Keeping the downloaded torrent in memory rather than file libtorrent

Question

Working with Rasterbar libtorrent I dont want the downloaded data to sit on my hard drive rather a pipe or variable or something Soft so I can redirect it to somewhere else, Mysql, or even trash if it is not what I want, is there anyway of doing this in preferably python binding if not in C++ using Libtorrent?

EDIT:--> I like to point out this is a libtorrent question not a Linux file handling or Python file handling question. I need to tell libtorrent to instead of save the file traditionally in a normal file save it to my python pipe or variable or etc.

Answer 1

You can do this by implementing your own storage class to use with libtorrent. Unfortunately this is not possible to do in python, but you can do it in c++. The documentation for it is a bit scarce and can be found here.

Here's a simple example of how to do this by storing all the data in RAM:

struct temp_storage : storage_interface
{
   temp_storage(file_storage const& fs) : m_files(fs) {}
   virtual bool initialize(bool allocate_files) { return false; }
   virtual bool has_any_file() { return false; }
   virtual int read(char* buf, int slot, int offset, int size)
   {
      std::map<int, std::vector<char> >::const_iterator i = m_file_data.find(slot);
      if (i == m_file_data.end()) return 0;
      int available = i->second.size() - offset;
      if (available <= 0) return 0;
      if (available > size) available = size;
      memcpy(buf, &i->second[offset], available);
      return available;
   }
   virtual int write(const char* buf, int slot, int offset, int size)
   {
      std::vector<char>& data = m_file_data[slot];
      if (data.size() < offset + size) data.resize(offset + size);
      std::memcpy(&data[offset], buf, size);
      return size;
   }
   virtual bool rename_file(int file, std::string const& new_name) { assert(false); return false; }
   virtual bool move_storage(std::string const& save_path) { return false; }
   virtual bool verify_resume_data(lazy_entry const& rd, error_code& error) { return false; }
   virtual bool write_resume_data(entry& rd) const { return false; }
   virtual bool move_slot(int src_slot, int dst_slot) { assert(false); return false; }
   virtual bool swap_slots(int slot1, int slot2) { assert(false); return false; }
   virtual bool swap_slots3(int slot1, int slot2, int slot3) { assert(false); return false; }
   virtual size_type physical_offset(int slot, int offset) { return slot * m_files.piece_length() + offset; };
   virtual sha1_hash hash_for_slot(int slot, partial_hash& ph, int piece_size)
   {
      int left = piece_size - ph.offset;
      TORRENT_ASSERT(left >= 0);
      if (left > 0)
      {
         std::vector<char>& data = m_file_data[slot];
         // if there are padding files, those blocks will be considered
         // completed even though they haven't been written to the storage.
         // in this case, just extend the piece buffer to its full size
         // and fill it with zeroes.
         if (data.size() < piece_size) data.resize(piece_size, 0);
         ph.h.update(&data[ph.offset], left);
      }
      return ph.h.final();
   }
   virtual bool release_files() { return false; }
   virtual bool delete_files() { return false; }

   std::map<int, std::vector<char> > m_file_data;
   file_storage m_files;
};

You'd also need a constructor function to pass in through the add_torrent_params struct when adding a torrent:

storage_interface* temp_storage_constructor(
   file_storage const& fs, file_storage const* mapped
   , std::string const& path, file_pool& fp
   , std::vector<boost::uint8_t> const& prio)
{
   return new temp_storage(fs);
}

From this point it should be fairly straight forward to store it in a MySQL database or any other back-end.