Date: Sun, 23 Jun 2002 21:06:15 +0200 From: Bernd Walter <ticso@cicely5.cicely.de> To: Christian Weisgerber <naddy@mips.inka.de> Cc: freebsd-alpha@FreeBSD.ORG Subject: Re: -CURRENT: UA in locate Message-ID: <20020623190614.GW53233@cicely5.cicely.de> In-Reply-To: <af4u6m$21cu$1@kemoauc.mips.inka.de> References: <af4u6m$21cu$1@kemoauc.mips.inka.de>
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On Sun, Jun 23, 2002 at 04:49:26PM +0000, Christian Weisgerber wrote:
> The locate(1) command throws unaligned access errors in -CURRENT.
> This has probably been triggered by the switch to gcc 3.1.
>
> Here's a diff with extended context to show what's going on:
>
> Index: util.c
> ===================================================================
> RCS file: /cvs/src/usr.bin/locate/locate/util.c,v
> retrieving revision 1.9
> diff -u -U9 -r1.9 util.c
> --- util.c 22 Mar 2002 01:22:48 -0000 1.9
> +++ util.c 23 Jun 2002 16:33:24 -0000
> @@ -225,19 +225,19 @@
> * Convert network byte order to host byte order if neccessary.
> * So we can read on FreeBSD/i386 (little endian) a locate database
> * which was built on SunOS/sparc (big endian).
> */
>
> int
> getwm(p)
> caddr_t p;
> {
> - static char buf[INTSIZE];
> + char buf[INTSIZE];
> register int i;
>
> for (i = 0; i < INTSIZE; i++)
> buf[i] = *p++;
>
> i = *(int *)buf;
>
> if (i > MAXPATHLEN || i < -(MAXPATHLEN)) {
> i = ntohl(i);
> ===================================================================
>
> Apparently the author assumed that buf[] would be properly aligned,
> so that dereferencing an integer pointer would be safe. I'm at a
> loss how somebody can arrive at this assumption for a static object.
> For an automatic variable on the other hand it is a reasonable
> guess.
>
> Is that fix okay, or should we play games with "int buf; (char *)&buf"?
The fix doesn't change the alignment contraints.
Either make it a union with a stronger aligned type or malloc() it.
But malloc'ing just an int is silly.
It's used as an int later so it should be either be a union with an
int or just an int and cast inside the loop as you already wrote.
--
B.Walter COSMO-Project http://www.cosmo-project.de
ticso@cicely.de Usergroup info@cosmo-project.de
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