From: Christian Brauner <christian@brauner.io>
To: Florian Weimer <fweimer@redhat.com>
Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
linux-kernel@vger.kernel.org, dhowells@redhat.com,
linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org,
shuah@kernel.org, linux-arch@vger.kernel.org,
linux-s390@vger.kernel.org, miklos@szeredi.hu, x86@kernel.org,
torvalds@linux-foundation.org, linux-mips@vger.kernel.org,
linux-xtensa@linux-xtensa.org, tkjos@android.com, arnd@arndb.de,
jannh@google.com, linux-m68k@lists.linux-m68k.org,
viro@zeniv.linux.org.uk, tglx@linutronix.de, ldv@altlinux.org,
linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org, linux-api@vger.kernel.org,
oleg@redhat.com, linux-alpha@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/2] open: add close_range()
Date: Tue, 21 May 2019 13:23:23 +0000 [thread overview]
Message-ID: <20190521132252.y5wt7d7o4bdjns4e@brauner.io> (raw)
In-Reply-To: <87h89o9cng.fsf@oldenburg2.str.redhat.com>
On Tue, May 21, 2019 at 03:10:11PM +0200, Florian Weimer wrote:
> * Christian Brauner:
>
> >> Solaris has an fdwalk function:
> >>
> >> <https://docs.oracle.com/cd/E88353_01/html/E37843/closefrom-3c.html>
> >>
> >> So a different way to implement this would expose a nextfd system call
> >
> > Meh. If nextfd() then I would like it to be able to:
> > - get the nextfd(fd) >= fd
> > - get highest open fd e.g. nextfd(-1)
>
> The highest open descriptor isn't istering for fdwalk because nextfd
> would just fail.
Sure. I was thinking about other usecases. For example, sometimes in
userspace you want to do the following:
save_fd = dup(fd, <well-known-number-at-the-end-of-the-range);
close_range(3, (save_fd - 1));
Which brings me to another point. So even if we don't do close_range() I
would like libc to maybe give us something like close_range() for such
scenarios.
>
> > But then I wonder if nextfd() needs to be a syscall and isn't just
> > either:
> > fcntl(fd, F_GET_NEXT)?
> > or
> > prctl(PR_GET_NEXT)?
>
> I think the fcntl route is a bit iffy because you might need it to get
> the *first* valid descriptor.
>
> >> to userspace, so that we can use that to implement both fdwalk and
> >> closefrom. But maybe fdwalk is just too obscure, given the existence of
> >> /proc.
> >
> > Yeah we probably don't need fdwalk.
>
> Agreed. Just wanted to bring it up for completeness. I certainly don't
> want to derail the implementation of close_range.
>
> Thanks,
> Florian
WARNING: multiple messages have this Message-ID (diff)
From: Christian Brauner <christian@brauner.io>
To: Florian Weimer <fweimer@redhat.com>
Cc: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
jannh@google.com, oleg@redhat.com, tglx@linutronix.de,
torvalds@linux-foundation.org, arnd@arndb.de, shuah@kernel.org,
dhowells@redhat.com, tkjos@android.com, ldv@altlinux.org,
miklos@szeredi.hu, linux-alpha@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org,
linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org,
linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH 1/2] open: add close_range()
Date: Tue, 21 May 2019 15:23:23 +0200 [thread overview]
Message-ID: <20190521132252.y5wt7d7o4bdjns4e@brauner.io> (raw)
In-Reply-To: <87h89o9cng.fsf@oldenburg2.str.redhat.com>
On Tue, May 21, 2019 at 03:10:11PM +0200, Florian Weimer wrote:
> * Christian Brauner:
>
> >> Solaris has an fdwalk function:
> >>
> >> <https://docs.oracle.com/cd/E88353_01/html/E37843/closefrom-3c.html>
> >>
> >> So a different way to implement this would expose a nextfd system call
> >
> > Meh. If nextfd() then I would like it to be able to:
> > - get the nextfd(fd) >= fd
> > - get highest open fd e.g. nextfd(-1)
>
> The highest open descriptor isn't istering for fdwalk because nextfd
> would just fail.
