From 4ee8cf5610bdf81cf88b078a7046832ea7371823 Mon Sep 17 00:00:00 2001
From: Peter Jones <pjones@redhat.com>
Date: Fri, 25 Oct 2019 15:39:35 -0400
Subject: Make: make "make DESTDIR=../foo install" work right.

This makes the normal DESTDIR= variable work on the command line, and
makes relative paths always relative to the top-level directory.

Signed-off-by: Peter Jones <pjones@redhat.com>
---
 Make.defaults | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/Make.defaults b/Make.defaults
index d663397..516caad 100755
--- a/Make.defaults
+++ b/Make.defaults
@@ -45,7 +45,19 @@ TOPDIR := $(shell if [ "$$PWD" != "" ]; then echo $$PWD; else pwd; fi)
 # Where to install the package. GNU-EFI will create and access
 # lib and include under the root
 #
-INSTALLROOT  := /
+DESTDIR ?= /
+ifeq ($(origin INSTALLROOT),undefined)
+INSTALLROOT = $(DESTDIR)
+endif
+
+empty :=
+space := $(empty) $(empty)
+stripped = $(subst $(space),/,$(strip $(subst /,$(space),$(1))))
+unstripped = $(subst $(space),/,$(subst /,$(space),$(1)))
+is_absolute = $(subst $(call stripped,$(1)),$(empty),$(call unstripped,$(1)))
+
+override INSTALLROOT:=$(if $(call is_absolute,$(INSTALLROOT)),,$(TOPDIR)/)$(INSTALLROOT)
+
 PREFIX       := /usr/local
 LIBDIR 	     := $(PREFIX)/lib
 INSTALL	     := install
-- 
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