Mailing-List: contact dev-help@httpd.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@httpd.apache.org
Received-SPF: pass (nike.apache.org: domain of jkaluza@redhat.com designates
 209.132.183.28 as permitted sender)
Message-ID: <54F5973C.6010800@redhat.com>
Date: Tue, 03 Mar 2015 12:13:00 +0100
From: =?UTF-8?B?SmFuIEthbHXFvmE=?= <jkaluza@redhat.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
 rv:31.0) Gecko/20100101 Thunderbird/31.4.0
MIME-Version: 1.0
To: dev@httpd.apache.org
Subject: Re: What is the lifetime of apr_dbd_get_entry(...); result?
References: <54D2246A.2010709@redhat.com>	<54F40F9B.6080909@redhat.com>
	<CAKQ1sVP+N8_9icPXgfuEFtzkfa5NCwHy-=U=x9jqVzwJ0+ch7Q@mail.gmail.com>
 <CAKQ1sVOOURoN=LbY+RgMFnGip=jhyMb8pXXgOKodEM1q+cCTnA@mail.gmail.com>
In-Reply-To: 
 <CAKQ1sVOOURoN=LbY+RgMFnGip=jhyMb8pXXgOKodEM1q+cCTnA@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit

On 03/02/2015 11:24 AM, Yann Ylavic wrote:
> I meant to reply to all...
 >
> On Mon, Mar 2, 2015 at 11:23 AM, Yann Ylavic <ylavic.dev@gmail.com> wrote:
>> On Mon, Mar 2, 2015 at 8:22 AM, Jan Kaluža <jkaluza@redhat.com> wrote:
>>> On 02/04/2015 02:53 PM, Jan Kaluža wrote:
>>>
>>>> httpd's mod_authn_dbd module currently seems to expect that lifetime of
>>>> apr_dbd_get_entry(...) result is the same as of the pool used in
>>>> apr_dbd_get_row(...) function.
>>
>> It seems that the result's lifetime is really the one of the row, but
>> mod_authn_dbd keep reading rows (sequentially) to cleanup the results
>> (before exiting the loop, probably for connection keepalive purpose).
>>
>>>>
>>>> But this is not a true for at least pgsql backend. Its get_entry
>>>> function returns "return PQgetvalue(row->res->res, row->n, n);".
>>>> Documentation for PQgetvalue says following:
>>>>
>>>> "One must explicitly copy the data into other storage if it is to be
>>>> used past the lifetime of the PGresult structure itself."
>>>>
>>>> res->res is also freed in dbd_pgsql_get_row(...).
>>
>> Only the results out-of-range are freed (wrt asked rownum), but not
>> the current one(s).
>>
>>>>
>>>> Is that correct behaviour and httpd's mod_authn_dbd module should strdup
>>>> the result, or is it apr_dbd, which should return result with expected
>>>> lifetime?
>>
>> I think the fix is to be mod_authn_dbd only, APR looks correct here,
>> and so is your patch.

Thanks for answer, I've committed it in r1663647.

>> Regards,
>> Yann.

Regards,
Jan Kaluza