socket-util: introduce type-safe, dereferencing wrapper CMSG_FIND_DATA around cmsg_find()

let's take this once step further, and add type-safety to cmsg_find(),
and imply the CMSG_DATA() macro for finding the cmsg payload.

1 files changed, 2 insertions, 11 deletions

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index cc2f1521ff..c2148596b7 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -3698,8 +3698,7 @@ static int nspawn_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t r
                 .msg_control = &control,
                 .msg_controllen = sizeof(control),
         };
-        struct cmsghdr *cmsg;
-        struct ucred *ucred = NULL;
+        struct ucred *ucred;
         ssize_t n;
         pid_t inner_child_pid;
         _cleanup_strv_free_ char **tags = NULL;
@@ -3721,15 +3720,7 @@ static int nspawn_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t r
 
         cmsg_close_all(&msghdr);
 
-        CMSG_FOREACH(cmsg, &msghdr) {
-                if (cmsg->cmsg_level == SOL_SOCKET &&
-                           cmsg->cmsg_type == SCM_CREDENTIALS &&
-                           cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) {
-
-                        ucred = (struct ucred*) CMSG_DATA(cmsg);
-                }
-        }
-
+        ucred = CMSG_FIND_DATA(&msghdr, SOL_SOCKET, SCM_CREDENTIALS, struct ucred);
         if (!ucred || ucred->pid != inner_child_pid) {
                 log_debug("Received notify message without valid credentials. Ignoring.");
                 return 0;