From: Simon McVittie <smcv@debian.org>
Date: Thu, 14 Sep 2017 11:23:58 +0100
Subject: ctf: Use SOURCE_DATE_EPOCH for reproducible build

Forwarded: https://github.com/yquake2/ctf/pull/3
---
 ctf/Makefile     |  7 +++++++
 ctf/src/g_save.c | 12 ++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/ctf/Makefile b/ctf/Makefile
index 0908881..e2a18d6 100644
--- a/ctf/Makefile
+++ b/ctf/Makefile
@@ -102,6 +102,13 @@ endif
 
 # ----------
 
+# https://reproducible-builds.org/specs/source-date-epoch/
+ifdef SOURCE_DATE_EPOCH
+CFLAGS += -DBUILD_DATE=\"$(shell date --utc --date="@${SOURCE_DATE_EPOCH}" +"%b %_d %Y" | sed -e 's/ /\\ /g')\"
+endif
+
+# ----------
+
 # Builds everything
 all: ctf
 
diff --git a/ctf/src/g_save.c b/ctf/src/g_save.c
index b2f4bd6..893eccc 100644
--- a/ctf/src/g_save.c
+++ b/ctf/src/g_save.c
@@ -28,6 +28,10 @@
 
 #include "header/local.h"
 
+#ifndef BUILD_DATE
+#define BUILD_DATE __DATE__
+#endif
+
 field_t fields[] = {
 	{"classname", FOFS(classname), F_LSTRING},
 	{"origin", FOFS(s.origin), F_VECTOR},
@@ -141,7 +145,7 @@ void
 InitGame(void)
 {
 	gi.dprintf("Game is starting up.\n");
-	gi.dprintf("Game is ctf built on %s.\n", GAMEVERSION, __DATE__);
+	gi.dprintf("Game is ctf built on %s.\n", GAMEVERSION, BUILD_DATE);
 
 	gun_x = gi.cvar("gun_x", "0", 0);
 	gun_y = gi.cvar("gun_y", "0", 0);
@@ -157,7 +161,7 @@ InitGame(void)
 	/* latched vars */
 	sv_cheats = gi.cvar("cheats", "0", CVAR_SERVERINFO | CVAR_LATCH);
 	gi.cvar("gamename", GAMEVERSION, CVAR_SERVERINFO | CVAR_LATCH);
-	gi.cvar("gamedate", __DATE__, CVAR_SERVERINFO | CVAR_LATCH);
+	gi.cvar("gamedate", BUILD_DATE, CVAR_SERVERINFO | CVAR_LATCH);
 	maxclients = gi.cvar("maxclients", "4", CVAR_SERVERINFO | CVAR_LATCH);
 	deathmatch = gi.cvar("deathmatch", "0", CVAR_LATCH);
 	coop = gi.cvar("coop", "0", CVAR_LATCH);
@@ -493,7 +497,7 @@ WriteGame(char *filename, qboolean autosave)
 	}
 
 	memset(str, 0, sizeof(str));
-	strcpy(str, __DATE__);
+	strcpy(str, BUILD_DATE);
 	fwrite(str, sizeof(str), 1, f);
 
 	game.autosaved = autosave;
@@ -526,7 +530,7 @@ ReadGame(char *filename)
 
 	fread(str, sizeof(str), 1, f);
 
-	if (strcmp(str, __DATE__))
+	if (strcmp(str, BUILD_DATE))
 	{
 		fclose(f);
 		gi.error("Savegame from an older version.\n");