deluge/docs/building/libtorrent.md

Build libtorrent from source

Check libtorrent documentation for any updates to build procedures.

Ubuntu / Debian

1. Install dependencies for libtorrent build automatically using build-dep:

sudo apt-get build-dep libtorrent-rasterbar
sudo apt-get install checkinstall

OR if that fails manually install them:

sudo apt-get install build-essential checkinstall libboost-system-dev libboost-python-dev libboost-chrono-dev libboost-random-dev libssl-dev

2. Download libtorrent and extract:

tar xf libtorrent-rasterbar.tar.gz
cd libtorrent-rasterbar

3. Configure:

./configure --enable-python-binding --with-libiconv

• Missing configure script: (e.g. source code from git) create it with ./autotool.sh (requires extra packages: sudo apt-get install autoconf automake libtool).
• Logging: Add --enable-logging=default to get logs in the current working directory. verbose and error can also be used.
• Debug: To create a debug build add --enable-debug=yes.
• ARM architecture (Raspberry Pi, etc): add --with-boost-libdir=/usr/lib/arm-linux-gnueabihf at the end to avoid boost library error.

4. Build:

make -j$(nproc)

• CPU Cores: The make option -j$(nproc) will utilize all available cpu cores.
• Non-specific errors: e.g. g++: internal compiler error: Killed (program cc1plus) try using a [#TemporarySwapFileforRasperryPiorlowmemorysystems temporary swap file]

5. Install library and python bindings:

sudo checkinstall
sudo ldconfig

Substituted make install for checkinstall as it creates a deb package for easier removal/re-install by dpkg.

Running ldconfig avoids an ImportError for libtorrent-rasterbar.so, a result of Python being unable to find the main library.

6. Verify libtorrent and the python bindings are installed correctly:

python3 -c "import libtorrent; print (libtorrent.version)"
>> 1.0.6.0

Temporary Swap File for Rasperry Pi or low memory systems

Compiling libtorrent requires a lot of memory/swap during the make process ~1-2GB.

If you get an internal error during the make phase on a computer with low memory and/or no swap partition (verify with free -m ) you can try the below procedure.

1. Create a 1GB empty swap file, (use a drive location that has enough free space):

dd if=/dev/zero of=/.swapfile bs=1M count=1024

2. Format swap file:

mkswap /.swapfile

3. Activate swap file:

sudo swapon /.swapfile

4. Verify swap file is recognized:

swapon -s

5. Start/restart your libtorrent build.
6. Disable swap file:

swapoff /.swapfile

7. Delete swap file:

rm -f /.swapfile

Windows

1. Download and install/extract these packages:

   • MS VC++ Compiler for Python
   • OpenSSL requirement needs building from source.
   • Python 2.7
   • MSVC 2008 SP1 Redist Package (x86)
   • .NET Framework 3.5
   • Boost
   • libtorrent

   Note: Install or extract to a path without spaces e.g. C:\ drive.

2. Setup the Windows Command Prompt by executing VC for Python vcvarsall.bat, e.g.:

   "%USERPROFILE%\AppData\Local\Programs\Common\Microsoft\Visual C++ for Python\9.0\vcvarsall.bat"
   

   Note: If using Visual Studio simple open a Visual Studio 2008 Command Prompt.

3. Boost Build Steps:

   In the boost directory run the following:

   bootstrap.bat
   

   Due to a boost bug with VC for Python, need to edit project-config.jam in boost folder to the following:

   using msvc : : : <setup>"%USERPROFILE%\\AppData\\Local\\Programs\\Common\\Microsoft\\Visual C++ for Python\\9.0\\vcvarsall.bat" ;
   

   Then run:

    b2 --with-system --with-date_time --with-python --with-chrono --with-random
   

4. Create a Boost user-config.jam file in the toplevel folder (e.g. C:\boost) with the following to force msvc version:

   using msvc : 9.0 : : <setup>"%USERPROFILE%\\AppData\\Local\\Programs\\Common\\Microsoft\\Visual C++ for Python\\9.0\\vcvarsall.bat" ;
   

   Note: For Visual Studio, simply using msvc : 9.0 ; is required.

5. libtorrent Build Steps:

   a. Setup the Environmental Variables:

   set BOOST_BUILD_PATH=C:\boost
   set PATH=%BOOST_BUILD_PATH%;%PATH%
   

   b. Navigate to libtorrent Python bindings folder:

   cd C:\libtorrent-rasterbar\bindings\python
   

   c. Build libtorrent with Python bindings:

   b2 boost=source libtorrent-link=static geoip=static boost-link=static release optimization=space encryption=openssl include=C:\OpenSSL-Win32\include linkflags=/LIBPATH:C:\OpenSSL-Win32\lib -j%NUMBER_OF_PROCESSORS% --hash
   

   Note1: Modify the paths for OpenSSL if installed to a different location.

   Note2: For libtorrent versions <=1.0.6 rename libtorrent-link to link.

   For libtorrent versions >=1.1:

   b2 libtorrent-link=static boost-link=static release optimization=space encryption=on crypto=openssl include=C:\OpenSSL-Win32\include linkflags=/LIBPATH:C:\OpenSSL-Win32\lib -j%NUMBER_OF_PROCESSORS% --hash
   

   Upon a successful build the library file named libtorrent.pyd is created in the current bindings/python directory.

Debugging libtorrent on Windows

• Download and install just the debug tools:

  • Standalone Debugging Tools for Windows (WinDbg)

• Build libtorrent with debug enabled by changing release to debug in the b2 build line.

• Open windbg (C:\Program Files\Debugging Tools for Windows (x86)\windbg.exe):

  • File|Open Executable and tick Debug child processes
  • Hit F5 or Go a few times to get the program running
  • After the crash execute: !analyze -v -f.

• Symbols for libtorrent will be in the build output path:

  C:\libtorrent-rasterbar\bindings\python\bin\msvc-9.0\debug\boost-source\geoip-static\link-static\optimization-space\threading-multi
  

  So the full symbols line should look something like this:

srv*;C:\libtorrent-rasterbar\bindings\python\bin\msvc-9.0\debug\boost-source\geoip-static\link-static\optimization-space\threading-multi;C:\Python27\symbols;srvc:\Symbolshttp://msdl.microsoft.com/download/symbols

Debug References:
* [Mozilla WinDbg stacktrace](https://developer.mozilla.org/en/docs/How_to_get_a_stacktrace_with_WinDbg)
* [Windbg for Beginners](http://gui-at.blogspot.co.uk/2010/01/windbg-for-beginners.html)

## Further Resources

* [libtorrent](http://libtorrent.org/building.html)
* [Leechcraft](http://leechcraft.org/development-building-from-source-win32#Building_libtorrent)
* [QBittorrent](https://github.com/qbittorrent/qBittorrent/wiki/Compiling-with-MSVC-2008%28static-linkage%29)