1 // Copyright 2012 The Chromium Authors
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 <ntstatus.h>
8 #include <stddef.h>
9
10 #include <algorithm>
11 #include <iterator>
12 #include <memory>
13 #include <string>
14 #include <utility>
15 #include <vector>
16
17 #include "base/check_op.h"
18 #include "base/functional/callback.h"
19 #include "base/notreached.h"
20 #include "base/strings/string_util.h"
21 #include "base/strings/string_util_win.h"
22 #include "base/threading/thread_restrictions.h"
23 #include "base/win/object_watcher.h"
24 #include "base/win/scoped_handle.h"
25 #include "base/win/shlwapi.h"
26
27 extern "C" NTSTATUS WINAPI NtDeleteKey(IN HANDLE KeyHandle);
28
29 namespace base::win {
30
31 namespace {
32
33 // RegEnumValue() reports the number of characters from the name that were
34 // written to the buffer, not how many there are. This constant is the maximum
35 // name size, such that a buffer with this size should read any name.
36 constexpr DWORD MAX_REGISTRY_NAME_SIZE = 16384;
37
38 // Registry values are read as BYTE* but can have wchar_t* data whose last
39 // wchar_t is truncated. This function converts the reported |byte_size| to
40 // a size in wchar_t that can store a truncated wchar_t if necessary.
to_wchar_size(DWORD byte_size)41 inline DWORD to_wchar_size(DWORD byte_size) {
42 return (byte_size + sizeof(wchar_t) - 1) / sizeof(wchar_t);
43 }
44
45 // Mask to pull WOW64 access flags out of REGSAM access.
46 constexpr REGSAM kWow64AccessMask = KEY_WOW64_32KEY | KEY_WOW64_64KEY;
47
48 constexpr DWORD kInvalidIterValue = static_cast<DWORD>(-1);
49
50 } // namespace
51
52 // Watches for modifications to a key.
53 class RegKey::Watcher : public ObjectWatcher::Delegate {
54 public:
55 Watcher() = default;
56
57 Watcher(const Watcher&) = delete;
58 Watcher& operator=(const Watcher&) = delete;
59
60 ~Watcher() override = default;
61
62 bool StartWatching(HKEY key, ChangeCallback callback);
63
64 // ObjectWatcher::Delegate:
OnObjectSignaled(HANDLE object)65 void OnObjectSignaled(HANDLE object) override {
66 DCHECK(watch_event_.is_valid());
67 DCHECK_EQ(watch_event_.get(), object);
68 std::move(callback_).Run();
69 }
70
71 private:
72 ScopedHandle watch_event_;
73 ObjectWatcher object_watcher_;
74 ChangeCallback callback_;
75 };
76
StartWatching(HKEY key,ChangeCallback callback)77 bool RegKey::Watcher::StartWatching(HKEY key, ChangeCallback callback) {
78 DCHECK(key);
79 DCHECK(callback_.is_null());
80
81 if (!watch_event_.is_valid()) {
82 watch_event_.Set(CreateEvent(nullptr, TRUE, FALSE, nullptr));
83 }
84
85 if (!watch_event_.is_valid()) {
86 return false;
87 }
88
89 DWORD filter = REG_NOTIFY_CHANGE_NAME | REG_NOTIFY_CHANGE_ATTRIBUTES |
90 REG_NOTIFY_CHANGE_LAST_SET | REG_NOTIFY_CHANGE_SECURITY |
91 REG_NOTIFY_THREAD_AGNOSTIC;
92 // Watch the registry key for a change of value.
93 LONG result =
94 RegNotifyChangeKeyValue(key, /*bWatchSubtree=*/TRUE, filter,
95 watch_event_.get(), /*fAsynchronous=*/TRUE);
96 if (result != ERROR_SUCCESS) {
97 watch_event_.Close();
98 return false;
99 }
100
101 callback_ = std::move(callback);
102 return object_watcher_.StartWatchingOnce(watch_event_.get(), this);
103 }
104
105 // RegKey ----------------------------------------------------------------------
106
107 RegKey::RegKey() = default;
108
RegKey(HKEY key)109 RegKey::RegKey(HKEY key) : key_(key) {}
110
RegKey(HKEY rootkey,const wchar_t * subkey,REGSAM access)111 RegKey::RegKey(HKEY rootkey, const wchar_t* subkey, REGSAM access) {
112 if (rootkey) {
113 if (access & (KEY_SET_VALUE | KEY_CREATE_SUB_KEY | KEY_CREATE_LINK)) {
114 (void)Create(rootkey, subkey, access);
115 } else {
116 (void)Open(rootkey, subkey, access);
117 }
118 } else {
119 DCHECK(!subkey);
120 wow64access_ = access & kWow64AccessMask;
121 }
122 }
123
RegKey(RegKey && other)124 RegKey::RegKey(RegKey&& other) noexcept
125 : key_(other.key_),
126 wow64access_(other.wow64access_),
127 key_watcher_(std::move(other.key_watcher_)) {
128 other.key_ = nullptr;
129 other.wow64access_ = 0;
130 }
131
operator =(RegKey && other)132 RegKey& RegKey::operator=(RegKey&& other) {
133 Close();
134 std::swap(key_, other.key_);
135 std::swap(wow64access_, other.wow64access_);
136 key_watcher_ = std::move(other.key_watcher_);
137 return *this;
138 }
139
~RegKey()140 RegKey::~RegKey() {
141 Close();
142 }
143
Create(HKEY rootkey,const wchar_t * subkey,REGSAM access)144 LONG RegKey::Create(HKEY rootkey, const wchar_t* subkey, REGSAM access) {
145 DWORD disposition_value;
146 return CreateWithDisposition(rootkey, subkey, &disposition_value, access);
147 }
148
CreateWithDisposition(HKEY rootkey,const wchar_t * subkey,DWORD * disposition,REGSAM access)149 LONG RegKey::CreateWithDisposition(HKEY rootkey,
150 const wchar_t* subkey,
151 DWORD* disposition,
152 REGSAM access) {
153 DCHECK(rootkey && subkey && access && disposition);
154 HKEY subhkey = nullptr;
155 LONG result =
156 RegCreateKeyEx(rootkey, subkey, 0, nullptr, REG_OPTION_NON_VOLATILE,
157 access, nullptr, &subhkey, disposition);
158 if (result == ERROR_SUCCESS) {
159 Close();
160 key_ = subhkey;
161 wow64access_ = access & kWow64AccessMask;
162 }
163
164 return result;
165 }
166
CreateKey(const wchar_t * name,REGSAM access)167 LONG RegKey::CreateKey(const wchar_t* name, REGSAM access) {
168 DCHECK(name && access);
169
170 if (!Valid()) {
171 // The parent key has not been opened or created.
172 return ERROR_INVALID_HANDLE;
173 }
174
175 // After the application has accessed an alternate registry view using one
176 // of the [KEY_WOW64_32KEY / KEY_WOW64_64KEY] flags, all subsequent
177 // operations (create, delete, or open) on child registry keys must
178 // explicitly use the same flag. Otherwise, there can be unexpected
179 // behavior.
180 // http://msdn.microsoft.com/en-us/library/windows/desktop/aa384129.aspx.
