iostat

[Steve Kargl]

On Wed, Aug 23, 2006 at 07:53:10PM +0200, Daniel Franke wrote:
> > void
> > iostat_to_msg(GFC_INTEGER_4 *iostat, char *msg, gfc_charlen_type len)
> > {
> >    strncpy(msg, strerror(*iostat), len-1);
> > }
> 
> Isn't this what the perror() extension is about? 
> It does not take iostat as argument, but works nevertheless ...
> 

libc perror() finds the error message corresponding to the 
current value of the global variable errno.  It may have
changed for example by any cleanup in gfortran's open()
that may occur after a failed libc open(2).

   str = 'Main: '
   open(unit=1, file='yada', iostat=i1)
   if (i1 /= 0) then
      call perror(str)  ! Does errno correspond to i1?
   end if

Additionally, the libc perror() writes to stderr.  For
whatever reason, a user may want to query for an error string 
and take evasive action

   if (i1 /= 0) then
      call iostat_to_msg(i1, msg)
      if (index(msg, 'not found') /= 0) then
         ! Do something about a missing file.
      else if (index(msg, 'permission') /= 0) then
         ! Change the permission if possible
         call chmod(...) ! Nonportable
      else
         ...
      end if
   end if

-- 
Steve