Merge lp:~gqmelo/pyopengl/load-library-linux into lp:pyopengl

[Guilherme Quentel Melo]

Fix library loading on Linux

The function util.find_library does not respect variables like
LD_LIBRARY_PATH.

Also files ending with .so are intended to be used at compilation time
and therefore are normally shipped by a dev package on most Linux
distributions.

At runtime, applications should use the filename with major version
(.so.x)

[Mike C. Fletcher (mcfletch)]

Okay, merged. Sorry it took so long, but it just failed when I merged and I didn't have the time to investigate (it would load a non-functional DLL when the base_name was loaded (i.e. it would load libOpenGL.so and that would have no visuals etc), so it would completely bomb out on my (Kubuntu) box).

We really do mean "the latest version" here, so the .so really is what we *mean*, but ld-preload and the like should be respected, and while I don't like the arbitrary "up to 9" thing, we're currently in the 1-3 range for our used dlls, so we'll look at it again when they get up to api version 9 I suppose.

Thanks,
Mike

[Guilherme Quentel Melo (gqmelo)]

Thanks for the feedback!

> and while I don't like the arbitrary "up to 9" thing, we're currently in the 1-3 range for our used > dlls, so we'll look at it again when they get up to api version 9

Yeah, I don't like it either, but I don't see a better way to dynamically load the last version of a library.

I checked the code you merged, and it seems fine except that I think it breaks OSX, don't it? It is not trying any name for OSX

[Mike C. Fletcher (mcfletch)]

Good point, added base name if we're on darwin.

[Guilherme Quentel Melo (gqmelo)]

> Good point, added base name if we're on darwin.

Great! Should I do something about this pull request? Mark as merged?

[Mike C. Fletcher (mcfletch)]

Weird, I thought it would automatically mark it as merged... ah, no, because I wound up doing a revert and then re-applying as I was debugging it wound up unmarked.

Have Mac people trying to figure out how to make it work on Mac now...

Unmerged revisions

1000. By Guilherme Quentel Melo on 2016-05-05

Fix library loading on Linux

The function util.find_library does not respect variables like
LD_LIBRARY_PATH.

Also files ending with .so are intended to be used at compilation time
and therefore are normally shipped by a dev package on most Linux
distributions.

At runtime, applications should use the filename with major version
(.so.x)

=== modified file 'OpenGL/platform/ctypesloader.py'
--- OpenGL/platform/ctypesloader.py	2014-04-08 04:04:23 +0000
+++ OpenGL/platform/ctypesloader.py	2016-05-05 18:27:25 +0000
@@ -30,6 +30,47 @@
     """
     if isinstance( dllType, ctypes.LibraryLoader ):
         dllType = dllType._dlltype
+    if os.name == 'posix':
+        return _loadLibraryPosix(dllType, name, mode)
+    else:
+        return _loadLibraryWindows(dllType, name, mode)
+
+
+def _loadLibraryPosix(dllType, name, mode):
+    """Load a given library for posix systems
+
+    The problem with util.find_library is that it does not respect linker runtime variables like
+    LD_LIBRARY_PATH.
+
+    Also we cannot rely on libGLU.so to be available, for example. Most of Linux distributions will
+    ship only libGLU.so.1 by default. Files ending with .so are normally used when compiling and are
+    provided by dev packages.
+
+    returns the ctypes C-module object
+    """
+    prefix = 'lib'
+    if sys.platform == 'darwin':
+        suffix = '.dylib'
+    else:
+        suffix = '.so'
+    base_name = prefix + name + suffix
+    filenames_to_try = [base_name]
+
+    # If a .so is missing, let's try libs with so version (e.g libGLU.so.9, libGLU.so.8 and so on)
+    if sys.platform.startswith('linux'):
+        filenames_to_try.extend(list(reversed([base_name + '.%i' % i for i in range(0, 10)])))
+
+    for filename in filenames_to_try:
+        try:
+            return dllType(filename, mode)
+        except Exception, err:
+            _log.info('''Failed to load library ( %r ): %s''', filename, err)
+
+def _loadLibraryWindows(dllType, name, mode):
+    """Load a given library for Windows systems
+
+    returns the ctypes C-module object
+    """
     fullName = None
     try:
         fullName = util.find_library( name )