181 if ((access & kWow64AccessMask) != wow64access_) {
182 NOTREACHED();
183 return ERROR_INVALID_PARAMETER;
184 }
185 HKEY subkey = nullptr;
186 LONG result = RegCreateKeyEx(key_, name, 0, nullptr, REG_OPTION_NON_VOLATILE,
187 access, nullptr, &subkey, nullptr);
188 if (result == ERROR_SUCCESS) {
189 Close();
190 key_ = subkey;
191 wow64access_ = access & kWow64AccessMask;
192 }
193
194 return result;
195 }
196
Open(HKEY rootkey,const wchar_t * subkey,REGSAM access)197 LONG RegKey::Open(HKEY rootkey, const wchar_t* subkey, REGSAM access) {
198 return Open(rootkey, subkey, /*options=*/0, access);
199 }
200
OpenKey(const wchar_t * relative_key_name,REGSAM access)201 LONG RegKey::OpenKey(const wchar_t* relative_key_name, REGSAM access) {
202 DCHECK(relative_key_name && access);
203
204 if (!Valid()) {
205 // The parent key has not been opened or created.
206 return ERROR_INVALID_HANDLE;
207 }
208
209 // After the application has accessed an alternate registry view using one
210 // of the [KEY_WOW64_32KEY / KEY_WOW64_64KEY] flags, all subsequent
211 // operations (create, delete, or open) on child registry keys must
212 // explicitly use the same flag. Otherwise, there can be unexpected
213 // behavior.
214 // http://msdn.microsoft.com/en-us/library/windows/desktop/aa384129.aspx.
215 if ((access & kWow64AccessMask) != wow64access_) {
216 NOTREACHED();
217 return ERROR_INVALID_PARAMETER;
218 }
219 HKEY subkey = nullptr;
220 LONG result = RegOpenKeyEx(key_, relative_key_name, 0, access, &subkey);
221
222 // We have to close the current opened key before replacing it with the new
223 // one.
224 if (result == ERROR_SUCCESS) {
225 Close();
226 key_ = subkey;
227 wow64access_ = access & kWow64AccessMask;
228 }
229 return result;
230 }
231
Close()232 void RegKey::Close() {
233 if (key_) {
234 ::RegCloseKey(key_);
235 key_ = nullptr;
236 wow64access_ = 0;
237 }
238 }
239
240 // TODO(wfh): Remove this and other unsafe methods. See http://crbug.com/375400
Set(HKEY key)241 void RegKey::Set(HKEY key) {
242 if (key_ != key) {
243 Close();
244 key_ = key;
245 }
246 }
247
Take()248 HKEY RegKey::Take() {
249 DCHECK_EQ(wow64access_, 0u);
250 HKEY key = key_;
251 key_ = nullptr;
252 return key;
253 }
254
HasValue(const wchar_t * name) const255 bool RegKey::HasValue(const wchar_t* name) const {
256 return RegQueryValueEx(key_, name, nullptr, nullptr, nullptr, nullptr) ==
257 ERROR_SUCCESS;
258 }
259
GetValueCount() const260 base::expected<DWORD, LONG> RegKey::GetValueCount() const {
261 DWORD count = 0;
262 LONG result =
263 RegQueryInfoKey(key_, nullptr, nullptr, nullptr, nullptr, nullptr,
264 nullptr, &count, nullptr, nullptr, nullptr, nullptr);
265 if (result == ERROR_SUCCESS) {
266 return base::ok(count);
267 }
268 return base::unexpected(result);
269 }
270
GetValueNameAt(DWORD index,std::wstring * name) const271 LONG RegKey::GetValueNameAt(DWORD index, std::wstring* name) const {
272 wchar_t buf[256];
273 DWORD bufsize = std::size(buf);
274 LONG r = ::RegEnumValue(key_, index, buf, &bufsize, nullptr, nullptr, nullptr,
275 nullptr);
276 if (r == ERROR_SUCCESS) {
277 name->assign(buf, bufsize);
278 }
279
280 return r;
281 }
282
DeleteKey(const wchar_t * name,RecursiveDelete recursive)283 LONG RegKey::DeleteKey(const wchar_t* name, RecursiveDelete recursive) {
284 DCHECK(name);
285
286 if (!Valid()) {
287 return ERROR_INVALID_HANDLE;
288 }
289
290 // Verify the key exists before attempting delete to replicate previous
291 // behavior.
