Re: [PATCH] fsck: it is OK for a tag and a commit to lack the body

[Eric Sunshine <sunshine@sunshineco.com>]

On Sun, Jun 28, 2015 at 2:18 PM, Junio C Hamano <gitster@pobox.com> wrote:
> When fsck validates a commit or a tag object, it scans each line in
> the header the object using helper functions such as "start_with()",

s/header/& of/

> etc. that work on a NUL terminated buffer, but before a1e920a0
> (index-pack: terminate object buffers with NUL, 2014-12-08), the
> validation functions were fed the object data as counted strings,
> not necessarily terminated with a NUL.  We added a helper function
> require_end_of_header() to be called at the beginning of these
> validation functions to insist that the object data contains an
> empty line before its end.  The theory is that the validating
> functions will notice and stop when it hits an empty line as a
> normal end of header (or a required header line that is missing)
> before scanning past the end of potentially not NUL-terminated
> buffer.
>
> But the theory forgot that in the older days, Git itself happily
> created objects with only the header lines without a body. This
> caused Git 2.2 and later to issue an unnecessary warning on some
> existing repositories.
>
> With a1e920a0, we do not need to require an empty line (or the body)
> in these objects to safely parse and validate them.  Drop the
> offending "must have an empty line" check from this helper function,
> while keeping the other check to make sure that there is no NUL in
> the header part of the object, and adjust the name of the helper to
> what it does accordingly.
>
> Noticed-by: Wolfgang Denk <wd@denx.de>
> Helped-by: Jeff King <peff@peff.net>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>