Sure. I was thinking about other usecases. For example, sometimes in
userspace you want to do the following:
save_fd = dup(fd, <well-known-number-at-the-end-of-the-range);
close_range(3, (save_fd - 1));
Which brings me to another point. So even if we don't do close_range() I
would like libc to maybe give us something like close_range() for such
scenarios.
>
> > But then I wonder if nextfd() needs to be a syscall and isn't just
> > either:
> > fcntl(fd, F_GET_NEXT)?
> > or
> > prctl(PR_GET_NEXT)?
>
> I think the fcntl route is a bit iffy because you might need it to get
> the *first* valid descriptor.
>
> >> to userspace, so that we can use that to implement both fdwalk and
> >> closefrom. But maybe fdwalk is just too obscure, given the existence of
> >> /proc.
> >
> > Yeah we probably don't need fdwalk.
>
> Agreed. Just wanted to bring it up for completeness. I certainly don't
> want to derail the implementation of close_range.
>
> Thanks,
> Florian
WARNING: multiple messages have this Message-ID (diff)
From: Christian Brauner <christian@brauner.io>
To: Florian Weimer <fweimer@redhat.com>
Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
linux-kernel@vger.kernel.org, dhowells@redhat.com,
linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org,
shuah@kernel.org, linux-arch@vger.kernel.org,
linux-s390@vger.kernel.org, miklos@szeredi.hu, x86@kernel.org,
torvalds@linux-foundation.org, linux-mips@vger.kernel.org,
linux-xtensa@linux-xtensa.org, tkjos@android.com, arnd@arndb.de,
jannh@google.com, linux-m68k@lists.linux-m68k.org,
viro@zeniv.linux.org.uk, tglx@linutronix.de, ldv@altlinux.org,
linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org, linux-api@vger.kernel.org,
oleg@redhat.com, linux-alpha@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/2] open: add close_range()
Date: Tue, 21 May 2019 15:23:23 +0200 [thread overview]
Message-ID: <20190521132252.y5wt7d7o4bdjns4e@brauner.io> (raw)
In-Reply-To: <87h89o9cng.fsf@oldenburg2.str.redhat.com>
On Tue, May 21, 2019 at 03:10:11PM +0200, Florian Weimer wrote:
> * Christian Brauner:
>
> >> Solaris has an fdwalk function:
> >>
> >> <https://docs.oracle.com/cd/E88353_01/html/E37843/closefrom-3c.html>
> >>
> >> So a different way to implement this would expose a nextfd system call
> >
> > Meh. If nextfd() then I would like it to be able to:
> > - get the nextfd(fd) >= fd
> > - get highest open fd e.g. nextfd(-1)
>
> The highest open descriptor isn't istering for fdwalk because nextfd
> would just fail.
Sure. I was thinking about other usecases. For example, sometimes in
userspace you want to do the following:
save_fd = dup(fd, <well-known-number-at-the-end-of-the-range);
close_range(3, (save_fd - 1));
Which brings me to another point. So even if we don't do close_range() I
would like libc to maybe give us something like close_range() for such
scenarios.
>
> > But then I wonder if nextfd() needs to be a syscall and isn't just
> > either:
> > fcntl(fd, F_GET_NEXT)?
> > or
> > prctl(PR_GET_NEXT)?
>
> I think the fcntl route is a bit iffy because you might need it to get
> the *first* valid descriptor.
>
> >> to userspace, so that we can use that to implement both fdwalk and
> >> closefrom. But maybe fdwalk is just too obscure, given the existence of
> >> /proc.
> >
> > Yeah we probably don't need fdwalk.
>
> Agreed. Just wanted to bring it up for completeness. I certainly don't
> want to derail the implementation of close_range.
