Don't let libpq PGEVT_CONNRESET callbacks break a PGconn.

tglsfdc · tglsfdc · commit 2e372869aa38 · 2022-02-18T11:43:04.000-05:00
As currently implemented, failure of a PGEVT_CONNRESET callback forces the PGconn into the CONNECTION_BAD state (without closing the socket, which is inconsistent with other failure paths), and prevents later callbacks from being called. This seems highly questionable, and indeed is questioned by comments in the source. Instead, let's just ignore the result value of PGEVT_CONNRESET calls. Like the preceding commit, this converts event callbacks into "pure observers" that cannot affect libpq's processing logic. Discussion: https://postgr.es/m/3185105.1644960083@sss.pgh.pa.us
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
@@ -7183,12 +7183,11 @@ typedef struct
       <para>
        The connection reset event is fired on completion of
        <xref linkend="libpq-PQreset"/> or <function>PQresetPoll</function>.  In
-       both cases, the event is only fired if the reset was successful.  If
-       the event procedure fails, the entire connection reset will fail; the
-       <structname>PGconn</structname> is put into
-       <literal>CONNECTION_BAD</literal> status and
-       <function>PQresetPoll</function> will return
-       <literal>PGRES_POLLING_FAILED</literal>.
+       both cases, the event is only fired if the reset was successful.
+       The return value of the event procedure is ignored
+       in <productname>PostgreSQL</productname> v15 and later.
+       With earlier versions, however, it's important to return success
+       (nonzero) or the connection will be aborted.
 
 <synopsis>
 typedef struct
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
@@ -4276,8 +4276,7 @@ PQreset(PGconn *conn)
 		if (connectDBStart(conn) && connectDBComplete(conn))
 		{
 			/*
-			 * Notify event procs of successful reset.  We treat an event proc
-			 * failure as disabling the connection ... good idea?
+			 * Notify event procs of successful reset.
 			 */
 			int			i;
 
@@ -4286,15 +4285,8 @@ PQreset(PGconn *conn)
 				PGEventConnReset evt;
 
 				evt.conn = conn;
-				if (!conn->events[i].proc(PGEVT_CONNRESET, &evt,
-										  conn->events[i].passThrough))
-				{
-					conn->status = CONNECTION_BAD;
-					appendPQExpBuffer(&conn->errorMessage,
-									  libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"),
-									  conn->events[i].name);
-					break;
-				}
+				(void) conn->events[i].proc(PGEVT_CONNRESET, &evt,
+											conn->events[i].passThrough);
 			}
 		}
 	}
@@ -4336,8 +4328,7 @@ PQresetPoll(PGconn *conn)
 		if (status == PGRES_POLLING_OK)
 		{
 			/*
-			 * Notify event procs of successful reset.  We treat an event proc
-			 * failure as disabling the connection ... good idea?
+			 * Notify event procs of successful reset.
 			 */
 			int			i;
 
@@ -4346,15 +4337,8 @@ PQresetPoll(PGconn *conn)
 				PGEventConnReset evt;
 
 				evt.conn = conn;
-				if (!conn->events[i].proc(PGEVT_CONNRESET, &evt,
-										  conn->events[i].passThrough))
-				{
-					conn->status = CONNECTION_BAD;
-					appendPQExpBuffer(&conn->errorMessage,
-									  libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"),
-									  conn->events[i].name);
-					return PGRES_POLLING_FAILED;
-				}
+				(void) conn->events[i].proc(PGEVT_CONNRESET, &evt,
+											conn->events[i].passThrough);
 			}
 		}
 
