Brian Inglis via Cygwin-apps wrote:
On 2023-08-23 11:39, Christian Franke via Cygwin-apps wrote:
A small step towards reproducible packaging...
Currently only tested with upcoming smartmontools package - contains
only exe, man, doc files (no dll, lib, ...). Multiple cygport runs
produce binary identical distribution tarballs if SOURCE_DATE_EPOCH
(from the past) is specified in the cygport file.
What format is this variable?
Unix epoch, see: https://reproducible-builds.org/docs/source-date-epoch/
Some tools like gcc and gropdf already support this:
$ echo '__DATE__ __TIME__' | SOURCE_DATE_EPOCH=1672531200 gcc -E -xc -
# 0 "<stdin>"
# 0 "<built-in>"
# 0 "<command-line>"
# 1 "<stdin>"
"Jan 1 2023" "00:00:00"
$ TZ=UTC SOURCE_DATE_EPOCH=1672531200 man -Tpdf ls | TZ=UTC pdfinfo -
Creator: groff version 1.23.0
Producer: gropdf version 1.23.0
CreationDate: Sun Jan 1 00:00:00 2023 UTC
ModDate: Sun Jan 1 00:00:00 2023 UTC
...
If binutils, gzip and tar also would support this, the patch would be
empty :-)
Would be best to use some ISO format e.g.
%Y-%m-%dT%H:%M:%SZ or
%Y-%m-%dT%H:%M:%S [local]
that is human readable and can be used by all POSIX command options
[e.g. see touch(1p) -d] that accept date-time stamps.
I use this in smartmontools.cygport:
SOURCE_DATE=2023-08-23
SOURCE_DATE_EPOCH=$(date -d "$SOURCE_DATE UTC" +%s)
This relies on GNU date, BSD date is very different, a POSIX-only date
would be useless in this context.
Could do with docs and NEWS entries for new variables, otherwise
packagers do not know it exists, and how to use it e.g.
#****f* Information/BUILD_REQUIRES
# SYNOPSIS
...
Of course this should be documented, but I left this for a later patch.
--
Regards,
Christian
