+
+const char* bus_message_get_arg(sd_bus_message *m, unsigned i) {
+ int r;
+ const char *t;
+ char type;
+
+ assert(m);
+
+ r = sd_bus_message_rewind(m, true);
+ if (r < 0)
+ return NULL;
+
+ while (i > 0) {
+ r = sd_bus_message_peek_type(m, &type, NULL);
+ if (r < 0)
+ return NULL;
+
+ if (type != SD_BUS_TYPE_STRING &&
+ type != SD_BUS_TYPE_OBJECT_PATH &&
+ type != SD_BUS_TYPE_SIGNATURE)
+ return NULL;
+
+ r = sd_bus_message_read_basic(m, type, &t);
+ if (r < 0)
+ return NULL;
+
+ i--;
+ }
+
+ r = sd_bus_message_rewind(m, true);
+ if (r < 0)
+ return NULL;
+
+ return t;
+}
+
+int bus_header_size(struct bus_header *h, size_t *sum) {
+ size_t fs, bs;
+
+ assert(h);
+ assert(sum);
+
+ if (h->endian == SD_BUS_NATIVE_ENDIAN) {
+ fs = h->fields_size;
+ bs = h->body_size;
+ } else if (h->endian == SD_BUS_REVERSE_ENDIAN) {
+ fs = bswap_32(h->fields_size);
+ bs = bswap_32(h->body_size);
+ } else
+ return -EBADMSG;
+
+ *sum = sizeof(struct bus_header) + ALIGN8(fs) + bs;
+ return 0;
+}