[PATCH][BZ 21340] add support for POSIX_SPAWN_SETSID

[Florian Weimer]

On 04/03/2017 09:35 PM, Adhemerval Zanella wrote:
>
>
> On 03/04/2017 16:12, Florian Weimer wrote:
>> On 04/01/2017 04:29 PM, daurnimator wrote:
>>> diff --git a/posix/spawn.h b/posix/spawn.h
>>> index 36e3867e17..8d2ace1b87 100644
>>> --- a/posix/spawn.h
>>> +++ b/posix/spawn.h
>>> @@ -60,6 +60,7 @@ typedef struct
>>>  #ifdef __USE_GNU
>>>  # define POSIX_SPAWN_USEVFORK        0x40
>>>  #endif
>>> +#define POSIX_SPAWN_SETSID        0x80
>>>
>>
>> Doesn't this add the flag to past POSIX versions?
>
> I do not think this is an issue since afaik POSIX does not state any
> constraint regarding the flags values [1].  For instance, the example
> library implementation uses spawn as example and just use constant
> different than glibc [2].

Sorry, this is not what I meant.  I was wondering if it was acceptable, 
from a namespace point of view, to define the constant unconditionally, 
or if we have to use a feature test macro here.

>> I wonder if we should add a new symbol version for posix_spawnattr_setflags, so that applications which do not perform error checking for the function call fail in a predictable manner.
>>
>
> I do not follow, which semantic difference are you proposing for
> posix_spawnattr_setflags that are not covered currently?

I'm worried about applications which ignore the error return value from 
posix_spawnattr_setflags, use POSIX_SPAWN_SETSID, and accidentally spawn 
processes with the wrong flags.

Thanks,
Florian