// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/win/registry.h"
#include <shlwapi.h>
#include <algorithm>
#include "base/logging.h"
#include "base/strings/string_util.h"
#include "base/threading/thread_restrictions.h"
#include "base/win/windows_version.h"
namespace base {
namespace win {
namespace {
// RegEnumValue() reports the number of characters from the name that were
// written to the buffer, not how many there are. This constant is the maximum
// name size, such that a buffer with this size should read any name.
const DWORD MAX_REGISTRY_NAME_SIZE = 16384;
// Registry values are read as BYTE* but can have wchar_t* data whose last
// wchar_t is truncated. This function converts the reported |byte_size| to
// a size in wchar_t that can store a truncated wchar_t if necessary.
inline DWORD to_wchar_size(DWORD byte_size) {
return (byte_size + sizeof(wchar_t) - 1) / sizeof(wchar_t);
}
// Mask to pull WOW64 access flags out of REGSAM access.
const REGSAM kWow64AccessMask = KEY_WOW64_32KEY | KEY_WOW64_64KEY;
} // namespace
// RegKey ----------------------------------------------------------------------
RegKey::RegKey()
: key_(NULL),
watch_event_(0),
wow64access_(0) {
}
RegKey::RegKey(HKEY key)
: key_(key),
watch_event_(0),
wow64access_(0) {
}
RegKey::RegKey(HKEY rootkey, const wchar_t* subkey, REGSAM access)
: key_(NULL),
watch_event_(0),
wow64access_(0) {
if (rootkey) {
if (access & (KEY_SET_VALUE | KEY_CREATE_SUB_KEY | KEY_CREATE_LINK))
Create(rootkey, subkey, access);
else
Open(rootkey, subkey, access);
} else {
DCHECK(!subkey);
wow64access_ = access & kWow64AccessMask;
}
}
RegKey::~RegKey() {
Close();
}
LONG RegKey::Create(HKEY rootkey, const wchar_t* subkey, REGSAM access) {
DWORD disposition_value;
return CreateWithDisposition(rootkey, subkey, &disposition_value, access);
}
LONG RegKey::CreateWithDisposition(HKEY rootkey, const wchar_t* subkey,
DWORD* disposition, REGSAM access) {
DCHECK(rootkey && subkey && access && disposition);
HKEY subhkey = NULL;
LONG result = RegCreateKeyEx(rootkey, subkey, 0, NULL,
REG_OPTION_NON_VOLATILE, access, NULL, &subhkey,
disposition);
if (result == ERROR_SUCCESS) {
Close();
key_ = subhkey;
wow64access_ = access & kWow64AccessMask;
}
return result;
}
LONG RegKey::CreateKey(const wchar_t* name, REGSAM access) {
DCHECK(name && access);
// After the application has accessed an alternate registry view using one of
// the [KEY_WOW64_32KEY / KEY_WOW64_64KEY] flags, all subsequent operations
// (create, delete, or open) on child registry keys must explicitly use the
// same flag. Otherwise, there can be unexpected behavior.
// http://msdn.microsoft.com/en-us/library/windows/desktop/aa384129.aspx.
if ((access & kWow64AccessMask) != wow64access_) {
NOTREACHED();
return ERROR_INVALID_PARAMETER;
}
HKEY subkey = NULL;
LONG result = RegCreateKeyEx(key_, name, 0, NULL, REG_OPTION_NON_VOLATILE,
access, NULL, &subkey, NULL);
if (result == ERROR_SUCCESS) {
Close();
key_ = subkey;
wow64access_ = access & kWow64AccessMask;
}
return result;
}
LONG RegKey::Open(HKEY rootkey, const wchar_t* subkey, REGSAM access) {
DCHECK(rootkey && subkey && access);
HKEY subhkey = NULL;
LONG result = RegOpenKeyEx(rootkey, subkey, 0, access, &subhkey);
if (result == ERROR_SUCCESS) {
Close();
key_ = subhkey;
wow64access_ = access & kWow64AccessMask;
}
return result;
}
LONG RegKey::OpenKey(const wchar_t* relative_key_name, REGSAM access) {
DCHECK(relative_key_name && access);
// After the application has accessed an alternate registry view using one of
// the [KEY_WOW64_32KEY / KEY_WOW64_64KEY] flags, all subsequent operations
// (create, delete, or open) on child registry keys must explicitly use the
// same flag. Otherwise, there can be unexpected behavior.
