archive: expand only a single %(describe) per archive

Every %(describe) placeholder in $Format:...$ strings in files with the
attribute export-subst is expanded by calling git describe.  This can
potentially result in a lot of such calls per archive.  That's OK for
local repositories under control of the user of git archive, but could
be a problem for hosted repositories.

Expand only a single %(describe) placeholder per archive for now to
avoid denial-of-service attacks.  We can make this limit configurable
later if needed, but let's start out simple.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions