Merge remote-tracking branch 'origin/maint-0.2.6' into release-0.2.6

changes/ticket15176

@@ -0,0 +1,3 @@
+  o Code simplification and refactoring:
+    - Refactor main loop to extract the 'loop' part.  This makes it easier
+      to run Tor under Shadow. Closes ticket 15176.

src/or/main.c

@@ -97,6 +97,7 @@ static void second_elapsed_callback(periodic_timer_t *timer, void *args);
 static int conn_close_if_marked(int i);
 static void connection_start_reading_from_linked_conn(connection_t *conn);
 static int connection_should_read_from_linked_conn(connection_t *conn);
+static int run_main_loop_until_done(void);
 
 /********* START VARIABLES **********/
 
@@ -1955,7 +1956,6 @@ do_hup(void)
 int
 do_main_loop(void)
 {
-  int loop_result;
   time_t now;
 
   /* initialize dns resolve map, spawn workers if needed */
@@ -2084,7 +2084,18 @@ do_main_loop(void)
   }
 #endif
 
-  for (;;) {
+  return run_main_loop_until_done();
+}
+
+/**
+ * Run the main loop a single time. Return 0 for "exit"; -1 for "exit with
+ * error", and 1 for "run this again."
+ */
+static int
+run_main_loop_once(void)
+{
+  int loop_result;
+
   if (nt_service_is_stopping())
     return 0;
 
@@ -2125,10 +2136,26 @@ do_main_loop(void)
       log_debug(LD_NET,"libevent call interrupted.");
       /* You can't trust the results of this poll(). Go back to the
        * top of the big for loop. */
-        continue;
-      }
+      return 1;
     }
   }
+
+  return 1;
+}
+
+/** Run the run_main_loop_once() function until it declares itself done,
+ * and return its final return value.
+ *
+ * Shadow won't invoke this function, so don't fill it up with things.
+ */
+static int
+run_main_loop_until_done(void)
+{
+  int loop_result = 1;
+  do {
+    loop_result = run_main_loop_once();
+  } while (loop_result == 1);
+  return loop_result;
 }
 
 #ifndef _WIN32 /* Only called when we're willing to use signals */