Re: Shared libraries and posix threads question

[Tzvetan Chaliavski <ceco_(_at_)_commandcom_(_dot_)_com>]

Never mind the question. I figured out how to make it work. You should
include the -lc_r library before you link with the user specified
library.
Thanx anyways ;-) I'm out of this list.

Tzvetan Chaliavski wrote:
> 
> Hi all,
> 
> Does anyone know if OpenBSD allows invocation of pthread_xxxx functions
> from within shared library initialization function (e.g. _init())?
> I have piece of code that relies on some data being initialized when
> the shared library is lodaded. The following fragment (below) ilustrates
> the logic. Now after I've compiled and linked everything if I try to
> run test I get:
> 
> $ Memory fault (core dumped)
> 
> I've found out that the problem comes from the line:
> 
>         pthread_mutex_lock(&mtx);
> 
> which seems to be failing. I was also surprised to find out that
> OpenBSD does not support attribute declarations like:
> 
> void _init(void) __attribute__((section(".init")));
> 
> However, if you have single function named _init() it will still
> be invoked during the shared object initialization. It would seem though
> that the _fini() function is never called. Is that the expected
> behaviour?
> If so - does anyone know how to code shared library that relies on these
> two functions being properly called. I've performed all tests on
> OpenBSD v2.9. Any suggestions are welcome,
> 
> ceco
> 
> --------------- libmain.c -----------------------
> #include <stdio.h>
> #include <pthread.h>
> 
> pthread_mutex_t mtx;
> 
> void _init(void)
> {
>         printf("_init() called\n");
>         pthread_mutex_init(&mtx, NULL);
>         pthread_mutex_lock(&mtx);
>         pthread_mutex_unlock(&mtx);
> }
> 
> void _fini(void)
> {
>         printf("_fini() called\n");
>         pthread_mutex_destroy(&mtx);
> }
> 
> void func(void)
> {
>         pthread_mutex_lock(&mtx);
>         printf("func() called\n");
>         pthread_mutex_unlock(&mtx);
> }
> ----------------------------------------------
> 
> --------- test.c --------
> #include <stdio.h>
> 
> extern void func(void);
> 
> int main()
> {
>         printf("calling func()\n");
>         func();
>         printf("done\n");
>         return 0;
> }
> -----------------------------
> 
> -------- Makefile ---------
> 
> test: test.c libfoo.so
>         gcc -pthread -o test test.c libfoo.so
> 
> libfoo.so: libmain.c
>         gcc -pthread -c -fPIC -o libmain.o libmain.c
>         ld -Bforcearchive -Bdynamic -shared -o libfoo.so libmain.o
> 
> clean:
>         rm -f *.so
>         rm -f *.o
>         rm -f test
>         rm -f test.core
> ----------------------------------
> 
> --
> Tzvetan Chaliavski                 Command Software Systems, Inc.
> ceco_(_at_)_commandcom_(_dot_)_com                1061 E. Indiantown Road
> Phone (561)575-3200 x4197          Jupiter
> Fax   (561)575-3026                FL 33477

-- 
@*** Flap's Law ***
      Any inanimate object, regardless of its position or
      configuration, may be expected to perform at any time
      in a totally unexpected manner for reasons that are
      either entirely obscure or else completely mysterious.

--
Tzvetan Chaliavski                 Command Software Systems, Inc.
ceco_(_at_)_commandcom_(_dot_)_com                1061 E. Indiantown Road
Phone (561)575-3200 x4197          Jupiter
Fax   (561)575-3026                FL 33477