Tricky question about '_init' function of a shared lib

[wsonguci at my-deja dot com]

Hi, folks

I'm using gcc/g++ in Redhat6.0 to build a
shared library. I need to do some initialization
and cleaning up when the shared library is loaded
and unloaded.

So I put the intitialization code into the
_init function, because this function will be
called when the shared library is loaded.

// sharelib.cpp

// Global object
MyClass mclass;

#ifdef __cplusplus
extern "C" {
#endif

void _init(void)
{
	printf("I'm _init!\n");
	....
}

void _fini(void)
{
	printf("I'm _fini!\n");
	....
}

#ifdef __cplusplus
}
#endif

Since there is a default _init and _fini fuction in
the standard library, when linking, I have to specify
'-nostdlib' switch together with '-fpic -shared', and
then link with '-lgcc'.

But the problem is that, when I load the shared library,
_init did get called, but the global C++ object was not
initialized, I mean, 'MyClass mclass', the constructor
of mclass was not executed. If I remove '-nostdlib' switch,
the constructor of mclass can be executed, however, I
have no way to link my own '_init' function which conflicts
with the system default '_init' function. (BTW, if I specify
static void _init(void), it'll never be executed!)

This looks like a chicken-egg problem. Can any gcc/g++ guru
help me out?

Thanks in advance.

-Song


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