[Bug 898172] Re: ctypes broken on armhf

Dr. David Alan Gilbert 898172 at bugs.launchpad.net
Thu Dec 1 12:13:32 UTC 2011


Beware that ctypes may be broken in other ways on armhf as well; in
particular it uses libffi to do its binding and a while ago when I
looked I came to the conclusion it probably won't call variadic
functions correctly if they are passed FP values.

My post to the ctypes list:
http://permalink.gmane.org/gmane.comp.python.ctypes/4657

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https://bugs.launchpad.net/bugs/898172

Title:
  ctypes broken on armhf

Status in Python:
  Unknown
Status in “python2.6” package in Ubuntu:
  Won't Fix
Status in “python2.7” package in Ubuntu:
  New
Status in “python3.2” package in Ubuntu:
  New

Bug description:
  Hi

  Python's ctypes allows dynamically loading libraries.  On linux, it
  parses ldconfig -p output for a given library name, skipping over
  incompatible ABIs.  ABI is derived from uname output, which is
  incorrect.  Currently, the code can't cope with "hard-float" in the
  ldconfig -p output on armhf.

  I will attach a debdiff which allows ctypes to work on either armel or
  armhf, but wont work on a biarch or multiarch armel + armhf system.

  The code should be redesigned to check the real ABI, not the uname
  output; one option to do so is to check the ABI of the currently
  running executable, e.g. ldd on sys.executable as done elsewhere in
  the script, but still seems fragile; another option is to look at
  /proc/$pid/maps (probably not portable); another option is to ask libc
  to do the loading (seems the safest).

  Cheers,

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