Eric Blake wrote:
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.
Casting from sockaddr to sockaddr_storage still produces an error with clang. However, I was reading the related code and noticed a similar union in the virSocketAddr type, so I decided to use that instead; that also allowed to reduce size of the code a little. Roman Bogorodskiy