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unix: use union to follow strict aliasing rules

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With strict-aliasing rules, a char* type can be cast to any other
pointer type. However, that does not necessarily mean char array
type. So instead of de-referencing a char array, use a union with an
additional char member for aliasing.

PR-URL: https://github.com/libuv/libuv/pull/1211
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>
This commit is contained in:
jBarz 2017-01-27 09:49:41 -05:00 committed by Saúl Ibarra Corretgé
parent f277cb6f92
commit d7cf771072
2 changed files with 15 additions and 6 deletions
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9
src/unix/stream.c
View File

@ -785,7 +785,12 @@ start:
struct msghdr msg;
struct cmsghdr *cmsg;
int fd_to_send = uv__handle_fd((uv_handle_t*) req->send_handle);
char scratch[64] = {0};
union {
char data[64];
struct cmsghdr alias;
} scratch;
memset(&scratch, 0, sizeof(scratch));
assert(fd_to_send >= 0);
@ -795,7 +800,7 @@ start:
msg.msg_iovlen = iovcnt;
msg.msg_flags = 0;
msg.msg_control = (void*) scratch;
msg.msg_control = &scratch.alias;
msg.msg_controllen = CMSG_SPACE(sizeof(fd_to_send));
cmsg = CMSG_FIRSTHDR(&msg);

12
src/unix/udp.c
View File

@ -349,7 +349,11 @@ out:
static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
int domain,
unsigned int flags) {
unsigned char taddr[sizeof(struct sockaddr_in6)];
union {
struct sockaddr_in6 in6;
struct sockaddr_in in;
struct sockaddr addr;
} taddr;
socklen_t addrlen;
if (handle->io_watcher.fd != -1)
@ -358,7 +362,7 @@ static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
switch (domain) {
case AF_INET:
{
struct sockaddr_in* addr = (void*)&taddr;
struct sockaddr_in* addr = &taddr.in;
memset(addr, 0, sizeof *addr);
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = INADDR_ANY;
@ -367,7 +371,7 @@ static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
}
case AF_INET6:
{
struct sockaddr_in6* addr = (void*)&taddr;
struct sockaddr_in6* addr = &taddr.in6;
memset(addr, 0, sizeof *addr);
addr->sin6_family = AF_INET6;
addr->sin6_addr = in6addr_any;
@ -379,7 +383,7 @@ static int uv__udp_maybe_deferred_bind(uv_udp_t* handle,
abort();
}
return uv__udp_bind(handle, (const struct sockaddr*) &taddr, addrlen, flags);
return uv__udp_bind(handle, &taddr.addr, addrlen, flags);
}