tree 6e42dd04e82fdce97983392fca1ca058a74b7e27
parent 937b71cc8b5b998963a7f9a33312ba3549d55510
author Patrick Steinhardt <ps@pks.im> 1669906030 +0100
committer Junio C Hamano <gitster@pobox.com> 1670563581 +0900

utf8: fix checking for glyph width in `strbuf_utf8_replace()`

In `strbuf_utf8_replace()`, we call `utf8_width()` to compute the width
of the current glyph. If the glyph is a control character though it can
be that `utf8_width()` returns `-1`, but because we assign this value to
a `size_t` the conversion will cause us to underflow. This bug can
easily be triggered with the following command:

    $ git log --pretty='format:xxx%<|(1,trunc)%x10'

>From all I can see though this seems to be a benign underflow that has
no security-related consequences.

Fix the bug by using an `int` instead. When we see a control character,
we now copy it into the target buffer but don't advance the current
width of the string.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>