// http://msdn.microsoft.com/en-us/library/windows/desktop/aa384129.aspx.
if ((access & kWow64AccessMask) != wow64access_) {
NOTREACHED();
return ERROR_INVALID_PARAMETER;
}
HKEY subkey = NULL;
LONG result = RegOpenKeyEx(key_, relative_key_name, 0, access, &subkey);
// We have to close the current opened key before replacing it with the new
// one.
if (result == ERROR_SUCCESS) {
Close();
key_ = subkey;
wow64access_ = access & kWow64AccessMask;
}
return result;
}
void RegKey::Close() {
StopWatching();
if (key_) {
::RegCloseKey(key_);
key_ = NULL;
wow64access_ = 0;
}
}
// TODO(wfh): Remove this and other unsafe methods. See http://crbug.com/375400
void RegKey::Set(HKEY key) {
if (key_ != key) {
Close();
key_ = key;
}
}
HKEY RegKey::Take() {
DCHECK(wow64access_ == 0);
StopWatching();
HKEY key = key_;
key_ = NULL;
return key;
}
bool RegKey::HasValue(const wchar_t* name) const {
return RegQueryValueEx(key_, name, 0, NULL, NULL, NULL) == ERROR_SUCCESS;
}
DWORD RegKey::GetValueCount() const {
DWORD count = 0;
LONG result = RegQueryInfoKey(key_, NULL, 0, NULL, NULL, NULL, NULL, &count,
NULL, NULL, NULL, NULL);
return (result == ERROR_SUCCESS) ? count : 0;
}
LONG RegKey::GetValueNameAt(int index, std::wstring* name) const {
wchar_t buf[256];
DWORD bufsize = arraysize(buf);
LONG r = ::RegEnumValue(key_, index, buf, &bufsize, NULL, NULL, NULL, NULL);
if (r == ERROR_SUCCESS)
*name = buf;
return r;
}
LONG RegKey::DeleteKey(const wchar_t* name) {
DCHECK(key_);
DCHECK(name);
HKEY subkey = NULL;
// Verify the key exists before attempting delete to replicate previous
// behavior.
LONG result =
RegOpenKeyEx(key_, name, 0, READ_CONTROL | wow64access_, &subkey);
if (result != ERROR_SUCCESS)
return result;
RegCloseKey(subkey);
return RegDelRecurse(key_, std::wstring(name), wow64access_);
}
LONG RegKey::DeleteEmptyKey(const wchar_t* name) {
DCHECK(key_);
DCHECK(name);
HKEY target_key = NULL;
LONG result = RegOpenKeyEx(key_, name, 0, KEY_READ | wow64access_,
&target_key);
if (result != ERROR_SUCCESS)
return result;
DWORD count = 0;
result = RegQueryInfoKey(target_key, NULL, 0, NULL, NULL, NULL, NULL, &count,
NULL, NULL, NULL, NULL);
RegCloseKey(target_key);
if (result != ERROR_SUCCESS)
return result;
if (count == 0)
return RegDeleteKeyExWrapper(key_, name, wow64access_, 0);
return ERROR_DIR_NOT_EMPTY;
}
LONG RegKey::DeleteValue(const wchar_t* value_name) {
DCHECK(key_);
LONG result = RegDeleteValue(key_, value_name);
return result;
}
LONG RegKey::ReadValueDW(const wchar_t* name, DWORD* out_value) const {
DCHECK(out_value);
DWORD type = REG_DWORD;
DWORD size = sizeof(DWORD);
DWORD local_value = 0;
LONG result = ReadValue(name, &local_value, &size, &type);
if (result == ERROR_SUCCESS) {
if ((type == REG_DWORD || type == REG_BINARY) && size == sizeof(DWORD))
*out_value = local_value;
else
result = ERROR_CANTREAD;
}
return result;
}
LONG RegKey::ReadInt64(const wchar_t* name, int64* out_value) const {
DCHECK(out_value);
DWORD type = REG_QWORD;
int64 local_value = 0;
DWORD size = sizeof(local_value);
LONG result = ReadValue(name, &local_value, &size, &type);
if (result == ERROR_SUCCESS) {
if ((type == REG_QWORD || type == REG_BINARY) &&
size == sizeof(local_value))
*out_value = local_value;
else
result = ERROR_CANTREAD;
}
return result;
}
LONG RegKey::ReadValue(const wchar_t* name, std::wstring* out_value) const {
DCHECK(out_value);
const size_t kMaxStringLength = 1024; // This is after expansion.
