The Tor Browser: storage/src/Variant.h@97036ab72558 (annotated)

storage/src/Variant.h@97036ab72558 (annotated)

storage/src/Variant.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef mozilla_storage_Variant_h__
 #define mozilla_storage_Variant_h__
 #include <utility>
 #include "nsIVariant.h"
 #include "nsString.h"
 #include "nsTArray.h"
 /**
  * This class is used by the storage module whenever an nsIVariant needs to be
  * returned.  We provide traits for the basic sqlite types to make use easier.
  * The following types map to the indicated sqlite type:
  * int64_t   -> INTEGER (use IntegerVariant)
  * double    -> FLOAT (use FloatVariant)
  * nsString  -> TEXT (use TextVariant)
  * nsCString -> TEXT (use UTF8TextVariant)
  * uint8_t[] -> BLOB (use BlobVariant)
  * nullptr   -> NULL (use NullVariant)
  */
 namespace mozilla {
 namespace storage {
 ////////////////////////////////////////////////////////////////////////////////
 //// Base Class
 class Variant_base : public nsIVariant
 {
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIVARIANT
 protected:
   virtual ~Variant_base() { }
 };
 ////////////////////////////////////////////////////////////////////////////////
 //// Traits
 /**
  * Generics
  */
 template <typename DataType>
 struct variant_traits
 {
   static inline uint16_t type() { return nsIDataType::VTYPE_EMPTY; }
 };
 template <typename DataType, bool Adopting=false>
 struct variant_storage_traits
 {
   typedef DataType ConstructorType;
   typedef DataType StorageType;
   static inline void storage_conversion(const ConstructorType aData, StorageType* _storage)
   {
     *_storage = aData;
   }
   static inline void destroy(const StorageType& _storage)
   { }
 };
 #define NO_CONVERSION return NS_ERROR_CANNOT_CONVERT_DATA;
 template <typename DataType, bool Adopting=false>
 struct variant_integer_traits
 {
   typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
   static inline nsresult asInt32(const StorageType &, int32_t *) { NO_CONVERSION }
   static inline nsresult asInt64(const StorageType &, int64_t *) { NO_CONVERSION }
 };
 template <typename DataType, bool Adopting=false>
 struct variant_float_traits
 {
   typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
   static inline nsresult asDouble(const StorageType &, double *) { NO_CONVERSION }
 };
 template <typename DataType, bool Adopting=false>
 struct variant_text_traits
 {
   typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
   static inline nsresult asUTF8String(const StorageType &, nsACString &) { NO_CONVERSION }
   static inline nsresult asString(const StorageType &, nsAString &) { NO_CONVERSION }
 };
 template <typename DataType, bool Adopting=false>
 struct variant_blob_traits
 {
   typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
   static inline nsresult asArray(const StorageType &, uint16_t *, uint32_t *, void **)
   { NO_CONVERSION }
 };
 #undef NO_CONVERSION
 /**
  * INTEGER types
  */
 template < >
 struct variant_traits<int64_t>
 {
   static inline uint16_t type() { return nsIDataType::VTYPE_INT64; }
 };
 template < >
 struct variant_integer_traits<int64_t>
 {
   static inline nsresult asInt32(int64_t aValue,
                                  int32_t *_result)
   {
     if (aValue > INT32_MAX || aValue < INT32_MIN)
       return NS_ERROR_CANNOT_CONVERT_DATA;
     *_result = static_cast<int32_t>(aValue);
     return NS_OK;
   }
   static inline nsresult asInt64(int64_t aValue,
                                  int64_t *_result)
   {
     *_result = aValue;
     return NS_OK;
   }
 };
 // xpcvariant just calls get double for integers...
 template < >
 struct variant_float_traits<int64_t>
 {
   static inline nsresult asDouble(int64_t aValue,
                                   double *_result)
   {
     *_result = double(aValue);
