+int sd_bus_message_append_string_memfd(sd_bus_message *m, sd_memfd *memfd) {
+ _cleanup_close_ int copy_fd = -1;
+ struct bus_body_part *part;
+ struct bus_container *c;
+ uint64_t size;
+ void *a;
+ int r;
+
+ if (!m)
+ return -EINVAL;
+ if (!memfd)
+ return -EINVAL;
+ if (m->sealed)
+ return -EPERM;
+ if (m->poisoned)
+ return -ESTALE;
+
+ r = sd_memfd_set_sealed(memfd, true);
+ if (r < 0)
+ return r;
+
+ copy_fd = sd_memfd_dup_fd(memfd);
+ if (copy_fd < 0)
+ return copy_fd;
+
+ r = sd_memfd_get_size(memfd, &size);
+ if (r < 0)
+ return r;
+
+ /* We require this to be NUL terminated */
+ if (size == 0)
+ return -EINVAL;
+
+ if (size > (uint64_t) (uint32_t) -1)
+ return -EINVAL;
+
+ c = message_get_container(m);
+ if (c->signature && c->signature[c->index]) {
+ /* Container signature is already set */
+
+ if (c->signature[c->index] != SD_BUS_TYPE_STRING)
+ return -ENXIO;
+ } else {
+ char *e;
+
+ /* Maybe we can append to the signature? But only if this is the top-level container*/
+ if (c->enclosing != 0)
+ return -ENXIO;
+
+ e = strextend(&c->signature, CHAR_TO_STR(SD_BUS_TYPE_STRING), NULL);
+ if (!e) {
+ m->poisoned = true;
+ return -ENOMEM;
+ }
+ }
+
+ a = message_extend_body(m, 4, 4);
+ if (!a)
+ return -ENOMEM;
+
+ *(uint32_t*) a = size - 1;
+
+ part = message_append_part(m);
+ if (!part)
+ return -ENOMEM;
+
+ part->memfd = copy_fd;
+ part->sealed = true;
+ part->size = size;
+ copy_fd = -1;
+
+ message_extend_containers(m, size);
+ m->header->body_size += size;
+
+ if (c->enclosing != SD_BUS_TYPE_ARRAY)
+ c->index++;
+
+ return 0;
+}
+