[avahi] arm memory alignment problems

[pHilipp Zabel]

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;
}

> lathiat showed some interest in fixing this?

--
Philipp