Add reference counting around the thread state hash table.

Unfortunately, this means that the dynamic ENGINE version just went up, and
isn't backward compatible.
PR: 678

crypto/err/err.c

@@ -226,6 +226,7 @@ struct st_ERR_FNS
 	ERR_STRING_DATA *(*cb_err_del_item)(ERR_STRING_DATA *);
 	/* Works on the "thread_hash" error-state table */
 	LHASH *(*cb_thread_get)(int create);
+	void (*cb_thread_release)(LHASH **hash);
 	ERR_STATE *(*cb_thread_get_item)(const ERR_STATE *);
 	ERR_STATE *(*cb_thread_set_item)(ERR_STATE *);
 	void (*cb_thread_del_item)(const ERR_STATE *);
@@ -240,6 +241,7 @@ static ERR_STRING_DATA *int_err_get_item(const ERR_STRING_DATA *);
 static ERR_STRING_DATA *int_err_set_item(ERR_STRING_DATA *);
 static ERR_STRING_DATA *int_err_del_item(ERR_STRING_DATA *);
 static LHASH *int_thread_get(int create);
+static void int_thread_release(LHASH **hash);
 static ERR_STATE *int_thread_get_item(const ERR_STATE *);
 static ERR_STATE *int_thread_set_item(ERR_STATE *);
 static void int_thread_del_item(const ERR_STATE *);
@@ -253,6 +255,7 @@ static const ERR_FNS err_defaults =
 	int_err_set_item,
 	int_err_del_item,
 	int_thread_get,
+	int_thread_release,
 	int_thread_get_item,
 	int_thread_set_item,
 	int_thread_del_item,
@@ -272,6 +275,7 @@ static const ERR_FNS *err_fns = NULL;
  * and state in the loading application. */
 static LHASH *int_error_hash = NULL;
 static LHASH *int_thread_hash = NULL;
+static int int_thread_hash_references = 0;
 static int int_err_library_number= ERR_LIB_USER;
 
 /* Internal function that checks whether "err_fns" is set and if not, sets it to
@@ -418,11 +422,37 @@ static LHASH *int_thread_get(int create)
 		CRYPTO_pop_info();
 		}
 	if (int_thread_hash)
+		{
+		int_thread_hash_references++;
 		ret = int_thread_hash;
+		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ERR);
 	return ret;
 	}
 
+static void int_thread_release(LHASH **hash)
+	{
+	int i;
+
+	if (hash == NULL || *hash == NULL)
+		return;
+
+	i = CRYPTO_add(&int_thread_hash_references, -1, CRYPTO_LOCK_ERR);
+
+#ifdef REF_PRINT
+	fprintf(stderr,"%4d:%s\n",int_thread_hash_references,"ERR");
+#endif
+	if (i > 0) return;
+#ifdef REF_CHECK
+	if (i < 0)
+		{
+		fprintf(stderr,"int_thread_release, bad reference count\n");
+		abort(); /* ok */
+		}
+#endif
+	*hash = NULL;
+	}
+
 static ERR_STATE *int_thread_get_item(const ERR_STATE *d)
 	{
 	ERR_STATE *p;
@@ -437,6 +467,7 @@ static ERR_STATE *int_thread_get_item(const ERR_STATE *d)
 	p = (ERR_STATE *)lh_retrieve(hash, d);
 	CRYPTO_r_unlock(CRYPTO_LOCK_ERR);
 
+	ERRFN(thread_release)(&hash);
 	return p;
 	}
 
@@ -454,6 +485,7 @@ static ERR_STATE *int_thread_set_item(ERR_STATE *d)
 	p = (ERR_STATE *)lh_insert(hash, d);
 	CRYPTO_w_unlock(CRYPTO_LOCK_ERR);
 
+	ERRFN(thread_release)(&hash);
 	return p;
 	}
 
@@ -470,13 +502,15 @@ static void int_thread_del_item(const ERR_STATE *d)
 	CRYPTO_w_lock(CRYPTO_LOCK_ERR);
 	p = (ERR_STATE *)lh_delete(hash, d);
 	/* make sure we don't leak memory */
-	if (int_thread_hash && (lh_num_items(int_thread_hash) == 0))
+	if (int_thread_hash_references == 1
+		&& int_thread_hash && (lh_num_items(int_thread_hash) == 0))
 		{
 		lh_free(int_thread_hash);
 		int_thread_hash = NULL;
 		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ERR);
 
+	ERRFN(thread_release)(&hash);
 	if (p)
 		ERR_STATE_free(p);
 	}
@@ -855,6 +889,12 @@ LHASH *ERR_get_err_state_table(void)
 	return ERRFN(thread_get)(0);
 	}
 
+void ERR_release_err_state_table(LHASH **hash)
+	{
+	err_fns_check();
+	ERRFN(thread_release)(hash);
+	}
+
 const char *ERR_lib_error_string(unsigned long e)
 	{
 	ERR_STRING_DATA d,*p;

crypto/err/err.h

@@ -293,6 +293,7 @@ ERR_STATE *ERR_get_state(void);
 #ifndef OPENSSL_NO_LHASH
 LHASH *ERR_get_string_table(void);
 LHASH *ERR_get_err_state_table(void);
+void ERR_release_err_state_table(LHASH **hash);
 #endif
 
 int ERR_get_next_error_library(void);