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Re: [patch, libgfortran] PR31052 Bad IOSTAT values when readings NAMELISTs past EOF

On Sat, Mar 10, 2007 at 08:57:19AM -0800, Jerry DeLisle wrote:
> Steve Kargl wrote:
> >On Fri, Mar 09, 2007 at 11:45:33PM -0800, Jerry DeLisle wrote:
> >>I would rather keep the patch as I have it and leave dev_null.f90 alone.  
> >>In this case we are user proofing.  st_rewind is simply seeking to 
> >>position zero of the file and then resetting all the internal libgfortran 
> >>accounting stuff. /dev/null is a "special seekable" file.
> >>
> >>I have also tested this on an empty file and it works OK for that.  The 
> >>adjustment in the patch occurs well after all the rewind stuff is done.
> >>
> >>I will await approval.
> >>
> >
> >I have you tested with /dev/zero and /dev/random?
> >
> I had not, but now I have and the test_endfile does not "work" for a rewind 
> on these.  In other words, I get an EOF condition on a read following a 
> rewind.  It seems that the whole concept is askew.  The /dev/null is 
> defined to always give an EOF on a read.  The others should never give an 
> EOF.
> I want to give this some thinking time.  The OS should give the correct 
> response and rewind should ideally have no effect.  I think I should 
> address why it does have an effect now, with or without test_endfile.
> In the interim, I would like to fix the original PR by eliminating 
> test_endfile and open a new PR related to the behavior of these special 
> devices.
> Is there agreement on this?


The handling of special files (and fifo and pipes) is probably
a messy system dependent pit.

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