[HELP]: Name conflicting in dynamically loading shared libraries

[HELP]: Name conflicting in dynamically loading shared libraries

[Jovi Zhang]

Hi,
   I encounter a problem about several .so library linked by a
problem, when a library A executing call function which source at same
.so, but strangly it jump to another library B address with same
function name, then program crash.

   Why library A don't find function name in itself address space
firstly? because compiled using option -fPIC? and how can we avoid
this problem except change function name?
   I know C++ namespace can do this, but it only suit for C++, how
about C face these problem? Can we use some gcc option help me?

   Thanks for your time.

.jovi

Re: [HELP]: Name conflicting in dynamically loading shared libraries

[Ian Lance Taylor]

Jovi Zhang <bookjovi@gmail.com> writes:

>    I encounter a problem about several .so library linked by a
> problem, when a library A executing call function which source at same
> .so, but strangly it jump to another library B address with same
> function name, then program crash.
>
>    Why library A don't find function name in itself address space
> firstly? because compiled using option -fPIC? and how can we avoid
> this problem except change function name?
>    I know C++ namespace can do this, but it only suit for C++, how
> about C face these problem? Can we use some gcc option help me?

Please never send messages to both gcc@gcc.gnu.org and
gcc-help@gcc.gnu.org.  This message is appropriate for
gcc-help@gcc.gnu.org; it is not appropriate for gcc@gcc.gnu.org.  Please
keep any followups on gcc-help.  Thanks.

You did not mention what operationg system you are using.  Assuming it
is GNU/Linux, then this is expected behaviour.  Shared libraries on
GNU/Linux and other ELF systems act approximately like static
libraries.  When two shared libraries define a symbol with the same
name, the first one encountered is used.

There are a number of ways to change this default behaviour: GCC's
-fvisibility option, GCC's visibility attribute, the linker's -Bsymbolic
option, linker version scripts, etc.

Ian