base/win/registry.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/win/registry.h"
   6
   7 #include <shlwapi.h>
   8 #include <algorithm>
   9
  10 #include "base/logging.h"
  11 #include "base/string_util.h"
  12 #include "base/threading/thread_restrictions.h"
  13
  14 #pragma comment(lib, "shlwapi.lib")  // for SHDeleteKey
  15
  16 namespace base {
  17 namespace win {
  18
  19 namespace {
  20
  21 // RegEnumValue() reports the number of characters from the name that were
  22 // written to the buffer, not how many there are. This constant is the maximum
  23 // name size, such that a buffer with this size should read any name.
  24 const DWORD MAX_REGISTRY_NAME_SIZE = 16384;
  25
  26 // Registry values are read as BYTE* but can have wchar_t* data whose last
  27 // wchar_t is truncated. This function converts the reported |byte_size| to
  28 // a size in wchar_t that can store a truncated wchar_t if necessary.
  29 inline DWORD to_wchar_size(DWORD byte_size) {
  30   return (byte_size + sizeof(wchar_t) - 1) / sizeof(wchar_t);
  31 }
  32
  33 }  // namespace
  34
  35 // RegKey ----------------------------------------------------------------------
  36
  37 RegKey::RegKey()
  38     : key_(NULL),
  39       watch_event_(0) {
  40 }
  41
  42 RegKey::RegKey(HKEY rootkey, const wchar_t* subkey, REGSAM access)
  43     : key_(NULL),
  44       watch_event_(0) {
  45   if (rootkey) {
  46     if (access & (KEY_SET_VALUE | KEY_CREATE_SUB_KEY | KEY_CREATE_LINK))
  47       Create(rootkey, subkey, access);
  48     else
  49       Open(rootkey, subkey, access);
  50   } else {
  51     DCHECK(!subkey);
  52   }
  53 }
  54
  55 RegKey::~RegKey() {
  56   Close();
  57 }
  58
  59 LONG RegKey::Create(HKEY rootkey, const wchar_t* subkey, REGSAM access) {
  60   DWORD disposition_value;
  61   return CreateWithDisposition(rootkey, subkey, &disposition_value, access);
  62 }
  63
  64 LONG RegKey::CreateWithDisposition(HKEY rootkey, const wchar_t* subkey,
  65                                    DWORD* disposition, REGSAM access) {
  66   DCHECK(rootkey && subkey && access && disposition);
  67   Close();
  68
  69   LONG result = RegCreateKeyEx(rootkey, subkey, 0, NULL,
  70                                REG_OPTION_NON_VOLATILE, access, NULL, &key_,
  71                                disposition);
  72   return result;
  73 }
  74
  75 LONG RegKey::CreateKey(const wchar_t* name, REGSAM access) {
  76   DCHECK(name && access);
  77   HKEY subkey = NULL;
  78   LONG result = RegCreateKeyEx(key_, name, 0, NULL, REG_OPTION_NON_VOLATILE,
  79                                access, NULL, &subkey, NULL);
  80   Close();
  81
  82   key_ = subkey;
  83   return result;
  84 }
  85
  86 LONG RegKey::Open(HKEY rootkey, const wchar_t* subkey, REGSAM access) {
  87   DCHECK(rootkey && subkey && access);
  88   Close();
  89
  90   LONG result = RegOpenKeyEx(rootkey, subkey, 0, access, &key_);
  91   return result;
  92 }
  93
  94 LONG RegKey::OpenKey(const wchar_t* relative_key_name, REGSAM access) {
  95   DCHECK(relative_key_name && access);
  96   HKEY subkey = NULL;
  97   LONG result = RegOpenKeyEx(key_, relative_key_name, 0, access, &subkey);
  98
  99   // We have to close the current opened key before replacing it with the new
 100   // one.
