[avahi] arm memory alignment problems

[Trent Lloyd]

On Fri, Sep 23, 2005 at 10:53:50AM +0200, pHilipp Zabel wrote:
> Hi Lennart,
> 
> On 9/22/05, Lennart Poettering <lennart at poettering.de> wrote:
> > The corresponding code looks like this:
> >
> > <snip>
> > uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v)
> > {
> >     uint8_t *d;
> >     assert(p);
> >
> >     if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
> >         return NULL;
> >
> >     *((uint32_t*) d) = htonl(v);  /** SIGBUS HERE **/
> >
> >     return d;
> > }
> > </snip>
> >
> > The pointer d is not necessarily aligned to 32bit multiples. The fix
> > is easy: just write all four bytes of the uint32_t value seperately
> > and manually to the memory d points to.
> 
> Do you mean something like this?
> 
> uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) {
>     uint8_t *d;
>     uint32_t tmp_v;
>     assert(p);
> 
>     if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
>         return NULL;
> 
>     tmp_v = htonl(v);
>     d[0] = tmp_v & 0xFF000000 >> 24;
>     d[1] = tmp_v & 0xFF0000 >> 16;
>     d[2] = tmp_v & 0xFF00 >> 8;
>     d[3] = tmp_v & 0xFF;
> 
>     return d;
> }

Well, I have no idea if this is correct, but it seems to work, does it
work on arm?

Trent

> 
> > lathiat showed some interest in fixing this?
> 
> --
> Philipp
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-- 
Trent Lloyd <lathiat at bur.st>
Bur.st Networking Inc.