test/host: checks for invalid fd handling

Check that we properly handle `dispatch` returning invalid fds and
that all fds are properly closed.

test/mod/test_host.py

@@ -4,6 +4,7 @@
 # Runtime Tests for Host Services
 #
 
+import errno
 import os
 import sys
 import tempfile
@@ -17,6 +18,13 @@ from osbuild.util.jsoncomm import FdSet
 
 class ServiceTest(host.Service):
 
+    def __init__(self, args):
+        super().__init__(args)
+        self.fds = []
+
+    def register_fds(self, fds):
+        self.fds.extend(fds)
+
     def dispatch(self, method: str, args: Any, fds: FdSet):
         ret = None
 
@@ -31,9 +39,28 @@ class ServiceTest(host.Service):
                     f.write(d.read())
                 f.seek(0)
                 fds = [os.dup(f.fileno())]
+                self.register_fds(fds)
 
         elif method == "identify":
             ret = self.id
+        elif method == "invalid-fd":
+            ret = []
+            with tempfile.TemporaryFile("w+") as f:
+                valid_fd = os.dup(f.fileno())
+            invalid_fd = valid_fd + 10
+            fds = [valid_fd, invalid_fd]
+            self.register_fds([valid_fd])
+        elif method == "check-fds-are-closed":
+            while self.fds:
+                fd = self.fds.pop()
+                try:
+                    os.close(fd)
+                except OSError as e:
+                    if e.errno == errno.EBADF:
+                        print(f"fd '{fd}' was closed")
+                        continue
+                    raise
+                raise ValueError(f"fd '{fd}' was not closed")
         else:
             raise host.ProtocolError("unknown method:", method)
 
@@ -79,6 +106,8 @@ def test_pass_fd():
             with os.fdopen(fds.steal(0)) as d:
                 assert data == d.read()
 
+            client.call_with_fds("check-fds-are-closed")
+
             remote_id = client.call("identify")
             assert remote_id == str(i)
 
@@ -90,6 +119,15 @@ def test_pass_fd():
             client.stop()
 
 
+def test_pass_fd_invalid():
+    with host.ServiceManager() as mgr:
+
+        client = mgr.start(str("test-invalid-fd"), __file__)
+        with pytest.raises(host.RemoteError):
+            client.call_with_fds("invalid-fd")
+        client.call_with_fds("check-fds-are-closed")
+
+
 def test_exception():
     with host.ServiceManager() as mgr:
         client = mgr.start("exception", __file__)