oss-security - wordexp(3)

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Message-ID: <20150210172756.GA8690@openwall.com>
Date: Tue, 10 Feb 2015 20:27:56 +0300
From: Solar Designer <solar@...nwall.com>
To: oss-security@...ts.openwall.com
Subject: wordexp(3)

Hi,

I found this curious and relevant to this list, off Twitter:

(x250) <%worr> RT @FioraAeterna: oh my gosh, Apple's libc literally implements "wordexp" by shelling out to perl: https://github.com/Apple-FOSS-Mirror/Libc/blob/2ca2ae74647714acfc18674c3114b1a5d3325d7d/gen/wordexp.c#L192

<worr> So yesterday, @FioraAeterna tweeted this: https://github.com/Apple-FOSS-Mirror/Libc/blob/2ca2ae74647714acfc18674c3114b1a5d3325d7d/gen/wordexp.c#L192. I've decided to take a tour of wordexp(3) implementations
<@worr> They can't all be that bad
(x2) <@worr> NetBSD and FreeBSD both use a sh builtin to implement wordexp(3): http://svnweb.freebsd.org/base/head/lib/libc/gen/wordexp.c?revision=254977&view=markup http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/gen/wordexp.c?rev=1.3&content-type=text/x-cvsweb-markup&only_with_tag=MAIN
(x5) <@worr> OpenBSD wins the wordexp(3) contest, by refusing to implement it altogether.
<@worr> Correction: glibc implements a huge recursive descent parser, and only shells out when it needs to do subshell expansions.
<@worr> tbh, wordexp(3) is an antifeature. Maybe even a misfeature.
<@worr> Here's the implementation, btw: https://sourceware.org/git/?p=glibc.git;a=blob;f=posix/wordexp.c;h=26f3a2653feba2b1a5904937d9d6b58c32109e24;hb=a39208bd7fb76c1b01c127b4c61f9bfd915bfe7c#l872
<@worr> Continuing on my tour of wordexp(3) implementations, here's Illumos': https://github.com/joyent/illumos-joyent/blob/master/usr/src/lib/libc/port/regex/wordexp.c#L218-L290 It constructs a small shell script and runs it

Alexander

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