[U-Boot] [RFC PATCH] Makefile: search for GNU date

[Paul Kocialkowski <contact@paulk.fr>]

Le jeudi 27 ao?t 2015 ? 10:13 +0200, Andreas Bie?mann a ?crit :
> The SOURCE_DATE_EPOCH mechanism for reproducible builds requires the GNU
> variant of date. Respect this and search it, error on missing GNU date.

Well, IMHO we shouldn't check for GNU date but for the extensions it
implements. Those could be included in other date implementations. For
instance, it looks like busybox's date implements the -u and -d options
too.

> Signed-off-by: Andreas Bie?mann <andreas.devel@googlemail.com>
> ---
> This commit tries to figure out if we have a GNU date variant
> available. It errors on missing GNU date when it is required (for
> SOURCE_DATE_EPOCH set). The result is:

Also, I don't think it should be up to the Makefile to figure out which
date binary to use. It should be up to the user to put the right one as
"date", e.g. with an alias. That is, unless the name for GNU date is
something really standardized on non-GNU systems.

> ---8<---
> abiessmann at punisher % PATH=$ARMv5_PATH:$PATH CROSS_COMPILE=arm-v5te-linux-gnueabi- make SOURCE_DATE_EPOCH="`date -R`" O=/tmp/picosam ARCH=arm include/generated/timestamp_autogenerated.h
> make[1]: Entering directory '/tmp/picosam'
> /home/abiessmann/src/u-boot/Makefile:1303: *** "No GNU date found".  Stop.
> make[1]: Leaving directory '/tmp/picosam'
> Makefile:146: recipe for target 'sub-make' failed
> make: *** [sub-make] Error 2
> abiessmann at punisher % PATH=$ARMv5_PATH:$PATH CROSS_COMPILE=arm-v5te-linux-gnueabi- make O=/tmp/picosam ARCH=arm include/generated/timestamp_autogenerated.h
> make[1]: Entering directory '/tmp/picosam'
>   CHK     include/generated/timestamp_autogenerated.h
>   UPD     include/generated/timestamp_autogenerated.h
> make[1]: Leaving directory '/tmp/picosam'
> --->8---
> 
> It applies on top of http://patchwork.ozlabs.org/patch/506856/ (Makefile: Use correct timezone for U_BOOT_TZ).
> 
>  Makefile | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index b9b2375..95eae64 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -346,6 +346,9 @@ PERL		= perl
>  PYTHON		= python
>  DTC		= dtc
>  CHECK		= sparse
> +GNUDATE	       := $(foreach date,gdate date.gnu date, \
> +		    $(shell _date=`which $(date)`; \
> +		      $${_date} --version 2> /dev/null | $(AWK) "/GNU coreutils/ { print \"$${_date}\"; }"))

I advise running date with the needed options (-u -d) and checked the
error code instead of this. And of course, the variable names shouldn't
mention GNU date.

>  CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
>  		  -Wbitwise -Wno-return-void -D__CHECK_ENDIAN__ $(CF)
> @@ -1281,9 +1284,9 @@ 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 "$${SOURCE_DATE}" +'#define U_BOOT_TZ "%z"'; \
> +		LC_ALL=C $(GNUDATE) -u -d "$${SOURCE_DATE}" +'#define U_BOOT_DATE "%b %d %C%y"'; \
> +		LC_ALL=C $(GNUDATE) -u -d "$${SOURCE_DATE}" +'#define U_BOOT_TIME "%T"'; \
> +		LC_ALL=C $(GNUDATE) -u -d "$${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"'; \
> @@ -1295,6 +1298,11 @@ $(version_h): include/config/uboot.release FORCE
>  	$(call filechk,version.h)
>  
>  $(timestamp_h): $(srctree)/Makefile FORCE
> +ifneq ($(strip $(SOURCE_DATE_EPOCH)),)
> +ifeq ($(strip $(GNUDATE)),)
> +	$(error "No GNU date found")
> +endif
> +endif
>  	$(call filechk,timestamp.h)
>  
>  # ---------------------------------------------------------------------------

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