A NOTE has been added to this issue.
==
https://austingroupbugs.net/view.php?id=1396
==
Reported By:rillig
Assigned To:
Steffen Nurpmeso wrote, on 01 Sep 2020:
>
> |Do the existing implementations ever return such things? Do they
> |hide them by making the reclen of the previous entry (if there is
> |one in the buffer) bigger, or do they squash them out, moving the
> |next existing entry down to follow
Wojtek Lerch wrote, on 01 Sep 2020:
>
> Geoff Clare wrote:
> > We can't require d_name in struct dirent to be a VLA since there are
> > implementations where it is not.
>
> Another good reason is that standard C does not allow structure members to be
> VLAs.
Mea culpa. I tried to save some
Philip Guenther wrote, on 01 Sep 2020:
>
> If a posix_getdents() implementation returned the names of all the files
> that ever existed in the given directory, including ones that were removed
> before the fd for this call was opened, what requirement in the standard
> would that violate? I don't
That example still has a byte of added padding, or the offsetof would be 5. The
sizeof value is just incorrect, as it assumes one flex member is present. It
should be 5 or 6, and which is the required value is what is ambiguous.
As you say, these are used most often with malloc(). Padding
Wojtek Lerch via austin-group-l at The Open Group
wrote:
> A structure member can be a "flexible array" in standard C, but that's not
> the same thing as a VLA.
Are you speaking about array[] in contrast to array[size] with size being a
variable?
Jörg
--
EMail:jo...@schily.net
Steffen Nurpmeso via austin-group-l at The Open Group
wrote:
> I personally would say that these should be skipped. The data is
> copied over to user buffers, and these entries are simply not
> copied. That seems to be the best. The Group does not seem to
> want to add DT_WHITEOUT or similar
Yes I made the flexible member a "short" on purpose -- I wanted that byte of
padding before the flexible array.
No, the sizeof can't be 5 or 6 unless the implementation is okay with unaligned
access. If I declare an array of these structs, the int32 inside each element
needs to be aligned
On 2020-09-02 10:34, Joerg Schilling wrote:
Wojtek Lerch via austin-group-l at The Open Group
wrote:
A structure member can be a "flexible array" in standard C, but that's not the
same thing as a VLA.
Are you speaking about array[] in contrast to array[size] with size being a
variable?
No, it does not need to be aligned to a multiple of 4, except on some lame RISC
architectures. The logical model is unaligned accesses are always permitted;
aligned accesses are the exception, not the rule. This is why the language is
padding bytes may be added, not shall be added. The
Hallo Jörg.
Joerg Schilling wrote in
<5f4fabb0.NZ6ZB9gXMVdfs/6x%joerg.schill...@fokus.fraunhofer.de>:
|Steffen Nurpmeso via austin-group-l at The Open Group wrote:
|
|> I personally would say that these should be skipped. The data is
|> copied over to user buffers, and these entries are
Philip Guenther via austin-group-l at The Open Group wrote in
:
|On Tue, Sep 1, 2020 at 1:20 PM Steffen Nurpmeso wrote:
|> Philip Guenther wrote in
|> :
|>|On Tue, Sep 1, 2020 at 6:22 AM Steffen Nurpmeso via austin-group-l at The
|>|Open Group wrote:
|>|> Robert Elz via austin-group-l at
On Thu, 2020-09-03 at 00:31 +, shwaresyst wrote:
> No, it does not need to be aligned to a multiple of 4, except on some
> lame RISC architectures. The logical model is unaligned accesses are
> always permitted; aligned accesses are the exception, not the rule.
No, the logical model is that
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