// Use the one of the other forms of ReadValue if 1024 is too small for you.
wchar_t raw_value[kMaxStringLength];
DWORD type = REG_SZ, size = sizeof(raw_value);
LONG result = ReadValue(name, raw_value, &size, &type);
if (result == ERROR_SUCCESS) {
if (type == REG_SZ) {
*out_value = raw_value;
} else if (type == REG_EXPAND_SZ) {
wchar_t expanded[kMaxStringLength];
size = ExpandEnvironmentStrings(raw_value, expanded, kMaxStringLength);
// Success: returns the number of wchar_t's copied
// Fail: buffer too small, returns the size required
// Fail: other, returns 0
if (size == 0 || size > kMaxStringLength) {
result = ERROR_MORE_DATA;
} else {
*out_value = expanded;
}
} else {
// Not a string. Oops.
result = ERROR_CANTREAD;
}
}
return result;
}
LONG RegKey::ReadValue(const wchar_t* name,
void* data,
DWORD* dsize,
DWORD* dtype) const {
LONG result = RegQueryValueEx(key_, name, 0, dtype,
reinterpret_cast<LPBYTE>(data), dsize);
return result;
}
LONG RegKey::ReadValues(const wchar_t* name,
std::vector<std::wstring>* values) {
values->clear();
DWORD type = REG_MULTI_SZ;
DWORD size = 0;
LONG result = ReadValue(name, NULL, &size, &type);
if (FAILED(result) || size == 0)
return result;
if (type != REG_MULTI_SZ)
return ERROR_CANTREAD;
std::vector<wchar_t> buffer(size / sizeof(wchar_t));
result = ReadValue(name, &buffer[0], &size, NULL);
if (FAILED(result) || size == 0)
return result;
// Parse the double-null-terminated list of strings.
// Note: This code is paranoid to not read outside of |buf|, in the case where
// it may not be properly terminated.
const wchar_t* entry = &buffer[0];
const wchar_t* buffer_end = entry + (size / sizeof(wchar_t));
while (entry < buffer_end && entry[0] != '\0') {
const wchar_t* entry_end = std::find(entry, buffer_end, L'\0');
values->push_back(std::wstring(entry, entry_end));
entry = entry_end + 1;
}
return 0;
}
LONG RegKey::WriteValue(const wchar_t* name, DWORD in_value) {
return WriteValue(
name, &in_value, static_cast<DWORD>(sizeof(in_value)), REG_DWORD);
}
LONG RegKey::WriteValue(const wchar_t * name, const wchar_t* in_value) {
return WriteValue(name, in_value,
static_cast<DWORD>(sizeof(*in_value) * (wcslen(in_value) + 1)), REG_SZ);
}
LONG RegKey::WriteValue(const wchar_t* name,
const void* data,
DWORD dsize,
DWORD dtype) {
DCHECK(data || !dsize);
LONG result = RegSetValueEx(key_, name, 0, dtype,
reinterpret_cast<LPBYTE>(const_cast<void*>(data)), dsize);
return result;
}
LONG RegKey::StartWatching() {
DCHECK(key_);
if (!watch_event_)
watch_event_ = CreateEvent(NULL, TRUE, FALSE, NULL);
DWORD filter = REG_NOTIFY_CHANGE_NAME |
REG_NOTIFY_CHANGE_ATTRIBUTES |
REG_NOTIFY_CHANGE_LAST_SET |
REG_NOTIFY_CHANGE_SECURITY;
// Watch the registry key for a change of value.
