1100-Define-build-dates-time-based-on-SOURCE_DATE_EPOCH.patch

From a2855b81da57771863829568d535de53ba572d7b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Pierret=20=28fepitre=29?=
 <frederic.pierret@qubes-os.org>
Date: Sat, 31 Oct 2020 14:57:49 +0100
Subject: [PATCH] Define build dates/time based on SOURCE_DATE_EPOCH

Varibles impacting reproducibility are now defined with respect
to SOURCE_DATE_EPOCH.

Improvements from Jan Beuluch <jbeulich@suse.com>.
---
 Config.mk                         | 2 ++
 INSTALL                           | 6 ++++++
 tools/firmware/hvmloader/Makefile | 2 +-
 tools/firmware/vgabios/Makefile   | 3 ++-
 xen/Makefile                      | 4 ++--
 5 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/Config.mk b/Config.mk
index e7aa8ceaaf3b..729ed9e8434e 100644
--- a/Config.mk
+++ b/Config.mk
@@ -249,3 +249,5 @@ QEMU_UPSTREAM_LOC ?= $(call or,$(wildcard $(QEMU_UPSTREAM_INTREE)),\
                                $(QEMU_UPSTREAM_URL))
 
 CONFIG_TESTS       ?= y
+
+DATE_EPOCH_OPTS := $(if $(SOURCE_DATE_EPOCH),-u -d "@$(SOURCE_DATE_EPOCH)")
\ No newline at end of file
diff --git a/INSTALL b/INSTALL
index 88c1464816bd..22fce650f9a0 100644
--- a/INSTALL
+++ b/INSTALL
@@ -235,6 +235,12 @@ XEN_BUILD_TIME=hh:mm:ss
 SMBIOS_REL_DATE=mm/dd/yyyy
 VGABIOS_REL_DATE="dd Mon yyyy"
 
+It is sufficient to define only SOURCE_DATE_EPOCH instead of the above
+variables for having reproducible builds. By default, they use
+SOURCE_DATE_EPOCH if defined. For specifications of SOURCE_DATE_EPOCH,
+we refer to https://reproducible-builds.org/docs/source-date-epoch.
+SOURCE_DATE_EPOCH=
+
 This variable can be used to point to a different git binary to be used.
 GIT=
 
diff --git a/tools/firmware/hvmloader/Makefile b/tools/firmware/hvmloader/Makefile
index 84cba171cd6b..d94df1cd88b6 100644
--- a/tools/firmware/hvmloader/Makefile
+++ b/tools/firmware/hvmloader/Makefile
@@ -23,7 +23,7 @@ include $(XEN_ROOT)/tools/firmware/Rules.mk
 ld-option = $(shell if $(LD) -v $(1) >/dev/null 2>&1; then echo y; else echo n; fi)
 
 # SMBIOS spec requires format mm/dd/yyyy
-SMBIOS_REL_DATE ?= $(shell date +%m/%d/%Y)
+SMBIOS_REL_DATE ?= $(shell date $(DATE_EPOCH_OPTS) +%m/%d/%Y)
 
 CFLAGS += $(CFLAGS_xeninclude) -fno-pic
 
diff --git a/tools/firmware/vgabios/Makefile b/tools/firmware/vgabios/Makefile
index 3284812fdec8..4350ef402127 100644
--- a/tools/firmware/vgabios/Makefile
+++ b/tools/firmware/vgabios/Makefile
@@ -5,7 +5,8 @@ BCC = bcc
 AS86 = as86
 
 RELEASE = `pwd | sed "s-.*/--"`
-VGABIOS_REL_DATE ?= `date '+%d %b %Y'`
+VGABIOS_REL_DATE ?= $(shell date $(DATE_EPOCH_OPTS) +%d %b %Y)
+
 RELVERS = `pwd | sed "s-.*/--" | sed "s/vgabios//" | sed "s/-//"`
 
 VGABIOS_DATE = "-DVGABIOS_DATE=\"$(VGABIOS_REL_DATE)\""
diff --git a/xen/Makefile b/xen/Makefile
index e9fd19536f2c..02e947da95a0 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -15,10 +15,10 @@ ifeq ($(origin XEN_DOMAIN), undefined)
 export XEN_DOMAIN	:= $(shell ([ -x /bin/dnsdomainname ] && /bin/dnsdomainname) || ([ -x /bin/domainname ] && /bin/domainname || echo [unknown]))
 endif
 ifeq ($(origin XEN_BUILD_DATE), undefined)
-export XEN_BUILD_DATE	:= $(shell LC_ALL=C date)
+export XEN_BUILD_DATE	:= $(shell LC_ALL=C date $(DATE_EPOCH_OPTS))
 endif
 ifeq ($(origin XEN_BUILD_TIME), undefined)
-export XEN_BUILD_TIME	:= $(shell LC_ALL=C date +%T)
+export XEN_BUILD_TIME	:= $(shell LC_ALL=C date $(DATE_EPOCH_OPTS) +%T)
 endif
 ifeq ($(origin XEN_BUILD_HOST), undefined)
 export XEN_BUILD_HOST	:= $(shell hostname)
-- 
2.44.0