1 // Copyright 2015 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4 5 //go:build windows
6 7 // Package registry provides access to the Windows registry.
8 //
9 // Here is a simple example, opening a registry key and reading a string value from it.
10 //
11 // k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
12 // if err != nil {
13 // log.Fatal(err)
14 // }
15 // defer k.Close()
16 //
17 // s, _, err := k.GetStringValue("SystemRoot")
18 // if err != nil {
19 // log.Fatal(err)
20 // }
21 // fmt.Printf("Windows system root is %q\n", s)
22 package registry
23 24 import (
25 "io"
26 "runtime"
27 "syscall"
28 "time"
29 )
30 31 const (
32 // Registry key security and access rights.
33 // See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724878.aspx
34 // for details.
35 ALL_ACCESS = 0xf003f
36 CREATE_LINK = 0x00020
37 CREATE_SUB_KEY = 0x00004
38 ENUMERATE_SUB_KEYS = 0x00008
39 EXECUTE = 0x20019
40 NOTIFY = 0x00010
41 QUERY_VALUE = 0x00001
42 READ = 0x20019
43 SET_VALUE = 0x00002
44 WOW64_32KEY = 0x00200
45 WOW64_64KEY = 0x00100
46 WRITE = 0x20006
47 )
48 49 // Key is a handle to an open Windows registry key.
50 // Keys can be obtained by calling OpenKey; there are
51 // also some predefined root keys such as CURRENT_USER.
52 // Keys can be used directly in the Windows API.
53 type Key syscall.Handle
54 55 const (
56 // Windows defines some predefined root keys that are always open.
57 // An application can use these keys as entry points to the registry.
58 // Normally these keys are used in OpenKey to open new keys,
59 // but they can also be used anywhere a Key is required.
60 CLASSES_ROOT = Key(syscall.HKEY_CLASSES_ROOT)
61 CURRENT_USER = Key(syscall.HKEY_CURRENT_USER)
62 LOCAL_MACHINE = Key(syscall.HKEY_LOCAL_MACHINE)
63 USERS = Key(syscall.HKEY_USERS)
64 CURRENT_CONFIG = Key(syscall.HKEY_CURRENT_CONFIG)
65 PERFORMANCE_DATA = Key(syscall.HKEY_PERFORMANCE_DATA)
66 )
67 68 // Close closes open key k.
69 func (k Key) Close() error {
70 return syscall.RegCloseKey(syscall.Handle(k))
71 }
72 73 // OpenKey opens a new key with path name relative to key k.
74 // It accepts any open key, including CURRENT_USER and others,
75 // and returns the new key and an error.
76 // The access parameter specifies desired access rights to the
77 // key to be opened.
78 func OpenKey(k Key, path string, access uint32) (Key, error) {
79 p, err := syscall.UTF16PtrFromString(path)
80 if err != nil {
81 return 0, err
82 }
83 var subkey syscall.Handle
84 err = syscall.RegOpenKeyEx(syscall.Handle(k), p, 0, access, &subkey)
85 if err != nil {
86 return 0, err
87 }
88 return Key(subkey), nil
89 }
90 91 // OpenRemoteKey opens a predefined registry key on another
92 // computer pcname. The key to be opened is specified by k, but
93 // can only be one of LOCAL_MACHINE, PERFORMANCE_DATA or USERS.
94 // If pcname is "", OpenRemoteKey returns local computer key.
95 func OpenRemoteKey(pcname string, k Key) (Key, error) {
96 var err error
97 var p *uint16
98 if pcname != "" {
99 p, err = syscall.UTF16PtrFromString(`\\` + pcname)
100 if err != nil {
101 return 0, err
102 }
103 }
104 var remoteKey syscall.Handle
105 err = regConnectRegistry(p, syscall.Handle(k), &remoteKey)
106 if err != nil {
107 return 0, err
108 }
109 return Key(remoteKey), nil
110 }
111 112 // ReadSubKeyNames returns the names of subkeys of key k.
113 // The parameter n controls the number of returned names,
114 // analogous to the way os.File.Readdirnames works.
