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Date: Wed, 27 Nov 2013 20:26:02 +0000
From: Peter Stephenson <p.w.stephenson@ntlworld.com>
To: zsh-workers@zsh.org
Subject: Re: PATCH: utils.c: Fix use of uninitialized memory in metafy().
Message-ID: <20131127202602.3897f501@pws-pc.ntlworld.com>
In-Reply-To: <131127105409.ZM10472@torch.brasslantern.com>
References: <bb4a5a0bb37e036855648e28ad8c663c0e0763e7.1385573927.git.simon@ruderich.org>
	<20131127180719.1ad6acf0@pwslap01u.europe.root.pri>
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On Wed, 27 Nov 2013 10:54:09 -0800
Bart Schaefer <schaefer@brasslantern.com> wrote:
> On Nov 27,  6:07pm, Peter Stephenson wrote:
> } 
> } Hmm... I think the intention probably *is* to check if there's null
> } termination at "buf + len", on the assumption that the first "len" bytes
> } need metafying regardless.  So if we've got only len valid bytes, not
> } null-terminated (or null-terminated by accident because the next byte
> } that isn't actually valid for the allocation happens to be null), we've
> } got no way of knowing this given the current interface.
> 
> Does it actually matter?  The only reason for (*e != 0) as far as I can
> tell is to be sure we've actually done (*e = '\0') at the very end of
> the whole thing [comment: "... unchanged (a terminating null character
> is appended to buf if necessary)"].
> 
> Can't we just move the *e = '\0' outside the "if" body and skip the test
> in the condition?

Seems reasonable --- it requires the problem Simon was seeing to be in a
case that's requesting reallocation, else that assignment is going to
cause problems, but if it does cause problems we need to change the
caller.

pws