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Re: Guile test-ffi uses an unportable assumption
From: |
Eli Zaretskii |
Subject: |
Re: Guile test-ffi uses an unportable assumption |
Date: |
Sun, 24 Jul 2016 17:13:20 +0300 |
> From: Andy Wingo <address@hidden>
> Cc: address@hidden
> Date: Sat, 23 Jul 2016 23:17:58 +0200
>
> > It assumes that libltdl can only produce a handle for a symbol in the
> > the program itself, as opposed to those loaded from shared libraries.
> > It tries 'strerror'. This cannot work on MS-Windows, unless the
> > program was linked with -export-dynamic, which is not true for
> > the test program.
>
> Interesting. The test program is a Scheme script which looks up
> strerror in the dlopen(NULL). Libguile is compiled with -export-dynamic
> but the guile binary is not. Which part needs to be compiled with
> -export-dynamic, do you think?
The guile binary. Here's what the libltdl documentation has to say
about this:
-- Function: lt_dlhandle lt_dlopen (const char *FILENAME)
[...]
If FILENAME is `NULL' and the program was linked with
`-export-dynamic' or `-dlopen self', `lt_dlopen' will return a
handle for the program itself, which can be used to access its
symbols.
[...]
If you use `lt_dlopen (NULL)' to get a HANDLE for the running
binary, that handle will always be marked as resident, and
consequently cannot be successfully `lt_dlclose'd.
However, in the case in point even compiling guile with -export-dynamic
won't help, because the function being used by the test, strerror,
comes from the C library, and is not statically linked into the guile
binary. So I suggest to modify the test to use a function that is
part of the guile binary's own sources.