| // Copyright 2012 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #ifndef SYZYGY_MSF_MSF_STREAM_H_ |
| #define SYZYGY_MSF_MSF_STREAM_H_ |
| |
| #include "base/logging.h" |
| #include "base/memory/ref_counted.h" |
| #include "syzygy/common/buffer_writer.h" |
| #include "syzygy/msf/msf_decl.h" |
| |
| namespace msf { |
| namespace detail { |
| |
| // Forward declaration. |
| template <MsfFileType T> |
| class WritableMsfStreamImpl; |
| |
| // This class represents an MSF stream. It has a stream-like interface that |
| // allows invoking successive reads through the stream and seeking. |
| template <MsfFileType T> |
| class MsfStreamImpl : public base::RefCounted<MsfStreamImpl<T>> { |
| public: |
| explicit MsfStreamImpl(uint32_t length); |
| |
| // Reads @p count bytes of data starting at @p pos into the destination |
| // buffer. The caller is responsible for ensuring that the destination |
| // buffer has enough space to receive the data. |
| // |
| // @param pos the position in the stream of the first byte to read. |
| // @param dest the buffer to receive the data. May be modified on failure. |
| // @param count the number of bytes to read. |
| // @returns true if all @p count bytes are read, false otherwise. |
| virtual bool ReadBytesAt(size_t pos, size_t count, void* dest) = 0; |
| |
| // Returns a pointer to a WritableMsfStreamImpl if the underlying object |
| // supports this interface. If this returns non-NULL, it is up to the user to |
| // ensure thread safety; each writer should be used exclusively of any other |
| // writer, and no reader should be used while a writer is in use. Each of the |
| // reader and writer maintains its own cursor, but their view of the data (and |
| // its length) will remain in sync. |
| // |
| // NOTE: This function should act as a factory, with each call returning a |
| // heap allocated reference counted writer. However, since each |
| // WritableMsfStreamImpl is currently implemented using a BufferWriter, |
| // and the BufferWriter maintains its own state internally rather than a |
| // shared state, its possible that one writer causing a resize could |
| // invalidate the internal data pointer held by another writer. As a |
| // workaround, there is only a single writer allowed to be allocated |
| // right now. |
| // |
| // TODO(chrisha): Clean this up to return an interface, which can be wrapped |
| // in some common stream-writer functionality, reusing BufferWriter. |
| // |
| // @returns a pointer to a WritableMsfStreamImpl. |
| virtual scoped_refptr<WritableMsfStreamImpl<T>> GetWritableStream() { |
| return scoped_refptr<WritableMsfStreamImpl<T>>(); |
| } |
| |
| // Gets the stream's length. |
| // @returns the total number of bytes in the stream. |
| uint32_t length() const { return length_; } |
| |
| protected: |
| friend base::RefCounted<MsfStreamImpl>; |
| |
| // Protected to enforce use of ref-counted pointers at compile time. |
| virtual ~MsfStreamImpl(); |
| |
| // Sets the stream's length. |
| void set_length(uint32_t length) { length_ = length; } |
| |
| private: |
| // The length of the stream. |
| uint32_t length_; |
| |
| DISALLOW_COPY_AND_ASSIGN(MsfStreamImpl); |
| }; |
| |
| // Represents a writable MSF stream. |
| // TODO(chrisha): For now, this inherits from common::BufferWriter, but a far |
| // cleaner approach would be to hoist a basic WritableStreamInterface, and |
| // make BufferWriter accept a pointer to said interface. The same thing |
| // could be done to the common::BufferParser/BufferReader and MsfStreamImpl |
| // hierarchy. |
| template <MsfFileType T> |
| class WritableMsfStreamImpl : public base::RefCounted<WritableMsfStreamImpl<T>>, |
| public common::BufferWriter { |
| public: |
| // Constructor. |
| WritableMsfStreamImpl() : common::BufferWriter(NULL, 0) {} |
| |
| protected: |
| friend base::RefCounted<WritableMsfStreamImpl>; |
| |
| // Destructor. Protected to enforce use of ref-counted pointers at compile |
| // time. |
| virtual ~WritableMsfStreamImpl() {} |
| |
| // Forwarded from common::BufferWriter. |
| virtual uint8_t* GrowBuffer(uint32_t size) = 0; |
| }; |
| |
| } // namespace detail |
| |
| using WritableMsfStream = detail::WritableMsfStreamImpl<kGenericMsfFileType>; |
| using MsfStream = detail::MsfStreamImpl<kGenericMsfFileType>; |
| |
| } // namespace msf |
| |
| #include "syzygy/msf/msf_stream_impl.h" |
| |
| #endif // SYZYGY_MSF_MSF_STREAM_H_ |