busybox: show reproducible timestamp

On login busybox shows a timestamp per default contianing the build
date. Since the build date isn't reproducible per default this behaviour
was disabled by default via 34df4d40 "busybox: disable timestamp in
version".

This commit modifies busybox so that the printed timestamp reproducible
using SOURCE_DATE_EPOCH and therefore shouldn't be disabled anymore.

Before:

    BusyBox v1.33.1 () built-in shell (ash)

After:

    BusyBox v1.33.1 (2021-05-13 09:34:34 UTC) built-in shell (ash)

Signed-off-by: Paul Spooren <mail@aparcar.org>
This commit is contained in:
Paul Spooren 2021-05-13 23:57:45 +02:00
parent f716c30241
commit a725382978
2 changed files with 80 additions and 4 deletions

View File

@ -81,10 +81,6 @@ endef
Package/busybox-selinux/conffiles = $(Package/busybox/conffiles)
endif
# don't create a version string containing the actual timestamp
export KCONFIG_NOTIMESTAMP=1
ifndef CONFIG_USE_MUSL
LDLIBS:=m crypt
endif

View File

@ -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