292 RegKey target_key;
293 LONG result = target_key.Open(key_, name, REG_OPTION_OPEN_LINK,
294 wow64access_ | KEY_QUERY_VALUE | DELETE);
295 if (result != ERROR_SUCCESS) {
296 return result;
297 }
298
299 if (recursive.value()) {
300 target_key.Close();
301 return RegDelRecurse(key_, name, wow64access_);
302 }
303
304 // Next, try to delete the key if it is a symbolic link.
305 if (auto deleted_link = target_key.DeleteIfLink(); deleted_link.has_value()) {
306 return deleted_link.value();
307 }
308
309 // It's not a symbolic link, so try to delete it without recursing.
310 return ::RegDeleteKeyEx(target_key.key_, L"", wow64access_, 0);
311 }
312
DeleteValue(const wchar_t * value_name)313 LONG RegKey::DeleteValue(const wchar_t* value_name) {
314 // `RegDeleteValue()` will return an error if `key_` is invalid.
315 LONG result = RegDeleteValue(key_, value_name);
316 return result;
317 }
318
ReadValueDW(const wchar_t * name,DWORD * out_value) const319 LONG RegKey::ReadValueDW(const wchar_t* name, DWORD* out_value) const {
320 DCHECK(out_value);
321 DWORD type = REG_DWORD;
322 DWORD size = sizeof(DWORD);
323 DWORD local_value = 0;
324 LONG result = ReadValue(name, &local_value, &size, &type);
325 if (result == ERROR_SUCCESS) {
326 if ((type == REG_DWORD || type == REG_BINARY) && size == sizeof(DWORD)) {
327 *out_value = local_value;
328 } else {
329 result = ERROR_CANTREAD;
330 }
331 }
332
333 return result;
334 }
335
ReadInt64(const wchar_t * name,int64_t * out_value) const336 LONG RegKey::ReadInt64(const wchar_t* name, int64_t* out_value) const {
337 DCHECK(out_value);
338 DWORD type = REG_QWORD;
339 int64_t local_value = 0;
340 DWORD size = sizeof(local_value);
341 LONG result = ReadValue(name, &local_value, &size, &type);
342 if (result == ERROR_SUCCESS) {
343 if ((type == REG_QWORD || type == REG_BINARY) &&
344 size == sizeof(local_value)) {
345 *out_value = local_value;
346 } else {
347 result = ERROR_CANTREAD;
348 }
349 }
350
351 return result;
352 }
353
ReadValue(const wchar_t * name,std::wstring * out_value) const354 LONG RegKey::ReadValue(const wchar_t* name, std::wstring* out_value) const {
355 DCHECK(out_value);
356 const size_t kMaxStringLength = 1024; // This is after expansion.
357 // Use the one of the other forms of ReadValue if 1024 is too small for you.
358 wchar_t raw_value[kMaxStringLength];
359 DWORD type = REG_SZ, size = sizeof(raw_value);
360 LONG result = ReadValue(name, raw_value, &size, &type);
361 if (result == ERROR_SUCCESS) {
362 if (type == REG_SZ) {
363 *out_value = raw_value;
364 } else if (type == REG_EXPAND_SZ) {
365 wchar_t expanded[kMaxStringLength];
366 size = ExpandEnvironmentStrings(raw_value, expanded, kMaxStringLength);
367 // Success: returns the number of wchar_t's copied
368 // Fail: buffer too small, returns the size required
369 // Fail: other, returns 0
370 if (size == 0 || size > kMaxStringLength) {
371 result = ERROR_MORE_DATA;
372 } else {
373 *out_value = expanded;
374 }
375 } else {
376 // Not a string. Oops.
