码
文件路径：/src/syscall/pwd_plan9.go
/ 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
}
}
func fixwd(paths ...string) {
for _, path := range paths {
if path != "" && path[0] != '/' && path[0] != '#' {
Fixwd()
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 {
fixwd(path)
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
}