How to assign which symbols/functions to export from a .so file

["Chen(陈) Jun(军)"]

Thank you very much for your answer. I just want to do that in Linux 
building Linux DSO, and your answer is just right for me. I tried it on 
gcc 4.1.0(SuSE Linux 10.1) and it does just what I've expected.

By the way, it is better for gcc manual to tell since what gcc version a 
specific compiler option is introduced, so that a gcc user don't have to 
hunt around the change-log to know that. Don't you think so?

Brian Dessent 写道:
> "Chen(?) Jun(?)" wrote:
>
>   
>> I'd like to know, when I generate a .so file with ``gcc -shared'', how
>> can I assign which functions to export(visible by the  .so user).  This
>> is important , because a .so author would probably like to hide his
>> private functions so that the private symbols will not conflict with
>> that of .so from other programmers.
>>
>> Microsoft compiler use a .def to describe what symbols to export from a
>> DLL, or, __declspec(dllexport) can easily export functions of a whole
>> C++ class. Does the gcc world support this feature.
>>     
>
> What platform are you talking about?  gcc uses whatever the underlying
> platform supports, but that can vary considerably.  You have to remember
> that gcc targets dozens and dozens of various combinations of operating
> systems and architectures so don't assume that gcc=linux.
>
> On PE platforms, gcc works similarly to the MS toolchain: __declspec
> and/or a .def file, but also with the choice of using the auto-export
> feature of the GNU linker if neither of the former are used.
>
> On ELF platforms you use symbol visibility, either with
> __attribute__((visibility)) or -fvisibility.  Read the fine manual: 
>
> <http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#index-g_t_0040code_007bvisibility_007d-attribute-2100>
> <http://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#index-fvisibility-1837>
>
> Brian
>
>