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Re: [libvirt] [PATCH 1/2] tests: commandtest: handle tcmalloc hacking environment




On 17.11.2017 16:40, Daniel P. Berrange wrote:
> On Fri, Nov 17, 2017 at 04:31:13PM +0300, Nikolay Shirokovskiy wrote:
>>
>>
>> On 17.11.2017 16:24, Daniel P. Berrange wrote:
>>> On Fri, Nov 17, 2017 at 04:17:37PM +0300, Nikolay Shirokovskiy wrote:
>>>> If one of the libraries is compiled with tcmalloc then
>>>> the latter will add GLIBCPP_FORCE_NEW and GLIBCXX_FORCE_NEW to
>>>> environment at startup and thus break commandtest.
>>>
>>> How are they getting those envs into our environment after we clean it
>>> out ? We strongly aim to prevent any non-whitelisted env variable
>>> leakage into children we spawn, so I would really like to kill these
>>> env vars instead of changin the test.
>>
>> They inserted at process startup I guess [1]. They are cleared out by commandtest
>> but visible in commandhelper.
> 
> Hmm, so is comandhelper getting linked to tcmalloc by mistake then ?
> If so, how easy is it to stop it being linked

It is not liked directly. In my case the chain is 
libdevmapper.so -> libudev.so -> libtcmalloc.so. It is distro specific
but I guess other can step across this issue and for a different chain. One
just need to link on of the libraries libvirt uses to tcmalloc.

> 
>>
>> [1] https://github.com/gperftools/gperftools/blob/6e3a702fb9c86eb450f22b326ecbceef4b0d6604/src/malloc_extension.cc#L85
>>
>>>
>>>> ---
>>>>  tests/commandhelper.c | 11 +++++++++--
>>>>  1 file changed, 9 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/tests/commandhelper.c b/tests/commandhelper.c
>>>> index 1da2834..0f6ce07 100644
>>>> --- a/tests/commandhelper.c
>>>> +++ b/tests/commandhelper.c
>>>> @@ -94,8 +94,15 @@ int main(int argc, char **argv) {
>>>>      for (i = 0; i < n; i++) {
>>>>          /* Ignore the variables used to instruct the loader into
>>>>           * behaving differently, as they could throw the tests off. */
>>>> -        if (!STRPREFIX(newenv[i], "LD_"))
>>>> -            fprintf(log, "ENV:%s\n", newenv[i]);
>>>> +        if (STRPREFIX(newenv[i], "LD_"))
>>>> +            continue;
>>>> +
>>>> +        /* Fix tests if tcmalloc is used in libraries */
>>>> +        if (STRPREFIX(newenv[i], "GLIBCPP_FORCE_NEW=") ||
>>>> +            STRPREFIX(newenv[i], "GLIBCXX_FORCE_NEW="))
>>>> +            continue;
>>>> +
>>>> +        fprintf(log, "ENV:%s\n", newenv[i]);
>>>>      }
>>>>  
>>>>      open_max = sysconf(_SC_OPEN_MAX);
>>>> -- 
>>>> 1.8.3.1
>>>>
>>>> --
>>>> libvir-list mailing list
>>>> libvir-list redhat com
>>>> https://www.redhat.com/mailman/listinfo/libvir-list
>>>
>>> Regards,
>>> Daniel
>>>
> 
> Regards,
> Daniel
> 


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