[U-Boot] [RFC PATCH] Makefile: Add SOURCE_DATE_TZ

[Paul Kocialkowski <contact@paulk.fr>]

Le samedi 01 ao?t 2015 ? 22:32 +1200, Chris Packham a ?crit :
> Along with SOURCE_DATE_EPOCH SOURCE_DATE_TZ can be used to recreate a
> build with a specific date timestamp. This allows the verification of
> source supplied with a pre-compiled binary.
> 
> If SOURCE_DATE_EPOCH is supplied SOURCE_DATE_TZ can be used to specify
> what will appear in the output of the version command. If SOURCE_DATE_TZ
> is not specified UTC will be used.  SOURCE_DATE_TZ on it's own will not
> have an affect.

Well, I worked with the assumption that SOURCE_DATE_EPOCH would always
be provided in UTC, but I see no harm in providing SOURCE_DATE_TZ as
well, provided that it falls back to UTC when not set, as is the current
behaviour of tour patch.

Looks good to me!

> Signed-off-by: Chris Packham <judge.packham@gmail.com>
> ---
> This is a quick proof of concept that allows some control of how the
> timezone is displayed.
> 
>  Makefile | 7 ++++---
>  README   | 9 ++++++---
>  2 files changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index f75c730..5102a9c 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1232,9 +1232,10 @@ endef
>  define filechk_timestamp.h
>  	(if test -n "$${SOURCE_DATE_EPOCH}"; then \
>  		SOURCE_DATE="@$${SOURCE_DATE_EPOCH}"; \
> -		LC_ALL=C date -u -d "$${SOURCE_DATE}" +'#define U_BOOT_DATE "%b %d %C%y"'; \
> -		LC_ALL=C date -u -d "$${SOURCE_DATE}" +'#define U_BOOT_TIME "%T"'; \
> -		LC_ALL=C date -u -d "$${SOURCE_DATE}" +'#define U_BOOT_TZ "%z"'; \
> +		SOURCE_TZ="$${SOURCE_DATE_TZ:-UTC}"; \
> +		TZ="$${SOURCE_TZ}" LC_ALL=C date -d "$${SOURCE_DATE}" +'#define U_BOOT_DATE "%b %d %C%y"'; \
> +		TZ="$${SOURCE_TZ}" LC_ALL=C date -d "$${SOURCE_DATE}" +'#define U_BOOT_TIME "%T"'; \
> +		TZ="$${SOURCE_TZ}" LC_ALL=C date -d "$${SOURCE_DATE}" +'#define U_BOOT_TZ "%z"'; \
>  	else \
>  		LC_ALL=C date +'#define U_BOOT_DATE "%b %d %C%y"'; \
>  		LC_ALL=C date +'#define U_BOOT_TIME "%T"'; \
> diff --git a/README b/README
> index 1bcb63c..d2e3e94 100644
> --- a/README
> +++ b/README
> @@ -5087,11 +5087,14 @@ Reproducible builds
>  In order to achieve reproducible builds, timestamps used in the U-Boot build
>  process have to be set to a fixed value.
>  
> -This is done using the SOURCE_DATE_EPOCH environment variable.
> -SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
> -option for U-Boot or an environment variable in U-Boot.
> +This is done using the SOURCE_DATE_EPOCH and SOURCE_DATE_TZ environment
> +variables. These are to be set on the build host's shell, not as a
> +configuration option for U-Boot or an environment variable in U-Boot.
>  
>  SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
> +SOURCE_DATE_TZ will default to UTC but can be set to another timezone and is
> +used to determine how the date is displayed (tzselect(1) can be used to
> +determine an appropriate value).
>  
>  Building the Software:
>  ======================

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