RE: Again: Runtime system doesn't notice changed file descriptor status

On 20 January 2005 00:49, Volker Wysk wrote:

> However, I'd still expect "hClose stdin" to actually close the file
> descriptor. I've taken a look at the hClose implementation. It's
> problematic not to actually close any standard file descriptors. For
> instance, some process might be reading the standard output of a
> Haskell program. When that program calls "hClose stdout", the
> process' read will block, rather than succeed with zero bytes read
> (EOF). The process won't notice that the program has finished
> outputting, until the program terminates. Imagine a case where a
> program outputs some status messages and then forks into demon mode,
> closing its standard file descriptors in order to detach itself from
> the terminal. I'm wondering if there's any particular reason for not
> actually closing the standard file descriptors. 

I see your point.  I don't know why hClose doesn't actually close the
std file descriptors - that bit of code was inherited from the previous
incarnation of the IO library.

Unless anyone can think of a good reason why not, I'll remove that
restriction and make hClose work on stdin, stdout, and stderr.  Be
careful not to do this under GHCi, though!

Cheers,
        Simon