From 165009cd8d3fee72fcc66ff79a06617e917cf283 Mon Sep 17 00:00:00 2001
From: Jeffrey Townsend <jeffrey.townsend@bigswitch.com>
Date: Mon, 27 May 2019 18:56:46 +0000
Subject: [PATCH] Add an error-checking template for Makefile shell calls onlpm
 --find-file.

Makefiles that call $(shell onlpm --find-file *) have always failed poorly
when the file cannot be found.

The onlp_find_file template can be called to both assign and check the
results. If an error occurred in getting the value then a Makefile error is raised.
---
 make/config.mk    | 2 ++
 make/templates.mk | 6 ++++++
 2 files changed, 8 insertions(+)
 create mode 100644 make/templates.mk

diff --git a/make/config.mk b/make/config.mk
index b7ffb5c0..085c4e06 100644
--- a/make/config.mk
+++ b/make/config.mk
@@ -89,3 +89,5 @@ ONL_MAKE := $(MAKE) $(ONL_MAKE_FLAGS)
 #
 export SUBMODULE_INFRA := $(ONL)/sm/infra
 export SUBMODULE_BIGCODE := $(ONL)/sm/bigcode
+
+include $(ONL)/make/templates.mk
diff --git a/make/templates.mk b/make/templates.mk
new file mode 100644
index 00000000..edcf265a
--- /dev/null
+++ b/make/templates.mk
@@ -0,0 +1,6 @@
+define onlpm_find_file
+$(1) := $$(shell $(ONLPM) --find-file $(2) $(3))
+ifeq ($$($(1)),)
+$$(error $(2):$(3) not found)
+endif
+endef