377 result = ERROR_CANTREAD;
378 }
379 }
380
381 return result;
382 }
383
ReadValue(const wchar_t * name,void * data,DWORD * dsize,DWORD * dtype) const384 LONG RegKey::ReadValue(const wchar_t* name,
385 void* data,
386 DWORD* dsize,
387 DWORD* dtype) const {
388 LONG result = RegQueryValueEx(key_, name, nullptr, dtype,
389 reinterpret_cast<LPBYTE>(data), dsize);
390 return result;
391 }
392
ReadValues(const wchar_t * name,std::vector<std::wstring> * values)393 LONG RegKey::ReadValues(const wchar_t* name,
394 std::vector<std::wstring>* values) {
395 values->clear();
396
397 DWORD type = REG_MULTI_SZ;
398 DWORD size = 0;
399 LONG result = ReadValue(name, nullptr, &size, &type);
400 if (result != ERROR_SUCCESS || size == 0) {
401 return result;
402 }
403
404 if (type != REG_MULTI_SZ) {
405 return ERROR_CANTREAD;
406 }
407
408 std::vector<wchar_t> buffer(size / sizeof(wchar_t));
409 result = ReadValue(name, buffer.data(), &size, nullptr);
410 if (result != ERROR_SUCCESS || size == 0) {
411 return result;
412 }
413
414 // Parse the double-null-terminated list of strings.
415 // Note: This code is paranoid to not read outside of |buf|, in the case where
416 // it may not be properly terminated.
417 auto entry = buffer.cbegin();
418 auto buffer_end = buffer.cend();
419 while (entry < buffer_end && *entry != '\0') {
420 auto entry_end = std::find(entry, buffer_end, '\0');
421 values->emplace_back(entry, entry_end);
422 entry = entry_end + 1;
423 }
424 return 0;
425 }
426
WriteValue(const wchar_t * name,DWORD in_value)427 LONG RegKey::WriteValue(const wchar_t* name, DWORD in_value) {
428 return WriteValue(name, &in_value, static_cast<DWORD>(sizeof(in_value)),
429 REG_DWORD);
430 }
431
WriteValue(const wchar_t * name,const wchar_t * in_value)432 LONG RegKey::WriteValue(const wchar_t* name, const wchar_t* in_value) {
433 return WriteValue(
434 name, in_value,
435 static_cast<DWORD>(sizeof(*in_value) *
436 (std::char_traits<wchar_t>::length(in_value) + 1)),
437 REG_SZ);
438 }
439
WriteValue(const wchar_t * name,const void * data,DWORD dsize,DWORD dtype)440 LONG RegKey::WriteValue(const wchar_t* name,
441 const void* data,
442 DWORD dsize,
443 DWORD dtype) {
444 DCHECK(data || !dsize);
445
446 LONG result =
447 RegSetValueEx(key_, name, 0, dtype,
448 reinterpret_cast<LPBYTE>(const_cast<void*>(data)), dsize);
449 return result;
450 }
451
StartWatching(ChangeCallback callback)452 bool RegKey::StartWatching(ChangeCallback callback) {
453 if (!key_watcher_) {
454 key_watcher_ = std::make_unique<Watcher>();
455 }
456
457 if (!key_watcher_->StartWatching(key_, std::move(callback))) {
458 return false;
459 }
460
461 return true;
462 }
463
Open(HKEY rootkey,const wchar_t * subkey,DWORD options,REGSAM access)464 LONG RegKey::Open(HKEY rootkey,
465 const wchar_t* subkey,
466 DWORD options,
467 REGSAM access) {
468 DCHECK(options == 0 || options == REG_OPTION_OPEN_LINK) << options;
469 DCHECK(rootkey && subkey && access);
470 HKEY subhkey = nullptr;
471
472 LONG result = RegOpenKeyEx(rootkey, subkey, options, access, &subhkey);
473 if (result == ERROR_SUCCESS) {
474 Close();
475 key_ = subhkey;
476 wow64access_ = access & kWow64AccessMask;
477 }
478
479 return result;
480 }
481
IsLink() const482 expected<bool, LONG> RegKey::IsLink() const {
483 DWORD value_type = 0;
484 LONG result = ::RegQueryValueEx(key_, L"SymbolicLinkValue",
485 /*lpReserved=*/nullptr, &value_type,
486 /*lpData=*/nullptr, /*lpcbData=*/nullptr);
487 if (result == ERROR_FILE_NOT_FOUND) {
488 return ok(false);
489 }
490 if (result == ERROR_SUCCESS) {
491 return ok(value_type == REG_LINK);
492 }
493 return unexpected(result);
494 }
495
DeleteIfLink()496 std::optional<LONG> RegKey::DeleteIfLink() {
497 if (auto is_link = IsLink(); !is_link.has_value()) {
498 return is_link.error(); // Failed to determine if a link.
