Odd. Let's see what other core devs say. On Sat, Sep 10, 2011 at 2:50 PM, Howard B. Golden <howard_b_gol...@yahoo.com> wrote: > I don't know why, but some Linux distributions place scripts into .so > files instead of the actual binaries. This takes advantage of a feature > of GNU ld that it will process the script (which points to the actual > binary) when it links the .so file. > > This feature works fine when you are linking a binary, but it doesn't > take into account that binaries can be loaded dynamically by > interpreters (e.g., Python or GHCi). If dlopen finds a linker script, it > doesn't know what to do with it. It simply diagnoses the file as either > an invalid ELF header or too short. > > On Gentoo Linux, some common libraries that are represented as linker > scripts include libm.so, libpthread.so and libpcre.so. I know this also > affects Ubuntu. > > Howard > > On Sat, 2011-09-10 at 14:39 -0700, Guido van Rossum wrote: >> Excuse me for asking a newbie question, but what are linker scripts >> and why are they important? I don't recall anyone ever having >> requested this feature before. >> >> --Guido >> >> On Wed, Sep 7, 2011 at 12:33 PM, Howard B. Golden >> <howard_b_gol...@yahoo.com> wrote: >> > Hi, >> > >> > In Haskell I experienced a situation where dynamically loaded modules >> > were experiencing "invalid ELF header" errors. This was caused by the >> > module names actually referring to linker scripts rather than ELF >> > binaries. I patched the GHC runtime system to deal with these scripts. >> > >> > I noticed that this same patch has been ported to Ruby and Node.js, so I >> > suggested to the libc developers that they might wish to incorporate the >> > patch into their library, making it available to all languages. They >> > rejected this suggestion, so I am making the suggestion to the Python >> > devs in case it is of interest to you. >> > >> > Basically, when a linker script is loaded by dlopen, an "invalid ELF >> > header" error occurs. The patch checks to see if the file is a linker >> > script. If so, it finds the name of the real ELF binary with a regular >> > expression and tries to dlopen it. If successful, processing proceeds. >> > Otherwise, the original "invalid ELF error" message is returned. >> > >> > If you want to add this code to Python, you can look at my original >> > patch (http://hackage.haskell.org/trac/ghc/ticket/2615) or the Ruby >> > version (https://github.com/ffi/ffi/pull/117) or the Node.js version >> > (https://github.com/rbranson/node-ffi/pull/5) to help port it. >> > >> > Note that the GHC version in GHC 7.2.1 has been enhanced to also handle >> > another possible error when the linker script is too short, so you might >> > also want to add this enhancement also (see >> > https://github.com/ghc/blob/master/rts/Linker.c line 1191 for the >> > revised regular expression): >> > >> > "(([^ \t()])+\\.so([^ \t:()])*):([ \t])*(invalid ELF header|file too >> > short)" >> > >> > At this point, I don't have the free time to write the Python patch >> > myself, so I apologize in advance for not providing it to you. >> > >> > HTH, >> > >> > Howard B. Golden >> > Northridge, California, USA >> > >> > _______________________________________________ >> > Python-Dev mailing list >> > Python-Dev@python.org >> > http://mail.python.org/mailman/listinfo/python-dev >> > Unsubscribe: >> > http://mail.python.org/mailman/options/python-dev/guido%40python.org >> > >> >> >> > > >
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