 101   Close();
 102
 103   key_ = subkey;
 104   return result;
 105 }
 106
 107 void RegKey::Close() {
 108   StopWatching();
 109   if (key_) {
 110     ::RegCloseKey(key_);
 111     key_ = NULL;
 112   }
 113 }
 114
 115 bool RegKey::HasValue(const wchar_t* name) const {
 116   return RegQueryValueEx(key_, name, 0, NULL, NULL, NULL) == ERROR_SUCCESS;
 117 }
 118
 119 DWORD RegKey::GetValueCount() const {
 120   DWORD count = 0;
 121   LONG result = RegQueryInfoKey(key_, NULL, 0, NULL, NULL, NULL, NULL, &count,
 122                                 NULL, NULL, NULL, NULL);
 123   return (result == ERROR_SUCCESS) ? count : 0;
 124 }
 125
 126 LONG RegKey::GetValueNameAt(int index, std::wstring* name) const {
 127   wchar_t buf[256];
 128   DWORD bufsize = arraysize(buf);
 129   LONG r = ::RegEnumValue(key_, index, buf, &bufsize, NULL, NULL, NULL, NULL);
 130   if (r == ERROR_SUCCESS)
 131     *name = buf;
 132
 133   return r;
 134 }
 135
 136 LONG RegKey::DeleteKey(const wchar_t* name) {
 137   DCHECK(key_);
 138   DCHECK(name);
 139   LONG result = SHDeleteKey(key_, name);
 140   return result;
 141 }
 142
 143 LONG RegKey::DeleteValue(const wchar_t* value_name) {
 144   DCHECK(key_);
 145   LONG result = RegDeleteValue(key_, value_name);
 146   return result;
 147 }
 148
 149 LONG RegKey::ReadValueDW(const wchar_t* name, DWORD* out_value) const {
 150   DCHECK(out_value);
 151   DWORD type = REG_DWORD;
 152   DWORD size = sizeof(DWORD);
 153   DWORD local_value = 0;
 154   LONG result = ReadValue(name, &local_value, &size, &type);
 155   if (result == ERROR_SUCCESS) {
 156     if ((type == REG_DWORD || type == REG_BINARY) && size == sizeof(DWORD))
 157       *out_value = local_value;
 158     else
 159       result = ERROR_CANTREAD;
 160   }
 161
 162   return result;
 163 }
 164
 165 LONG RegKey::ReadInt64(const wchar_t* name, int64* out_value) const {
 166   DCHECK(out_value);
 167   DWORD type = REG_QWORD;
 168   int64 local_value = 0;
 169   DWORD size = sizeof(local_value);
 170   LONG result = ReadValue(name, &local_value, &size, &type);
 171   if (result == ERROR_SUCCESS) {
 172     if ((type == REG_QWORD || type == REG_BINARY) &&
 173         size == sizeof(local_value))
 174       *out_value = local_value;
 175     else
 176       result = ERROR_CANTREAD;
 177   }
 178
 179   return result;
 180 }
 181
 182 LONG RegKey::ReadValue(const wchar_t* name, std::wstring* out_value) const {
 183   DCHECK(out_value);
 184   const size_t kMaxStringLength = 1024;  // This is after expansion.
 185   // Use the one of the other forms of ReadValue if 1024 is too small for you.
 186   wchar_t raw_value[kMaxStringLength];
 187   DWORD type = REG_SZ, size = sizeof(raw_value);
 188   LONG result = ReadValue(name, raw_value, &size, &type);
 189   if (result == ERROR_SUCCESS) {
 190     if (type == REG_SZ) {
 191       *out_value = raw_value;
 192     } else if (type == REG_EXPAND_SZ) {
 193       wchar_t expanded[kMaxStringLength];
 194       size = ExpandEnvironmentStrings(raw_value, expanded, kMaxStringLength);
 195       // Success: returns the number of wchar_t's copied
 196       // Fail: buffer too small, returns the size required
 197       // Fail: other, returns 0
 198       if (size == 0 || size > kMaxStringLength) {
 199         result = ERROR_MORE_DATA;
 200       } else {
 201         *out_value = expanded;
 202       }
 203     } else {
 204       // Not a string. Oops.
 205       result = ERROR_CANTREAD;
 206     }
 207   }
 208
 209   return result;
 210 }
 211
 212 LONG RegKey::ReadValue(const wchar_t* name,
 213                        void* data,
 214                        DWORD* dsize,
 215                        DWORD* dtype) const {
 216   LONG result = RegQueryValueEx(key_, name, 0, dtype,
 217                                 reinterpret_cast<LPBYTE>(data), dsize);
 218   return result;
 219 }
 220
 221 LONG RegKey::ReadValues(const wchar_t* name,
 222                         std::vector<std::wstring>* values) {
 223   values->clear();
 224
 225   DWORD type = REG_MULTI_SZ;
 226   DWORD size = 0;
 227   LONG result = ReadValue(name, NULL, &size, &type);
 228   if (FAILED(result) || size == 0)
 229     return result;
 230
 231   if (type != REG_MULTI_SZ)
 232     return ERROR_CANTREAD;
 233
 234   std::vector<wchar_t> buffer(size / sizeof(wchar_t));
 235   result = ReadValue(name, &buffer[0], &size, NULL);
 236   if (FAILED(result) || size == 0)
 237     return result;
 238
 239   // Parse the double-null-terminated list of strings.
