Close automatically created dup sockets

src/nemu/passfd.py

@@ -21,17 +21,17 @@ import struct
 from io import IOBase
 
 
-def __check_socket(sock: socket.socket | IOBase) -> socket.socket:
+def __check_socket(sock: socket.socket | IOBase) -> (socket.socket, bool):
     if hasattr(sock, 'family') and sock.family != socket.AF_UNIX:
         raise ValueError("Only AF_UNIX sockets are allowed")
 
     if hasattr(sock, 'fileno'):
-        sock = socket.fromfd(sock.fileno(), family=socket.AF_UNIX, type=socket.SOCK_STREAM)
+        return socket.fromfd(sock.fileno(), family=socket.AF_UNIX, type=socket.SOCK_STREAM), True
 
     if not isinstance(sock, socket.socket):
         raise TypeError("An socket object or file descriptor was expected")
 
-    return sock
+    return sock, False
 
 def __check_fd(fd) -> int:
     try:
@@ -46,7 +46,10 @@ def __check_fd(fd) -> int:
 
 def recvfd(sock: socket.socket | IOBase, msg_buf: int = 4096) -> tuple[int, str]:
     size = struct.calcsize("@i")
-    msg, ancdata, flags, addr = __check_socket(sock).recvmsg(msg_buf, socket.CMSG_SPACE(size))
+    sock, close = __check_socket(sock)
+    msg, ancdata, flags, addr = sock.recvmsg(msg_buf, socket.CMSG_SPACE(size))
+    if close:
+        sock.close()
     cmsg_level, cmsg_type, cmsg_data = ancdata[0]
     if not (cmsg_level == socket.SOL_SOCKET and cmsg_type == socket.SCM_RIGHTS):
         raise RuntimeError("The message received did not contain exactly one" +
@@ -60,6 +63,11 @@ def recvfd(sock: socket.socket | IOBase, msg_buf: int = 4096) -> tuple[int, str]
 
 
 def sendfd(sock: socket.socket | IOBase, fd: int, message: bytes = b"NONE") -> int:
-    return __check_socket(sock).sendmsg(
-        [message],
-        [(socket.SOL_SOCKET, socket.SCM_RIGHTS, struct.pack("@i", fd))])
+    sock, close = __check_socket(sock)
+    try:
+        return sock.sendmsg(
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+            [message],
+            [(socket.SOL_SOCKET, socket.SCM_RIGHTS, struct.pack("@i", fd))])
+    finally:
+        if close:
+            sock.close()
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