http: improve error path for bufferevent_{setfd,enable,disable}()

We have calls to the next functions but do not check return values,
though they can be invalid and it is better to show this somehow.

Also do bufferevent_setfd() first and only after it
bufferevent_enable()/bufferevent_disable() since:
a) it is more natural
b) it will avoid extra operations
c) it will not fail first bufferevent_enable() (this is the case for
   buffbufferevent_async at least)

In this case we could add more information for issues like #709

diff --git a/http.c b/http.c
index 27d3bd9e6957cb97091c43a257d561cd679e5308..b49bc04cf0bbf857d8d9a356492766f2cdafcede 100644 (file)
--- a/http.c
+++ b/http.c
@@ -1339,7 +1339,8 @@ evhttp_connection_reset_(struct evhttp_connection *evcon)
                evutil_closesocket(evcon->fd);
                evcon->fd = -1;
        }
-       bufferevent_setfd(evcon->bufev, -1);
+       err = bufferevent_setfd(evcon->bufev, -1);
+       EVUTIL_ASSERT(!err && "setfd");
 
        /* we need to clean up any buffered data */
        tmp = bufferevent_get_output(evcon->bufev);
@@ -1358,7 +1359,6 @@ static void
 evhttp_connection_start_detectclose(struct evhttp_connection *evcon)
 {
        evcon->flags |= EVHTTP_CON_CLOSEDETECT;
-
        bufferevent_enable(evcon->bufev, EV_READ);
 }
 
@@ -1366,7 +1366,6 @@ static void
 evhttp_connection_stop_detectclose(struct evhttp_connection *evcon)
 {
        evcon->flags &= ~EVHTTP_CON_CLOSEDETECT;
-
        bufferevent_disable(evcon->bufev, EV_READ);
 }
 
@@ -2558,9 +2557,11 @@ evhttp_connection_connect_(struct evhttp_connection *evcon)
                        return (-1);
                }
 
-               bufferevent_setfd(evcon->bufev, evcon->fd);
+               if (bufferevent_setfd(evcon->bufev, evcon->fd))
+                       return (-1);
        } else {
-               bufferevent_setfd(evcon->bufev, -1);
+               if (bufferevent_setfd(evcon->bufev, -1))
+                       return (-1);
        }
 
        /* Set up a callback for successful connection setup */
@@ -2576,7 +2577,8 @@ evhttp_connection_connect_(struct evhttp_connection *evcon)
                bufferevent_set_timeouts(evcon->bufev, &evcon->timeout, &evcon->timeout);
        }
        /* make sure that we get a write callback */
-       bufferevent_enable(evcon->bufev, EV_WRITE);
+       if (bufferevent_enable(evcon->bufev, EV_WRITE))
+               return (-1);
 
        evcon->state = EVCON_CONNECTING;
 
@@ -4241,12 +4243,19 @@ evhttp_get_request_connection(
 
        evcon->fd = fd;
 
-       bufferevent_enable(evcon->bufev, EV_READ);
-       bufferevent_disable(evcon->bufev, EV_WRITE);
-       bufferevent_setfd(evcon->bufev, fd);
+       if (bufferevent_setfd(evcon->bufev, fd))
+               goto err;
+       if (bufferevent_enable(evcon->bufev, EV_READ))
+               goto err;
+       if (bufferevent_disable(evcon->bufev, EV_WRITE))
+               goto err;
        bufferevent_socket_set_conn_address_(evcon->bufev, sa, salen);
 
        return (evcon);
+
+err:
+       evhttp_connection_free(evcon);
+       return (NULL);
 }
 
 static int