>
> Thanks,
> Florian
WARNING: multiple messages have this Message-ID (diff)
From: christian at brauner.io (Christian Brauner)
Subject: [PATCH 1/2] open: add close_range()
Date: Tue, 21 May 2019 15:23:23 +0200 [thread overview]
Message-ID: <20190521132252.y5wt7d7o4bdjns4e@brauner.io> (raw)
In-Reply-To: <87h89o9cng.fsf@oldenburg2.str.redhat.com>
On Tue, May 21, 2019 at 03:10:11PM +0200, Florian Weimer wrote:
> * Christian Brauner:
>
> >> Solaris has an fdwalk function:
> >>
> >> <https://docs.oracle.com/cd/E88353_01/html/E37843/closefrom-3c.html>
> >>
> >> So a different way to implement this would expose a nextfd system call
> >
> > Meh. If nextfd() then I would like it to be able to:
> > - get the nextfd(fd) >= fd
> > - get highest open fd e.g. nextfd(-1)
>
> The highest open descriptor isn't istering for fdwalk because nextfd
> would just fail.
Sure. I was thinking about other usecases. For example, sometimes in
userspace you want to do the following:
save_fd = dup(fd, <well-known-number-at-the-end-of-the-range);
close_range(3, (save_fd - 1));
Which brings me to another point. So even if we don't do close_range() I
would like libc to maybe give us something like close_range() for such
scenarios.
>
> > But then I wonder if nextfd() needs to be a syscall and isn't just
> > either:
> > fcntl(fd, F_GET_NEXT)?
> > or
> > prctl(PR_GET_NEXT)?
>
> I think the fcntl route is a bit iffy because you might need it to get
> the *first* valid descriptor.
>
> >> to userspace, so that we can use that to implement both fdwalk and
> >> closefrom. But maybe fdwalk is just too obscure, given the existence of
> >> /proc.
> >
> > Yeah we probably don't need fdwalk.
>
> Agreed. Just wanted to bring it up for completeness. I certainly don't
> want to derail the implementation of close_range.
>
> Thanks,
> Florian
WARNING: multiple messages have this Message-ID (diff)
From: christian@brauner.io (Christian Brauner)
Subject: [PATCH 1/2] open: add close_range()
Date: Tue, 21 May 2019 15:23:23 +0200 [thread overview]
Message-ID: <20190521132252.y5wt7d7o4bdjns4e@brauner.io> (raw)
Message-ID: <20190521132323.GhH49TPlTwXn6TTf6pkS7eSKVyZgg-3x7UyrlqBwa4M@z> (raw)
In-Reply-To: <87h89o9cng.fsf@oldenburg2.str.redhat.com>
On Tue, May 21, 2019@03:10:11PM +0200, Florian Weimer wrote:
> * Christian Brauner:
>
> >> Solaris has an fdwalk function:
> >>
> >> <https://docs.oracle.com/cd/E88353_01/html/E37843/closefrom-3c.html>
> >>
> >> So a different way to implement this would expose a nextfd system call
> >
> > Meh. If nextfd() then I would like it to be able to:
> > - get the nextfd(fd) >= fd
> > - get highest open fd e.g. nextfd(-1)
>
> The highest open descriptor isn't istering for fdwalk because nextfd
> would just fail.
Sure. I was thinking about other usecases. For example, sometimes in
userspace you want to do the following:
save_fd = dup(fd, <well-known-number-at-the-end-of-the-range);
close_range(3, (save_fd - 1));
Which brings me to another point. So even if we don't do close_range() I
would like libc to maybe give us something like close_range() for such
scenarios.
>
> > But then I wonder if nextfd() needs to be a syscall and isn't just
> > either:
> > fcntl(fd, F_GET_NEXT)?
> > or
> > prctl(PR_GET_NEXT)?
>
> I think the fcntl route is a bit iffy because you might need it to get
> the *first* valid descriptor.
>
> >> to userspace, so that we can use that to implement both fdwalk and
> >> closefrom. But maybe fdwalk is just too obscure, given the existence of
> >> /proc.
