From b116b80b2775b004e35a9e7be0a057ee2724041b Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Thu, 30 Sep 2021 15:47:23 +1300
Subject: [PATCH 1/2] HACK: A function to control the OID allocator.

---
 src/test/modules/chaos/Makefile       | 21 +++++++++++++++++++++
 src/test/modules/chaos/chaos--1.0.sql |  8 ++++++++
 src/test/modules/chaos/chaos.c        | 26 ++++++++++++++++++++++++++
 src/test/modules/chaos/chaos.control  |  4 ++++
 4 files changed, 59 insertions(+)
 create mode 100644 src/test/modules/chaos/Makefile
 create mode 100644 src/test/modules/chaos/chaos--1.0.sql
 create mode 100644 src/test/modules/chaos/chaos.c
 create mode 100644 src/test/modules/chaos/chaos.control

diff --git a/src/test/modules/chaos/Makefile b/src/test/modules/chaos/Makefile
new file mode 100644
index 0000000000..ac69721af6
--- /dev/null
+++ b/src/test/modules/chaos/Makefile
@@ -0,0 +1,21 @@
+# src/test/modules/chaos/Makefile
+
+MODULE_big = chaos
+OBJS = \
+	$(WIN32RES) \
+	chaos.o
+PGFILEDESC = "chaos - module in which to write throwaway fault-injection hacks"
+
+EXTENSION = chaos
+DATA = chaos--1.0.sql
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/chaos
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/chaos/chaos--1.0.sql b/src/test/modules/chaos/chaos--1.0.sql
new file mode 100644
index 0000000000..5016f7e586
--- /dev/null
+++ b/src/test/modules/chaos/chaos--1.0.sql
@@ -0,0 +1,8 @@
+/* src/test/modules/chaos/chaos--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION chaos" to load this file. \quit
+
+CREATE FUNCTION clobber_next_oid(size BIGINT)
+	RETURNS pg_catalog.void STRICT
+	AS 'MODULE_PATHNAME' LANGUAGE C;
diff --git a/src/test/modules/chaos/chaos.c b/src/test/modules/chaos/chaos.c
new file mode 100644
index 0000000000..f1052f865e
--- /dev/null
+++ b/src/test/modules/chaos/chaos.c
@@ -0,0 +1,26 @@
+#include "postgres.h"
+
+#include "access/transam.h"
+#include "fmgr.h"
+#include "storage/lwlock.h"
+
+#include <limits.h>
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(clobber_next_oid);
+
+Datum
+clobber_next_oid(PG_FUNCTION_ARGS)
+{
+	int64		oid = PG_GETARG_INT64(0);
+
+	if (oid < FirstNormalObjectId || oid > UINT_MAX)
+		elog(ERROR, "invalid oid");
+
+	LWLockAcquire(OidGenLock, LW_EXCLUSIVE);
+	ShmemVariableCache->nextOid = oid;
+	LWLockRelease(OidGenLock);
+
+	PG_RETURN_VOID();
+}
diff --git a/src/test/modules/chaos/chaos.control b/src/test/modules/chaos/chaos.control
new file mode 100644
index 0000000000..137ab8a58d
--- /dev/null
+++ b/src/test/modules/chaos/chaos.control
@@ -0,0 +1,4 @@
+comment = 'Test module for throwaway fault-injection hacks...'
+default_version = '1.0'
+module_pathname = '$libdir/chaos'
+relocatable = true
-- 
2.30.2