package/utils/busybox/patches/530-use-SOURCE_DATE_EPOCH-for-timestamp-if-available.patch

   1 From 59f773ee81a8945321f4aa20abc5e9577e6483e4 Mon Sep 17 00:00:00 2001
   2 From: Paul Spooren <mail@aparcar.org>
   3 Date: Thu, 13 May 2021 11:25:34 +0200
   4 Subject: [PATCH] use SOURCE_DATE_EPOCH for timestamp if available
   5
   6 The SOURCE_DATE_EPOCH is an effort of the Reproducible Builds
   7 organization to make timestamps/build dates in compiled tools
   8 deterministic over several repetitive builds.
   9
  10 Busybox shows by default the build date timestamp which changes whenever
  11 compiled. To have a reasonable accurate build date while staying
  12 reproducible, it's possible to use the *date of last source
  13 modification* rather than the current time and date.
  14
  15 Further information on SOURCE_DATE_EPOCH are available online [1].
  16
  17 This patch modifies `confdata.c` so that the content of the
  18 SOURCE_DATE_EPOCH env variable is used as timestamp.
  19
  20 To be independent of different timezones between builds, whenever
  21 SOURCE_DATE_EPOCH is defined the GMT time is used.
  22
  23 [1]: https://reproducible-builds.org/docs/source-date-epoch/
  24
  25 Signed-off-by: Paul Spooren <mail@aparcar.org>
  26 ---
  27  scripts/kconfig/confdata.c | 17 ++++++++++++++---
  28  1 file changed, 14 insertions(+), 3 deletions(-)
  29
  30 diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
  31 index b05b96e45..73c25e3a8 100644
  32 --- a/scripts/kconfig/confdata.c
  33 +++ b/scripts/kconfig/confdata.c
  34 @@ -342,6 +342,8 @@ int conf_write(const char *name)
  35         time_t now;
  36         int use_timestamp = 1;
  37         char *env;
  38 +       char *source_date_epoch;
  39 +       struct tm *build_time;
  40
  41         dirname[0] = 0;
  42         if (name && name[0]) {
  43 @@ -378,7 +380,16 @@ int conf_write(const char *name)
  44         }
  45         sym = sym_lookup("KERNELVERSION", 0);
  46         sym_calc_value(sym);
  47 -       time(&now);
  48 +
  49 +       source_date_epoch = getenv("SOURCE_DATE_EPOCH");
  50 +       if (source_date_epoch && *source_date_epoch) {
  51 +               now = strtoull(source_date_epoch, NULL, 10);
  52 +               build_time = gmtime(&now);
  53 +       } else {
  54 +               time(&now);
  55 +               build_time = localtime(&now);
  56 +       }
  57 +
  58         env = getenv("KCONFIG_NOTIMESTAMP");
  59         if (env && *env)
  60                 use_timestamp = 0;
  61 @@ -398,14 +409,14 @@ int conf_write(const char *name)
  62                 if (use_timestamp) {
  63                         size_t ret = \
  64                                 strftime(buf, sizeof(buf), "#define AUTOCONF_TIMESTAMP "
  65 -                                       "\"%Y-%m-%d %H:%M:%S %Z\"\n", localtime(&now));
  66 +                                       "\"%Y-%m-%d %H:%M:%S %Z\"\n", build_time);
  67                         /* if user has Factory timezone or some other odd install, the
  68                          * %Z above will overflow the string leaving us with undefined
  69                          * results ... so let's try again without the timezone.
  70                          */
  71                         if (ret == 0)
  72                                 strftime(buf, sizeof(buf), "#define AUTOCONF_TIMESTAMP "
  73 -                                       "\"%Y-%m-%d %H:%M:%S\"\n", localtime(&now));
  74 +                                       "\"%Y-%m-%d %H:%M:%S\"\n", build_time);
  75                 } else { /* bbox */
  76                         strcpy(buf, "#define AUTOCONF_TIMESTAMP \"\"\n");
  77                 }
  78 --
  79 2.30.2
  80