torram

torram (former torrent-upstart) is a utility that recreates a torrent download directory from fully and partially downloaded file(s). If several partially-downloaded sources of the same incompleted torrent files are found, it merges all downloaded chunks into the target files together.

Use cases

There are two major cases when this utility will help you to save traffic or to help recovering the files:

"hey, where are all seeders?" situation

That's the most common situation: you have several torrents having the same file(s) but for some reason these torrents are dead, so you have 75% done for one source and 85% done of another... there are chances that you actually have enough information to combine downloaded blocks from incomplete file #1 with downloaded blocks from file #2 to get a complete file as a result. The more sources you have, the better result you'll get.

⚠️ After files are combined, do "Force check" in your torrent client. Otherwise the torrent client won't know that the files were changed.

Note: I had positive experience recovering some extra rare artifacts by merging partially downloaded files obtained by different p2p sources: torrent and mlDonkey temp directory. In that case just make sure that both files are children of the root directory (see Usage section).

"I don't like to download it twice" situation

It's a good idea to scan your HDD drive with this utility before starting downloading in terms of reusing already downloaded files.

⚠️ Again, make sure that you "Force check" torrent after you run this tool...

Note: Due to technical implementation of how files are being split into chunks in .torrent, sometimes it's impossible to check md5 sum of first and last chunk of the file. So after "Force check" is done you may see that the file is 99% complete even though it's actually 100%.

How does it work

Each .torrent file consists of one or several files, each of them defined as a record of fields: file name, file size, file's hash, plus an error detection information in the form of md5 hash sum for all chunks. This error detection part allows us to do the trick - find chunks with the same md5 sum from files in your filesystem and generate output file using these chunks.

So the algorithm is:

scan root directory (last positional arg) recursively and find ponential pretenders for each file of .torrent file using two simple matching rules: file should either be named as required or should have the same file size
for each pretender of .torrent file we do split pretender file into chunks and calculate md5 sum for every chunk in order to find blocks that we will use to put in destination file
if multiple pretenders found having reusable blocks then we prompt user to choose one of these methods: merge from multiple files (default); use one of files without merging; or skip the file
based on user's selection the tool will create a file (or skip creation) and place it in output directory (-o argument)

Features

Combine several partially-downloaded sources into one (yes, it does work!)
Autodetect output directory (qBittorrent only for now)
Use symlinks instead of copying a file (danger... danger... danger...)
Manual and automatic modes (several levels of automation. See -s, -ss switches)

Requirements

Python >= 3.4
bencode.py (https://pypi.python.org/pypi/bencode)
PyQt4 (only if you use qBittorrent output directory autodetection, switch --autodetect_output_dir)

Usage

> ./torram.py --help
usage: torram [-h] [--symlink] [--minsize MINSIZE] [-v] [-o OUTPUT_DIR] [-a]
              [-c] [-s] [--fileext FILE_EXT] [--version]
              torrentFile root

Recreate download directory for .torrent file from fully and partially
downloaded file(s).

positional arguments:
  torrentFile           .torrent file to analyze
  root                  Directory to recursively search files in

optional arguments:
  -h, --help            show this help message and exit
  --symlink             Use symlinks instead of copying files. (Caution: You
                        may lose your data if files are not actually
                        identical.)
  --minsize MINSIZE     Minimum file size in bytes to be recoverable. Default:
                        1048576
  -v, --verbose         Be verbose (multiple levels: use -vv or -vvv to see
                        more)
  -o OUTPUT_DIR, --output_dir OUTPUT_DIR
                        Output directory where to place recreated files
  -a, --autodetect_output_dir
                        Autodetect output directory (only qBittorrent
                        currently supported)
  -c, --use_color       Output format: [ansi, ascii]
  -s, --autoskip        Dont ask questions if there is only one viable choice.
                        Use -ss to behave even more automated
  --fileext FILE_EXT    Extension to be added to output files (ex, .!qB for
                        incomplete qBittorrent files)
  --version             show program's version number and exit

vbuell/torram