     return NS_OK;
   }
 };
 /**
  * FLOAT types
  */
 template < >
 struct variant_traits<double>
 {
   static inline uint16_t type() { return nsIDataType::VTYPE_DOUBLE; }
 };
 template < >
 struct variant_float_traits<double>
 {
   static inline nsresult asDouble(double aValue,
                                   double *_result)
   {
     *_result = aValue;
     return NS_OK;
   }
 };
 /**
  * TEXT types
  */
 template < >
 struct variant_traits<nsString>
 {
   static inline uint16_t type() { return nsIDataType::VTYPE_ASTRING; }
 };
 template < >
 struct variant_storage_traits<nsString>
 {
   typedef const nsAString & ConstructorType;
   typedef nsString StorageType;
   static inline void storage_conversion(ConstructorType aText, StorageType* _outData)
   {
     *_outData = aText;
   }
   static inline void destroy(const StorageType& _outData)
   { }
 };
 template < >
 struct variant_text_traits<nsString>
 {
   static inline nsresult asUTF8String(const nsString &aValue,
                                       nsACString &_result)
   {
     CopyUTF16toUTF8(aValue, _result);
     return NS_OK;
   }
   static inline nsresult asString(const nsString &aValue,
                                   nsAString &_result)
   {
     _result = aValue;
     return NS_OK;
   }
 };
 template < >
 struct variant_traits<nsCString>
 {
   static inline uint16_t type() { return nsIDataType::VTYPE_UTF8STRING; }
 };
 template < >
 struct variant_storage_traits<nsCString>
 {
   typedef const nsACString & ConstructorType;
   typedef nsCString StorageType;
   static inline void storage_conversion(ConstructorType aText, StorageType* _outData)
   {
     *_outData = aText;
   }
   static inline void destroy(const StorageType &aData)
   { }
 };
 template < >
 struct variant_text_traits<nsCString>
 {
   static inline nsresult asUTF8String(const nsCString &aValue,
                                       nsACString &_result)
   {
     _result = aValue;
     return NS_OK;
   }
   static inline nsresult asString(const nsCString &aValue,
                                   nsAString &_result)
   {
     CopyUTF8toUTF16(aValue, _result);
     return NS_OK;
   }
 };
 /**
  * BLOB types
  */
 template < >
 struct variant_traits<uint8_t[]>
 {
   static inline uint16_t type() { return nsIDataType::VTYPE_ARRAY; }
 };
 template < >
 struct variant_storage_traits<uint8_t[], false>
 {
   typedef std::pair<const void *, int> ConstructorType;
   typedef FallibleTArray<uint8_t> StorageType;
   static inline void storage_conversion(ConstructorType aBlob, StorageType* _outData)
   {
     _outData->Clear();
     _outData->SetCapacity(aBlob.second);
     (void)_outData->AppendElements(static_cast<const uint8_t *>(aBlob.first),
                                    aBlob.second);
   }
   static inline void destroy(const StorageType& _outData)
   { }
 };
 template < >
 struct variant_storage_traits<uint8_t[], true>
 {
   typedef std::pair<uint8_t *, int> ConstructorType;
   typedef std::pair<uint8_t *, int> StorageType;
   static inline void storage_conversion(ConstructorType aBlob, StorageType* _outData)
   {
     *_outData = aBlob;
   }
   static inline void destroy(StorageType &aData)
   {
     if (aData.first) {
       NS_Free(aData.first);
       aData.first = nullptr;
     }
   }
 };
 template < >
 struct variant_blob_traits<uint8_t[], false>
 {
   static inline nsresult asArray(FallibleTArray<uint8_t> &aData,
                                  uint16_t *_type,
                                  uint32_t *_size,
                                  void **_result)
   {
     // For empty blobs, we return nullptr.
     if (aData.Length() == 0) {
       *_result = nullptr;
       *_type = nsIDataType::VTYPE_UINT8;
       *_size = 0;
       return NS_OK;
     }
     // Otherwise, we copy the array.
