...

src/calibre/srv/sendfile.py

@@ -11,7 +11,7 @@ from io import DEFAULT_BUFFER_SIZE
 from select import select
 
 from calibre.constants import iswindows, isosx
-from calibre.utils.ipc import eintr_retry_call
+from calibre.srv.utils import eintr_retry_call
 
 def file_metadata(fileobj):
     try:

src/calibre/srv/utils.py

@@ -165,3 +165,12 @@ def create_sock_pair(port=0):
         client_sock.setblocking(True)
 
     return client_sock, srv_sock
+
+def eintr_retry_call(func, *args, **kwargs):
+    while True:
+        try:
+            return func(*args, **kwargs)
+        except EnvironmentError as e:
+            if getattr(e, 'errno', None) in socket_error_eintr:
+                continue
+            raise