main/busybox: show reproducible timestamp

This backports a patch which uses a reproducible timestamp in the
version/help/login message. It's based on SOURCE_DATE_EPOCH.

The added patch is already part of upstream.

Signed-off-by: Paul Spooren <mail@aparcar.org>

2 files changed, 83 insertions, 4 deletions

diff --git a/main/busybox/0013-use-SOURCE_DATE_EPOCH-for-timestamp-if-available.patch b/main/busybox/0013-use-SOURCE_DATE_EPOCH-for-timestamp-if-available.patch
new file mode 100644
index 00000000000..af473622ed2
--- /dev/null
+++ b/main/busybox/0013-use-SOURCE_DATE_EPOCH-for-timestamp-if-available.patch
@@ -0,0 +1,80 @@
+From 59f773ee81a8945321f4aa20abc5e9577e6483e4 Mon Sep 17 00:00:00 2001
+From: Paul Spooren <mail@aparcar.org>
+Date: Thu, 13 May 2021 11:25:34 +0200
+Subject: [PATCH] use SOURCE_DATE_EPOCH for timestamp if available
+
+The SOURCE_DATE_EPOCH is an effort of the Reproducible Builds
+organization to make timestamps/build dates in compiled tools
+deterministic over several repetitive builds.
+
+Busybox shows by default the build date timestamp which changes whenever
+compiled. To have a reasonable accurate build date while staying
+reproducible, it's possible to use the *date of last source
+modification* rather than the current time and date.
+
+Further information on SOURCE_DATE_EPOCH are available online [1].
+
+This patch modifies `confdata.c` so that the content of the
+SOURCE_DATE_EPOCH env variable is used as timestamp.
+
+To be independent of different timezones between builds, whenever
+SOURCE_DATE_EPOCH is defined the GMT time is used.
+
+[1]: https://reproducible-builds.org/docs/source-date-epoch/
+
+Signed-off-by: Paul Spooren <mail@aparcar.org>
+---
+ scripts/kconfig/confdata.c | 17 ++++++++++++++---
+ 1 file changed, 14 insertions(+), 3 deletions(-)
+
+diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
+index b05b96e45..73c25e3a8 100644
+--- a/scripts/kconfig/confdata.c
++++ b/scripts/kconfig/confdata.c
+@@ -342,6 +342,8 @@ int conf_write(const char *name)
+ 	time_t now;
+ 	int use_timestamp = 1;
+ 	char *env;
++	char *source_date_epoch;
++	struct tm *build_time;
+ 
+ 	dirname[0] = 0;
+ 	if (name && name[0]) {
+@@ -378,7 +380,16 @@ int conf_write(const char *name)
+ 	}
+ 	sym = sym_lookup("KERNELVERSION", 0);
+ 	sym_calc_value(sym);
+-	time(&now);
++
++	source_date_epoch = getenv("SOURCE_DATE_EPOCH");
++	if (source_date_epoch && *source_date_epoch) {
++		now = strtoull(source_date_epoch, NULL, 10);
++		build_time = gmtime(&now);
++	} else {
++		time(&now);
++		build_time = localtime(&now);
++	}
++
+ 	env = getenv("KCONFIG_NOTIMESTAMP");
+ 	if (env && *env)
+ 		use_timestamp = 0;
+@@ -398,14 +409,14 @@ int conf_write(const char *name)
+ 		if (use_timestamp) {
+ 			size_t ret = \
+ 				strftime(buf, sizeof(buf), "#define AUTOCONF_TIMESTAMP "
+-					"\"%Y-%m-%d %H:%M:%S %Z\"\n", localtime(&now));
++					"\"%Y-%m-%d %H:%M:%S %Z\"\n", build_time);
+ 			/* if user has Factory timezone or some other odd install, the
+ 			 * %Z above will overflow the string leaving us with undefined
+ 			 * results ... so let's try again without the timezone.
+ 			 */
+ 			if (ret == 0)
+ 				strftime(buf, sizeof(buf), "#define AUTOCONF_TIMESTAMP "
+-					"\"%Y-%m-%d %H:%M:%S\"\n", localtime(&now));
++					"\"%Y-%m-%d %H:%M:%S\"\n", build_time);
+ 		} else { /* bbox */
+ 			strcpy(buf, "#define AUTOCONF_TIMESTAMP \"\"\n");
+ 		}
+-- 
+2.30.2
+
diff --git a/main/busybox/APKBUILD b/main/busybox/APKBUILD
index ecf9a3ce1e5..c9026f95585 100644
--- a/main/busybox/APKBUILD
+++ b/main/busybox/APKBUILD
@@ -4,7 +4,7 @@
 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=busybox
 pkgver=1.33.1
-pkgrel=4
+pkgrel=5
 pkgdesc="Size optimized toolbox of many common UNIX utilities"
 url="https://busybox.net/"
 arch="all"
@@ -35,6 +35,7 @@ source="https://busybox.net/downloads/busybox-$pkgver.tar.bz2
 	0009-depmod-support-generating-kmod-binary-index-files.patch
 	0010-Add-flag-for-not-following-symlinks-when-recursing.patch
 	0012-udhcpc-Don-t-background-if-n-is-given.patch
+	0013-use-SOURCE_DATE_EPOCH-for-timestamp-if-available.patch
 
