Subject: Re: implementing closeall via a syscall
To: mouss <firstname.lastname@example.org>
From: Matt Thomas <email@example.com>
Date: 01/05/2004 14:47:21
At 02:28 PM 1/5/2004, you wrote:
>- As of now, fcntl seems to be the right way, adding both a closem and a
>maxfd commands. Thanks Matt for your comments. So I'm gonna go for that
>and update the manpage accordingly. I'll probably also try to do this on
>other *bsd (dragonfly, free, open) just to go for the "convergence project":-)
Note that the diffs have already been applied to NetBSD. :)
>- at user level, I suggest adding closefrom() and fdwalk() for solaris
>compatibility, closeall() replacement, and an ifdef bit of code for
>portability. a closem() call (with ebadf as an error) doesn't seem needed,
>or is it? (we could return the "worst" error from the close's).
closefrom/fdwalk seem fine from a compatibility area. closem
doesn't seem to be needed.
>- Andrew: I don't have a solaris at hands, so I can't confirm, but...
>- Matt: After some analysis, I came back to my original code.
>Indeed, the fdrelease(p, fdp->fd_lastfile) suffers an infinite loop if
>fdrelease fails. So it's better to call fdrelease on an already closed fd.
>Otherwise, we'd need an <if (i> fd_lastfile) i=fd_last> test, which is
>suboptimal in the "normal" case (when all the fd's ranging from k to N are
>open), when it's better to fdrelease even if fd is not open. Or did I miss
>something? (I realize that I should have kept a "natural" loop [from i=f
>to max], but now that we are in, we gotta find the right way:).
fdrelease can't fail. it will always close the descriptor. So there is no
Matt Thomas email: firstname.lastname@example.org
3am Software Foundry www: http://3am-software.com/bio/matt/
Cupertino, CA disclaimer: I avow all knowledge of this message.