+/* precondition: there must be something for us to write. */
+static int write_vec(xcb_connection_t *c, struct iovec **vector, int *count)
+{
+ int n;
+ assert(!c->out.queue_len);
+ n = writev(c->fd, *vector, *count);
+ if(n < 0 && errno == EAGAIN)
+ return 1;
+ if(n <= 0)
+ {
+ _xcb_conn_shutdown(c);
+ return 0;
+ }
+
+ for(; *count; --*count, ++*vector)
+ {
+ int cur = (*vector)->iov_len;
+ if(cur > n)
+ cur = n;
+ (*vector)->iov_len -= cur;
+ (*vector)->iov_base = (char *) (*vector)->iov_base + cur;
+ n -= cur;
+ if((*vector)->iov_len)
+ break;
+ }
+ if(!*count)
+ *vector = 0;
+ assert(n == 0);
+ return 1;
+}
+