Re: sysconf & AIO_LISTIO_MAX

[Andreas Jaeger <aj at suse dot de>]

>>>>> Andreas Schwab writes:

 > Neale.Ferguson@SoftwareAG-USA.com writes:
 > |> On Linux, how do I interpret getting a -1 value from
 > |> sysconf(_SC_AIO_LISTIO_MAX) with a ERRNO of 0 (i.e. successful)? Does that
 > |> mean Linux has no limit?

 > It means that it is not supported.  From SUS2
 > (http://www.unix-systems.org/onlinepubs/007908799/xsh/sysconf.html):

 >  RETURN VALUE

 >      If name is an invalid value, sysconf() returns -1 and sets errno to
 >      indicate the error. If the variable corresponding to name is
 >      associated with functionality that is not supported by the system,
 >      sysconf() returns -1 without changing the value of errno.

Is the glibc manual correct here?  It confuses me:

From conf.texi:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@deftypefun {long int} sysconf (int @var{parameter})
This function is used to inquire about runtime system parameters.  The
@var{parameter} argument should be one of the @samp{_SC_} symbols listed
below.

The normal return value from @code{sysconf} is the value you requested.
A value of @code{-1} is returned both if the implementation does not
impose a limit, and in case of an error.

The following @code{errno} error conditions are defined for this function:

@table @code
@item EINVAL
The value of the @var{parameter} is invalid.
@end table
@end deftypefun
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj