dynamic loadable library multiple degined symbols

[Peter Blok]

Your pointers helped me find a solution.

The samba build environment generates a runner script to build the module. I have added this symbol in the script amongst other “hidden” ones and it now works.

Now I have to find out where and how the script is generated and have a patch ready for upstream.



> On 28 Nov 2019, at 14:48, Peter Blok <pblok at bsd4all.org> wrote:
> 
> I’m trying to change this because named dies with an assert. named checks the arguments of dns_name_equal which is completely different from the one intended out of the shared module.
> 
> 
>> On 28 Nov 2019, at 14:12, Konstantin Belousov <kostikbel at gmail.com> wrote:
>> 
>> On Thu, Nov 28, 2019 at 01:50:15PM +0100, Peter Blok wrote:
>>> Hi,
>>> 
>>> named (bind9.14) has a function called dns_name_equal. (0000000000443ac0 T dns_name_equal)
>>> 
>>> named dynamically  loads dlz_bind9_14.so is build from dlz_bind9.c and calls this function, but dns_name_equal was undefined so it got resolved to the version of named.
>>> 
>>> The function is defined in dns_utils.c, so I changed the building to include that file.
>>> 
>>> Now dlz_bind9_14.so is using dlz_bind9.c and dns_utils.c also has the right dns_name_equal (000000000000bee0 T dns_name_equal) defined
>>> 
>>> Unfortunately the code inside dlz_bind9_14.so still calls the function out of named.
>>> 
>>> Is this something that should have been resolved at compile/link time of dlz_bind9_14.so? If so, how?
>> No, default ELF name resolution rules would give the behaviour you described,
>> assuming the main binary was linked with -Wl,-E (and it must be to export
>> symbols to loadable modules).  The shared libraries and loadable modules
>> are interposable by default, unless linked with -B symbolic, and the symbol
>> resolution order starts from the main binary object.
>> 
>> Why do you try to change this ?
>> 
>>> 
>>> Note that the samba build uses waf and wscript files.
>>> 
>>> Peter
>>> 
>>> 
>> 
>> 
> 

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