calling s2n_cleanup with no s2n_init corrupts thread-local storage

[arielb1]

Problem:

This is a regression caused by the fix in #4024

This program fails as the my_key TLS key is corrupted (overwritten with NULL).

#include <pthread.h>

#include "s2n_test.h"

static int my_global;

static void my_destructor(void *arg) {}

/* Checks that calling s2n_cleanup without s2n_init does not corrupt
 * thread-local storage. */

int main(int argc, char **argv)
{
    BEGIN_TEST_NO_INIT();

    pthread_key_t my_key;

    /* Init the pthread key */
    EXPECT_SUCCESS(pthread_key_create(&my_key, my_destructor));

    /* Set it a value */
    EXPECT_SUCCESS(pthread_setspecific(my_key, &my_global));

    /* Call s2n_cleanup with no init */
    EXPECT_SUCCESS(s2n_cleanup());

    /* Check that the key is not corrupted */
    int *new_value = (int*) pthread_getspecific(my_key);
    EXPECT_EQUAL(new_value, &my_global);

    /* Delete the key */
    EXPECT_SUCCESS(pthread_key_delete(my_key));

    END_TEST_NO_INIT();
}

Solution:

This should work, or at least crash in a safe way without corruption.