Load service configuration files with long names

Previously they were skipped.

Fixes: QubesOS/qubes-issues#9099

Author: DemiMarie

libqrexec/exec.c

@@ -278,7 +278,7 @@ static int load_service_config_raw(struct qrexec_parsed_command *cmd,
     if (!config_path)
         config_path = QUBES_RPC_CONFIG_PATH;
 
-    char config_full_path[256];
+    char config_full_path[QUBES_SOCKADDR_UN_MAX_PATH_LEN];
 
     int ret = find_file(config_path, cmd->service_descriptor,
                         config_full_path, sizeof(config_full_path), NULL);

qrexec/tests/socket/agent.py

@@ -409,7 +409,6 @@ def test_exec_service_with_config(self):
 
     def test_wait_for_session(self):
         self._test_wait_for_session("qubes.Service+arg")
-    @unittest.expectedFailure
     def test_wait_for_session_huge_path(self):
         l = 255 - len("qubes.Service+")
         arg = l * "a"