+/*
+ * Copy data from an mbuf chain starting "off" bytes from the beginning,
+ * continuing for "len" bytes, into the indicated buffer.
+ */
+m_copydata(m, off, len, cp)
+ register struct mbuf *m;
+ register int off;
+ register int len;
+ caddr_t cp;
+{
+ register unsigned count;
+
+ if (off < 0 || len < 0)
+ panic("m_copydata");
+ while (off > 0) {
+ if (m == 0)
+ panic("m_copydata");
+ if (off < m->m_len)
+ break;
+ off -= m->m_len;
+ m = m->m_next;
+ }
+ while (len > 0) {
+ if (m == 0)
+ panic("m_copydata");
+ count = MIN(m->m_len - off, len);
+ bcopy(mtod(m, caddr_t) + off, cp, count);
+ len -= count;
+ cp += count;
+ off = 0;
+ m = m->m_next;
+ }
+}
+
+/*
+ * Concatenate mbuf chain n to m.
+ * Both chains must be of the same type (e.g. MT_DATA).
+ * Any m_pkthdr is not updated.
+ */