LONG result = RegNotifyChangeKeyValue(key_, TRUE, filter, watch_event_, TRUE);
if (result != ERROR_SUCCESS) {
CloseHandle(watch_event_);
watch_event_ = 0;
}
return result;
}
bool RegKey::HasChanged() {
if (watch_event_) {
if (WaitForSingleObject(watch_event_, 0) == WAIT_OBJECT_0) {
StartWatching();
return true;
}
}
return false;
}
LONG RegKey::StopWatching() {
LONG result = ERROR_INVALID_HANDLE;
if (watch_event_) {
CloseHandle(watch_event_);
watch_event_ = 0;
result = ERROR_SUCCESS;
}
return result;
}
// static
LONG RegKey::RegDeleteKeyExWrapper(HKEY hKey,
const wchar_t* lpSubKey,
REGSAM samDesired,
DWORD Reserved) {
typedef LSTATUS(WINAPI* RegDeleteKeyExPtr)(HKEY, LPCWSTR, REGSAM, DWORD);
RegDeleteKeyExPtr reg_delete_key_ex_func =
reinterpret_cast<RegDeleteKeyExPtr>(
GetProcAddress(GetModuleHandleA("advapi32.dll"), "RegDeleteKeyExW"));
if (reg_delete_key_ex_func)
return reg_delete_key_ex_func(hKey, lpSubKey, samDesired, Reserved);
// Windows XP does not support RegDeleteKeyEx, so fallback to RegDeleteKey.
return RegDeleteKey(hKey, lpSubKey);
}
// static
LONG RegKey::RegDelRecurse(HKEY root_key,
const std::wstring& name,
REGSAM access) {
// First, see if the key can be deleted without having to recurse.
LONG result = RegDeleteKeyExWrapper(root_key, name.c_str(), access, 0);
if (result == ERROR_SUCCESS)
return result;
HKEY target_key = NULL;
result = RegOpenKeyEx(
root_key, name.c_str(), 0, KEY_ENUMERATE_SUB_KEYS | access, &target_key);
if (result == ERROR_FILE_NOT_FOUND)
return ERROR_SUCCESS;
if (result != ERROR_SUCCESS)
return result;
std::wstring subkey_name(name);
// Check for an ending slash and add one if it is missing.
if (!name.empty() && subkey_name[name.length() - 1] != L'\\')
subkey_name += L"\\";
// Enumerate the keys
result = ERROR_SUCCESS;
const DWORD kMaxKeyNameLength = MAX_PATH;
const size_t base_key_length = subkey_name.length();
std::wstring key_name;
while (result == ERROR_SUCCESS) {
DWORD key_size = kMaxKeyNameLength;
result = RegEnumKeyEx(target_key,
0,
WriteInto(&key_name, kMaxKeyNameLength),
&key_size,
NULL,
NULL,
NULL,
NULL);
if (result != ERROR_SUCCESS)
break;
key_name.resize(key_size);
subkey_name.resize(base_key_length);
subkey_name += key_name;
if (RegDelRecurse(root_key, subkey_name, access) != ERROR_SUCCESS)
break;
}
RegCloseKey(target_key);
// Try again to delete the key.
result = RegDeleteKeyExWrapper(root_key, name.c_str(), access, 0);
return result;
}
// RegistryValueIterator ------------------------------------------------------
RegistryValueIterator::RegistryValueIterator(HKEY root_key,
const wchar_t* folder_key)
: name_(MAX_PATH, L'\0'),
value_(MAX_PATH, L'\0') {
LONG result = RegOpenKeyEx(root_key, folder_key, 0, KEY_READ, &key_);
if (result != ERROR_SUCCESS) {
key_ = NULL;
} else {
DWORD count = 0;
result = ::RegQueryInfoKey(key_, NULL, 0, NULL, NULL, NULL, NULL, &count,
NULL, NULL, NULL, NULL);
if (result != ERROR_SUCCESS) {
::RegCloseKey(key_);
key_ = NULL;
} else {
index_ = count - 1;
}
}
Read();
}
RegistryValueIterator::~RegistryValueIterator() {
if (key_)
::RegCloseKey(key_);
}
DWORD RegistryValueIterator::ValueCount() const {
DWORD count = 0;
LONG result = ::RegQueryInfoKey(key_, NULL, 0, NULL, NULL, NULL, NULL,
&count, NULL, NULL, NULL, NULL);
if (result != ERROR_SUCCESS)
return 0;
return count;
}
bool RegistryValueIterator::Valid() const {
return key_ != NULL && index_ >= 0;
}
void RegistryValueIterator::operator++() {
--index_;
Read();
}
bool RegistryValueIterator::Read() {
if (Valid()) {
DWORD capacity = static_cast<DWORD>(name_.capacity());
DWORD name_size = capacity;
// |value_size_| is in bytes. Reserve the last character for a NUL.
