From e06d2a8dc1e60c177b67b71e87a5423a5ae1af60 Mon Sep 17 00:00:00 2001
From: Masahiko Sawada <sawada.mshk@gmail.com>
Date: Fri, 28 Jun 2019 17:46:53 +0900
Subject: [PATCH 4/9] Add facility to give process-local encryption key.

---
 src/backend/storage/kmgr/Makefile  |  2 +-
 src/backend/storage/kmgr/tempkey.c | 39 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 src/backend/storage/kmgr/tempkey.c

diff --git a/src/backend/storage/kmgr/Makefile b/src/backend/storage/kmgr/Makefile
index e695dcf..60073d2 100644
--- a/src/backend/storage/kmgr/Makefile
+++ b/src/backend/storage/kmgr/Makefile
@@ -12,6 +12,6 @@ subdir = src/backend/storage/kmgr
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global

-OBJS = kmgr.o plugin.o
+OBJS = kmgr.o tempkey.o plugin.o

 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/storage/kmgr/tempkey.c b/src/backend/storage/kmgr/tempkey.c
new file mode 100644
index 0000000..5df283c
--- /dev/null
+++ b/src/backend/storage/kmgr/tempkey.c
@@ -0,0 +1,39 @@
+/*-------------------------------------------------------------------------
+ *
+ * tempkey.c
+ *	 Provide backend-local temporary key
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/storage/kmgr/tempkey.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "storage/kmgr.h"
+
+static bool tempkey_initialized = false;
+static char tempkey[ENCRYPTION_KEY_SIZE];
+
+char *
+GetBackendKey(void)
+{
+	if (!tempkey_initialized)
+	{
+		char keybuf[ENCRYPTION_KEY_SIZE];
+		int ret;
+
+		ret = pg_strong_random(keybuf, ENCRYPTION_KEY_SIZE);
+		if (!ret)
+			ereport(ERROR,
+					(errmsg("failed to generate temporary key")));
+
+		memcpy(tempkey, keybuf, ENCRYPTION_KEY_SIZE);
+		tempkey_initialized = true;
+	}
+
+	return tempkey;
+}
-- 
1.8.3.1