499 } else if (is_link.value() == false) {
500 return std::nullopt; // Not a link.
501 }
502
503 const NTSTATUS delete_result = ::NtDeleteKey(key_);
504 if (delete_result == STATUS_SUCCESS) {
505 return ERROR_SUCCESS;
506 }
507 using RtlNtStatusToDosErrorFunction = ULONG(WINAPI*)(NTSTATUS);
508 static const RtlNtStatusToDosErrorFunction rtl_nt_status_to_dos_error =
509 reinterpret_cast<RtlNtStatusToDosErrorFunction>(::GetProcAddress(
510 ::GetModuleHandle(L"ntdll.dll"), "RtlNtStatusToDosError"));
511 // The most common cause of failure is the presence of subkeys, which is
512 // reported as `STATUS_CANNOT_DELETE` and maps to `ERROR_ACCESS_DENIED`.
513 return rtl_nt_status_to_dos_error
514 ? static_cast<LONG>(rtl_nt_status_to_dos_error(delete_result))
515 : ERROR_ACCESS_DENIED;
516 }
517
518 // static
RegDelRecurse(HKEY root_key,const wchar_t * name,REGSAM access)519 LONG RegKey::RegDelRecurse(HKEY root_key, const wchar_t* name, REGSAM access) {
520 // First, open the key; taking care not to traverse symbolic links.
521 RegKey target_key;
522 LONG result = target_key.Open(
523 root_key, name, REG_OPTION_OPEN_LINK,
524 access | KEY_ENUMERATE_SUB_KEYS | KEY_QUERY_VALUE | DELETE);
525 if (result == ERROR_FILE_NOT_FOUND) { // The key doesn't exist.
526 return ERROR_SUCCESS;
527 }
528 if (result != ERROR_SUCCESS) {
529 return result;
530 }
531
532 // Next, try to delete the key if it is a symbolic link.
533 if (auto deleted_link = target_key.DeleteIfLink(); deleted_link.has_value()) {
534 return deleted_link.value();
535 }
536
537 // It's not a symbolic link, so try to delete it without recursing.
538 result = ::RegDeleteKeyEx(target_key.key_, L"", access, 0);
539 if (result == ERROR_SUCCESS) {
540 return result;
541 }
542
543 // Enumerate the keys.
544 const DWORD kMaxKeyNameLength = 256; // Includes string terminator.
545 auto subkey_buffer = std::make_unique<wchar_t[]>(kMaxKeyNameLength);
546 while (true) {
547 DWORD key_size = kMaxKeyNameLength;
548 if (::RegEnumKeyEx(target_key.key_, 0, &subkey_buffer[0], &key_size,
549 nullptr, nullptr, nullptr, nullptr) != ERROR_SUCCESS) {
550 break;
551 }
552 CHECK_LT(key_size, kMaxKeyNameLength);
553 CHECK_EQ(subkey_buffer[key_size], L'\0');
554 if (RegDelRecurse(target_key.key_, &subkey_buffer[0], access) !=
555 ERROR_SUCCESS) {
556 break;
557 }
558 }
559
560 // Try again to delete the key.
