key.go

     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  //
    23  // NOTE: This package is a copy of golang.org/x/sys/windows/registry
    24  // with KeyInfo.ModTime removed to prevent dependency cycles.
    25  //
    26  package registry
    27  
    28  import (
    29  	"runtime"
    30  	"syscall"
    31  )
    32  
    33  const (
    34  	// Registry key security and access rights.
    35  	// See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724878.aspx
    36  	// for details.
    37  	ALL_ACCESS         = 0xf003f
    38  	CREATE_LINK        = 0x00020
    39  	CREATE_SUB_KEY     = 0x00004
    40  	ENUMERATE_SUB_KEYS = 0x00008
    41  	EXECUTE            = 0x20019
    42  	NOTIFY             = 0x00010
    43  	QUERY_VALUE        = 0x00001
    44  	READ               = 0x20019
    45  	SET_VALUE          = 0x00002
    46  	WOW64_32KEY        = 0x00200
    47  	WOW64_64KEY        = 0x00100
    48  	WRITE              = 0x20006
    49  )
    50  
    51  // Key is a handle to an open Windows registry key.
    52  // Keys can be obtained by calling OpenKey; there are
    53  // also some predefined root keys such as CURRENT_USER.
    54  // Keys can be used directly in the Windows API.
    55  type Key syscall.Handle
    56  
    57  const (
    58  	// Windows defines some predefined root keys that are always open.
    59  	// An application can use these keys as entry points to the registry.
    60  	// Normally these keys are used in OpenKey to open new keys,
    61  	// but they can also be used anywhere a Key is required.
    62  	CLASSES_ROOT   = Key(syscall.HKEY_CLASSES_ROOT)
    63  	CURRENT_USER   = Key(syscall.HKEY_CURRENT_USER)
    64  	LOCAL_MACHINE  = Key(syscall.HKEY_LOCAL_MACHINE)
    65  	USERS          = Key(syscall.HKEY_USERS)
    66  	CURRENT_CONFIG = Key(syscall.HKEY_CURRENT_CONFIG)
    67  )
    68  
    69  // Close closes open key k.
    70  func (k Key) Close() error {
    71  	return syscall.RegCloseKey(syscall.Handle(k))
    72  }
    73  
    74  // OpenKey opens a new key with path name relative to key k.
    75  // It accepts any open key, including CURRENT_USER and others,
    76  // and returns the new key and an error.
    77  // The access parameter specifies desired access rights to the
    78  // key to be opened.
    79  func OpenKey(k Key, path string, access uint32) (Key, error) {
    80  	p, err := syscall.UTF16PtrFromString(path)
    81  	if err != nil {
    82  		return 0, err
    83  	}
    84  	var subkey syscall.Handle
    85  	err = syscall.RegOpenKeyEx(syscall.Handle(k), p, 0, access, &subkey)
    86  	if err != nil {
    87  		return 0, err
    88  	}
    89  	return Key(subkey), nil
    90  }
    91  
    92  // ReadSubKeyNames returns the names of subkeys of key k.
    93  func (k Key) ReadSubKeyNames() ([]string, error) {
    94  	// RegEnumKeyEx must be called repeatedly and to completion.
    95  	// During this time, this goroutine cannot migrate away from
    96  	// its current thread. See #49320.
    97  	runtime.LockOSThread()
    98  	defer runtime.UnlockOSThread()
    99  
   100  	names := make([]string, 0)
   101  	// Registry key size limit is 255 bytes and described there:
   102  	// https://msdn.microsoft.com/library/windows/desktop/ms724872.aspx
   103  	buf := make([]uint16, 256) //plus extra room for terminating zero byte
   104  loopItems:
   105  	for i := uint32(0); ; i++ {
   106  		l := uint32(len(buf))
   107  		for {
   108  			err := syscall.RegEnumKeyEx(syscall.Handle(k), i, &buf[0], &l, nil, nil, nil, nil)
   109  			if err == nil {
   110  				break
   111  			}
   112  			if err == syscall.ERROR_MORE_DATA {
   113  				// Double buffer size and try again.
   114  				l = uint32(2 * len(buf))
   115  				buf = make([]uint16, l)
   116  				continue
   117  			}
   118  			if err == _ERROR_NO_MORE_ITEMS {
   119  				break loopItems
   120  			}
   121  			return names, err
   122  		}
   123  		names = append(names, syscall.UTF16ToString(buf[:l]))
   124  	}
   125  	return names, nil
   126  }
   127  
   128  // CreateKey creates a key named path under open key k.
   129  // CreateKey returns the new key and a boolean flag that reports
   130  // whether the key already existed.
   131  // The access parameter specifies the access rights for the key
   132  // to be created.
   133  func CreateKey(k Key, path string, access uint32) (newk Key, openedExisting bool, err error) {
   134  	var h syscall.Handle
   135  	var d uint32
   136  	err = regCreateKeyEx(syscall.Handle(k), syscall.StringToUTF16Ptr(path),
   137  		0, nil, _REG_OPTION_NON_VOLATILE, access, nil, &h, &d)
   138  	if err != nil {
   139  		return 0, false, err
   140  	}
   141  	return Key(h), d == _REG_OPENED_EXISTING_KEY, nil
   142  }
   143  
   144  // DeleteKey deletes the subkey path of key k and its values.
   145  func DeleteKey(k Key, path string) error {
   146  	return regDeleteKey(syscall.Handle(k), syscall.StringToUTF16Ptr(path))
   147  }
   148  
   149  // A KeyInfo describes the statistics of a key. It is returned by Stat.
   150  type KeyInfo struct {
   151  	SubKeyCount     uint32
   152  	MaxSubKeyLen    uint32 // size of the key's subkey with the longest name, in Unicode characters, not including the terminating zero byte
   153  	ValueCount      uint32
   154  	MaxValueNameLen uint32 // size of the key's longest value name, in Unicode characters, not including the terminating zero byte
   155  	MaxValueLen     uint32 // longest data component among the key's values, in bytes
   156  	lastWriteTime   syscall.Filetime
   157  }
   158  
   159  // Stat retrieves information about the open key k.
   160  func (k Key) Stat() (*KeyInfo, error) {
   161  	var ki KeyInfo
   162  	err := syscall.RegQueryInfoKey(syscall.Handle(k), nil, nil, nil,
   163  		&ki.SubKeyCount, &ki.MaxSubKeyLen, nil, &ki.ValueCount,
   164  		&ki.MaxValueNameLen, &ki.MaxValueLen, nil, &ki.lastWriteTime)
   165  	if err != nil {
   166  		return nil, err
   167  	}
   168  	return &ki, nil
   169  }
   170
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