+ w->begin = begin;
+ w->n_offsets = w->offsets_allocated = 0;
+ w->offsets = NULL;
+ w->need_offsets = need_offsets;
+
+ return 0;
+}
+
+static size_t determine_word_size(size_t sz, size_t extra) {
+ if (sz + extra <= 0xFF)
+ return 1;
+ else if (sz + extra*2 <= 0xFFFF)
+ return 2;
+ else if (sz + extra*4 <= 0xFFFFFFFF)
+ return 4;
+ else
+ return 8;
+}
+
+static size_t read_word_le(void *p, size_t sz) {
+ union {
+ uint16_t u16;
+ uint32_t u32;
+ uint64_t u64;
+ } x;
+
+ assert(p);
+
+ if (sz == 1)
+ return *(uint8_t*) p;
+
+ memcpy(&x, p, sz);
+
+ if (sz == 2)
+ return le16toh(x.u16);
+ else if (sz == 4)
+ return le32toh(x.u32);
+ else if (sz == 4)
+ return le64toh(x.u64);
+
+ assert_not_reached("unknown word width");
+}
+
+static void write_word_le(void *p, size_t sz, size_t value) {
+ union {
+ uint16_t u16;
+ uint32_t u32;
+ uint64_t u64;
+ } x;
+
+ assert(p);
+ assert(sz == 8 || (value < (1ULL << (sz*8))));
+
+ if (sz == 1) {
+ *(uint8_t*) p = value;
+ return;
+ } else if (sz == 2)
+ x.u16 = htole16((uint16_t) value);
+ else if (sz == 4)
+ x.u32 = htole32((uint32_t) value);
+ else if (sz == 8)
+ x.u64 = htole64((uint64_t) value);
+ else
+ assert_not_reached("unknown word width");
+
+ memcpy(p, &x, sz);
+}
+
+static int bus_message_close_array(sd_bus_message *m, struct bus_container *c) {
+
+ assert(m);
+ assert(c);
+
+ if (!BUS_MESSAGE_IS_GVARIANT(m))
+ return 0;
+
+ if (c->need_offsets) {
+ size_t payload, sz, i;
+ uint8_t *a;
+
+ /* Variable-width arrays */
+
+ payload = c->n_offsets > 0 ? c->offsets[c->n_offsets-1] - c->begin : 0;
+ sz = determine_word_size(payload, c->n_offsets);
+
+ a = message_extend_body(m, 1, sz * c->n_offsets, true);
+ if (!a)
+ return -ENOMEM;
+
+ for (i = 0; i < c->n_offsets; i++)
+ write_word_le(a + sz*i, sz, c->offsets[i] - c->begin);
+ } else {
+ void *a;
+
+ /* Fixed-width or empty arrays */
+
+ a = message_extend_body(m, 1, 0, true); /* let's add offset to parent */
+ if (!a)
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static int bus_message_close_variant(sd_bus_message *m, struct bus_container *c) {
+ uint8_t *a;
+ size_t l;
+
+ assert(m);
+ assert(c);
+
+ if (!BUS_MESSAGE_IS_GVARIANT(m))
+ return 0;
+
+ l = strlen(c->signature);
+
+ a = message_extend_body(m, 1, 1 + l, true);
+ if (!a)
+ return -ENOMEM;
+
+ a[0] = 0;
+ memcpy(a+1, c->signature, l);
+
+ return 0;
+}
+
+static int bus_message_close_struct(sd_bus_message *m, struct bus_container *c, bool add_offset) {
+ size_t n_variable = 0;
+ unsigned i = 0;
+ const char *p;
+ uint8_t *a;
+ int r;
+
+ assert(m);
+ assert(c);
+
+ if (!BUS_MESSAGE_IS_GVARIANT(m))
+ return 0;
+
+ p = strempty(c->signature);
+ while (*p != 0) {
+ size_t n;
+
+ r = signature_element_length(p, &n);
+ if (r < 0)
+ return r;
+ else {
+ char t[n+1];
+
+ memcpy(t, p, n);
+ t[n] = 0;
+
+ r = bus_gvariant_is_fixed_size(t);
+ if (r < 0)
+ return r;
+ }
+
+ assert(i <= c->n_offsets);
+
+ /* We need to add an offset for each item that has a
+ * variable size and that is not the last one in the
+ * list */
+ if (r == 0 && p[n] != 0)
+ n_variable++;
+
+ i++;
+ p += n;
+ }
+
+ assert(i == c->n_offsets);
+
+ if (n_variable <= 0) {
+ a = message_extend_body(m, 1, 0, add_offset);
+ if (!a)
+ return -ENOMEM;
+ } else {
+ size_t sz;
+ unsigned j;
+
+ assert(c->offsets[c->n_offsets-1] == m->header->body_size);
+
+ sz = determine_word_size(m->header->body_size - c->begin, n_variable);
+
+ a = message_extend_body(m, 1, sz * n_variable, add_offset);
+ if (!a)
+ return -ENOMEM;
+
+ p = strempty(c->signature);
+ for (i = 0, j = 0; i < c->n_offsets; i++) {
+ unsigned k;
+ size_t n;
+
+ r = signature_element_length(p, &n);
+ if (r < 0)
+ return r;
+ else {
+ char t[n+1];
+
+ memcpy(t, p, n);
+ t[n] = 0;
+
+ p += n;
+
+ r = bus_gvariant_is_fixed_size(t);
+ if (r < 0)
+ return r;
+ if (r > 0 || p[0] == 0)
+ continue;
+ }
+
+ k = n_variable - 1 - j;
+
+ write_word_le(a + k * sz, sz, c->offsets[i] - c->begin);
+
+ j++;
+ }
+ }