When closure of the backend connection is detected during pqFlush,

do the right thing: look for a NOTICE message from the backend before we
close our side of the socket.  6.4 libpq did not reliably print the backend's
hara-kiri message, 'The Postmaster has informed me ...', because it only
did the right thing if connection closure was detected during a read
attempt instead of a write attempt.

Author: tglsfdc

src/interfaces/libpq/fe-exec.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.80 1999/05/25 16:15:12 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.81 1999/05/28 01:54:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -47,6 +47,7 @@ const char *const pgresStatus[] = {
 
 static int	addTuple(PGresult *res, PGresAttValue *tup);
 static void parseInput(PGconn *conn);
+static void handleSendFailure(PGconn *conn);
 static int	getRowDescriptions(PGconn *conn);
 static int	getAnotherTuple(PGconn *conn, int binary);
 static int	getNotify(PGconn *conn);
@@ -433,18 +434,53 @@ PQsendQuery(PGconn *conn, const char *query)
 
 	/* send the query to the backend; */
 	/* the frontend-backend protocol uses 'Q' to designate queries */
-	if (pqPutnchar("Q", 1, conn))
-		return 0;
-	if (pqPuts(query, conn))
-		return 0;
-	if (pqFlush(conn))
+	if (pqPutnchar("Q", 1, conn) ||
+		pqPuts(query, conn) ||
+		pqFlush(conn))
+	{
+		handleSendFailure(conn);
 		return 0;
+	}
 
 	/* OK, it's launched! */
 	conn->asyncStatus = PGASYNC_BUSY;
 	return 1;
 }
 
+/*
+ * handleSendFailure: try to clean up after failure to send command.
+ *
+ * Primarily, what we want to accomplish here is to process an async
+ * NOTICE message that the backend might have sent just before it died.
+ *
+ * NOTE: this routine should only be called in PGASYNC_IDLE state.
+ */
+
+static void
+handleSendFailure(PGconn *conn)
+{
+	/* Preserve the error message emitted by the failing output routine */
+	char * svErrMsg = strdup(conn->errorMessage);
+
+	/*
+	 * Accept any available input data, ignoring errors.  Note that if
+	 * pqReadData decides the backend has closed the channel, it will
+	 * close our side of the socket --- that's just what we want here.
+	 */
+	while (pqReadData(conn) > 0)
+		/* loop until no more data readable */ ;
+
+	/*
+	 * Parse any available input messages.  Since we are in PGASYNC_IDLE
+	 * state, only NOTICE and NOTIFY messages will be eaten.
+	 */
+	parseInput(conn);
+
+	/* Restore error message generated by output routine, if any. */
+	if (*svErrMsg != '\0')
+		strcpy(conn->errorMessage, svErrMsg);
+	free(svErrMsg);
+}
 
 /*
  * Consume any available input from the backend
@@ -1399,31 +1435,44 @@ PQfn(PGconn *conn,
 	/* clear the error string */
 	conn->errorMessage[0] = '\0';
 
-	if (pqPuts("F ", conn))		/* function */
-		return NULL;
-	if (pqPutInt(fnid, 4, conn))/* function id */
-		return NULL;
-	if (pqPutInt(nargs, 4, conn))		/* # of args */
+	if (pqPuts("F ", conn) ||			/* function */
+		pqPutInt(fnid, 4, conn) ||		/* function id */
+		pqPutInt(nargs, 4, conn))		/* # of args */
+	{
+		handleSendFailure(conn);
 		return NULL;
+	}
 
 	for (i = 0; i < nargs; ++i)
 	{							/* len.int4 + contents	   */
 		if (pqPutInt(args[i].len, 4, conn))
+		{
+			handleSendFailure(conn);
 			return NULL;
+		}
 
 		if (args[i].isint)
 		{
 			if (pqPutInt(args[i].u.integer, 4, conn))
+			{
+				handleSendFailure(conn);
 				return NULL;
+			}
 		}
 		else
 		{
 			if (pqPutnchar((char *) args[i].u.ptr, args[i].len, conn))
+			{
+				handleSendFailure(conn);
 				return NULL;
+			}
 		}
 	}
 	if (pqFlush(conn))
+	{
+		handleSendFailure(conn);
 		return NULL;
+	}
 
 	for (;;)
 	{

src/interfaces/libpq/fe-misc.c

@@ -24,7 +24,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-misc.c,v 1.24 1999/05/25 16:15:13 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-misc.c,v 1.25 1999/05/28 01:54:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -471,7 +471,6 @@ pqFlush(PGconn *conn)
 		/* Prevent being SIGPIPEd if backend has closed the connection. */
 #ifndef WIN32
 		pqsigfunc	oldsighandler = pqsignal(SIGPIPE, SIG_IGN);
-
 #endif
 
 		int			sent = send(conn->sock, ptr, len, 0);
@@ -498,6 +497,7 @@ pqFlush(PGconn *conn)
 				case EWOULDBLOCK:
 					break;
 #endif
+
 				case EPIPE:
 #ifdef ECONNRESET
 				case ECONNRESET:
@@ -506,14 +506,15 @@ pqFlush(PGconn *conn)
 							"pqFlush() -- backend closed the channel unexpectedly.\n"
 							"\tThis probably means the backend terminated abnormally"
 							" before or while processing the request.\n");
-					conn->status = CONNECTION_BAD;		/* No more connection */
-#ifdef WIN32
-					closesocket(conn->sock);
-#else
-					close(conn->sock);
-#endif
-					conn->sock = -1;
+					/*
+					 * We used to close the socket here, but that's a bad
+					 * idea since there might be unread data waiting
+					 * (typically, a NOTICE message from the backend telling
+					 * us it's committing hara-kiri...).  Leave the socket
+					 * open until pqReadData finds no more data can be read.
+					 */
 					return EOF;
+
 				default:
 					sprintf(conn->errorMessage,
 					  "pqFlush() --  couldn't send data: errno=%d\n%s\n",