561 return ::RegDeleteKeyEx(target_key.key_, L"", access, 0);
562 }
563
564 // RegistryValueIterator ------------------------------------------------------
565
RegistryValueIterator(HKEY root_key,const wchar_t * folder_key,REGSAM wow64access)566 RegistryValueIterator::RegistryValueIterator(HKEY root_key,
567 const wchar_t* folder_key,
568 REGSAM wow64access)
569 : name_(MAX_PATH, '\0'), value_(MAX_PATH, '\0') {
570 Initialize(root_key, folder_key, wow64access);
571 }
572
RegistryValueIterator(HKEY root_key,const wchar_t * folder_key)573 RegistryValueIterator::RegistryValueIterator(HKEY root_key,
574 const wchar_t* folder_key)
575 : name_(MAX_PATH, '\0'), value_(MAX_PATH, '\0') {
576 Initialize(root_key, folder_key, 0);
577 }
578
Initialize(HKEY root_key,const wchar_t * folder_key,REGSAM wow64access)579 void RegistryValueIterator::Initialize(HKEY root_key,
580 const wchar_t* folder_key,
581 REGSAM wow64access) {
582 DCHECK_EQ(wow64access & ~kWow64AccessMask, static_cast<REGSAM>(0));
583 LONG result =
584 RegOpenKeyEx(root_key, folder_key, 0, KEY_READ | wow64access, &key_);
585 if (result != ERROR_SUCCESS) {
586 key_ = nullptr;
587 } else {
588 DWORD count = 0;
589 result =
590 ::RegQueryInfoKey(key_, nullptr, nullptr, nullptr, nullptr, nullptr,
591 nullptr, &count, nullptr, nullptr, nullptr, nullptr);
592
593 if (result != ERROR_SUCCESS) {
594 ::RegCloseKey(key_);
595 key_ = nullptr;
596 } else {
597 index_ = count - 1;
598 }
599 }
600
601 Read();
602 }
603
~RegistryValueIterator()604 RegistryValueIterator::~RegistryValueIterator() {
605 if (key_)
606 ::RegCloseKey(key_);
607 }
608
ValueCount() const609 DWORD RegistryValueIterator::ValueCount() const {
610 DWORD count = 0;
611 LONG result =
612 ::RegQueryInfoKey(key_, nullptr, nullptr, nullptr, nullptr, nullptr,
613 nullptr, &count, nullptr, nullptr, nullptr, nullptr);
614 if (result != ERROR_SUCCESS)
615 return 0;
616
617 return count;
618 }
619
Valid() const620 bool RegistryValueIterator::Valid() const {
621 return key_ != nullptr && index_ != kInvalidIterValue;
622 }
623
operator ++()624 void RegistryValueIterator::operator++() {
625 if (index_ != kInvalidIterValue)
626 --index_;
627 Read();
628 }
629
Read()630 bool RegistryValueIterator::Read() {
631 if (Valid()) {
632 DWORD capacity = static_cast<DWORD>(name_.capacity());
633 DWORD name_size = capacity;
634 // |value_size_| is in bytes. Reserve the last character for a NUL.
635 value_size_ = static_cast<DWORD>((value_.size() - 1) * sizeof(wchar_t));
636 LONG result = ::RegEnumValue(
637 key_, index_, WriteInto(&name_, name_size), &name_size, nullptr, &type_,
638 reinterpret_cast<BYTE*>(value_.data()), &value_size_);
639
640 if (result == ERROR_MORE_DATA) {
641 // Registry key names are limited to 255 characters and fit within
642 // MAX_PATH (which is 260) but registry value names can use up to 16,383
643 // characters and the value itself is not limited
644 // (from http://msdn.microsoft.com/en-us/library/windows/desktop/
645 // ms724872(v=vs.85).aspx).
646 // Resize the buffers and retry if their size caused the failure.
