core/service: use array rather than list for extra fds, limit max number

Follow-up for 3543456f84ec2e83e07b6c9bf2b3a1c5d30241d8

I don't think list is particularly useful here. The passed fds are
constant for the lifetime of service, and with this commit we track
the number of extra fds in a dedicated var anyway.

1 files changed, 8 insertions, 12 deletions

diff --git a/src/core/service.h b/src/core/service.h
index 504595b028..74b2b1c55e 100644
--- a/src/core/service.h
+++ b/src/core/service.h
@@ -115,8 +115,6 @@ struct ServiceFDStore {
 struct ServiceExtraFD {
         int fd;
         char *fdname;
-
-        LIST_FIELDS(ServiceExtraFD, extra_fd);
 };
 
 struct Service {
@@ -228,23 +226,24 @@ struct Service {
         unsigned n_fd_store_max;
         ExecPreserveMode fd_store_preserve_mode;
 
-        char *usb_function_descriptors;
-        char *usb_function_strings;
-
         int stdin_fd;
         int stdout_fd;
         int stderr_fd;
 
-        OOMPolicy oom_policy;
+        /* If service spawned from transient unit, extra file descriptors can be passed via dbus API */
+        ServiceExtraFD *extra_fds;
+        size_t n_extra_fds;
 
         LIST_HEAD(OpenFile, open_files);
 
-        /* If service spawned from transient unit, extra file descriptors can be passed via dbus API */
-        LIST_HEAD(ServiceExtraFD, extra_fds);
-
         int reload_signal;
         usec_t reload_begin_usec;
 
+        OOMPolicy oom_policy;
+
+        char *usb_function_descriptors;
+        char *usb_function_strings;
+
         /* The D-Bus request, we will reply once the operation is finished, so that callers can block */
         sd_bus_message *mount_request;
 };
@@ -306,6 +305,3 @@ DEFINE_CAST(SERVICE, Service);
 
 /* Only exported for unit tests */
 int service_deserialize_exec_command(Unit *u, const char *key, const char *value);
-
-ServiceExtraFD* service_extra_fd_free(ServiceExtraFD *efd);
-DEFINE_TRIVIAL_CLEANUP_FUNC(ServiceExtraFD*, service_extra_fd_free);