+
+/*
+ * Partition an mbuf chain in two pieces, returning the tail --
+ * all but the first len0 bytes. In case of failure, it returns NULL and
+ * attempts to restore the chain to its original state.
+ */
+struct mbuf *
+m_split(m0, len0, wait)
+ register struct mbuf *m0;
+ int len0, wait;
+{
+ register struct mbuf *m, *n;
+ unsigned len = len0, remain;
+
+ for (m = m0; m && len > m->m_len; m = m->m_next)
+ len -= m->m_len;
+ if (m == 0)
+ return (0);
+ remain = m->m_len - len;
+ if (m0->m_flags & M_PKTHDR) {
+ MGETHDR(n, wait, m0->m_type);
+ if (n == 0)
+ return (0);
+ n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
+ n->m_pkthdr.len = m0->m_pkthdr.len - len0;
+ m0->m_pkthdr.len = len0;
+ if (m->m_flags & M_EXT)
+ goto extpacket;
+ if (remain > MHLEN) {
+ /* m can't be the lead packet */
+ MH_ALIGN(n, 0);
+ n->m_next = m_split(m, len, wait);
+ if (n->m_next == 0) {
+ (void) m_free(n);
+ return (0);
+ } else
+ return (n);
+ } else
+ MH_ALIGN(n, remain);
+ } else if (remain == 0) {
+ n = m->m_next;
+ m->m_next = 0;
+ return (n);
+ } else {
+ MGET(n, wait, m->m_type);
+ if (n == 0)
+ return (0);
+ M_ALIGN(n, remain);
+ }
+extpacket:
+ if (m->m_flags & M_EXT) {
+ n->m_flags |= M_EXT;
+ n->m_ext = m->m_ext;
+ mclrefcnt[mtocl(m->m_ext.ext_buf)]++;
+ m->m_ext.ext_size = 0; /* For Accounting XXXXXX danger */
+ n->m_data = m->m_data + len;
+ } else {
+ bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
+ }
+ n->m_len = remain;
+ m->m_len = len;
+ n->m_next = m->m_next;
+ m->m_next = 0;
+ return (n);
+}
+/*
+ * Routine to copy from device local memory into mbufs.
+ */
+struct mbuf *
+m_devget(buf, totlen, off0, ifp, copy)
+ char *buf;
+ int totlen, off0;
+ struct ifnet *ifp;
+ void (*copy)();
+{
+ register struct mbuf *m;
+ struct mbuf *top = 0, **mp = ⊤
+ register int off = off0, len;
+ register char *cp;
+ char *epkt;
+
+ cp = buf;
+ epkt = cp + totlen;
+ if (off) {
+ cp += off + 2 * sizeof(u_short);
+ totlen -= 2 * sizeof(u_short);
+ }
+ MGETHDR(m, M_DONTWAIT, MT_DATA);
+ if (m == 0)
+ return (0);
+ m->m_pkthdr.rcvif = ifp;
+ m->m_pkthdr.len = totlen;
+ m->m_len = MHLEN;
+
+ while (totlen > 0) {
+ if (top) {
+ MGET(m, M_DONTWAIT, MT_DATA);
+ if (m == 0) {
+ m_freem(top);
+ return (0);
+ }
+ m->m_len = MLEN;
+ }
+ len = min(totlen, epkt - cp);
+ if (len >= MINCLSIZE) {
+ MCLGET(m, M_DONTWAIT);
+ if (m->m_flags & M_EXT)
+ m->m_len = len = min(len, MCLBYTES);
+ else
+ len = m->m_len;
+ } else {
+ /*
+ * Place initial small packet/header at end of mbuf.
+ */
+ if (len < m->m_len) {
+ if (top == 0 && len + max_linkhdr <= m->m_len)
+ m->m_data += max_linkhdr;
+ m->m_len = len;
+ } else
+ len = m->m_len;
+ }
+ if (copy)
+ copy(cp, mtod(m, caddr_t), (unsigned)len);
+ else
+ bcopy(cp, mtod(m, caddr_t), (unsigned)len);
+ cp += len;
+ *mp = m;
+ mp = &m->m_next;
+ totlen -= len;
+ if (cp == epkt)
+ cp = buf;
+ }
+ return (top);
+}
projects / unix-history / blobdiff