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Re: [PATCH] libio: Avoid dup already opened file descriptor [BZ#21393]
On Friday 19 May 2017 01:13 AM, Adhemerval Zanella wrote:
> I think for BZ#21393 we won't get any sufficient conforming implementation
> with proper kernel help or without relaxing the POSIX definition to also
> allow this kind of errno. So I still think that checking for EBUSY and
> returning it is still the correct approach. Specially because for the cases
> where it fails then application might still seeing spurious issue due freopen
> returning a valid return code but without dupping correctly the file
> descriptor.
OK, then this would require a NEWS item declaring that freopen behaviour
is fixed and that its failure can now also set errno as EBUSY. Maybe
the man page needs updating as well.
> Also I think for proper underlying kernel support it would potentially
> require dup3 to indefinitely block (which still be even more troublesome due
> underlying FS like NFS that might timeout). I would require to extend dup3
> semantic, possible making it a cancelable entrypoint, and imho I think kernel
> won't take this path lightly.
They don't.
Siddhesh