[U-Boot] [PATCH] Reproducible U-Boot build support, using SOURCE_DATE_EPOCH

[Heiko Schocher]

Hello Paul,

Am 20.07.2015 um 10:06 schrieb Paul Kocialkowski:
> Le lundi 20 juillet 2015 à 10:01 +0200, Paul Kocialkowski a écrit :
>> In order to achieve reproducible builds in U-Boot, timestamps that are defined
>> at build-time have to be somewhat eliminated. The SOURCE_DATE_EPOCH environment
>> variable allows setting a fixed value for those timestamps.
>>
>> Simply by setting SOURCE_DATE_EPOCH to a fixed value, a number of targets can be
>> built reproducibly. This is the case for e.g. sunxi devices.
>>
>> However, some other devices might need some more tweaks, especially regarding
>> the image generation tools.
>
> Lunar, since you have contributed to this patch, feel free to add your
> Signed-Off-By line here before it's merged!
>
> Heiko, since this is based on your original patch, feel free to do the
> same!

I am just on the jump into my holidays, so I have not yet the time
to test it ... I want to try it for all builds with the scripts
I posted with my v2 ... but a first fast look into your patch looks
nice, if it works, it is ok with me ... I am back aprox. july 5th.

maybe a README entry would be fine ;-)

Thanks!

bye,
Heiko
>
> It would be nice to have this tested on as many boards as possible to
> spot other areas that make the binaries not reproducible. However, I
> doubt this patch will evolve much and other fixes should be sent in
> subsequent patches.
>
>> Signed-off-by: Paul Kocialkowski <contact at paulk.fr>
>> ---
>>   Makefile              |  7 ++++---
>>   tools/default_image.c | 21 ++++++++++++++++++++-
>>   2 files changed, 24 insertions(+), 4 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 37cc4c3..71aeac7 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -1231,9 +1231,10 @@ define filechk_version.h
>>   endef
>>
>>   define filechk_timestamp.h
>> -	(LC_ALL=C date +'#define U_BOOT_DATE "%b %d %C%y"'; \
>> -	LC_ALL=C date +'#define U_BOOT_TIME "%T"'; \
>> -	LC_ALL=C date +'#define U_BOOT_TZ "%z"')
>> +	(SOURCE_DATE="$${SOURCE_DATE_EPOCH:+@$$SOURCE_DATE_EPOCH}"; \
>> +	LC_ALL=C date -u -d "$${SOURCE_DATE:-now}" +'#define U_BOOT_DATE "%b %d %C%y"'; \
>> +	LC_ALL=C date -u -d "$${SOURCE_DATE:-now}" +'#define U_BOOT_TIME "%T"'; \
>> +	LC_ALL=C date -u -d "$${SOURCE_DATE:-now}" +'#define U_BOOT_TZ "%z"' )
>>   endef
>>
>>   $(version_h): include/config/uboot.release FORCE
>> diff --git a/tools/default_image.c b/tools/default_image.c
>> index cf5c0d4..18940af 100644
>> --- a/tools/default_image.c
>> +++ b/tools/default_image.c
>> @@ -88,6 +88,9 @@ static void image_set_header(void *ptr, struct stat *sbuf, int ifd,
>>   				struct image_tool_params *params)
>>   {
>>   	uint32_t checksum;
>> +	char *source_date_epoch;
>> +	struct tm *time_universal;
>> +	time_t time;
>>
>>   	image_header_t * hdr = (image_header_t *)ptr;
>>
>> @@ -96,9 +99,25 @@ static void image_set_header(void *ptr, struct stat *sbuf, int ifd,
>>   				sizeof(image_header_t)),
>>   			sbuf->st_size - sizeof(image_header_t));
>>
>> +	source_date_epoch = getenv("SOURCE_DATE_EPOCH");
>> +	if (source_date_epoch != NULL) {
>> +		time = (time_t) strtol(source_date_epoch, NULL, 10);
>> +
>> +		time_universal = gmtime(&time);
>> +		if (time_universal == NULL) {
>> +			fprintf(stderr, "%s: SOURCE_DATE_EPOCH is not valid\n",
>> +				__func__);
>> +			time = 0;
>> +		} else {
>> +			time = mktime(time_universal);
>> +		}
>> +	} else {
>> +		time = sbuf->st_mtime;
>> +	}
>> +
>>   	/* Build new header */
>>   	image_set_magic(hdr, IH_MAGIC);
>> -	image_set_time(hdr, sbuf->st_mtime);
>> +	image_set_time(hdr, time);
>>   	image_set_size(hdr, sbuf->st_size - sizeof(image_header_t));
>>   	image_set_load(hdr, params->addr);
>>   	image_set_ep(hdr, params->ep);
>

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