 	0001-echo-do-not-assume-that-free-leaves-errno-unmodified.patch
 	0001-ash-add-built-in-BB_ASH_VERSION-variable.patch
@@ -89,9 +90,6 @@ build() {
 	${CC:-${CROSS_COMPILE}gcc} ${CPPFLAGS} ${CFLAGS} $(pkg-config --cflags libtls) \
 		"$srcdir"/ssl_client.c -o "$_dyndir"/ssl_client ${LDFLAGS} $(pkg-config --libs libtls)
 
-	# no timestamp in build
-	export KCONFIG_NOTIMESTAMP=1
-
 	# build dynamic
 	cd "$_dyndir"
 	msg "Building dynamic busybox"
@@ -251,6 +249,7 @@ ecbe5c890d966f09280c7eb534109f785c68e292765f17ed7ff62fcc61d20f61443c4155add0a1eb
 d12246f1134bbd3993462d27172c4739cc601b251d57ce8e088745773afa965551236e8cb8b9013dfc142fd055e369a771d86c7c54615c89bd30393400bfa390  0001-ash-add-built-in-BB_ASH_VERSION-variable.patch
 6f8fa4ec190d64d6c3d5377994be933885ed0b40361c99ca35881684db3b1b79664d6eab56a389df290b9f6c4db502c617ec8e4ffa6d5284bd41cea1f478b26c  0001-cpio-add-support-for-ignore-devno-like-GNU-cpio.patch
 97109be04445b7b887c402b7072c1da57212ef11f2eca6d34c24d5a4e3b2866ee79aca7a0ca41043726293d9bed1b2fa8aab100501569f00b8670c280a87a01c  0002-cpio-add-support-for-renumber-inodes-like-GNU-cpio.patch
+aebb6bbce0ebd0b3eb090ef379ddc43d7fffb8da7c1dfebed046ddd40e4c5666ab7653c416dca34e1ddd8a788888cb783ab21e8e9734ce48ead9403b0c3b4163  0013-use-SOURCE_DATE_EPOCH-for-timestamp-if-available.patch
 aa93095e20de88730f526c6f463cef711b290b9582cdbd8c1ba2bd290019150cbeaa7007c2e15f0362d5b9315dd63f60511878f0ea05e893f4fdfb4a54af3fb1  acpid.logrotate
 9fc6424fb28e1fb5d6fba7a389ced7b8fdedb20ba418db22b5092de0db3faee9cedbccb14f9e9e1ff5f173e58ddc2d92417241bde0006fbdb99986f3fc397e01  busyboxconfig
 470a646505887dbf20dd8c3c3b5c8ab25f363f3a0bfbca577de115b8ec61f28e9843f4f3a7978c634e863dbf28bae987f20e7fa1aa529450ff6c17bc188cae53  busyboxconfig-extras