> >
> > Yeah we probably don't need fdwalk.
>
> Agreed. Just wanted to bring it up for completeness. I certainly don't
> want to derail the implementation of close_range.
>
> Thanks,
> Florian
WARNING: multiple messages have this Message-ID (diff)
From: Christian Brauner <christian@brauner.io>
To: Florian Weimer <fweimer@redhat.com>
Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
linux-kernel@vger.kernel.org, dhowells@redhat.com,
linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org,
shuah@kernel.org, linux-arch@vger.kernel.org,
linux-s390@vger.kernel.org, miklos@szeredi.hu, x86@kernel.org,
torvalds@linux-foundation.org, linux-mips@vger.kernel.org,
linux-xtensa@linux-xtensa.org, tkjos@android.com, arnd@arndb.de,
jannh@google.com, linux-m68k@lists.linux-m68k.org,
viro@zeniv.linux.org.uk, tglx@linutronix.de, ldv@altlinux.org,
linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org, linux-api@vger.kernel.org,
oleg@redhat.com, linux-alpha@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/2] open: add close_range()
Date: Tue, 21 May 2019 15:23:23 +0200 [thread overview]
Message-ID: <20190521132252.y5wt7d7o4bdjns4e@brauner.io> (raw)
In-Reply-To: <87h89o9cng.fsf@oldenburg2.str.redhat.com>
On Tue, May 21, 2019 at 03:10:11PM +0200, Florian Weimer wrote:
> * Christian Brauner:
>
> >> Solaris has an fdwalk function:
> >>
> >> <https://docs.oracle.com/cd/E88353_01/html/E37843/closefrom-3c.html>
> >>
> >> So a different way to implement this would expose a nextfd system call
> >
> > Meh. If nextfd() then I would like it to be able to:
> > - get the nextfd(fd) >= fd
> > - get highest open fd e.g. nextfd(-1)
>
> The highest open descriptor isn't istering for fdwalk because nextfd
> would just fail.
Sure. I was thinking about other usecases. For example, sometimes in
userspace you want to do the following:
save_fd = dup(fd, <well-known-number-at-the-end-of-the-range);
close_range(3, (save_fd - 1));
Which brings me to another point. So even if we don't do close_range() I
would like libc to maybe give us something like close_range() for such
scenarios.
>
> > But then I wonder if nextfd() needs to be a syscall and isn't just
> > either:
> > fcntl(fd, F_GET_NEXT)?
> > or
> > prctl(PR_GET_NEXT)?
>
> I think the fcntl route is a bit iffy because you might need it to get
> the *first* valid descriptor.
>
> >> to userspace, so that we can use that to implement both fdwalk and
> >> closefrom. But maybe fdwalk is just too obscure, given the existence of
> >> /proc.
> >
> > Yeah we probably don't need fdwalk.
>
> Agreed. Just wanted to bring it up for completeness. I certainly don't
> want to derail the implementation of close_range.
