From ea6cc29e83e6773cc9f5e00fd5b57be86d900e3f Mon Sep 17 00:00:00 2001
From: Chris Lamb <lamby@debian.org>
Date: Mon, 2 Oct 2023 09:43:15 -0400
Subject: [PATCH] MT#55283 make the build reproducible

Whilst working on the Reproducible Builds effort [0], we noticed that
rtpengine could not be built reproducibly.

This is because the manpages generated by pandoc contained the current
build date.

An (upstreamable) patch is attached that uses the value from the
SOURCE_DATE_EPOCH environment variable if available.

 [0] https://reproducible-builds.org/

Change-Id: I2eb22dc5f57af69d217fb06c1c126e7e40dbd451
---
 lib/common.Makefile | 2 +-
 lib/lib.Makefile    | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/common.Makefile b/lib/common.Makefile
index c6f7b427e..b62530dae 100644
--- a/lib/common.Makefile
+++ b/lib/common.Makefile
@@ -38,7 +38,7 @@ $(DAEMONSRCS) $(HASHSRCS):	$(patsubst %,../daemon/%,$(DAEMONSRCS)) $(patsubst %,
 	cat "$<" | sed '/^# /d; s/^##/#/' | \
 		pandoc -s -t man \
 			-M "footer:$(RTPENGINE_VERSION)" \
-			-M "date:$(shell date -I)" \
+			-M "date:$(BUILD_DATE)" \
 			-o "$@"
 
 resample.c codeclib.strhash.c mix.c packet.c:	fix_frame_channel_layout.h
diff --git a/lib/lib.Makefile b/lib/lib.Makefile
index bd90aa5d8..f323ec245 100644
--- a/lib/lib.Makefile
+++ b/lib/lib.Makefile
@@ -64,3 +64,11 @@ ifneq ($(DBG),yes)
     endif
   endif
 endif
+
+
+DATE_FMT = +%Y-%m-%d
+ifdef SOURCE_DATE_EPOCH
+    BUILD_DATE ?= $(shell date -u -d "@$(SOURCE_DATE_EPOCH)" "$(DATE_FMT)" 2>/dev/null || date -u -r "$(SOURCE_DATE_EPOCH)" "$(DATE_FMT)" 2>/dev/null || date -u "$(DATE_FMT)")
+else
+    BUILD_DATE ?= $(shell date "$(DATE_FMT)")
+endif