bug in DDD

[Jorge Enrique Perez Martinez]

I have this program:

#define _REENTRANT
#include <assert.h>
#include <semaphore.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>

static pthread_t t_cliente;
static sem_t s1;

void *cliente(void *basura) {
 int r;
 printf ("Comienza el cliente\n");
 r = sem_wait (&s1);
 printf ("Cliente pasa semaforo\n");
 if (r != 0) printf("Valro devuelto por el sem wait = %d\n", r);
 pthread_exit (NULL);
 return NULL;
}
int main (int argc, char *argv[]) {
 assert (sem_init (&s1, 0, 0) == 0);
 assert (pthread_create(&t_cliente,  NULL, cliente,  NULL) == 0);
 sleep (4);
 assert (sem_post (&s1) == 0);
 assert (pthread_join (t_cliente,  NULL) == 0);
 exit (0);
}

I compile this program with gcc and I execute it on a 64-bit computer. 
The running operating system is Linux (kernel 2.6).
The execution is correct. However, with DDD (versions 3.3.8, 3.3.9 and 
3.3.10) I set a breakpoint in the sentence
sem_wait of the client. I hit Run and then Next. The client goes through 
the sem_wait sentence (incorrectly) returning
the value -1. On the other hand, if we are displaying the data structure 
s1, the field sem_waiting always has the value 0x0.
How can I solve this problem?

Thanks in advance,

Jorge Enrique Pérez Martínez
Departamento de Informática Aplicada
Universidad Politécnica de Madrid. Spain