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Re: [PATCH] Use offsetof instead of magic number in scandir()
- From: Sebastian Huber <sebastian dot huber at embedded-brains dot de>
- To: newlib at sourceware dot org
- Date: Thu, 28 Mar 2013 14:43:42 +0100
- Subject: Re: [PATCH] Use offsetof instead of magic number in scandir()
- References: <1364468303-7319-1-git-send-email-sebastian dot huber at embedded-brains dot de> <20130328111705 dot GI11431 at calimero dot vinschen dot de> <51542D28 dot 7020708 at embedded-brains dot de> <20130328124241 dot GK11431 at calimero dot vinschen dot de> <5154476E dot 6060604 at embedded-brains dot de>
On 03/28/2013 02:36 PM, Sebastian Huber wrote:
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.
Sorry, FreeBSD fixed also this bug, but slightly different.
--
Sebastian Huber, embedded brains GmbH
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