 240   // Note: This code is paranoid to not read outside of |buf|, in the case where
 241   // it may not be properly terminated.
 242   const wchar_t* entry = &buffer[0];
 243   const wchar_t* buffer_end = entry + (size / sizeof(wchar_t));
 244   while (entry < buffer_end && entry[0] != '\0') {
 245     const wchar_t* entry_end = std::find(entry, buffer_end, L'\0');
 246     values->push_back(std::wstring(entry, entry_end));
 247     entry = entry_end + 1;
 248   }
 249   return 0;
 250 }
 251
 252 LONG RegKey::WriteValue(const wchar_t* name, DWORD in_value) {
 253   return WriteValue(
 254       name, &in_value, static_cast<DWORD>(sizeof(in_value)), REG_DWORD);
 255 }
 256
 257 LONG RegKey::WriteValue(const wchar_t * name, const wchar_t* in_value) {
 258   return WriteValue(name, in_value,
 259       static_cast<DWORD>(sizeof(*in_value) * (wcslen(in_value) + 1)), REG_SZ);
 260 }
 261
 262 LONG RegKey::WriteValue(const wchar_t* name,
 263                         const void* data,
 264                         DWORD dsize,
 265                         DWORD dtype) {
 266   DCHECK(data || !dsize);
 267
 268   LONG result = RegSetValueEx(key_, name, 0, dtype,
 269       reinterpret_cast<LPBYTE>(const_cast<void*>(data)), dsize);
 270   return result;
 271 }
 272
 273 LONG RegKey::StartWatching() {
 274   DCHECK(key_);
 275   if (!watch_event_)
 276     watch_event_ = CreateEvent(NULL, TRUE, FALSE, NULL);
 277
 278   DWORD filter = REG_NOTIFY_CHANGE_NAME |
 279                  REG_NOTIFY_CHANGE_ATTRIBUTES |
 280                  REG_NOTIFY_CHANGE_LAST_SET |
 281                  REG_NOTIFY_CHANGE_SECURITY;
 282
 283   // Watch the registry key for a change of value.
 284   LONG result = RegNotifyChangeKeyValue(key_, TRUE, filter, watch_event_, TRUE);
 285   if (result != ERROR_SUCCESS) {
 286     CloseHandle(watch_event_);
 287     watch_event_ = 0;
 288   }
 289
 290   return result;
 291 }
 292
 293 bool RegKey::HasChanged() {
 294   if (watch_event_) {
 295     if (WaitForSingleObject(watch_event_, 0) == WAIT_OBJECT_0) {
 296       StartWatching();
 297       return true;
 298     }
 299   }
 300   return false;
 301 }
 302
 303 LONG RegKey::StopWatching() {
 304   LONG result = ERROR_INVALID_HANDLE;
 305   if (watch_event_) {
 306     CloseHandle(watch_event_);
 307     watch_event_ = 0;
 308     result = ERROR_SUCCESS;
 309   }
 310   return result;
 311 }
 312
 313 // RegistryValueIterator ------------------------------------------------------
 314
 315 RegistryValueIterator::RegistryValueIterator(HKEY root_key,
 316                                              const wchar_t* folder_key)
 317     : name_(MAX_PATH, L'\0'),
 318       value_(MAX_PATH, L'\0') {
 319   LONG result = RegOpenKeyEx(root_key, folder_key, 0, KEY_READ, &key_);
 320   if (result != ERROR_SUCCESS) {
 321     key_ = NULL;
 322   } else {
 323     DWORD count = 0;
 324     result = ::RegQueryInfoKey(key_, NULL, 0, NULL, NULL, NULL, NULL, &count,
 325                                NULL, NULL, NULL, NULL);
 326
 327     if (result != ERROR_SUCCESS) {
 328       ::RegCloseKey(key_);
 329       key_ = NULL;
 330     } else {
 331       index_ = count - 1;
 332     }
 333   }
 334
 335   Read();
 336 }
 337
 338 RegistryValueIterator::~RegistryValueIterator() {
 339   if (key_)
 340     ::RegCloseKey(key_);
 341 }
 342
 343 DWORD RegistryValueIterator::ValueCount() const {
 344   DWORD count = 0;
 345   LONG result = ::RegQueryInfoKey(key_, NULL, 0, NULL, NULL, NULL, NULL,
 346                                   &count, NULL, NULL, NULL, NULL);
 347   if (result != ERROR_SUCCESS)
 348     return 0;
 349
 350   return count;
 351 }
 352
 353 bool RegistryValueIterator::Valid() const {
 354   return key_ != NULL && index_ >= 0;
 355 }
 356
 357 void RegistryValueIterator::operator++() {
 358   --index_;
 359   Read();
 360 }
 361
 362 bool RegistryValueIterator::Read() {
 363   if (Valid()) {
 364     DWORD capacity = static_cast<DWORD>(name_.capacity());
 365     DWORD name_size = capacity;
 366     // |value_size_| is in bytes. Reserve the last character for a NUL.
