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Date: Thu, 30 Jun 2016 16:34:39 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Change in behavior (bug) in ctypes
Message-ID: <20160630143439.GS981@calimero.vinschen.de>
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On Jun 30 10:05, Marvin Greenberg wrote:
> Code like this was working until sometime recently,
>=20
> $ python
> >>> import ctypes
> >>> cygdll =3D ctypes.cdll.cygwin1
>=20
> But with the latest cygwin update, it is failing.  On a couple older
> machines, I do:
>=20
>=20
> $ python -c "import ctypes; print ctypes._dlopen('cygwin1')"; cygcheck -V;
> python -V
> 6442713088
> cygcheck (cygwin) 2.1.0
> System Checker for Cygwin ...<snip>
> Python 2.7.10
>=20
> $  python -c "import ctypes; print ctypes._dlopen('cygwin1')"; cygcheck -=
V;
> python -V
> 6442713088
> cygcheck (cygwin) 2.5.1
> System Checker for Cygwin ...<snip>
> Python 2.7.10
>=20
> This last was on a windows 8.1 (Windows 8.1 Enterprise Ver 6.3 Build 9600)
> system.  I updated cygwin completely on that system to cygwin latest from=
 a
> mirror.  And, then
>=20
> $  python -c "import ctypes; print ctypes._dlopen('cygwin1')"; cygcheck -=
V;
> python -V
> Traceback (most recent call last):
>   File "<string>", line 1, in <module>
> OSError: No such file or directory
> cygcheck (cygwin) 2.5.2
> System Checker for Cygwin  ...<snip>
> Python 2.7.10
>=20
> Note that simply changing the call to explicitly append the dll extension
> works fine:
>=20
> $  python -c "import ctypes; print ctypes._dlopen('cygwin1.dll')"
> 6442713088
>=20
> But that won't work with the former attribute-style of loading the dll.

Same as on Linux:

$ python -c "import ctypes; print ctypes._dlopen('libcurl')"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
OSError: libcurl: cannot open shared object file: No such file or directory

$ python -c "import ctypes; print ctypes._dlopen('libcurl.so')"
94888239442336

This was a fix for POSIX compat.

There's a bit of internal magic in Cygwin's dlopen() to handle .dll vs.
.so, but dlopen() does NOT add suffixes to the file on its own.


Corinna

--=20
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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