Import Errors on Ubuntu 16.10

[arbox]

Dear @mrkn ,

I'm trying to run examples from this repo, but I cannot go further the first require statement:

irb(main):001:0> require 'pycall/import'
LoadError: no library specified
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/ffi-1.9.18/lib/ffi/library.rb:176:in `ffi_libraries'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/ffi-1.9.18/lib/ffi/library.rb:336:in `attach_variable'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/pycall-0.1.0.alpha.20170311/lib/pycall/libpython.rb:106:in `<module:LibPython>'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/pycall-0.1.0.alpha.20170311/lib/pycall/libpython.rb:4:in `<module:PyCall>'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/pycall-0.1.0.alpha.20170311/lib/pycall/libpython.rb:3:in `<top (required)>'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/pycall-0.1.0.alpha.20170311/lib/pycall.rb:2:in `<top (required)>'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/pycall-0.1.0.alpha.20170311/lib/pycall/import.rb:1:in `<top (required)>'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:133:in `require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:133:in `rescue in require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:40:in `require'
from (irb):1
from /home/arbox/.rbenv/versions/2.4.0/bin/irb:11:in `<main>'

Setting PYTHONHOME and PYTHONPATH does not change the picture.

Could you please provide requirements for the Python side as well? Thank you!

[mrkn]

@arbox How do you install python?

Pycall uses PYTHON environment variable to find Python's executable such as /usr/bin/python3.
This environment variable is referred to execute investigator.py script, which investigates the installation directory and the path of shared library of the specified Python environment.

If you installed python into a non-standard location, please do either:

• Specify the full-path of python command in PYTHON environment variable
• Specify the name of python command in PYTHON and put the bin directory in PATH.

[arbox]

Hi, @mrkn, thank you for a reply!

Python is installed on my machine pretty standard, from the Ubuntu repositories.

I looked up your Travis configuration, so at least python python-dev python-all as well python3 python3-dev python3-all are installed. It's a fresh Ubuntu 16.10 installation.

I could run investigator.py manually with the following output:

executable: /usr/bin/python
exec_prefix: /usr
prefix: /usr
VERSION: 2.7
LIBRARY: libpython2.7.a
LDLIBRARY: libpython2.7.so
LIBDIR: /usr/lib
PYTHONFRAMEWORKPREFIX:

It seems to be a screwed Python installation here. But setting the environment as follows does not change the picture:

arbox@aplha:~/work_space/sandbox/pycall/pycall$ env | grep PYTHON
PYTHONHOME=/usr/lib/python2.7
PYTHONPATH=/usr/lib/python2.7
PYTHON=/usr/bin/python2.7

I've inspected the Hash which is returned by Pycall.investigate_python_config() in libpython.rb:

arbox@aplha:~/work_space/sandbox/pycall/pycall$ irb -I lib
irb(main):001:0> require 'pycall/import'
{:executable=>"/usr/bin/python2.7", :exec_prefix=>"/usr/lib/python2.7", :prefix=>"/usr/lib/python2.7", :VERSION=>"2.7", :LIBRARY=>"libpython2.7.a", :LDLIBRARY=>"libpython2.7.so", :LIBDIR=>"/usr/lib", :PYTHONFRAMEWORKPREFIX=>""}
LoadError: no library specified
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/ffi-1.9.18/lib/ffi/library.rb:176:in `ffi_libraries'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/ffi-1.9.18/lib/ffi/library.rb:336:in `attach_variable'
from /home/arbox/work_space/sandbox/pycall/pycall/lib/pycall/libpython.rb:109:in `<module:LibPython>'
from /home/arbox/work_space/sandbox/pycall/pycall/lib/pycall/libpython.rb:4:in `<module:PyCall>'
from /home/arbox/work_space/sandbox/pycall/pycall/lib/pycall/libpython.rb:3:in `<top (required)>'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/work_space/sandbox/pycall/pycall/lib/pycall.rb:2:in `<top (required)>'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/work_space/sandbox/pycall/pycall/lib/pycall/import.rb:1:in `<top (required)>'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/arbox/.rbenv/versions/2.4.0/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from (irb):1
from /home/arbox/.rbenv/versions/2.4.0/bin/irb:11:in `<main>'

The value of the same hash without any env vars set:

{:executable=>"/usr/bin/python", :exec_prefix=>"/usr", :prefix=>"/usr", :VERSION=>"2.7", :LIBRARY=>"libpython2.7.a", :LDLIBRARY=>"libpython2.7.so", :LIBDIR=>"/usr/lib", :PYTHONFRAMEWORKPREFIX=>""}

Could I do something to provide you with additional debug info? Thank you!

[mrkn]

I could reproduce this issue with ubuntu 16.10 on VMware.
And I found the reason of this issue. It is due to multiarch support of Ubuntu (and Debian).

While Python said that the libdir is /usr/lib, but ubuntu's python package put libpython in /usr/lib/x86_64-linux-gnu.

Probably Python does not know libpython is located in /usr/lib/x86_64-linux-gnu.
If so, I cannot resolve the path of libpython from the information obtained by investigator.py.

[mrkn]

@arbox Now you can specify libpython's full path in LIBPYTHON environment variable.
On Ubuntu 16.10, LIBPYTHON=/usr/lib/x86_64-linux-gnu/libpython2.7.so.1 for Python 2.7 or LIBPYTHON=/usr/lib/x86_64-linux-gnu/libpython3.5m.so.1 for Python 3.5 can be used.
Try again.

[arbox]

@mrkn thank you! Cool support here! And very demanded library for Ruby :)

[mrkn]

@arbox I've released the new version of pycall. The latest pycall supports multiarch system in Debian and Ubuntu. Check it.