[PATCH] Use offsetof instead of magic number in scandir()

[Sebastian Huber]

On 03/28/2013 01:42 PM, Corinna Vinschen wrote:
> On Mar 28 12:44, Sebastian Huber wrote:
>> >On 03/28/2013 12:17 PM, Corinna Vinschen wrote:
>>> > >Shouldn't we better use the upstream version as used in FreeBSD and
>>> > >OpenBSD?
>>> > >
>>> > >   #define DIRSIZ(dp)                                                      \
>>> > >           ((sizeof(struct dirent) - sizeof(dp)->d_name) +                 \
>>> > >	      (((dp)->d_namlen + 1 + 3) &~ 3))
>> >
>> >I have problems to understand this expression.  What is
>> >"sizeof(dp)->d_name"? I think this looks like a hand-crafted
>> >offsetof variant.
> sizeof(dp)->d_name is sizeof((dp)->d_name), but without the lexically
> unnecessary parens.  I was just thinking that using the upstream
> version has the advnatage to use easier comparable code, given that
> our scandir.c is the BSD version anyway.

Ok, this makes sense.  Should I use the FreeBSD version of DIRSIZ() including 
its formatting?

http://svnweb.freebsd.org/base/head/lib/libc/gen/scandir.c?revision=202693&view=markup

It seems that the scandir() implementations diverged a bit.  In Newlib we have 
this bugfix:

commit c7ec1406e5abb6f1ec6363e1d13061934c1746e9
Author: Jeff Johnston <jjohnstn@redhat.com>
Date:   Mon Nov 24 20:42:33 2008 +0000

     2008-11-24  Joel Sherrill <joel.sherrill@oarcorp.com>

             * libc/posix/scandir.c: Fix memory leaks.

Maybe we should report this to the BSDs.

-- 
Sebastian Huber, embedded brains GmbH

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