Merge branch 'restart_nocrash'

changes/bug24581

@@ -0,0 +1,7 @@
+  o Major features (embedding):
+    - Tor now has support for restarting in the same process.
+      Controllers that run Tor using the "tor_api.h" interface can now
+      restart Tor after Tor has exited. This support is incomplete, however:
+      we have fixed the crash bugs that prevented it from working at all
+      before, but many bugs probably remain. Implements ticket 24581.
+

src/common/compat_libevent.c

@@ -237,6 +237,16 @@ tor_init_libevent_rng(void)
   return rv;
 }
 
+/**
+ * Un-initialize libevent in preparation for an exit
+ */
+void
+tor_libevent_free_all(void)
+{
+  event_base_free(the_event_base);
+  the_event_base = NULL;
+}
+
 #if defined(LIBEVENT_VERSION_NUMBER) &&         \
   LIBEVENT_VERSION_NUMBER >= V(2,1,1) &&        \
   !defined(TOR_UNIT_TESTS)

src/common/compat_libevent.h

@@ -52,6 +52,7 @@ const char *tor_libevent_get_method(void);
 void tor_check_libevent_header_compatibility(void);
 const char *tor_libevent_get_version_str(void);
 const char *tor_libevent_get_header_version_str(void);
+void tor_libevent_free_all(void);
 
 int tor_init_libevent_rng(void);
 

src/common/crypto.c

@@ -3470,6 +3470,8 @@ crypto_global_cleanup(void)
   if (dh_param_g)
     BN_clear_free(dh_param_g);
 
+  dh_param_p = dh_param_p_tls = dh_param_g = NULL;
+
 #ifndef DISABLE_ENGINES
   ENGINE_cleanup();
 #endif

src/or/config.c

@@ -805,6 +805,8 @@ static smartlist_t *configured_ports = NULL;
 /** True iff we're currently validating options, and any calls to
  * get_options() are likely to be bugs. */
 static int in_option_validation = 0;
+/* True iff we've initialized libevent */
+static int libevent_initialized = 0;
 
 /** Return the contents of our frontpage string, or NULL if not configured. */
 MOCK_IMPL(const char*,
@@ -995,6 +997,7 @@ config_free_all(void)
   tor_free(the_tor_version);
 
   have_parsed_cmdline = 0;
+  libevent_initialized = 0;
 }
 
 /** Make <b>address</b> -- a piece of information related to our operation as
@@ -1345,7 +1348,6 @@ options_act_reversible(const or_options_t *old_options, char **msg)
 {
   smartlist_t *new_listeners = smartlist_new();
   smartlist_t *replaced_listeners = smartlist_new();
-  static int libevent_initialized = 0;
   or_options_t *options = get_options_mutable();
   int running_tor = options->command == CMD_RUN_TOR;
   int set_conn_limit = 0;

src/or/main.c

@@ -3478,6 +3478,7 @@ tor_free_all(int postfork)
   if (!postfork) {
     release_lockfile();
   }
+  tor_libevent_free_all();
   /* Stuff in util.c and address.c*/
   if (!postfork) {
     escaped(NULL);

src/or/tor_api.h

@@ -71,8 +71,9 @@ void tor_main_configuration_free(tor_main_configuration_t *cfg);
  * fix it.
  *
  * BUG 23847: You can only call tor_main() once in a single process; if it
- * returns and you call it again, you may crash. This is not intended
- * long-term behavior; we are trying to fix it.
+ * returns and you call it again, you may crash, or you may encounter other
+ * unexpected behavior.  This is not intended long-term behavior; we are
+ * trying to fix it.
  *
  * LIMITATION: You cannot run more than one instance of Tor in the same
  * process at the same time. Concurrent calls will cause undefined behavior.