The Tor Browser / file revision

 // 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"

 #pragma comment(lib, "shlwapi.lib")  // for SHDeleteKey

 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);

 }

 }  // namespace

 // RegKey ----------------------------------------------------------------------

 RegKey::RegKey()

     : key_(NULL),

       watch_event_(0) {

 }

 RegKey::RegKey(HKEY key)

     : key_(key),

       watch_event_(0) {

 }

 RegKey::RegKey(HKEY rootkey, const wchar_t* subkey, REGSAM access)

     : key_(NULL),

       watch_event_(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);

   }

 }

 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);

   Close();

   LONG result = RegCreateKeyEx(rootkey, subkey, 0, NULL,

                                REG_OPTION_NON_VOLATILE, access, NULL, &key_,

                                disposition);

   return result;

 }

 LONG RegKey::CreateKey(const wchar_t* name, REGSAM access) {

   DCHECK(name && access);

   HKEY subkey = NULL;

   LONG result = RegCreateKeyEx(key_, name, 0, NULL, REG_OPTION_NON_VOLATILE,

                                access, NULL, &subkey, NULL);

   Close();

   key_ = subkey;

   return result;

 }

 LONG RegKey::Open(HKEY rootkey, const wchar_t* subkey, REGSAM access) {

   DCHECK(rootkey && subkey && access);

   Close();

   LONG result = RegOpenKeyEx(rootkey, subkey, 0, access, &key_);

   return result;

 }

 LONG RegKey::OpenKey(const wchar_t* relative_key_name, REGSAM access) {

   DCHECK(relative_key_name && access);

   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.

   Close();

   key_ = subkey;

   return result;

 }

 void RegKey::Close() {

   StopWatching();

   if (key_) {

     ::RegCloseKey(key_);

     key_ = NULL;

   }

 }

 void RegKey::Set(HKEY key) {

   if (key_ != key) {

     Close();

     key_ = key;

   }

 }

 HKEY RegKey::Take() {

   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);

   LONG result = SHDeleteKey(key_, name);

   return result;

 }

 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;

 }

 // 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