Don't use static storage for SaveTransactionCharacteristics().

This is pretty queasy-making on general principles, and the more so
once you notice that CommitTransactionCommand() is actually stomping
on the values saved by _SPI_commit().  It's okay as long as the
active values didn't change during HoldPinnedPortals(); but that's
a larger assumption than I think we want to make, especially since
the fix is so simple.

Discussion: https://postgr.es/m/1533956.1645731245@sss.pgh.pa.us

1 files changed, 14 insertions, 18 deletions

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index bb1f1069463..adf763a8ea4 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2983,24 +2983,20 @@ StartTransactionCommand(void)
  * GUC system resets the characteristics at transaction end, so for example
  * just skipping the reset in StartTransaction() won't work.)
  */
-static int	save_XactIsoLevel;
-static bool save_XactReadOnly;
-static bool save_XactDeferrable;
-
 void
-SaveTransactionCharacteristics(void)
+SaveTransactionCharacteristics(SavedTransactionCharacteristics *s)
 {
-	save_XactIsoLevel = XactIsoLevel;
-	save_XactReadOnly = XactReadOnly;
-	save_XactDeferrable = XactDeferrable;
+	s->save_XactIsoLevel = XactIsoLevel;
+	s->save_XactReadOnly = XactReadOnly;
+	s->save_XactDeferrable = XactDeferrable;
 }
 
 void
-RestoreTransactionCharacteristics(void)
+RestoreTransactionCharacteristics(const SavedTransactionCharacteristics *s)
 {
-	XactIsoLevel = save_XactIsoLevel;
-	XactReadOnly = save_XactReadOnly;
-	XactDeferrable = save_XactDeferrable;
+	XactIsoLevel = s->save_XactIsoLevel;
+	XactReadOnly = s->save_XactReadOnly;
+	XactDeferrable = s->save_XactDeferrable;
 }
 
 
@@ -3011,9 +3007,9 @@ void
 CommitTransactionCommand(void)
 {
 	TransactionState s = CurrentTransactionState;
+	SavedTransactionCharacteristics savetc;
 
-	if (s->chain)
-		SaveTransactionCharacteristics();
+	SaveTransactionCharacteristics(&savetc);
 
 	switch (s->blockState)
 	{
@@ -3071,7 +3067,7 @@ CommitTransactionCommand(void)
 				StartTransaction();
 				s->blockState = TBLOCK_INPROGRESS;
 				s->chain = false;
-				RestoreTransactionCharacteristics();
+				RestoreTransactionCharacteristics(&savetc);
 			}
 			break;
 
@@ -3097,7 +3093,7 @@ CommitTransactionCommand(void)
 				StartTransaction();
 				s->blockState = TBLOCK_INPROGRESS;
 				s->chain = false;
-				RestoreTransactionCharacteristics();
+				RestoreTransactionCharacteristics(&savetc);
 			}
 			break;
 
@@ -3115,7 +3111,7 @@ CommitTransactionCommand(void)
 				StartTransaction();
 				s->blockState = TBLOCK_INPROGRESS;
 				s->chain = false;
-				RestoreTransactionCharacteristics();
+				RestoreTransactionCharacteristics(&savetc);
 			}
 			break;
 
@@ -3182,7 +3178,7 @@ CommitTransactionCommand(void)
 					StartTransaction();
 					s->blockState = TBLOCK_INPROGRESS;
 					s->chain = false;
-					RestoreTransactionCharacteristics();
+					RestoreTransactionCharacteristics(&savetc);
 				}
 			}
 			else if (s->blockState == TBLOCK_PREPARE)