Re: BUG #16190: The usage of NULL pointer in refint.c

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On Mon, Jan 06, 2020 at 09:44:43AM -0800, Andres Freund wrote:
> I think we should consider either moving this out of contrib, or fixing
> it up. test/example code is fine, but contrib gets installed by default
> for a lot of people... And yea, this isn't just about contrib/spi.

No idea about moving that out of contrib/, but here is a patch to fix
things that just moves the allocations to TopMemoryContext and removes
the system calls.
--
Michael

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diff --git a/contrib/spi/refint.c b/contrib/spi/refint.c
index adf0490f85..05595c52c3 100644
--- a/contrib/spi/refint.c
+++ b/contrib/spi/refint.c
@@ -12,6 +12,7 @@
 #include "commands/trigger.h"
 #include "executor/spi.h"
 #include "utils/builtins.h"
+#include "utils/memutils.h"
 #include "utils/rel.h"
=20
 PG_MODULE_MAGIC;
@@ -186,12 +187,13 @@ check_primary_key(PG_FUNCTION_ARGS)
=20
 		/*
 		 * Remember that SPI_prepare places plan in current memory context -
-		 * so, we have to save plan in Top memory context for later use.
+		 * so, we have to save plan in TopMemoryContext for later use.
 		 */
 		if (SPI_keepplan(pplan))
 			/* internal error */
 			elog(ERROR, "check_primary_key: SPI_keepplan failed");
-		plan->splan =3D (SPIPlanPtr *) malloc(sizeof(SPIPlanPtr));
+		plan->splan =3D (SPIPlanPtr *) MemoryContextAlloc(TopMemoryContext,
+														sizeof(SPIPlanPtr));
 		*(plan->splan) =3D pplan;
 		plan->nplans =3D 1;
 	}
@@ -417,7 +419,8 @@ check_foreign_key(PG_FUNCTION_ARGS)
 		char		sql[8192];
 		char	  **args2 =3D args;
=20
-		plan->splan =3D (SPIPlanPtr *) malloc(nrefs * sizeof(SPIPlanPtr));
+		plan->splan =3D (SPIPlanPtr *) MemoryContextAlloc(TopMemoryContext,
+														nrefs * sizeof(SPIPlanPtr));
=20
 		for (r =3D 0; r < nrefs; r++)
 		{
@@ -614,6 +617,13 @@ find_plan(char *ident, EPlan **eplan, int *nplans)
 {
 	EPlan	   *newp;
 	int			i;
+	MemoryContext	oldcontext;
+
+	/*
+	 * All allocations done for the plans need to happen in a session-safe
+	 * context.
+	 */
+	oldcontext =3D MemoryContextSwitchTo(TopMemoryContext);
=20
 	if (*nplans > 0)
 	{
@@ -623,20 +633,24 @@ find_plan(char *ident, EPlan **eplan, int *nplans)
 				break;
 		}
 		if (i !=3D *nplans)
+		{
+			MemoryContextSwitchTo(oldcontext);
 			return (*eplan + i);
-		*eplan =3D (EPlan *) realloc(*eplan, (i + 1) * sizeof(EPlan));
+		}
+		*eplan =3D (EPlan *) repalloc(*eplan, (i + 1) * sizeof(EPlan));
 		newp =3D *eplan + i;
 	}
 	else
 	{
-		newp =3D *eplan =3D (EPlan *) malloc(sizeof(EPlan));
+		newp =3D *eplan =3D (EPlan *) palloc(sizeof(EPlan));
 		(*nplans) =3D i =3D 0;
 	}
=20
-	newp->ident =3D strdup(ident);
+	newp->ident =3D pstrdup(ident);
 	newp->nplans =3D 0;
 	newp->splan =3D NULL;
 	(*nplans)++;
=20
+	MemoryContextSwitchTo(oldcontext);
 	return newp;
 }

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