[issue9998] ctypes find_library should search LD_LIBRARY_PATH on linux

[Vinay Sajip]

Vinay Sajip <vinay_sajip at yahoo.co.uk> added the comment:

There is a problem in this area of the code, not especially with the patch but with how gcc works (or doesn't). To illustrate:

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Version info
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vinay at eta-hardy:/tmp$ uname -a
Linux eta-hardy 2.6.24-29-generic #1 SMP Wed Aug 10 16:34:32 UTC 2011 i686 GNU/Linux
vinay at eta-hardy:/tmp$ gcc --version
gcc (GCC) 4.2.4 (Ubuntu 4.2.4-1ubuntu4)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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Create an empty file:
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vinay at eta-hardy:/tmp$ touch dummy.c
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Compile a shared library from it:
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vinay at eta-hardy:/tmp$ gcc -shared -o libdummy.so dummy.c
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Invoke gcc with patched command line:
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vinay at eta-hardy:/tmp$ gcc -L /tmp -Wl,t -o /dev/null -ldummy
/usr/bin/ld: t: No such file: No such file or directory
collect2: ld returned 1 exit status
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It's not patch related, here's what happens with the unpatched line
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vinay at eta-hardy:/tmp$ gcc -Wl,t -o /dev/null -ldummy
/usr/bin/ld: t: No such file: No such file or directory
collect2: ld returned 1 exit status
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Calling ld directly works as expected. With no search path:
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vinay at eta-hardy:/tmp$ ld -t -o /dev/null -ldummy
ld: mode elf_i386
ld: cannot find -ldummy
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With the search path supplied:
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vinay at eta-hardy:/tmp$ ld -t -L /tmp -o /dev/null -ldummy
ld: mode elf_i386
-ldummy (/tmp/libdummy.so)
ld: warning: cannot find entry symbol _start; not setting start address
vinay at eta-hardy:/tmp$ 

So, ISTM that the find_library code needs changing to use ld, else it will not work on all platforms.

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nosy: +vinay.sajip

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue9998>
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