[MacPorts] #63492: py37-openslide @1.1.2_1: OSError: dlopen(libopenslide.0.dylib, 6): image not found (was: openslide @3.4.1_1 (active) py37-openslide @1.1.2_1 (active) Using python3.7.)

[MacPorts]

#63492: py37-openslide @1.1.2_1: OSError: dlopen(libopenslide.0.dylib, 6): image
not found
--------------------------------------+----------------------
  Reporter:  DavidBAEpstein           |      Owner:  bgilbert
      Type:  defect                   |     Status:  assigned
  Priority:  Normal                   |  Milestone:
 Component:  ports                    |    Version:  2.7.1
Resolution:                           |   Keywords:
      Port:  openslide, py-openslide  |
--------------------------------------+----------------------
Changes (by ryandesign):

 * status:  new => assigned
 * priority:  High => Normal
 * owner:  (none) => bgilbert
 * port:  openslide, py37-openslide => openslide, py-openslide


Old description:

> virtual environment created with
> conda create -n openslide_bug python=3.7
>
> python command import openslide fails
>
> Attaching files with descriptive names
>
> MacBook Pro (Retina, 15-inch, Mid 2015)
> Macos 11.5.2

New description:

 virtual environment created with
 {{{
 conda create -n openslide_bug python=3.7
 }}}

 python command import openslide fails

 Attaching files with descriptive names

 MacBook Pro (Retina, 15-inch, Mid 2015)\\
 Macos 11.5.2

--

Comment:

 The error shown in the first attached file is:
 {{{
 OSError: dlopen(libopenslide.0.dylib, 6): image not found
 }}}
 Does /opt/local/lib/libopenslide.0.dylib exist? If so, what's the output
 of `otool -L /opt/local/lib/libopenslide.0.dylib`? What I'm looking for is
 whether the second line of output lists the full library path as it should
 (/opt/local/lib/libopenslide.0.dylib) or just its name
 (libopenslide.0.dylib). Our binary packages of openslide look like they
 have the correct full library path.

 dlopen probably needs a full path to the library file to work, but the
 error message only listed the library name. Looking closer at the error
 message, I see that the problem is probably here:

 {{{
   File "/Users/dbae/opt/anaconda3/envs/openslide_bug/lib/python3.7/site-
 packages/openslide/lowlevel.py", line 46, in <module>
     _lib = cdll.LoadLibrary('libopenslide.0.dylib')
 }}}

 Looks like py-openslide's code explicitly calls
 `cdll.LoadLibrary('libopenslide.0.dylib')`. Presumably that will need to
 be changed to use the absolute library path, i.e.
 `cdll.LoadLibrary('/opt/local/lib/libopenslide.0.dylib')`.

 The code in lowlevel.py reads:

 {{{
 elif platform.system() == 'Darwin':
     try:
         _lib = cdll.LoadLibrary('libopenslide.0.dylib')
     except OSError:
         # MacPorts doesn't add itself to the dyld search path, but
         # does add itself to the find_library() search path
         # (DEFAULT_LIBRARY_FALLBACK in ctypes.macholib.dyld) on
         # Python 2.6 and 2.7.  Python 3 users on MacPorts should add
         # the MacPorts lib directory to DYLD_LIBRARY_PATH.
         import ctypes.util
         _lib = ctypes.util.find_library('openslide')
         if _lib is None:
             raise ImportError("Couldn't locate OpenSlide dylib.  " +
                     "Is OpenSlide installed?")
         _lib = cdll.LoadLibrary(_lib)
 }}}

 The advice in those comments seems terrible to me: users should most
 certainly not add the MacPorts lib directory to DYLD_LIBRARY_PATH; that
 will break immense numbers of things. The developers of py-openslide
 should fix their software so that that's not necessary.

-- 
Ticket URL: <https://trac.macports.org/ticket/63492#comment:2>
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