Avoid useless allocations for information of dumpable objects in pg_dump/

michaelpq · michaelpq · commit ac673a1aaff1 · 2020-09-14T10:44:23.000+09:00
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
@@ -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);
