= Build libtorrent from source =

[[PageOutline(2-4,,inline, unnumbered)]]

Check libtorrent [http://www.libtorrent.org/building.html 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 [https://github.com/arvidn/libtorrent/releases 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`.'' [[br]]
 ''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:
{{{
python -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:
  * [http://www.microsoft.com/en-us/download/details.aspx?id=44266 MS VC++ Compiler for Python]
  * [https://openssl.org/source/ OpenSSL] requirement needs [http://dev.deluge-torrent.org/wiki/Building/openssl#BuildingOpenSSLforWindows building from source].
  * [http://www.python.org/ Python 2.7]
  * [http://www.microsoft.com/en-us/download/details.aspx?id=5582 MSVC 2008 SP1 Redist Package (x86)]
  * [https://www.microsoft.com/en-gb/download/details.aspx?id=21 .NET Framework 3.5]
  * [http://sourceforge.net/projects/boost/files/boost/ Boost]
  * [https://github.com/arvidn/libtorrent/releases 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 [https://svn.boost.org/trac/boost/ticket/10817 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
 }}}

 5. 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.

 6. 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.'' [[br]]
   ''Note2: For libtorrent versions <=1.0.6 rename `libtorrent-link` to `link`.''

{{{#!comment
These are the old instructions but the setup.py in 0.16 does not build with openssl so not useful. 
  {{{
C:\python27\python.exe setup.py  build
}}}

  If there is no `setup.py` (i.e. tarball from version control repo) use `setup.py.in` instead.

  You can create setup.py on Ubuntu: (although makes no difference to the windows section of the script)
  {{{
sudo apt-get install libtool libboost1.46-all-dev
./autotool.sh
./configure  --enable-python-binding
}}}

 There might be an error at the end about `shutil` unable to move the lib but can be ignored.

 Upon a successful build the resulting library file is named `libtorrent.pyd` and is located under this directory: `libtorrent-rasterbar\bindings\python\bin\msvc-9.0\release\boost-source\geoip-static\link-static\optimization-space`
}}}
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`:
  * [http://msdn.microsoft.com/en-us/windows/hardware/hh852365.aspx 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;srv*c:\Symbols*http://msdl.microsoft.com/download/symbols
}}}

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

== Further Resources ==

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