From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 8 Aug 2003 19:18:21 +0000 (+0000)
Subject: Fix nasty little order-of-operations bug in _SPI_cursor_operation.
X-Git-Url: http://git.postgresql.org/gitweb/irc:/irc.freenode.net?a=commitdiff_plain;h=ec4fa569dd34948c5625e39bc783b90e2c949a8a;p=users%2Fbernd%2Fpostgres.git

Fix nasty little order-of-operations bug in _SPI_cursor_operation.
Per report from Mendola Gaetano.
---

diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 077e2e8229..7a1696c88e 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -1263,6 +1263,8 @@ static void
 _SPI_cursor_operation(Portal portal, bool forward, int count,
 					  DestReceiver *dest)
 {
+	long	nfetched;
+
 	/* Check that the portal is valid */
 	if (!PortalIsValid(portal))
 		elog(ERROR, "invalid portal in SPI cursor operation");
@@ -1277,11 +1279,20 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
 	_SPI_current->tuptable = NULL;
 
 	/* Run the cursor */
-	_SPI_current->processed =
-		PortalRunFetch(portal,
-					   forward ? FETCH_FORWARD : FETCH_BACKWARD,
-					   (long) count,
-					   dest);
+	nfetched = PortalRunFetch(portal,
+							  forward ? FETCH_FORWARD : FETCH_BACKWARD,
+							  (long) count,
+							  dest);
+
+	/*
+	 * Think not to combine this store with the preceding function call.
+	 * If the portal contains calls to functions that use SPI, then
+	 * SPI_stack is likely to move around while the portal runs.  When
+	 * control returns, _SPI_current will point to the correct stack entry...
+	 * but the pointer may be different than it was beforehand.  So we must
+	 * be sure to re-fetch the pointer after the function call completes.
+	 */
+	_SPI_current->processed = nfetched;
 
 	if (dest->mydest == SPI && _SPI_checktuples())
 		elog(ERROR, "consistency check on SPI tuple count failed");