Re: [PATCH 6/9] gnu: fontforge: Make SVG builds reproducible.

[Leo Famulari <leo@famulari.name>]

On Wed, Apr 06, 2016 at 12:44:31PM -0500, Eric Bavier wrote:
> On 2016-04-06 12:36, Leo Famulari wrote:
> >On Tue, Apr 05, 2016 at 11:32:58PM -0500, ericbavier@openmailbox.org
> >wrote:
> >>From: Eric Bavier <bavier@member.fsf.org>
> >>
> >>* gnu/packages/fontutils.scm (fontforge)[source]: Add snippet to clear
> >>  timestamp in svg.c.
> >>---
> >> gnu/packages/fontutils.scm | 7 ++++++-
> >> 1 file changed, 6 insertions(+), 1 deletion(-)
> >>
> >>diff --git a/gnu/packages/fontutils.scm b/gnu/packages/fontutils.scm
> >>index 75edd55..5ca9835 100644
> >>--- a/gnu/packages/fontutils.scm
> >>+++ b/gnu/packages/fontutils.scm
> >>@@ -512,7 +512,12 @@ definitions.")
> >>                ;; Make TTF builds bit-reproducible by clearing the
> >>timestamp
> >>                ;; that goes in TTF files.
> >>                (substitute* "fontforge/tottf.c"
> >>-                 (("cvt_unix_to_1904\\(now") "cvt_unix_to_1904(0"))))))
> >>+                 (("cvt_unix_to_1904\\(now") "cvt_unix_to_1904(0"))
> >>+
> >>+               ;; Make SVG builds bit-reproducible by clearing the
> >>timestamp
> >>+               ;; that goes in SVG files.
> >>+               (substitute* "fontforge/svg.c"
> >>+                 (("ctime\\(&now\\)") "ctime(0)"))))))
> >
> >Could you use the value of the environment variable SOURCE_DATE_EPOCH
> >instead of 0?
> 
> Probably.  But I'd save that for a later update, since it would be a much
> bigger change (that we could hopefully move upstream).

You could put the logic in the package definition and string-append the
value into svg.c.

If not, can you set the ctime to '1'? That is what we are using as the
value of SOURCE_DATE_EPOCH on Guix:

http://git.savannah.gnu.org/cgit/guix.git/tree/guix/build/gnu-build-system.scm#n46