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From:   Junio C Hamano <gitster@pobox.com>
To:     Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc:     Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
        git@vger.kernel.org
Subject: Re: [PATCH 1/4] compat/win32/syslog: fix use-after-realloc
References: <pull.1238.git.1653351786.gitgitgadget@gmail.com>
        <d0ade6531bc77b654c28cf7b1bfa42523150c015.1653351786.git.gitgitgadget@gmail.com>
        <nycvar.QRO.7.76.6.2205241431400.352@tvgsbejvaqbjf.bet>
Date:   Tue, 24 May 2022 13:58:38 -0700
In-Reply-To: <nycvar.QRO.7.76.6.2205241431400.352@tvgsbejvaqbjf.bet> (Johannes
        Schindelin's message of "Tue, 24 May 2022 14:39:41 +0200 (CEST)")
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Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

>>  		str = realloc(str, st_add(++str_len, 1));
>
> Since it has been raised elsewhere: Why is that `++str_len` not turned
> into an `st_add()`?
> ...
> Now you know,

I'd be more worried about a macro looking thing evalutating its
parameters more than once, though.  But unlike st_addN(), st_add()
is an inline function so we do not have to worry about that ;-)

>> @@ -50,6 +51,7 @@ void syslog(int priority, const char *fmt, ...)
>>  			warning_errno("realloc failed");
>>  			return;
>>  		}
>> +		pos = str + offset;

The adjustment using ofs is very much straight-forward.  Nicely
spotted and nicely corrected.

Thanks.