[CMake] Undefined reference

[Michael Hertling]

On 11/03/2011 06:20 PM, Mauricio Klein wrote:
> The error reported occurs in the launch time: the daemon doesn't starts and
> report (in terminal) a GLIBC version error. [...]

Usually, this means that it has *not* been linked statically against
the GLIBC on the build system. Which dependencies does ldd report?

> [...] I mean, the daemon was compiled
> in a old CentOS (4.8) and i'm trying to run in the latest Ubuntu.
> 
> But anyway, i will make more tests as you sugested and try to discovery
> what exactly is happening.
> 
> Once again, thank you so much for your help!
> 
> On Thu, Nov 3, 2011 at 3:09 PM, Michael Hertling <mhertling at online.de>wrote:
> 
>> On 11/03/2011 03:51 PM, Mauricio Klein wrote:
>>> Thank you Raphael, it worked!
>>>
>>> One last question: i've tried to compile my code using static linkage,
>> once
>>> i need my daemon runs in many Linux releases. But, even static, in many
>>> systems my code crashes because the GLIBC version.
>>
>> How do these crashes manifest themselves, e.g. shell/syslog messages,
>> return values, core dumps etc.? Are you sure they are related to the
>> GLIBC version? Does the executable actually have no single dependency
>> on any shared library, i.e. is it linked statically in its entirety?
>> What does ldd or readelf report?
>>
>>> My question is: asking for static linkage in CMake can solve this
>> problem?
>>
>> If even a statically linked executable crashes on the target system,
>> telling CMake to link statically will hardly solve this problem. ;)
>>
>>> Or maybe another approach in CMake, where i embed all the needed
>>> libraries...
>>
>> You might take a look the the BundleUtilities Module, but at first,
>> I'd recommend to investigate what exactly causes the crashes. Your
>> best bet is probably to provide a tiny but self-contained example
>> that works on your development platform and crashes on a target
>> system, along with some information about the latter's setup.
>>
>> Regards,
>>
>> Michael
>>
>>> On Thu, Nov 3, 2011 at 12:19 PM, Raphael Kubo da Costa
>>> <rakuco at freebsd.org>wrote:
>>>
>>>> Mauricio Klein
>>>> <mauricio.klein.msk at gmail.com> writes:
>>>>
>>>>> I can compile all my codes without problems, but in the linkage step, i
>>>>> receive a lot of errors about undefined reference to OpenSSL functions
>>>>> (yes, my code uses OpenSSL).
>>>>>
>>>>> In my own (and ugly :P) Makefile, i use "-lssl" flag in g++ compile
>> line.
>>>>>
>>>>> My question is: how can i pass this flag in CMake.
>>>>> Also, i'm not sure if i'm using CMake correctly. Is correctly use
>> "-lssl"
>>>>> flag in CMake or i need to copy the library to a folder inside my
>> project
>>>>> and link to this copy?
>>>>
>>>> You need to find OpenSSL with `find_package(OpenSSL)' and then, assuming
>>>> it is found (ie. OPENSSL_FOUND is true), link to its libraries with
>>>> `target_link_libraries(YOUR_APP ${OPENSSL_LIBRARIES})'.