More OSX debugging info

Author: asomers

src/sys/socket/mod.rs

@@ -452,8 +452,12 @@ impl<'a> Iterator for CmsgIterator<'a> {
                 // Advance the internal pointer.  Safe if mhdr and cmsghdr point
                 // to valid data returned by recvmsg(2)
                 self.cmsghdr = unsafe {
+                    println!("CMSG_NXRHDR({:?} len={:?})", hdr as *const _, hdr.cmsg_len);
+                    let pad = mem::align_of::<libc::cmsghdr>() - 1;
+                    println!("    pad={:?}", pad);
+                    println!("    next={:x}", hdr as *const _ as usize + hdr.cmsg_len as usize + pad & !pad);
                     let p = CMSG_NXTHDR(self.mhdr as *const _, hdr as *const _);
-                    println!("Next cmsg @ {:?}", p);
+                    println!("    Next cmsg @ {:?}", p);
                     p.as_ref()
                 };
                 cm