>
> Thanks,
> Florian
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-05-21 13:23 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 11:34 [PATCH 1/2] open: add close_range() Christian Brauner
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` christian
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` [PATCH 2/2] tests: add close_range() tests Christian Brauner
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` Christian Brauner
2019-05-21 11:34 ` christian
2019-05-21 11:34 ` Christian Brauner
2019-05-21 12:09 ` [PATCH 1/2] open: add close_range() Florian Weimer
2019-05-21 12:09 ` Florian Weimer
2019-05-21 12:09 ` Florian Weimer
2019-05-21 12:09 ` Florian Weimer
2019-05-21 12:09 ` Florian Weimer
2019-05-21 12:09 ` fweimer
2019-05-21 12:09 ` Florian Weimer
2019-05-21 13:04 ` Christian Brauner
2019-05-21 13:04 ` Christian Brauner
2019-05-21 13:04 ` Christian Brauner
2019-05-21 13:04 ` Christian Brauner
2019-05-21 13:04 ` Christian Brauner
2019-05-21 13:04 ` christian
2019-05-21 13:04 ` Christian Brauner
2019-05-21 13:10 ` Florian Weimer
2019-05-21 13:10 ` Florian Weimer
2019-05-21 13:10 ` Florian Weimer
2019-05-21 13:10 ` Florian Weimer
2019-05-21 13:10 ` fweimer
2019-05-21 13:10 ` Florian Weimer
2019-05-21 13:18 ` Christian Brauner
2019-05-21 13:18 ` Christian Brauner
2019-05-21 13:18 ` Christian Brauner
2019-05-21 13:18 ` Christian Brauner
2019-05-21 13:18 ` christian
2019-05-21 13:18 ` Christian Brauner
2019-05-21 13:23 ` Christian Brauner [this message]
2019-05-21 13:23 ` Christian Brauner
2019-05-21 13:23 ` Christian Brauner
2019-05-21 13:23 ` christian
2019-05-21 13:23 ` Christian Brauner
2019-05-21 13:23 ` Christian Brauner
2019-05-21 13:07 ` Marc Gonzalez
2019-05-21 13:12 ` Christian Brauner
2019-05-21 13:39 ` Rasmus Villemoes
2019-05-21 15:00 ` Al Viro
2019-05-21 15:00 ` Al Viro
2019-05-21 15:00 ` Al Viro
2019-05-21 15:00 ` Al Viro
2019-05-21 15:00 ` viro
2019-05-21 15:00 ` Al Viro
2019-05-21 16:53 ` Christian Brauner
2019-05-21 16:53 ` Christian Brauner
2019-05-21 16:53 ` Christian Brauner
2019-05-21 16:53 ` Christian Brauner
2019-05-21 16:53 ` christian
2019-05-21 16:53 ` Christian Brauner
2019-05-21 16:30 ` David Howells
2019-05-21 16:30 ` David Howells
2019-05-21 16:30 ` David Howells
2019-05-21 16:30 ` David Howells
2019-05-21 16:30 ` dhowells
2019-05-21 16:30 ` David Howells
2019-05-21 16:41 ` Christian Brauner
2019-05-21 16:41 ` Christian Brauner
2019-05-21 16:41 ` Christian Brauner
2019-05-21 16:41 ` Christian Brauner
2019-05-21 16:41 ` christian
2019-05-21 16:41 ` Christian Brauner
2019-05-21 20:23 ` Linus Torvalds
2019-05-21 20:23 ` Linus Torvalds
2019-05-21 20:23 ` Linus Torvalds
2019-05-21 20:23 ` Linus Torvalds
2019-05-21 20:23 ` Linus Torvalds
2019-05-21 20:23 ` torvalds
2019-05-21 20:23 ` Linus Torvalds
2019-05-21 20:23 ` Linus Torvalds
2019-05-22 8:12 ` Christian Brauner
2019-05-22 8:12 ` Christian Brauner
2019-05-22 8:12 ` Christian Brauner
2019-05-22 8:12 ` Christian Brauner
2019-05-22 8:12 ` Christian Brauner
2019-05-22 8:12 ` Christian Brauner
2019-05-22 8:12 ` christian
2019-05-22 8:12 ` Christian Brauner
2019-05-21 19:20 ` Al Viro
2019-05-21 19:20 ` Al Viro
2019-05-21 19:20 ` Al Viro
2019-05-21 19:20 ` Al Viro
2019-05-21 19:20 ` viro
2019-05-21 19:20 ` Al Viro
2019-05-21 19:59 ` Matthew Wilcox
2019-05-21 19:59 ` Matthew Wilcox
2019-05-21 19:59 ` Matthew Wilcox
2019-05-21 19:59 ` willy
2019-05-21 19:59 ` Matthew Wilcox
2019-05-21 19:59 ` Matthew Wilcox
2019-05-24 20:32 ` Michael Tirado
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