Fix bogus Name assignment in CreateStatistics

Apparently, it doesn't work to use a plain cstring as a Name datum: you
may end up having random bytes because of failing to zero the bytes
after the terminating \0, as indicated by valgrind.  I introduced this
bug in 5564c1181548, so backpatch this fix to REL_10_STABLE, like that
commit.

While at it, fix a slightly misleading comment, pointed out by David
Rowley.

1 files changed, 5 insertions, 2 deletions

diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index 9f963ddee98..1a989050984 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -56,6 +56,7 @@ CreateStatistics(CreateStatsStmt *stmt)
 	int16		attnums[STATS_MAX_DIMENSIONS];
 	int			numcols = 0;
 	char	   *namestr;
+	NameData	stxname;
 	Oid			statoid;
 	Oid			namespaceId;
 	Oid			stxowner = GetUserId();
@@ -134,7 +135,8 @@ CreateStatistics(CreateStatsStmt *stmt)
 	 * object in the same namespace as the relation, and cons up a name for it.
 	 */
 	if (stmt->defnames)
-		namespaceId = QualifiedNameGetCreationNamespace(stmt->defnames, &namestr);
+		namespaceId = QualifiedNameGetCreationNamespace(stmt->defnames,
+														&namestr);
 	else
 	{
 		namespaceId = RelationGetNamespace(rel);
@@ -143,6 +145,7 @@ CreateStatistics(CreateStatsStmt *stmt)
 											  "stat",
 											  namespaceId);
 	}
+	namestrcpy(&stxname, namestr);
 
 	/*
 	 * Deal with the possibility that the statistics object already exists.
@@ -306,7 +309,7 @@ CreateStatistics(CreateStatsStmt *stmt)
 	memset(values, 0, sizeof(values));
 	memset(nulls, false, sizeof(nulls));
 	values[Anum_pg_statistic_ext_stxrelid - 1] = ObjectIdGetDatum(relid);
-	values[Anum_pg_statistic_ext_stxname - 1] = CStringGetDatum(namestr);
+	values[Anum_pg_statistic_ext_stxname - 1] = NameGetDatum(&stxname);
 	values[Anum_pg_statistic_ext_stxnamespace - 1] = ObjectIdGetDatum(namespaceId);
 	values[Anum_pg_statistic_ext_stxowner - 1] = ObjectIdGetDatum(stxowner);
 	values[Anum_pg_statistic_ext_stxkeys - 1] = PointerGetDatum(stxkeys);