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 Fri, 17 Apr 2020 23:06:39 +0300 (MSK)
Date: Fri, 17 Apr 2020 20:06:38 +0000
From: Nikita Pettik <korablev@tarantool.org>
Message-ID: <20200417200638.GA14084@tarantool.org>
References: <3ee69eaa4ff23647e9ae6fe63e2ae77c427ffe01.1586993218.git.korablev@tarantool.org>
 <574107d5-cb85-1b08-3abf-c2c53497ab5e@tarantool.org>
 <20200416123400.GA6229@tarantool.org>
 <4d22bf0c-a363-719c-4198-46616f42ed48@tarantool.org>
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In-Reply-To: <4d22bf0c-a363-719c-4198-46616f42ed48@tarantool.org>
Subject: Re: [Tarantool-patches] [PATCH] box/error: ref error.prev while
	accessing it
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To: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org

On 16 Apr 23:17, Vladislav Shpilevoy wrote:
> Hi! Thanks for the fixes!
> 
> Now there is a new problem:
> 
>     value = 2147483647 + 100
>     e1 = box.error.new(1000, 'Message1')
>     e2 = box.error.new(1001, 'Message2')
>     e1:set_prev(e2)
>     prev = nil
>     for i = 1, value do prev = e1.prev end

Oh, if user wrote code like this I guess negative reference
counter would be fair panishment.

Still ref counter overflow can be achieved without stacked diag:
box.error.last() refs counter as well. So I introduced overflow
check in error_ref() in a separate patch.

 
>     tarantool> prev._refs
>     ---
>     - -2147483547
>     ...
> 
> Negative ref count.