tree-wide: introduce new SOCKADDR_UN_LEN() macro, and use it everywhere

The macro determines the right length of a AF_UNIX "struct sockaddr_un" to pass to
connect() or bind(). It automatically figures out if the socket refers to an
abstract namespace socket, or a socket in the file system, and properly handles
the full length of the path field.

This macro is not only safer, but also simpler to use, than the usual
offsetof() + strlen() logic.

2 files changed, 2 insertions, 4 deletions

diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c
index 04da94e7e3..ed5f94e136 100644
--- a/src/libsystemd/sd-bus/sd-bus.c
+++ b/src/libsystemd/sd-bus/sd-bus.c
@@ -836,7 +836,7 @@ static int parse_container_unix_address(sd_bus *b, const char **p, char **guid)
 
         b->sockaddr.un.sun_family = AF_UNIX;
         strncpy(b->sockaddr.un.sun_path, "/var/run/dbus/system_bus_socket", sizeof(b->sockaddr.un.sun_path));
-        b->sockaddr_size = offsetof(struct sockaddr_un, sun_path) + strlen("/var/run/dbus/system_bus_socket");
+        b->sockaddr_size = SOCKADDR_UN_LEN(b->sockaddr.un);
 
         return 0;
 }
diff --git a/src/libsystemd/sd-daemon/sd-daemon.c b/src/libsystemd/sd-daemon/sd-daemon.c
index bd1c7f15ff..4da9dbfd63 100644
--- a/src/libsystemd/sd-daemon/sd-daemon.c
+++ b/src/libsystemd/sd-daemon/sd-daemon.c
@@ -458,9 +458,7 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
         if (sockaddr.un.sun_path[0] == '@')
                 sockaddr.un.sun_path[0] = 0;
 
-        msghdr.msg_namelen = offsetof(struct sockaddr_un, sun_path) + strlen(e);
-        if (msghdr.msg_namelen > sizeof(struct sockaddr_un))
-                msghdr.msg_namelen = sizeof(struct sockaddr_un);
+        msghdr.msg_namelen = SOCKADDR_UN_LEN(sockaddr.un);
 
         have_pid = pid != 0 && pid != getpid();