[ kernel people added to Cc ]
On Tue, Sep 16, 2008 at 02:27:36PM +0200, Daniel Gollub wrote:
> Hi,
>
> with 2.6.27-rc1(?) linux/dirent.h got removed Kbuild headers_install targe and
> dirent struct got removed:
>
>
> commit cf6ae8b50e0ee3f764392dadd1970e3f03c40773
> Author: Adrian Bunk <bunk@xxxxxxxxxx>
> Date: Fri Jul 25 01:46:46 2008 -0700
>
> remove the in-kernel struct dirent{,64}
>
> The kernel struct dirent{,64} were different from the ones in
> userspace.
>
> Even worse, we exported the kernel ones to userspace.
>
> But after the fat usages are fixed we can remove the conflicting
> kernel versions.
>
>
> This broke the build of some LTP syscalls testcases for "getdents", since the
> <linux/dirent.h> include is missing and the "internal" dirent struct get/got
> used in:
>
> testcases/kernel/syscalls/getdents/getdents01.c
> testcases/kernel/syscalls/getdents/getdents03.c
> testcases/kernel/syscalls/getdents/getdents02.c
> testcases/kernel/syscalls/getdents/getdents04.c
>
> http://ltp.cvs.sourceforge.net/ltp/ltp/testcases/kernel/syscalls/getdents/
>
> Is it safe to use the userspace dirent struct from <dirent.h> to fix the build
> of this? Or what should be used for testing the getdents interface instead?
Thanks for your report.
I missed this since the kernel sys_getdents() did not use the
"struct dirent" from the header but an own "struct linux_dirent".
It might be safe since the LTP tests don't seem to care whether
getdents() returns nonsense.
But it is not correct since the reason why I removed this struct from
the userspace headers was that the kernel and libc structs are
*different*.
E.g. when I enable the commented out code in getdents01.c I get the
expected result that using <dirent.h> instead of <linux/dirent.h>
changes a PASS into a FAIL. [1]
IMHO the solution is something like:
- move "struct linux_dirent" from fs/readdir.c to include/linux/dirent.h
- re-export linux/dirent.h to userspace
- change getdents(2) to consistently use "struct linux_dirent"
Questions to fsdevel:
- Do we need to preserve API compatibility with compatibility #define's
for struct dirent{,64} here?
- LTP does malloc(sizeof(struct dirent)).
Is this considered a valid API usage that must continue to work?
> best regards,
> Daniel
cu
Adrian
[1] I don't know whether the code is valid and guaranteed to pass,
but it's obvious why it fails after the #include change
--
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
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