From: Phil Pennock <zsh-workers+phil.pennock@spodhuis.org>
To: Christopher Browne <cbbrowne@gmail.com>
Cc: rahul <rahul2012@gmail.com>, Zsh Users <zsh-users@zsh.org>
Subject: Re: Higher order functions in zsh (article link)
Date: Thu, 7 Mar 2013 14:08:42 -0500 [thread overview]
Message-ID: <20130307190842.GA67680@redoubt.spodhuis.org> (raw)
In-Reply-To: <CAFNqd5WwOHg3aed8OrbFdwfJ5cxemu6DzBOS5uxuDgGWH41HgQ@mail.gmail.com>
On 2013-03-07 at 11:59 -0500, Christopher Browne wrote:
> cbbrowne@cbbrowne /tmp/maptest> function map {
> local func_name=$1
> shift
> for elem in $@; print -- $(eval $func_name "${elem}")
> }
>
> But somewhat curiously that doesn't help :-(.
Why does this code have an eval in there? It's:
(1) breaking the f3 example
(2) introducing a security flaw
Hint: touch 'f4 `mkdir snert`'
This works fine:
----------------------------8< cut here >8------------------------------
function map {
local func_name=$1
shift
for elem in "$@"; print -- $($func_name "${elem}")
}
----------------------------8< cut here >8------------------------------
With the eval in there, with { map echo * } f3 loses the quotes and f4
just shows "f4" and creates a new sub-directory, snert.
Lose the eval and things work, no new security hole.
Oh, and you need to quote the $@ to "$@" if you want to preserve empty
elements -- whether you do or not depends on what you're mapping across,
but I tend to think "present but empty" is distinct from "not present".
-Phil
next prev parent reply other threads:[~2013-03-07 19:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-07 5:25 rahul
2013-03-07 16:59 ` Christopher Browne
2013-03-07 19:08 ` Phil Pennock [this message]
2013-03-07 21:12 ` Oliver Kiddle
2013-03-08 8:40 ` Stephen Blott
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