[ python-Bugs-1464444 ] ctypes should be able to link with installed libffi

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Bugs item #1464444, was opened at 2006-04-04 21:42
Message generated for change (Comment added) made by theller
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Category: Extension Modules
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Matthias Klose (doko)
Assigned to: Thomas Heller (theller)
Summary: ctypes should be able to link with installed libffi

Initial Comment:
ctypes always uses the included libffi implementation
(which should be updated to current GCC HEAD). Pleae
add an option to build and link against a libffi, which
is installed on the system.

attached is a hack to just always build using the
installed libffi. I'm unsure how to find the correct
ffi implementation (maybe check for LIBFFI_H defined in
the ffi header?), and where to implement this check
(configure.ac --with-system-ffi=/usr?).


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>Comment By: Thomas Heller (theller)
Date: 2006-04-06 14:34

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I tend to accept this patch.  Martin, any objections?

Matthias: do any of the buildbot slaves have a system libffi
installed?

About the code:
And, shouldn't it be enough to let the compiler find ffi.h?
 I assume that the presence of this file should indicate
that libffi.so is installed - why do we have to scan this
file for '#define LIBFFI_H', and why do we have to search
for the ffi shared library?

Would updating the included libffi code to GCC HEAD bring
any advantages?  The currently included code has been
patched in a few places, to avoid some of the compiler
warnings, and to allow compilation on OS X 10.3 (which does
not know the 'live_support' segment attribute, see Python
bug 1460514).

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Comment By: Matthias Klose (doko)
Date: 2006-04-05 00:43

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It's not an external dependency, if it's not found. The size
is not the argument. For distributors it's an additional
maintainance burden to update copies of libraries. Security
advisories for zlib (and pcre?) show this.

patch updated.


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Comment By: Martin v. Löwis (loewis)
Date: 2006-04-05 00:14

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Why is it desirable to link with the system ffi? That just
adds an external dependency, for a negligable space saving
(on x86, libffi.so.4.0.1 is 7840 bytes).

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