On 04/03/2013 09:06 AM, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
>
> To avoid
>
> virportallocatortest.c: In function 'bind':
> virportallocatortest.c:34:33: warning: cast increases required alignment of target type [-Wcast-align]
> struct sockaddr_in *saddr = (struct sockaddr_in *)addr;
> ^
>
> Signed-off-by: Daniel P. Berrange <berrange@xxxxxxxxxx>
> ---
> tests/virportallocatortest.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/tests/virportallocatortest.c b/tests/virportallocatortest.c
> index 9931e11..1935602 100644
> --- a/tests/virportallocatortest.c
> +++ b/tests/virportallocatortest.c
> @@ -31,12 +31,14 @@ int bind(int sockfd ATTRIBUTE_UNUSED,
> const struct sockaddr *addr,
> socklen_t addrlen ATTRIBUTE_UNUSED)
> {
> - struct sockaddr_in *saddr = (struct sockaddr_in *)addr;
> + struct sockaddr_in saddr;
Hmm. POSIX requires that apps use sockaddr_storage to guarantee
alignment before downcasting to struct sockaddr_in or further down to
struct sockaddr. But since we are providing a replacement bind(), and
POSIX doesn't give us any way to specify that 'struct sockaddr' in our
signature should have been aligned as struct sockaddr_storage by any
sane caller, we're stuck playing realignment games, or else using a pragma.
>
> - if (saddr->sin_port == htons(5900) ||
> - saddr->sin_port == htons(5904) ||
> - saddr->sin_port == htons(5905) ||
> - saddr->sin_port == htons(5906)) {
> + memcpy(&saddr, addr, sizeof(saddr));
Since this is just test code, performance doesn't matter, and using
memcpy() for the realignment game makes sense.
ACK.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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