1    :  // Copyright 2012 Google Inc. All Rights Reserved.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  
  15    :  #ifndef SYZYGY_MSF_MSF_FILE_STREAM_H_
  16    :  #define SYZYGY_MSF_MSF_FILE_STREAM_H_
  17    :  
  18    :  #include <stdio.h>
  19    :  
  20    :  #include "base/memory/ref_counted.h"
  21    :  #include "syzygy/msf/msf_decl.h"
  22    :  #include "syzygy/msf/msf_stream.h"
  23    :  
  24    :  namespace msf {
  25    :  
  26    :  // A reference counted FILE pointer object.
  27    :  // NOTE: This is not thread safe for a variety of reasons.
  28    :  class RefCountedFILE : public base::RefCounted<RefCountedFILE> {
  29    :   public:
  30  E :    explicit RefCountedFILE(FILE* file) : file_(file) {}
  31    :  
  32    :    // @returns the file pointer being reference counted.
  33  E :    FILE* file() { return file_; }
  34    :  
  35    :   private:
  36    :    friend base::RefCounted<RefCountedFILE>;
  37    :  
  38    :    // We disallow access to the destructor to enforce the use of reference
  39    :    // counting pointers.
  40  E :    ~RefCountedFILE() {
  41  E :      if (file_)
  42  E :        ::fclose(file_);
  43  E :    }
  44    :  
  45    :    FILE* file_;
  46    :  
  47    :    DISALLOW_COPY_AND_ASSIGN(RefCountedFILE);
  48    :  };
  49    :  
  50    :  namespace detail {
  51    :  
  52    :  // This class represents an MSF stream on disk.
  53    :  template <MsfFileType T>
  54    :  class MsfFileStreamImpl : public MsfStreamImpl<T> {
  55    :   public:
  56    :    // Constructor.
  57    :    // @param file the reference counted file housing this stream.
  58    :    // @param length the length of this stream.
  59    :    // @param pages the indices of the pages that make up this stream in the file.
  60    :    //     A copy is made of the data so the pointer need not remain valid
  61    :    //     beyond the constructor. The length of this array is implicit in the
  62    :    //     stream length and the page size.
  63    :    // @param page_size the size of the pages, in bytes.
  64    :    MsfFileStreamImpl(RefCountedFILE* file,
  65    :                      size_t length,
  66    :                      const uint32_t* pages,
  67    :                      size_t page_size);
  68    :  
  69    :    // MsfStreamImpl implementation.
  70    :    bool ReadBytesAt(size_t pos, size_t count, void* dest) override;
  71    :  
  72    :   protected:
  73    :    // Protected to enforce reference counted pointers at compile time.
  74    :    virtual ~MsfFileStreamImpl();
  75    :  
  76    :    // Read @p count bytes from @p offset byte offset from page @p page_num and
  77    :    // store them in @p dest.
  78    :    bool ReadFromPage(void* dest, uint32_t page_num, size_t offset, size_t count);
  79    :  
  80    :   private:
  81    :    // The handle to the open MSF file. This is reference counted so ownership of
  82    :    // that streams can outlive the MsfReaderImpl that created them.
  83    :    scoped_refptr<RefCountedFILE> file_;
  84    :  
  85    :    // The list of pages in the msf MSF that make up this stream.
  86    :    std::vector<uint32_t> pages_;
  87    :  
  88    :    // The size of pages within the stream.
  89    :    size_t page_size_;
  90    :  
  91    :    DISALLOW_COPY_AND_ASSIGN(MsfFileStreamImpl);
  92    :  };
  93    :  
  94    :  }  // namespace detail
  95    :  
  96    :  using MsfFileStream = detail::MsfFileStreamImpl<kGenericMsfFileType>;
  97    :  
  98    :  }  // namespace msf
  99    :  
 100    :  #include "syzygy/msf/msf_file_stream_impl.h"
 101    :  
 102    :  #endif  // SYZYGY_MSF_MSF_FILE_STREAM_H_