115 func (k Key) ReadSubKeyNames(n int) ([]string, error) {
116 // RegEnumKeyEx must be called repeatedly and to completion.
117 // During this time, this goroutine cannot migrate away from
118 // its current thread. See https://golang.org/issue/49320 and
119 // https://golang.org/issue/49466.
120 runtime.LockOSThread()
121 defer runtime.UnlockOSThread()
122 123 names := make([]string, 0)
124 // Registry key size limit is 255 bytes and described there:
125 // https://msdn.microsoft.com/library/windows/desktop/ms724872.aspx
126 buf := make([]uint16, 256) //plus extra room for terminating zero byte
127 loopItems:
128 for i := uint32(0); ; i++ {
129 if n > 0 {
130 if len(names) == n {
131 return names, nil
132 }
133 }
134 l := uint32(len(buf))
135 for {
136 err := syscall.RegEnumKeyEx(syscall.Handle(k), i, &buf[0], &l, nil, nil, nil, nil)
137 if err == nil {
138 break
139 }
140 if err == syscall.ERROR_MORE_DATA {
141 // Double buffer size and try again.
142 l = uint32(2 * len(buf))
143 buf = make([]uint16, l)
144 continue
145 }
146 if err == _ERROR_NO_MORE_ITEMS {
147 break loopItems
148 }
149 return names, err
150 }
151 names = append(names, syscall.UTF16ToString(buf[:l]))
152 }
153 if n > len(names) {
154 return names, io.EOF
155 }
156 return names, nil
157 }
158 159 // CreateKey creates a key named path under open key k.
160 // CreateKey returns the new key and a boolean flag that reports
161 // whether the key already existed.
162 // The access parameter specifies the access rights for the key
163 // to be created.
164 func CreateKey(k Key, path string, access uint32) (newk Key, openedExisting bool, err error) {
165 var h syscall.Handle
166 var d uint32
167 var pathPointer *uint16
168 pathPointer, err = syscall.UTF16PtrFromString(path)
169 if err != nil {
170 return 0, false, err
171 }
172 err = regCreateKeyEx(syscall.Handle(k), pathPointer,
173 0, nil, _REG_OPTION_NON_VOLATILE, access, nil, &h, &d)
174 if err != nil {
175 return 0, false, err
176 }
177 return Key(h), d == _REG_OPENED_EXISTING_KEY, nil
178 }
179 180 // DeleteKey deletes the subkey path of key k and its values.
181 func DeleteKey(k Key, path string) error {
182 pathPointer, err := syscall.UTF16PtrFromString(path)
183 if err != nil {
184 return err
185 }
186 return regDeleteKey(syscall.Handle(k), pathPointer)
187 }
188 189 // A KeyInfo describes the statistics of a key. It is returned by Stat.
190 type KeyInfo struct {
191 SubKeyCount uint32
192 MaxSubKeyLen uint32 // size of the key's subkey with the longest name, in Unicode characters, not including the terminating zero byte
193 ValueCount uint32
194 MaxValueNameLen uint32 // size of the key's longest value name, in Unicode characters, not including the terminating zero byte
195 MaxValueLen uint32 // longest data component among the key's values, in bytes
196 lastWriteTime syscall.Filetime
197 }
198 199 // ModTime returns the key's last write time.
200 func (ki *KeyInfo) ModTime() time.Time {
201 return time.Unix(0, ki.lastWriteTime.Nanoseconds())
202 }
203 204 // Stat retrieves information about the open key k.
205 func (k Key) Stat() (*KeyInfo, error) {
206 var ki KeyInfo
207 err := syscall.RegQueryInfoKey(syscall.Handle(k), nil, nil, nil,
208 &ki.SubKeyCount, &ki.MaxSubKeyLen, nil, &ki.ValueCount,
209 &ki.MaxValueNameLen, &ki.MaxValueLen, nil, &ki.lastWriteTime)
210 if err != nil {
211 return nil, err
212 }
213 return &ki, nil
214 }
215