help with dl module and clang

[Konstantin Belousov]

On Sat, Nov 03, 2018 at 07:31:33PM +0200, Daniel Braniss wrote:
> 
> 
> > On 3 Nov 2018, at 18:35, Konstantin Belousov <kostikbel at gmail.com> wrote:
> > 
> > On Sat, Nov 03, 2018 at 06:11:19PM +0200, Daniel Braniss wrote:
> >> 
> >> 
> >>> On 3 Nov 2018, at 17:58, Daniel Braniss <danny at cs.huji.ac.il> wrote:
> >>> 
> >>> 
> >>> 
> >>>> On 3 Nov 2018, at 17:47, Dimitry Andric <dim at FreeBSD.org> wrote:
> >>>> 
> >>>> On 3 Nov 2018, at 15:51, Daniel Braniss <danny at cs.huji.ac.il> wrote:
> >>>>> 
> >>>>> I have a program that loads some modules via dlopen(),  these modules call some routines
> >>>>> which are in the main program, this works when using gcc, but with cc it does not.
> >>>>> 
> >>>>> when compiling the main program I use  -export-dynamic, and the modules link fine when compiled with
> >>>>> gcc, but when compiling with clang/cc i get dlerror: ...Undefined symbol …
> >>>>> BTW, when linking the main program with cc I get
> >>>>> 	/usr/bin/ld: warning: cannot find entry symbol xport-dynamic; defaulting to 0000000000402140
> >>>> 
> >>>> Instead of using -export-dynamic (which is a linker flag) as a flag to
> >>>> cc, try using -Wl,-export-dynamic instead.  Now, the linker interprets
> >>>> this as the -e flag, which is something totally different.
> >>>> 
> >>> 
> >>> i had tried that before but i had -WI (upper case i) but re-reading the manual
> >>> it should be-Wl (lower case l as in lima :-))!!!!!
> >>> 
> >>> thanks!!!!!!
> >>> 
> >>> and now have to try profiling (gprof) which started this mess,
> >>> 
> >>> thanks again!!
> >>> 
> >>> danny
> >>> 
> >>> 
> >>>> I think this will also help with the exporting of the symbols of your
> >>>> main program.
> >>>> 
> >>>> -Dimitry
> >>>> 
> >>> 
> >> ok, new problem, it also happens with gcc:
> >> 
> >> when compiling the main program with flag -pg (gprof)
> >> dlopen fails with dlerror: Service unavailable
> > This means that your binary is linked statically.
> > dlopen(3) is not supported for static linking, ld-elf.so.1 is required
> > for dynamic loading to work.
> 
> as far as I can tell, it’s NOT statically linked:
> l
> e-kots-b# ldd /vol/src/libexec/idng/idngd/idngd 
> /vol/src/libexec/idng/idngd/idngd:
>        libpq.so.5 => /usr/local/lib/libpq.so.5 (0x800932000)
>        libcrypto.so.8 => /lib/libcrypto.so.8 (0x800c00000)
>        libldap-2.4.so.2 => /usr/local/lib/libldap-2.4.so.2 (0x801070000)
>        libthr.so.3 => /lib/libthr.so.3 (0x8012b7000)
>        libintl.so.8 => /usr/local/lib/libintl.so.8 (0x8014df000)
>        libssl.so.8 => /usr/lib/libssl.so.8 (0x8016ea000)
>        libc.so.7 => /lib/libc.so.7 (0x80195d000)
>        liblber-2.4.so.2 => /usr/local/lib/liblber-2.4.so.2 (0x801d18000)
> e-kots-b# file !$
> file /vol/src/libexec/idng/idngd/idngd
> /vol/src/libexec/idng/idngd/idngd: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), dynamically linked, interpreter /libexec/ld-elf.so.1, for FreeBSD 11.2 (1102501 <tel:1102501>), FreeBSD-style, not stripped

I suppose that dlopen(3) is called from the text of the idngd binary ?
Put the readelf -a idngd output somewhere.