value_size_ = static_cast<DWORD>((value_.size() - 1) * sizeof(wchar_t));
LONG result = ::RegEnumValue(
key_, index_, WriteInto(&name_, name_size), &name_size, NULL, &type_,
reinterpret_cast<BYTE*>(vector_as_array(&value_)), &value_size_);
if (result == ERROR_MORE_DATA) {
// Registry key names are limited to 255 characters and fit within
// MAX_PATH (which is 260) but registry value names can use up to 16,383
// characters and the value itself is not limited
// (from http://msdn.microsoft.com/en-us/library/windows/desktop/
// ms724872(v=vs.85).aspx).
// Resize the buffers and retry if their size caused the failure.
DWORD value_size_in_wchars = to_wchar_size(value_size_);
if (value_size_in_wchars + 1 > value_.size())
value_.resize(value_size_in_wchars + 1, L'\0');
value_size_ = static_cast<DWORD>((value_.size() - 1) * sizeof(wchar_t));
name_size = name_size == capacity ? MAX_REGISTRY_NAME_SIZE : capacity;
result = ::RegEnumValue(
key_, index_, WriteInto(&name_, name_size), &name_size, NULL, &type_,
reinterpret_cast<BYTE*>(vector_as_array(&value_)), &value_size_);
}
if (result == ERROR_SUCCESS) {
DCHECK_LT(to_wchar_size(value_size_), value_.size());
value_[to_wchar_size(value_size_)] = L'\0';
return true;
}
}
name_[0] = L'\0';
value_[0] = L'\0';
value_size_ = 0;
return false;
}
// RegistryKeyIterator --------------------------------------------------------
RegistryKeyIterator::RegistryKeyIterator(HKEY root_key,
const wchar_t* folder_key) {
LONG result = RegOpenKeyEx(root_key, folder_key, 0, KEY_READ, &key_);
if (result != ERROR_SUCCESS) {
key_ = NULL;
} else {
DWORD count = 0;
LONG result = ::RegQueryInfoKey(key_, NULL, 0, NULL, &count, NULL, NULL,
NULL, NULL, NULL, NULL, NULL);
if (result != ERROR_SUCCESS) {
::RegCloseKey(key_);
key_ = NULL;
} else {
index_ = count - 1;
}
}
Read();
}
RegistryKeyIterator::~RegistryKeyIterator() {
if (key_)
::RegCloseKey(key_);
}
DWORD RegistryKeyIterator::SubkeyCount() const {
DWORD count = 0;
LONG result = ::RegQueryInfoKey(key_, NULL, 0, NULL, &count, NULL, NULL,
NULL, NULL, NULL, NULL, NULL);
if (result != ERROR_SUCCESS)
return 0;
return count;
}
bool RegistryKeyIterator::Valid() const {
return key_ != NULL && index_ >= 0;
}
void RegistryKeyIterator::operator++() {
--index_;
Read();
}
bool RegistryKeyIterator::Read() {
if (Valid()) {
DWORD ncount = arraysize(name_);
FILETIME written;
LONG r = ::RegEnumKeyEx(key_, index_, name_, &ncount, NULL, NULL,
NULL, &written);
if (ERROR_SUCCESS == r)
return true;
}
name_[0] = '\0';
return false;
}
} // namespace win
} // namespace base