From: Mark H Weaver <mhw@netris.org>
To: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Cc: 30116@debbugs.gnu.org
Subject: bug#30116: [PATCH] `substitute' crashes when file contains NUL characters (core-updates))
Date: Sun, 17 Jun 2018 00:36:00 -0400 [thread overview]
Message-ID: <87d0wq3u8f.fsf@netris.org> (raw)
In-Reply-To: <87tvq2smpm.fsf@gmail.com> (Maxim Cournoyer's message of "Sat, 16 Jun 2018 12:47:01 -0400")
Hi Maxim,
Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:
> Mark H Weaver <mhw@netris.org> writes:
>
>> With the changes suggested above, I would have no objection to pushing
>> this to core-updates. However, it occurs to me that we could handle the
>> NUL case in a better way:
>>
>> Since the C regex functions that we use cannot handle NUL bytes, we
>> could use a different code point to represent NUL during those
>> operations. We could choose a code point from one of the Unicode
>> Private Use Areas <https://en.wikipedia.org/wiki/Private_Use_Areas> that
>> does not occur in the string.
>>
>> Let NUL* be the code point which will represent NUL bytes. First
>> replace all NULs with NUL*s, then perform the substitutions, and finally
>> replace all ALT*s with NULs before writing to the output.
>
> Do I understand this transformation as NULs -> NUL*s and back from NUL*s
> -> NULs correctly? I'm not sure how NUL*s became ALT*s in your explanation.
Sorry, it's a typo. Where I wrote "ALT*s", I meant to write "NUL*s".
>> What do you think?
>
> It raises the complexity level a bit for something which doesn't seem to
> be a very common scenario,
FWIW, I agree that it's not a common scenario, and it's not entirely
clear that it was worth the time I spent on it, or the added complexity.
On the other hand, I would dislike having a basic API like 'substitute*'
be subtly broken in this way.
> but otherwise seems a very elegant
> workaround. It seems to me that your implementation is already pretty
> complete. I'll try write a test for validating it and report back.
Sounds good. Thank you!
Mark
next prev parent reply other threads:[~2018-06-17 4:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-15 1:27 bug#30116: [PATCH] `substitute' crashes when file contains NUL characters (core-updates) Maxim Cournoyer
[not found] ` <handler.30116.B.15159796942311.ack@debbugs.gnu.org>
2018-01-15 1:38 ` bug#30116: [PATCH] `substitute' crashes when file contains NUL characters (core-updates)) Maxim Cournoyer
2018-01-17 14:37 ` Ludovic Courtès
2018-06-14 1:40 ` Maxim Cournoyer
2018-06-14 8:01 ` Ludovic Courtès
2018-06-14 7:02 ` Mark H Weaver
2018-06-14 8:02 ` Ludovic Courtès
2018-06-16 16:47 ` Maxim Cournoyer
2018-06-17 4:36 ` Mark H Weaver [this message]
2021-01-08 19:14 ` bug#30116: [PATCH] `substitute' crashes when file contains NUL characters (core-updates) Maxim Cournoyer
2021-01-08 21:42 ` Mark H Weaver
2018-01-16 11:23 ` Ludovic Courtès
2018-01-21 4:24 ` Maxim Cournoyer
2018-01-21 18:17 ` Mark H Weaver
2018-01-22 10:58 ` Ludovic Courtès
2018-01-23 4:27 ` Maxim Cournoyer
2018-01-23 14:11 ` Ludovic Courtès
2018-01-25 5:11 ` Maxim Cournoyer
2018-01-25 11:11 ` Ludovic Courtès
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