[Buildroot] [PATCH] package/systemd: importd broken on Sourcery CodeBench ARM 2014.05
Yann E. MORIN
yann.morin.1998 at free.fr
Sun Aug 28 14:36:47 UTC 2016
Thomas, All,
On 2016-08-28 09:29 +0200, Thomas Petazzoni spake thusly:
> > > * Add a workaround in the systemd code to define O_TMPFILE to the
> > > proper value when not provided by the C library.
> >
> > At the same time, I'm not really happy with patching systemd...
> >
> > O_TMPFILE is not the same value on all archs: generic, alpha, parisc and
> > sparc.
>
> I must say I still don't understand the overlap of the kernel headers
> and glibc here.
>
> In the kernel, we have:
>
> include/uapi/asm-generic/fcntl.h:#define __O_TMPFILE 020000000
>
> In glibc, we have:
>
> sysdeps/unix/sysv/linux/bits/fcntl-linux.h:# define __O_TMPFILE (020000000 | __O_DIRECTORY)
>
> Which is not even the same value.
Ah, I got the answer to that one! :-)
O_TMPFILE is defined as such to be sure to break at runtime on old
kernels that do not have O_TMPFILE, becasue open() silently ignores
unknown flags. So, a userland app may request O_TMPFILE but silently not
get it:
https://lwn.net/Articles/558940/
> I'd still say that patching systemd is the easiest solution, and we
> will be able to remove this patch once we get rid of those too old
> toolchains (which we will have to do at some point, when they become
> too annoying / irrelevant).
Fact is, upstream has a missing.h header that defines O_TMPFILE if not
already defined.
But they do it only for __i386__ and __x86_64__:
https://github.com/systemd/systemd/blob/master/src/basic/missing.h#L540
So the fix will be two-fold:
- use missing.h from importd,
- enhance missing.h to also define O_TMPFILE for other archs.
I'll be doing that shortly (first already done).
Regards,
Yann E. MORIN.
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