Re: (ITS#3524) libldap multiple select() without reinitializing FD_SETs

[ando@sys-net.it]

>>According to the select(2) man page
>
> Is there any other reason for this change?  Especially as it
> applies to the timeout?
>
> On some systems, when EINTR is returned, the timeout is
> decreased by the waited time.  Otherwise, the amount of
> time waited across the original and all restarts could be much
> then the specified timeout.

I think this might be an issue, although I haven't understood yet if the
code actually needs to be fixed or not.  I recall reading that note, for
an unrelated project, and I decided to externally recompute the value of
the timeout and reinitialize the value to avoid any portability problem.

However, the issue might simply be in the wording of that sentence, which
sounds a bit obscure to me (but my English might not be fluent enough...):

       ...

       On Linux, the function select modifies timeout to  reflect
       the  amount  of time not slept; most other implementations
       do not do this.  This causes problems both when Linux code
       which  reads timeout is ported to other operating systems,
       and when code is ported to  Linux  that  reuses  a  struct
       timeval  for multiple selects in a loop without reinitial-
       izing it.  Consider timeout to be undefined  after  select
       returns.

       ...

I assume who wrote that couldn't be much clearer in such a short sentence,
but the last statement is what usually gets impressed.

p.

-- 
Pierangelo Masarati
mailto:pierangelo.masarati@sys-net.it


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