Re: Syslets, Threadlets, generic AIO support, v6

From: Ulrich Drepper
Date: Wed May 30 2007 - 17:18:38 EST


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Linus Torvalds wrote:
> for (i = 0; i < NR_OPEN; i++)
> close(i);
>
> to clean up all file descriptors before doing something new. And yes, I
> think it was bash that used to *literally* do something like that a long
> time ago.

Indeed. It was not only bash, though, I fixed probably a dozen
applications. But even the new and better solution (readdir of
/proc/self/fd) does not prevent the problem of closing descriptors the
system might still need and the application doesn't know about.


> Which *could* be something as simple as saying "bit 30 in the file
> descriptor specifies a separate fd space" along with some flags to make
> open and friends return those separate fd's.

I don't like special cases. For me things better come in quantities 0,
1, and unlimited (well, reasonable high limit). Otherwise, who gets to
use that special namespace? The C library is not the only body of code
which would want to use descriptors.

And then the semantics: do these descriptors should show up in
/proc/self/fd? Are there separate directories for each namespace? Do
they count against the rlimit?

This seems to me like a shot from the hips without thinking about other
possibilities.

- --
â Ulrich Drepper â Red Hat, Inc. â 444 Castro St â Mountain View, CA â
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