[PATCH] set DEAD_PROCESS for died proccess with pid in utmp table

[Petr Lautrbach]

On 01/06/2011 11:10 AM, Scott James Remnant wrote:
> Why doesn't mingetty recreate the INIT_PROCESS record?

mingetty looks for INIT_PROCESS entry with same pid as itself. If it's not found
it creates new structure with LOGIN_PROCESS.



> On Thu, Jan 6, 2011 at 10:08 AM, Petr Lautrbach<plautrba at redhat.com>  wrote:
>> On 01/06/2011 08:38 AM, Scott James Remnant wrote:
>>>
>>> Could you explain the 3rd patch a bit more for me, how do you see the
>>> utmp entries working throughout the lifecycle - what would both
>>> Upstart and mingetty do?
>>>
>>
>> It's focused on respawning processes.
>>
>> There is no utmp entry when mingetty is run first time and mingetty sets it
>> itself
>> to LOGIN_PROCESS.
>> After mingetty's end this entry is set in job_process_terminated() to
>> DEAD_PROCES
>> and the job->utmp_id is set to value found in utmp table.
>> For respawning jobs this value stays in job structure for next
>> job_process_run().
>> It is used there for setting up UPSTART_UTMP_ID job environment variable
>> which is used in
>> job_process_spawn() to change DEAD_PROCESS utmp entry to INIT_PROCESS and
>> pid of new process.
>> So mingetty can find it and change it to LOGIN_PROCESS.
>>
>> Petr
>>
>>
>>> On Wed, Jan 5, 2011 at 3:36 PM, Petr Lautrbach<plautrba at redhat.com>
>>>   wrote:
>>>>
>>>> On 06/15/2010 04:39 PM, Petr Lautrbach wrote:
>>>>>
>>>>> Hello,
>>>>>
>>>>> Attached patch tries to fix #183729.
>>>>>
>>>>> If we assume that *getty takes care about setting
>>>>> INIT_PROCESS/LOGIN_PROCESS itself, we need
>>>>> just set DEAD_PROCESS for dead processes with pid in utmp table and log
>>>>> it
>>>>> into wtmp.
>>>>>
>>>>> Init goes through the utmp table, tries to find entry with dead process
>>>>> pid and sets it
>>>>> to DEAD_PROCESS. There is no need to create/set up "utmp" stanza.
>>>>>
>>>>> Test covers utmp table with 2 entries and with 2 situation - process is
>>>>> in
>>>>> LOGIN_PROCESS or USER_PROCESS.
>>>>>
>>>>
>>>> Hello.
>>>>
>>>> Sorry for very late response.
>>>>
>>>> There should not be setutxent() on job_process.c:1180. If there are more
>>>> than one record in utmp table then
>>>> it causes that only first entry will be overwritten every time. Attached
>>>> patch [1] adds test which covers this situation and
>>>> [2] removes this call.
>>>>
>>>> But this is not still ideal. It seems that mingetty doesn't use
>>>> DEAD_PROCESS
>>>> entry if it's not last entry in table.
>>>> So if there are some sequence of login/logout on various consoles utmp
>>>> will
>>>> grow. It's fixed by patch [3].
>>>> When utmp entry for dead process is found then job->utmp_id is set. When
>>>> new
>>>> process is spawned and job->utmp_id is set
>>>> then INIT_PROCESS utmp entry for its id is created. This works well for
>>>> respawning processes.
>>>>
>>>> [1] 0001-test-multiple-entries-with-same-ut_id.patch
>>>> [2] 0002-remove-setutxent-when-setting-DEAD_PROCESS.patch
>>>> [3] 0003-set-INIT_PROCESS-entry.patch
>>>>
>>>> Petr
>>>> --
>>>> Petr Lautrbach, Red Hat, Inc.
>>>>
>>>> --
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>>>>
>>>>
>>>
>>
>>
>> --
>> Petr Lautrbach, Red Hat, Inc.
>>
>


-- 
Petr Lautrbach, Red Hat, Inc.