You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: getwd.go
    path of file: ./repos/gccrs/libgo/go/os
    
    the code of the file until where you have to start completion: // 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"
	"syscall"
)

var getwdCache struct {
	sync.Mutex
	dir string
}

// Getwd returns a rooted path name corresponding to the
// current directory. If the current directory can be
// reached via multiple paths (due to symbolic links),
// Getwd may return any one of them.
func Getwd() (dir string, err error) {
	if runtime.GOOS == "windows" || runtime.GOOS == "plan9" {
		return syscall.Getwd()
	}

	// Clumsy but widespread kludge:
	// if $PWD is set and matches ".", use it.
	dot, err := statNolog(".")
	if err != nil {
		return "", err
	}
	dir = Getenv("PWD")
	if len(dir) > 0 && dir[0] == '/' {
		d, err := statNolog(dir)
		if err == nil && SameFile(dot, d) {
			return dir, nil
		}
	}

	// If the operating system provides a Getwd call, use it.
	// Otherwise, we're trying to find our way back to ".".
	if syscall.ImplementsGetwd {
		var (
			s string
			e error
		)
		for {
			s, e = syscall.Getwd()
			if e != syscall.EINTR {
				break
			}
		}
		return s, NewSyscallError("getwd", e)
	}

	// Apply same kludge but to cached dir instead of $PWD.
	getwdCache.Lock()
	dir = getwdCache.dir
	getwdCache.Unlock()
	if len(dir) > 0 {
		d, err := statNolog(dir)
		if err == nil && SameFile(dot, d) {
			return dir, nil
		}
	}

	// Root is a special case because it has no parent
	// and ends in a slash.
	root, err := statNolog("/")
	if err != nil {
		// Can't stat root - no hope.
		return "", err
	}
	if SameFile(root, dot) {
		return "/", nil
	}

	// General algorithm: find name in parent
	// and then find name of parent. Each iteration
	// adds /name to the beginning of dir.
	dir = ""
	for parent := ".."; ; parent = "../" + parent {
		if len(parent) >= 1024 { // Sanity check
			return "", syscall.ENAMETOOLONG
		}
		fd, err := openFileNolog(parent, O_RDONLY, 0)
		if err != nil {
			return "", err
		}

		for {
			names, err := fd
    
func Getwd() (dir string, err error) {
	if runtime.GOOS == "windows" || runtime.GOOS == "plan9" {
		return syscall.Getwd()
	}

	// Clumsy but widespread kludge:
	// if $PWD is set and matches ".", use it.
	dot, err := statNolog(".")
	if err != nil {
		return "", err
	}
	dir = Getenv("PWD")
	if len(dir) > 0 && dir[0] == '/' {
		d, err := statNolog(dir)
		if err == nil && SameFile(dot, d) {
			return dir, nil
		}
	}

	// If the operating system provides a Getwd call, use it.
	// Otherwise, we're trying to find our way back to ".".
	if syscall.ImplementsGetwd {
		var (
			s string
			e error
		)
		for {
			s, e = syscall.Getwd()
			if e != syscall.EINTR {
				break
			}
		}
		return s, NewSyscallError("getwd", e)
	}

	// Apply same kludge but to cached dir instead of $PWD.
	getwdCache.Lock()
	dir = getwdCache.dir
	getwdCache.Unlock()
	if len(dir) > 0 {
		d, err := statNolog(dir)
		if err == nil && SameFile(dot, d) {
			return dir, nil
		}
	}

	// Root is a special case because it has no parent
	// and ends in a slash.
	root, err := statNolog("/")
	if err != nil {
		// Can't stat root - no hope.
		return "", err
	}
	if SameFile(root, dot) {
		return "/", nil
	}

	// General algorithm: find name in parent
	// and then find name of parent. Each iteration
	// adds /name to the beginning of dir.
	dir = ""
	for parent := ".."; ; parent = "../" + parent {
		if len(parent) >= 1024 { // Sanity check
			return "", syscall.ENAMETOOLONG
		}
		fd, err := openFileNolog(parent, O_RDONLY, 0)
		if err != nil {
			return "", err
		}

		for {
			names, err := fd.Readdirnames(100)
			if err != nil {
				fd.Close()
				return "", err
			}
			for _, name := range names {
				d, _ := lstatNolog(parent + "/" + name)
				if SameFile(d, dot) {
					dir = "/" + name + dir
					goto Found
				}
			}
		}

	Found:
		pd, err := fd.Stat()
		fd.Close()
		if err != nil {
			return "", err
		}
		if SameFile(pd, root) {
			break
		}
		// Set up for next round.
		dot = pd
	}

	// Save answer as hint to avoid the expensive path next time.
	getwdCache.Lock()
	getwdCache.dir = dir
	getwdCache.Unlock()

	return dir, nil
}