     *_result = nsMemory::Clone(aData.Elements(), aData.Length() * sizeof(uint8_t));
     NS_ENSURE_TRUE(*_result, NS_ERROR_OUT_OF_MEMORY);
     // Set type and size
     *_type = nsIDataType::VTYPE_UINT8;
     *_size = aData.Length();
     return NS_OK;
   }
 };
 template < >
 struct variant_blob_traits<uint8_t[], true>
 {
   static inline nsresult asArray(std::pair<uint8_t *, int> &aData,
                                  uint16_t *_type,
                                  uint32_t *_size,
                                  void **_result)
   {
     // For empty blobs, we return nullptr.
     if (aData.second == 0) {
       *_result = nullptr;
       *_type = nsIDataType::VTYPE_UINT8;
       *_size = 0;
       return NS_OK;
     }
     // Otherwise, transfer the data out.
     *_result = aData.first;
     aData.first = nullptr;
     MOZ_ASSERT(*_result); // We asked for it twice, better not use adopting!
     // Set type and size
     *_type = nsIDataType::VTYPE_UINT8;
     *_size = aData.second;
     return NS_OK;
   }
 };
 /**
  * nullptr type
  */
 class NullVariant : public Variant_base
 {
 public:
   NS_IMETHOD GetDataType(uint16_t *_type)
   {
     NS_ENSURE_ARG_POINTER(_type);
     *_type = nsIDataType::VTYPE_EMPTY;
     return NS_OK;
   }
   NS_IMETHOD GetAsAUTF8String(nsACString &_str)
   {
     // Return a void string.
     _str.Truncate(0);
     _str.SetIsVoid(true);
     return NS_OK;
   }
   NS_IMETHOD GetAsAString(nsAString &_str)
   {
     // Return a void string.
     _str.Truncate(0);
     _str.SetIsVoid(true);
     return NS_OK;
   }
 };
 ////////////////////////////////////////////////////////////////////////////////
 //// Template Implementation
 template <typename DataType, bool Adopting=false>
 class Variant : public Variant_base
 {
   ~Variant()
   {
     variant_storage_traits<DataType, Adopting>::destroy(mData);
   }
 public:
   Variant(const typename variant_storage_traits<DataType, Adopting>::ConstructorType aData)
   {
     variant_storage_traits<DataType, Adopting>::storage_conversion(aData, &mData);
   }
   NS_IMETHOD GetDataType(uint16_t *_type)
   {
     *_type = variant_traits<DataType>::type();
     return NS_OK;
   }
   NS_IMETHOD GetAsInt32(int32_t *_integer)
   {
     return variant_integer_traits<DataType, Adopting>::asInt32(mData, _integer);
   }
   NS_IMETHOD GetAsInt64(int64_t *_integer)
   {
     return variant_integer_traits<DataType, Adopting>::asInt64(mData, _integer);
   }
   NS_IMETHOD GetAsDouble(double *_double)
   {
     return variant_float_traits<DataType, Adopting>::asDouble(mData, _double);
   }
   NS_IMETHOD GetAsAUTF8String(nsACString &_str)
   {
     return variant_text_traits<DataType, Adopting>::asUTF8String(mData, _str);
   }
   NS_IMETHOD GetAsAString(nsAString &_str)
   {
     return variant_text_traits<DataType, Adopting>::asString(mData, _str);
   }
   NS_IMETHOD GetAsArray(uint16_t *_type,
                         nsIID *,
                         uint32_t *_size,
                         void **_data)
   {
     return variant_blob_traits<DataType, Adopting>::asArray(mData, _type, _size, _data);
   }
 private:
   typename variant_storage_traits<DataType, Adopting>::StorageType mData;
 };
 ////////////////////////////////////////////////////////////////////////////////
 //// Handy typedefs!  Use these for the right mapping.
 typedef Variant<int64_t> IntegerVariant;
 typedef Variant<double> FloatVariant;
 typedef Variant<nsString> TextVariant;
 typedef Variant<nsCString> UTF8TextVariant;
 typedef Variant<uint8_t[], false> BlobVariant;
 typedef Variant<uint8_t[], true> AdoptedBlobVariant;
 } // namespace storage
 } // namespace mozilla
 #include "Variant_inl.h"
 #endif // mozilla_storage_Variant_h__

The Tor Browser / annotate

storage/src/Variant.h@97036ab72558 (annotated)

storage/src/Variant.h