regression with jexec?

[Bjoern A. Zeeb]

On Sun, 26 Jul 2009, Kostik Belousov wrote:

> On Sat, Jul 25, 2009 at 09:06:34PM -0400, Michael Butler wrote:
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> Jamie Gritton wrote:
>>> Michael Butler wrote:
>>>> imb at aaron:/home/imb> sudo jexec 5 tcsh
>>>> jexec: Unable to parse jail ID.: No such file or directory
>>
>>>
>>> The symptom in jexec can be fixed by this little patch:
>>>
>>> Index: usr.sbin/jexec/jexec.c
>>> ===================================================================
>>> --- usr.sbin/jexec/jexec.c    (revision 195879)
>>> +++ usr.sbin/jexec/jexec.c    (working copy)
>>> @@ -248,6 +248,7 @@
>>>      if (argc < 2)
>>>          usage();
>>>      if (strlen(argv[0]) > 0) {
>>> +        errno = 0;
>>>          jid = (int)strtol(argv[0], NULL, 10);
>>>          if (errno)
>>>              err(1, "Unable to parse jail ID.");
>>
>> Thanks - this certainly cures the effect.
>>
>>> But the broader problem is malloc.  It's leaving errno set to
>>> ENOENT when /etc/malloc.conf doesn't exist.  This seems like
>>> wrong behavior to me.
>>
>> Seems like a POLA violation to me,
>
> No, this is how errno generally work, it is not changed if no error
> happens.

I haven't really understood which part, when and why would set the errno in
first place so that it would still be there?  Is it something in jexec
that gets the errno in first place or is it something internal to
malloc that sets it returns successfully and doesn't clear it?

-- 
Bjoern A. Zeeb                      The greatest risk is not taking one.