1//go:build plan9
 2// +build plan9
 3
 4package osfs
 5
 6import (
 7	"io"
 8	"os"
 9	"path/filepath"
10	"syscall"
11)
12
13func (f *file) Lock() error {
14	// Plan 9 uses a mode bit instead of explicit lock/unlock syscalls.
15	//
16	// Per http://man.cat-v.org/plan_9/5/stat: “Exclusive use files may be open
17	// for I/O by only one fid at a time across all clients of the server. If a
18	// second open is attempted, it draws an error.”
19	//
20	// There is no obvious way to implement this function using the exclusive use bit.
21	// See https://golang.org/src/cmd/go/internal/lockedfile/lockedfile_plan9.go
22	// for how file locking is done by the go tool on Plan 9.
23	return nil
24}
25
26func (f *file) Unlock() error {
27	return nil
28}
29
30func rename(from, to string) error {
31	// If from and to are in different directories, copy the file
32	// since Plan 9 does not support cross-directory rename.
33	if filepath.Dir(from) != filepath.Dir(to) {
34		fi, err := os.Stat(from)
35		if err != nil {
36			return &os.LinkError{"rename", from, to, err}
37		}
38		if fi.Mode().IsDir() {
39			return &os.LinkError{"rename", from, to, syscall.EISDIR}
40		}
41		fromFile, err := os.Open(from)
42		if err != nil {
43			return &os.LinkError{"rename", from, to, err}
44		}
45		toFile, err := os.OpenFile(to, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, fi.Mode())
46		if err != nil {
47			return &os.LinkError{"rename", from, to, err}
48		}
49		_, err = io.Copy(toFile, fromFile)
50		if err != nil {
51			return &os.LinkError{"rename", from, to, err}
52		}
53
54		// Copy mtime and mode from original file.
55		// We need only one syscall if we avoid os.Chmod and os.Chtimes.
56		dir := fi.Sys().(*syscall.Dir)
57		var d syscall.Dir
58		d.Null()
59		d.Mtime = dir.Mtime
60		d.Mode = dir.Mode
61		if err = dirwstat(to, &d); err != nil {
62			return &os.LinkError{"rename", from, to, err}
63		}
64
65		// Remove original file.
66		err = os.Remove(from)
67		if err != nil {
68			return &os.LinkError{"rename", from, to, err}
69		}
70		return nil
71	}
72	return os.Rename(from, to)
73}
74
75func dirwstat(name string, d *syscall.Dir) error {
76	var buf [syscall.STATFIXLEN]byte
77
78	n, err := d.Marshal(buf[:])
79	if err != nil {
80		return &os.PathError{"dirwstat", name, err}
81	}
82	if err = syscall.Wstat(name, buf[:n]); err != nil {
83		return &os.PathError{"dirwstat", name, err}
84	}
85	return nil
86}
87
88func umask(new int) func() {
89	return func() {
90	}
91}