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Re: Linux Extended-stat system call
- From: Arnd Bergmann <arnd at arndb dot de>
- To: libc-alpha at sourceware dot org
- Cc: Florian Weimer <fweimer at redhat dot com>, David Howells <dhowells at redhat dot com>
- Date: Wed, 22 Jun 2016 18:03:27 +0200
- Subject: Re: Linux Extended-stat system call
- Authentication-results: sourceware.org; auth=none
- References: <32208 dot 1466604507 at warthog dot procyon dot org dot uk> <19673f8e-6bec-c4dc-0390-76d294e51bee at redhat dot com>
On Wednesday, June 22, 2016 5:03:43 PM CEST Florian Weimer wrote:
> On 06/22/2016 04:08 PM, David Howells wrote:
>
> > One thing I would like to do is make it so that stat() can use it with minimal
> > effort.
>
> Why is this an important goal?
>
> Existing architectures will keep using the old system call for the
> legacy stat interfaces. New architectures can use the new system call,
> but will probably have a different definition of struct stat (which
> might well be guided by our experience with the extended stat interface).
For the y2038 work, we have to replace the stat system call on all 32-bit
architectures (and mips64, which uses 32-bit st_mtime). We can do this
by adding just a new version of the fstatat() syscall to the kernel that
matches the ABI of the 64-bit architectures, or by mapping everything
onto the new xstat.
Adding just one new syscall entry point instead of two simplifies the
kernel implementation quite a bit, but if there are good reasons for
still providing a new fstatat version, we could do that too.
Arnd