Re: A glibc dynamic linker or gld bug?

[hjl@lucon.org (H.J. Lu)]

>    By "problem", I mean the same symbol will have different values in
>    executable and DSO. When you update one of them, you won't see the
>    change in the other. If you relink executable against the new DSO,
>    the symbol in executable will override the one in DSO.
> 
> I guess I don't understand.  The DSO should have relocations for all
> uses of the symbol, so it will wind up seeing the definition in the
> executable.  At runtime the symbol will not have different values.
> This is an ordinary case in which the executable overrides the DSO.

Here is the testcase.

> 
> As far as I know, the only way you can get a DSO to see a different
> value from the main executable is to use -Bsymbolic or version
> scripts.  Also, you have just reported a case in which it happens due
> to the use of weak defined symbols in the executable.  But there
> definitely should not be any way to make the DSO and the executable
> see a different value for a strong defined symbol.
> 

# make
cc -shared -o libfoo.so -fPIC -O -g foo.c
cc -o foo -O -g libfoo.so main.c -Wl,-rpath,.
for f in foo; do echo "Running: $f"; ./$f; \
  if [ $? != 0 ]; then echo Failed; fi; done
Running: foo
main: 0x8049670
DSO: (nil)
cc -shared -o libfoo.so -fPIC -O -g foo.c -DDEF
for f in foo; do echo "Running: $f"; ./$f; \
  if [ $? != 0 ]; then echo Failed; fi; done
Running: foo
main: 0x8049670
DSO: 0x2aac0634
Failed


-- 
H.J. Lu (hjl@gnu.org)
---
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# Made on 1999-07-07 07:52 PDT by <hjl@osmium.su.varesearch.com>.
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rm -fr _sh00601
exit 0