help with dl module and clang

[Daniel Braniss]

> On 4 Nov 2018, at 19:22, Konstantin Belousov <kostikbel at gmail.com> wrote:
> 
> 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 ?
correct

> Put the readelf -a idngd output somewhere.
	www.cs.huji.ac.il/~danny/idngd.elf.out <http://www.cs.huji.ac.il/~danny/idngd.elf.out>