Regression caused by commit 7682323a3a798d6f15708f228f859a64cb869aa3

[Khem Raj]

On Sat, Jan 14, 2012 at 6:10 PM, Khem Raj <raj.khem at gmail.com> wrote:
> On Fri, Jan 13, 2012 at 4:13 PM, Khem Raj <raj.khem at gmail.com> wrote:
>> On Fri, Jan 13, 2012 at 3:45 PM, Khem Raj <raj.khem at gmail.com> wrote:
>>> On Fri, Jan 13, 2012 at 1:37 AM, Carmelo AMOROSO <carmelo.amoroso at st.com> wrote:
>>>>> and since I see the same issue on all architectures probably its not
>>>>> elfinterp changes
>>>>> too. Mostly it seems likely that it could be in the way the scopes are
>>>>> being handled
>>>>>
>>>>
>>>> we have reviewed several times this change before committing. Anyway we
>>>> will review it again. We have not ever seen any failure in the lookup
>>>> with all of our tests. The only change in the way the symbol scope is
>>>> created is in where the ld.so is added.
>>>> In the original code it was the last entry of the global scope, while
>>>> with the new structure in place it was added as soon as found (as glibc
>>>> actually does).... and I don't really think this could have some impact.
>>>
>>> I tried to reverse it as well but the problem remained.
>>>
>>>>
>>>> We are trying to startup a X system on our platform. Is there any simple
>>>> X app we can run to show the failure ?
>>>>
>>>> Is some .so failing to be dl-opened due to unresolved symbol ?
>>>
>>> this is potentially possible. I will try to debug it through
>>
>> This is the problem that happens with the new scoping and does not
>> happen without it
>>
>> Error reading Pango modules file
>>
>> (matchbox-desktop:1058): Pango-CRITICAL **: No modules found:
>> No builtin or dynamically loaded modules were found.
>> PangoFc will not work correctly.
>> This probably means there was an error in the creation of:
>>  '/etc/pango/pango.modules'
>> You should create this file by running:
>>  pango-querymodules > '/etc/pango/pango.modules'
>>
>> (matchbox-desktop:1058): Pango-WARNING **: failed to choose a font,
>> expect ugly output. engine-type='PangoRenderFc', script='latin'
>>
>> (matchbox-desktop:1058): Pango-WARNING **: failed to choose a font,
>> expect ugly output. engine-type='PangoRenderFc', script='common'
>
> here is the error
>
> /usr/bin/pango-querymodules: can't resolve symbol
> '_ZNSt14error_categoryD2Ev' in lib '/usr/lib/libstdc++.so.6'.
>
> this does not happen without scope patch
>
> pango-querymodules loads a shared library
> /usr/lib/pango/1.6.0/modules/pango-basic-fc.so using dlopen and this
> library had libstdc++.so.6 in its DT_NEEDED entries
>
> I was trying to create a small testcase where I created a small binary
> which would dlopen another .so which has libstdc++ in DT_NEEDED in its
> header so not able to reproduce a small testcase but making some
> progress


I might have a test case here http://uclibc.org/~kraj/reproducer_v2.tar.gz
untar it on target and run make and the ./run.sh

with buggy libraries i get
root at qemux86:~/rep/reproducer_v2# ./run.sh
1)main:dlopen  libA.so
4)libC:dlopen  libB.so
5)libC:atexit(libC_fini)
6)main:dlclose libA.so
/home/root/rep/reproducer_v2/main: can't resolve symbol '_libC_fini'
in lib './/libC.so'.

whereas without the scopes patch I get

root at qemux86:~/rep/reproducer_v2# ./run.sh
1)main:dlopen  libA.so
4)libC:dlopen  libB.so
5)libC:atexit(libC_fini)
6)main:dlclose libA.so
7)libC:finish - atexit()
8)main:finish main
root at qemux86:~/rep/reproducer_v2#


I think thats the problem that I am facing in pango-querymodules as well
another data point is if I use BIND_NOW then it works too.

let me know if you can reproduce it with this testcase

Thanks
-Khem