[Pharo-project] Cog+linux: external module not found

David T. Lewis lewis at mail.msen.com
Sat Jan 7 20:16:29 EST 2012


On Sun, Jan 08, 2012 at 12:37:59AM +0000, Schwab,Wilhelm K wrote:
> Eliot,
> 
> SOL??  Is that really the message we want to send to current and *prospective* users?  Canonical does something that makes sense from a security perspective (one needs root privileges to alter the ldconfig mapping, not to to use it).  All the vm needs to do is request the #moduleName as given, and users of Pharo "SOL" as a result?
> 
> Please reconsider.
> 
> Bill
> 

I think you are taking the response out of context. The actual statement
was "Then you're SOL :)  You'd need to write new support for Ubuntu."

You might take that as a gentle suggestion to expend a bit of effort
on it yourself. After all, it is open source, and Eliot is only one
person. He can't do everything for everybody without a little help
from the rest of us.

Dave


> 
> 
> 
> ________________________________
> From: pharo-project-bounces at lists.gforge.inria.fr [pharo-project-bounces at lists.gforge.inria.fr] on behalf of Eliot Miranda [eliot.miranda at gmail.com]
> Sent: Saturday, January 07, 2012 6:38 PM
> To: Pharo-project at lists.gforge.inria.fr
> Subject: Re: [Pharo-project] Cog+linux: external module not found
> 
> 
> 
> On Sat, Jan 7, 2012 at 8:49 AM, Schwab,Wilhelm K <bschwab at anest.ufl.edu<mailto:bschwab at anest.ufl.edu>> wrote:
> Nick,
> 
> Partial success.  After a false start with getting output from strace (my fault), it showed me that the vm was looking a lot in the vm's directory.  A symlink by the same name, allowed it to see the library.  Clearly, this is not a fix, because one should not be forced to make links to any/every library on the system.  However, it *was* nice to see the version string in an inspector :)
> 
> Looking at the strace output (relevant parts below), it tries with prepending lib, appending .so, .so.dylib.  It looks in the vm's directory, and in the root directory, not /usr/lib.
> 
> It has been almost a year (based on a dated comment) since I last really strained my synapses on the workings of ldconfig.  On my systems, it would tell one to look for the library as follows:
> 
>     ldconfig -p | grep Acces
>     libAccesIO-USB.so (libc6) => /usr/lib/libAccesIO-USB.so
> 
> #moduleName answers 'libAccesIO-USB.so', and Ian's vm finds it.  My (and I use the term LOOSELY) understanding is that Ubuntu no longer uses LD_LIBRARY_PATH.  dlopen() seems to prefer that one use the names as reported by ldconfig.  The best explanation I have found is that the change was a security measure.
> 
> Then you're SOL :)  You'd need to write new support for Ubuntu.
> 
> 
> How does one get ldconfig to "know" where something lives?  Putting a .so file in /usr/lib (and perhaps other places too) and then running ldconfig as sudo appears to build a cache.  Then ldconfig -p (anyone can run this) will show the map, and one can grep the result to find something specifc, as above.
> 
> Putting files in /usr/lib is a pain for things under active development.  A file can live anywhere if one puts a .conf file in /etc/ld.so.confd; the .conf files should contain paths to directories to be searched for .so files - or at least that's how it *appears* to work.  Run ldconfig as sudo to refresh the mapping, and verify with ldconfig - p.
> 
> The fix might be as simply as having the cog vm try passing the #moduleName to dlopen().
> 
> Nick, thanks for the nudge in a working direction.  I will probably symlink another file and see if a mix of hardware and software will get closer to cooperating with me.
> 
> Bill
> 





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