From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mark H Weaver <mhw@netris.org>
Subject: bug#30116: [PATCH] `substitute' crashes when file contains NUL
	characters (core-updates)
Date: Sun, 21 Jan 2018 13:17:45 -0500
Message-ID: <877esb84ae.fsf@netris.org>
References: <87r2qrc3mq.fsf@gmail.com> <87o9lu6o9m.fsf@gnu.org>
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To: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Cc: 30116@debbugs.gnu.org

Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:

> ludo@gnu.org (Ludovic Court=C3=A8s) writes:
>
>> Maxim Cournoyer <maxim.cournoyer@gmail.com> skribis:
>>
>>> I've encountered the following crash when trying to use substitute on a
>>> file which contains NUL characters:
>>
>> Yes, that=E2=80=99s because Guile=E2=80=99s =E2=80=98regexp-exec=E2=80=
=99 simply wraps libc=E2=80=99s =E2=80=98regexec=E2=80=99,
>> which does not handle NULs.
>>
>> We should consider switching to the pure-Scheme SRFI-115:
>>
>>   https://srfi.schemers.org/srfi-115/srfi-115.html
>
> This looks good, and I started looking into porting `substitute' to it,
> but quickly noticed it doesn't seem to be implemented in Guile yet?

Indeed.  SRFI-115 for Guile is on my TODO list, although it might be
better to wait until after we switch to using UTF-8 encoding internally
for strings, since that will drastically affect the implementation of
any efficient regexp matcher on Scheme strings.

Anyway, 'substitute*' is to be used only on text files, and NUL bytes
are not a valid textual character.  So, I think that this case is
outside of what 'substitute*' is meant to do, and therefore not a bug in
'substitute*', although of course a more graceful error would surely be
preferable.

What do you think?

      Mark