Re: Can't use dynamic-link with any shared object file

[Chris Vine]

On Mon, 26 Dec 2016 09:25:00 -0800
address@hidden wrote:
> Hello, 
> I am working on a project that involves writing some core
> functionality in C/C++ and composing behavior in Guile (as I
> understand it, this one of the ways that Guile was intended to be
> used). However, I cannot load any libraries with dynamic-link. I first
> encountered this with my code, but I'm going to use libc in my
> examples since the error message is identical, libc is ubiquitous, and
> it is the library that is given as an example in the manual. I am on
> Arch Linux and I am fully upgraded; this is the error message that I
> get:
> ERROR: In procedure dynamic-link:
> ERROR: in procedure dynamic-link: file "libc.so", message: "file not
> found"
> I've seen dynamic-link called with and without the 'so' prefix in
> various places, so I have tried using "c", "libc", and "libc.so" as
> the argument in my call to dynamic-link. They all produced the same
> error message. Other people with a similar problem have been asked to
> show the output of `ldd -r` or `ldd -d`. Both of them give me the same
> output:
> ldd: warning: you do not have execute permission for "/lib/libc.so"not
> a dynamic executable
> Do you know why this error would occur? Any help you can give me would
> be appreciated.
> Thanks,saffronsnail

As regards libc, on a glibc/linux system the error you report is
correct.  libc.so is not linkable.  It is in fact a text file - do
'cat /usr/lib/libc.so' to see.  The one you are looking for is
libc.so.6, which is a dynamically executable.

As regards your own libraries, who knows?  Probably you did not build
them as relocatable shared libraries correctly.  If dynamic-link works
but your guile code cannot find its contents, possibly you have not
exported your C++ libraries with C linkage (that is, as extern "C") to
suppress name mangling.  Beyond saying that you must have done something
wrong, it is not possible to say what the problem is.

Chris