gistfile1.c

/* gcc -o dlopen-race dlopen-race.c -lpthread -ldl */

/* use "dlopen_test /lib/libwrap.so.0.7.6" */

/* dlopen_test.c */


/* Take from 
  http://sources.redhat.com/bugzilla/show_bug.cgi?id=4578
  and slightly modified.

  Added usleep() to trigger "Inconsistency detected by ld.so.."
  Error is encountered only in ~12% of the tries on Celeron M 440 with usleep(10).

  The error should not happen as fork() resets the locks
http://www.eglibc.org/cgi-bin/viewvc.cgi/branches/eglibc-2_11/libc/nptl/sysdeps/unix/sysv/linux/fork.c?annotate=9235  line 164

Commit message:
http://sourceware.org/git/?p=glibc.git;a=commit;f=nptl/sysdeps/unix/sysv/linux/fork.c;h=1d9d0b80d1412f8a272e0881d34538a041e56b4b
*/

#include <stdlib.h>
#include <stdio.h>
#include <dlfcn.h>
#include <pthread.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>

#define NTHREAD 4

void * th_fn(void *arg)
{
        char *dso_name = (char *)arg;
        void * handle = dlopen (dso_name, RTLD_NOW | RTLD_GLOBAL);

        if (handle == NULL) {
                fprintf(stderr, "Didn't open lib: %s: %s\n",
                        dso_name, dlerror());
                return (void *)-1;
        }
        dlclose(handle);
        return (void *)0;
}

int main(int argc, char *argv[])
{
	int i;
        char * dso_name;
        pthread_t child_th[NTHREAD];

        if (argc == 1) {
                printf("dlopen_test DSO_TO_LOAD\n");
                exit(-1);
        }

        dso_name = argv[1];
                	th_fn(dso_name);
	for (i = 0 ; i < NTHREAD ; i++) 
        	pthread_create(&child_th[i], NULL, th_fn, dso_name);

/* try with and without a call to usleep() */
#if 1
	 /* 
	 adjust sleep time, if needed, to trigger 
	 Inconsistency detected by ld.so: dl-open.c: 221: dl_open_worker: Assertion `_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT' failed! 
	*/
	 usleep(10);
#endif

	for (i = 0 ; i < NTHREAD ; i++) {
        	if (fork() == 0) {
                	th_fn(dso_name);
                	exit(0);
        	}
	}

	for (i = 0 ; i < NTHREAD ; i++) 
        	pthread_join(child_th[i], NULL);

        wait(NULL);
        return 0;
}