Sendfile on Solaris can raise EINVAL if offset is bigger than size of the file.
Because this would not send any data anyway, we can safely avoid calling this
function at all.

--- Python-3.8.0a3/Lib/socket.py
+++ Python-3.8.0a3/Lib/socket.py
@@ -301,6 +301,10 @@ class socket(_socket.socket):
                         blocksize = count - total_sent
                         if blocksize <= 0:
                             break
+                    # Sendfile on Solaris can raise EINVAL if offset >= size of the file.
+                    # In that case don't call it at all.
+                    elif offset >= fsize:
+                        break;
                     try:
                         sent = os_sendfile(sockno, fileno, offset, blocksize)
                     except BlockingIOError:
--- Python-3.8.0a3/Lib/asyncio/unix_events.py
+++ Python-3.8.0a3/Lib/asyncio/unix_events.py
@@ -357,6 +357,12 @@ class _UnixSelectorEventLoop(selector_ev
                 self._sock_sendfile_update_filepos(fileno, offset, total_sent)
                 fut.set_result(total_sent)
                 return
+        # Sendfile on Solaris can raise EINVAL if offset >= size of the file.
+        # In that case don't call it at all.
+        elif offset >= blocksize:
+            self._sock_sendfile_update_filepos(fileno, offset, total_sent)
+            fut.set_result(total_sent)
+            return
 
         try:
             sent = os.sendfile(fd, fileno, offset, blocksize)