647 DWORD value_size_in_wchars = to_wchar_size(value_size_);
648 if (value_size_in_wchars + 1 > value_.size())
649 value_.resize(value_size_in_wchars + 1, '\0');
650 value_size_ = static_cast<DWORD>((value_.size() - 1) * sizeof(wchar_t));
651 name_size = name_size == capacity ? MAX_REGISTRY_NAME_SIZE : capacity;
652 result = ::RegEnumValue(
653 key_, index_, WriteInto(&name_, name_size), &name_size, nullptr,
654 &type_, reinterpret_cast<BYTE*>(value_.data()), &value_size_);
655 }
656
657 if (result == ERROR_SUCCESS) {
658 DCHECK_LT(to_wchar_size(value_size_), value_.size());
659 value_[to_wchar_size(value_size_)] = '\0';
660 return true;
661 }
662 }
663
664 name_[0] = '\0';
665 value_[0] = '\0';
666 value_size_ = 0;
667 return false;
668 }
669
670 // RegistryKeyIterator --------------------------------------------------------
671
RegistryKeyIterator(HKEY root_key,const wchar_t * folder_key)672 RegistryKeyIterator::RegistryKeyIterator(HKEY root_key,
673 const wchar_t* folder_key) {
674 Initialize(root_key, folder_key, 0);
675 }
676
RegistryKeyIterator(HKEY root_key,const wchar_t * folder_key,REGSAM wow64access)677 RegistryKeyIterator::RegistryKeyIterator(HKEY root_key,
678 const wchar_t* folder_key,
679 REGSAM wow64access) {
680 Initialize(root_key, folder_key, wow64access);
681 }
682
~RegistryKeyIterator()683 RegistryKeyIterator::~RegistryKeyIterator() {
684 if (key_)
685 ::RegCloseKey(key_);
686 }
687
SubkeyCount() const688 DWORD RegistryKeyIterator::SubkeyCount() const {
689 DWORD count = 0;
690 LONG result =
691 ::RegQueryInfoKey(key_, nullptr, nullptr, nullptr, &count, nullptr,
692 nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
693 if (result != ERROR_SUCCESS)
694 return 0;
695
696 return count;
697 }
698
Valid() const699 bool RegistryKeyIterator::Valid() const {
700 return key_ != nullptr && index_ != kInvalidIterValue;
701 }
702
operator ++()703 void RegistryKeyIterator::operator++() {
704 if (index_ != kInvalidIterValue)
705 --index_;
706 Read();
707 }
708
Read()709 bool RegistryKeyIterator::Read() {
710 if (Valid()) {
711 DWORD ncount = static_cast<DWORD>(std::size(name_));
712 FILETIME written;
713 LONG r = ::RegEnumKeyEx(key_, index_, name_, &ncount, nullptr, nullptr,
714 nullptr, &written);
715 if (ERROR_SUCCESS == r)
716 return true;
717 }
718
719 name_[0] = '\0';
720 return false;
721 }
722
Initialize(HKEY root_key,const wchar_t * folder_key,REGSAM wow64access)723 void RegistryKeyIterator::Initialize(HKEY root_key,
724 const wchar_t* folder_key,
725 REGSAM wow64access) {
726 DCHECK_EQ(wow64access & ~kWow64AccessMask, static_cast<REGSAM>(0));
727 LONG result =
728 RegOpenKeyEx(root_key, folder_key, 0, KEY_READ | wow64access, &key_);
729 if (result != ERROR_SUCCESS) {
730 key_ = nullptr;
731 } else {
732 DWORD count = 0;
733 result =
734 ::RegQueryInfoKey(key_, nullptr, nullptr, nullptr, &count, nullptr,
735 nullptr, nullptr, nullptr, nullptr, nullptr, nullptr);
736
737 if (result != ERROR_SUCCESS) {
738 ::RegCloseKey(key_);
739 key_ = nullptr;
740 } else {
741 index_ = count - 1;
742 }
743 }
744
745 Read();
746 }
747
748 } // namespace base::win
749