Build crashes if NDK is installed system-wide without write permissions

[ghost]

Versions

shouldn't be relevant

Description

There is an issue (I thought it was a regression introduced by #1618 at first, but I think this was broken before) where in an environment where the NDK is installed system-wide, the build will crash because then files cannot simply be changed:

[INFO]:    Building lxml for armeabi-v7a
[INFO]:    lxml apparently isn't already in site-packages
[DEBUG]:   -> running ln -sf /ndk/platforms/android-21/arch-arm/usr/lib/libc.so /ndk/platforms/android-21/arch-arm/usr/lib/librt.so
[DEBUG]:   	/bin/ln: failed to create symbolic link '/ndk/platforms/android-21/arch-arm/usr/lib/librt.so': Permission denied
Exception in thread background thread for pid 18688:
Traceback (most recent call last):
  File "/usr/lib/python3.6/threading.py", line 916, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.6/threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "/home/userhome/.local/lib/python3.6/site-packages/sh.py", line 1540, in wrap
    fn(*args, **kwargs)
  File "/home/userhome/.local/lib/python3.6/site-packages/sh.py", line 2459, in background_thread
    handle_exit_code(exit_code)
  File "/home/userhome/.local/lib/python3.6/site-packages/sh.py", line 2157, in fn
    return self.command.handle_command_exit_code(exit_code)
  File "/home/userhome/.local/lib/python3.6/site-packages/sh.py", line 815, in handle_command_exit_code
    raise exc
sh.ErrorReturnCode_1: 

  RAN: /bin/ln -sf /ndk/platforms/android-21/arch-arm/usr/lib/libc.so /ndk/platforms/android-21/arch-arm/usr/lib/librt.so

  STDOUT:
/bin/ln: failed to create symbolic link '/ndk/platforms/android-21/arch-arm/usr/lib/librt.so': Permission denied


  STDERR:


Traceback (most recent call last):
  File "/home/userhome/.local/bin/p4a", line 11, in <module>
    sys.exit(main())
  File "/home/userhome/.local/lib/python3.6/site-packages/pythonforandroid/toolchain.py", line 1033, in main
    ToolchainCL()
  File "/home/userhome/.local/lib/python3.6/site-packages/pythonforandroid/toolchain.py", line 553, in __init__
    getattr(self, args.subparser_name.replace('-', '_'))(args)
  File "/home/userhome/.local/lib/python3.6/site-packages/pythonforandroid/toolchain.py", line 150, in wrapper_func
    build_dist_from_args(ctx, dist, args)
  File "/home/userhome/.local/lib/python3.6/site-packages/pythonforandroid/toolchain.py", line 191, in build_dist_from_args
    build_recipes(build_order, python_modules, ctx)
  File "/home/userhome/.local/lib/python3.6/site-packages/pythonforandroid/build.py", line 634, in build_recipes
    recipe.build_arch(arch)
  File "/home/userhome/.local/lib/python3.6/site-packages/pythonforandroid/recipe.py", line 902, in build_arch
    self.build_compiled_components(arch)
  File "/home/userhome/.local/lib/python3.6/site-packages/pythonforandroid/recipes/lxml/__init__.py", line 35, in build_compiled_components
    shprint(sh.ln, '-sf', link_c + '.so', link_rt + '.so')
  File "/home/userhome/.local/lib/python3.6/site-packages/pythonforandroid/logger.py", line 178, in shprint
    for line in output:
  File "/home/userhome/.local/lib/python3.6/site-packages/sh.py", line 863, in next
    self.wait()
  File "/home/userhome/.local/lib/python3.6/site-packages/sh.py", line 792, in wait
    self.handle_command_exit_code(exit_code)
  File "/home/userhome/.local/lib/python3.6/site-packages/sh.py", line 815, in handle_command_exit_code
    raise exc
sh.ErrorReturnCode_1: 

  RAN: /bin/ln -sf /ndk/platforms/android-21/arch-arm/usr/lib/libc.so /ndk/platforms/android-21/arch-arm/usr/lib/librt.so

  STDOUT:
/bin/ln: failed to create symbolic link '/ndk/platforms/android-21/arch-arm/usr/lib/librt.so': Permission denied

Now that I am pondering this, this also seems somewhat ugly to me (not the symlink in itself, but actually writing around inside the NDK folder - I don't think this is to be expected from the user). Therefore I think a better solution should be found that doesn't require write permissions in the NDK folder

[ghost]

Hmmmmm, shouldn't it be possible to set LD_LIBRARY_PATH to some separate place, and just add this symlink in a completely different folder? Or can anyone think of a reason why that wouldn't possibly work

[AndreMiras]

What about symlinking to the dumb recipe build folder? I mean just like if we were compiling a lib, at the end we just Recipe.get_recipe() and use it in our link -Ldir right?