From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 14 Sep 2020 01:44:23 +0000 (+0900)
Subject: Avoid useless allocations for information of dumpable objects in pg_dump/
X-Git-Tag: REL_14_BETA1~1661
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ac673a1aaff197f3e01f7bac69da0dd700854e13;p=thirdparty%2Fpostgresql.git

Avoid useless allocations for information of dumpable objects in pg_dump/

If there are no objects of a certain type, there is no need to do an
allocation for a set of DumpableObject items.  The previous coding did
an allocation of 1 byte instead as per the fallback of pg_malloc() in
the event of an allocation size of zero.  This assigns NULL instead for
a set of dumpable objects.

A similar rule already applied to findObjectByOid(), so this makes the
code more defensive as we would just fail with a pointer dereference
instead of attempting to use some incorrect data if a non-existing,
positive, OID is given by a caller of this function.

Author: Daniel Gustafsson
Reviewed-by: Julien Rouhaud, Ranier Vilela
Discussion: https://postgr.es/m/26C43E58-BDD0-4F1A-97CC-4A07B52E32C5@yesql.se
---

diff --git a/src/bin/pg_dump/common.c b/src/bin/pg_dump/common.c
index 08239dde4f9..634ca86cfb7 100644
--- a/src/bin/pg_dump/common.c
+++ b/src/bin/pg_dump/common.c
@@ -719,6 +719,9 @@ buildIndexArray(void *objArray, int numObjs, Size objSize)
 	DumpableObject **ptrs;
 	int			i;
 
+	if (numObjs <= 0)
+		return NULL;
+
 	ptrs = (DumpableObject **) pg_malloc(numObjs * sizeof(DumpableObject *));
 	for (i = 0; i < numObjs; i++)
 		ptrs[i] = (DumpableObject *) ((char *) objArray + i * objSize);