 367     value_size_ = static_cast<DWORD>((value_.size() - 1) * sizeof(wchar_t));
 368     LONG result = ::RegEnumValue(
 369         key_, index_, WriteInto(&name_, name_size), &name_size, NULL, &type_,
 370         reinterpret_cast<BYTE*>(vector_as_array(&value_)), &value_size_);
 371
 372     if (result == ERROR_MORE_DATA) {
 373       // Registry key names are limited to 255 characters and fit within
 374       // MAX_PATH (which is 260) but registry value names can use up to 16,383
 375       // characters and the value itself is not limited
 376       // (from http://msdn.microsoft.com/en-us/library/windows/desktop/
 377       // ms724872(v=vs.85).aspx).
 378       // Resize the buffers and retry if their size caused the failure.
 379       DWORD value_size_in_wchars = to_wchar_size(value_size_);
 380       if (value_size_in_wchars + 1 > value_.size())
 381         value_.resize(value_size_in_wchars + 1, L'\0');
 382       value_size_ = static_cast<DWORD>((value_.size() - 1) * sizeof(wchar_t));
 383       name_size = name_size == capacity ? MAX_REGISTRY_NAME_SIZE : capacity;
 384       result = ::RegEnumValue(
 385           key_, index_, WriteInto(&name_, name_size), &name_size, NULL, &type_,
 386           reinterpret_cast<BYTE*>(vector_as_array(&value_)), &value_size_);
 387     }
 388
 389     if (result == ERROR_SUCCESS) {
 390       DCHECK_LT(to_wchar_size(value_size_), value_.size());
 391       value_[to_wchar_size(value_size_)] = L'\0';
 392       return true;
 393     }
 394   }
 395
 396   name_[0] = L'\0';
 397   value_[0] = L'\0';
 398   value_size_ = 0;
 399   return false;
 400 }
 401
 402 // RegistryKeyIterator --------------------------------------------------------
 403
 404 RegistryKeyIterator::RegistryKeyIterator(HKEY root_key,
 405                                          const wchar_t* folder_key) {
 406   LONG result = RegOpenKeyEx(root_key, folder_key, 0, KEY_READ, &key_);
 407   if (result != ERROR_SUCCESS) {
 408     key_ = NULL;
 409   } else {
 410     DWORD count = 0;
 411     LONG result = ::RegQueryInfoKey(key_, NULL, 0, NULL, &count, NULL, NULL,
 412                                     NULL, NULL, NULL, NULL, NULL);
 413
 414     if (result != ERROR_SUCCESS) {
 415       ::RegCloseKey(key_);
 416       key_ = NULL;
 417     } else {
 418       index_ = count - 1;
 419     }
 420   }
 421
 422   Read();
 423 }
 424
 425 RegistryKeyIterator::~RegistryKeyIterator() {
 426   if (key_)
 427     ::RegCloseKey(key_);
 428 }
 429
 430 DWORD RegistryKeyIterator::SubkeyCount() const {
 431   DWORD count = 0;
 432   LONG result = ::RegQueryInfoKey(key_, NULL, 0, NULL, &count, NULL, NULL,
 433                                   NULL, NULL, NULL, NULL, NULL);
 434   if (result != ERROR_SUCCESS)
 435     return 0;
 436
 437   return count;
 438 }
 439
 440 bool RegistryKeyIterator::Valid() const {
 441   return key_ != NULL && index_ >= 0;
 442 }
 443
 444 void RegistryKeyIterator::operator++() {
 445   --index_;
 446   Read();
 447 }
 448
 449 bool RegistryKeyIterator::Read() {
 450   if (Valid()) {
 451     DWORD ncount = arraysize(name_);
 452     FILETIME written;
 453     LONG r = ::RegEnumKeyEx(key_, index_, name_, &ncount, NULL, NULL,
 454                             NULL, &written);
 455     if (ERROR_SUCCESS == r)
 456       return true;
 457   }
 458
 459   name_[0] = '\0';
 460   return false;
 461 }
 462
 463 }  // namespace win
 464 }  // namespace base