Re: [libvirt] [PATCH] Fix cast errors with clang

On 10/18/2014 10:41 AM, Roman Bogorodskiy wrote: > Build with clang fails with: > > CC util/libvirt_util_la-virsocketaddr.lo > util/virsocketaddr.c:904:17: error: cast from 'struct sockaddr *' to > 'struct sockaddr_in *' increases required alignment from 1 to 4 > [-Werror,-Wcast-align] > inet4 = (struct sockaddr_in*) res->ai_addr; > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > util/virsocketaddr.c:909:17: error: cast from 'struct sockaddr *' to > 'struct sockaddr_in6 *' increases required alignment from 1 to 4 > [-Werror,-Wcast-align] > inet6 = (struct sockaddr_in6*) res->ai_addr; > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 2 errors generated. > > Fix by introducing a union of the appropriate sturcts. s/sturcts/structs/ > --- > src/util/virsocketaddr.c | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > diff --git a/src/util/virsocketaddr.c b/src/util/virsocketaddr.c > index 5f54e68..162108c 100644 > --- a/src/util/virsocketaddr.c > +++ b/src/util/virsocketaddr.c > @@ -892,22 +892,25 @@ virSocketAddrIsNumericLocalhost(const char *addr) > { > struct addrinfo *res; > struct in_addr tmp = { .s_addr = htonl(INADDR_LOOPBACK) }; > - struct sockaddr_in *inet4; > - struct sockaddr_in6 *inet6; > + union { > + struct sockaddr *addr; > + struct sockaddr_in *inet4; > + struct sockaddr_in6 *inet6; > + } sa; Close, but not quite. The POSIX solution for this is the sockaddr_storage type, in <sys/socket.h>. You shouldn't need to create your own union, but instead reuse sockaddr_storage.