From: Stephane Chazelas <stephane@chazelas.org>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: [PATCH] (?) typeset array[position=index]=value
Date: Wed, 2 Jun 2021 10:11:45 +0100 [thread overview]
Message-ID: <20210602091145.xvyymjxdors6kqya@chazelas.org> (raw)
In-Reply-To: <CAH+w=7a+M7nTTqzmve+SZHwtEeRPTicQB5ZRy2XO6er4UhMb1w@mail.gmail.com>
2021-06-01 09:05:13 -0700, Bart Schaefer:
[...]
> > [...] unless we're happy to break backward
> > compatibility and make unset "assoc[$key]" work whatever the
> > value of $key (unset 'assoc[f\]oo]]' for unset the element of
> > key 'f\]oo]' for instance)
>
> Hm, I'm not sure what backward-compatibility would be broken? Do you
> mean that scripts that already have work-arounds for the current issue
> might stop working?
Yes, like that guy's unset_keys at
https://unix.stackexchange.com/questions/626393/in-zsh-how-do-i-unset-an-arbitrary-associative-array-element/626529#626529
mentioned earlier.
ATM, you need to do:
unset 'hash[\]]'
To unset the element of key "]" for instance.
Having said that, in practice, it's rare for values to be passed
literally. What you generally want to do is:
unset "hash[$key]"
With $key being any arbitrary string. And that's where the
problem is.
Maybe the best approach would be to make unset a dual
keyword/builtin like typeset/export... so one can do:
unset hash[$key]
And that hash[$key] being interpreted the same as when you do:
hash[$key]=value
Being able to do:
unset hash[(R)pattern]
unset hash[(I)pattern]
would also be useful. We don't want however subscript flags to
be interpreted in:
unset "hash[$key]"
as that would introduce command injection vulnerabilities, like
is already the case in things like:
$ key='(n:evil:)' evil='psvar[$(uname>&2)1]' zsh -c 'typeset -A a; (( a[$key]++ ))'
Linux
Linux
(though in that case, that's not limited to subscript flags,
key='x]+psvar[$(uname>&2)1' works as well, see
https://unix.stackexchange.com/questions/627474/how-to-use-associative-arrays-safely-inside-arithmetic-expressions/627475#627475
)
That's also why I was suggesting allowing:
hash[$key]=()
to unset an element, where you don't have the ambiguity of
whether the contents of $key is going to be interpreted
specially.
--
Stephane
next prev parent reply other threads:[~2021-06-02 9:12 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 21:10 regexp-replace and ^, word boundary or look-behind operators Stephane Chazelas
2019-12-16 21:27 ` Stephane Chazelas
2019-12-17 7:38 ` Stephane Chazelas
2019-12-17 11:11 ` [PATCH] " Stephane Chazelas
2019-12-18 0:22 ` Daniel Shahaf
2019-12-18 8:31 ` Stephane Chazelas
2020-01-01 14:03 ` [PATCH v2] " Stephane Chazelas
2021-04-30 6:11 ` Stephane Chazelas
2021-04-30 23:13 ` Bart Schaefer
2021-05-05 11:45 ` [PATCH v3] regexp-replace and ^, word boundary or look-behind operators (and more) Stephane Chazelas
2021-05-31 0:58 ` Lawrence Velázquez
2021-05-31 18:18 ` Bart Schaefer
2021-05-31 21:37 ` [PATCH] (?) typeset array[position=index]=value Bart Schaefer
2021-06-01 5:32 ` Stephane Chazelas
2021-06-01 16:05 ` Bart Schaefer
2021-06-02 2:51 ` [PATCH] (take two?) typeset array[position=index]=value / unset hash[$stuff] Bart Schaefer
2021-06-02 10:06 ` Stephane Chazelas
2021-06-02 14:52 ` Bart Schaefer
2021-06-02 16:02 ` Stephane Chazelas
2021-06-02 9:11 ` Stephane Chazelas [this message]
2021-06-02 13:34 ` [PATCH] (?) typeset array[position=index]=value Daniel Shahaf
2021-06-02 14:20 ` Stephane Chazelas
2021-06-02 15:59 ` Bart Schaefer
2021-06-03 2:04 ` [PATCH (not final)] (take three?) unset "array[$anything]" Bart Schaefer
2021-06-03 2:42 ` Bart Schaefer
2021-06-03 6:12 ` Bart Schaefer
2021-06-03 8:54 ` Peter Stephenson
2021-06-03 13:13 ` Stephane Chazelas
2021-06-03 14:41 ` Peter Stephenson
2021-06-04 19:25 ` Bart Schaefer
2021-06-05 18:18 ` Peter Stephenson
2021-06-09 23:31 ` Bart Schaefer
2021-06-13 16:51 ` Peter Stephenson
2021-06-13 18:04 ` Bart Schaefer
2021-06-13 19:48 ` Peter Stephenson
2021-06-13 21:44 ` Bart Schaefer
2021-06-14 7:19 ` Stephane Chazelas
2021-06-03 18:12 ` Bart Schaefer
2021-06-04 8:02 ` Stephane Chazelas
2021-06-04 18:36 ` Bart Schaefer
2021-06-04 20:21 ` Stephane Chazelas
2021-06-05 0:20 ` Bart Schaefer
2021-06-05 17:05 ` Stephane Chazelas
2021-06-10 0:14 ` Square brackets in command position Bart Schaefer
2021-06-03 6:05 ` [PATCH (not final)] (take three?) unset "array[$anything]" Stephane Chazelas
2021-06-03 6:43 ` Bart Schaefer
2021-06-03 7:31 ` Stephane Chazelas
2021-06-10 0:21 ` [PATCH] (?) typeset array[position=index]=value Bart Schaefer
2021-06-05 4:29 ` Mikael Magnusson
2021-06-05 5:49 ` Bart Schaefer
2021-06-05 11:06 ` Mikael Magnusson
2021-06-05 16:22 ` Bart Schaefer
2021-06-18 10:53 ` Mikael Magnusson
2024-03-08 15:30 ` [PATCH v3] regexp-replace and ^, word boundary or look-behind operators (and more) Stephane Chazelas
2024-03-09 8:41 ` [PATCH v5] " Stephane Chazelas
2024-03-09 9:21 ` MBEGIN when =~ finds bytes inside characters (Was: [PATCH v5] regexp-replace and ^, word boundary or look-behind operators (and more).) Stephane Chazelas
2024-03-09 13:03 ` [PATCH v3] regexp-replace and ^, word boundary or look-behind operators (and more) Stephane Chazelas
2024-03-10 19:52 ` [PATCH v6] " Stephane Chazelas
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