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-rw-r--r--sys/kern/uipc_mbuf2.c277
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diff --git a/sys/kern/uipc_mbuf2.c b/sys/kern/uipc_mbuf2.c
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+/* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */
+
+/*
+ * Copyright (C) 1999 WIDE Project.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Copyright (c) 1982, 1986, 1988, 1991, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
+ */
+
+#define PULLDOWN_STAT
+/*#define PULLDOWN_DEBUG*/
+
+#ifdef PULLDOWN_STAT
+#if defined(__NetBSD__) || (defined(__FreeBSD__) && __FreeBSD__ >= 3)
+#include "opt_inet.h"
+#endif
+#endif
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/proc.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#if defined(PULLDOWN_STAT) && defined(INET6)
+#include <netinet/in.h>
+#include <netinet6/ip6.h>
+#include <netinet6/ip6_var.h>
+#endif
+
+/*
+ * ensure that [off, off + len) is contiguous on the mbuf chain "m".
+ * packet chain before "off" is kept untouched.
+ * if offp == NULL, the target will start at <retval, 0> on resulting chain.
+ * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
+ *
+ * on error return (NULL return value), original "m" will be freed.
+ *
+ * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
+ */
+struct mbuf *
+m_pulldown(m, off, len, offp)
+ struct mbuf *m;
+ int off, len;
+ int *offp;
+{
+ struct mbuf *n, *o;
+ int hlen, tlen, olen;
+ int sharedcluster;
+
+ /* check invalid arguments. */
+ if (m == NULL)
+ panic("m == NULL in m_pulldown()");
+ if (len > MCLBYTES) {
+ m_freem(m);
+ return NULL; /* impossible */
+ }
+
+#if defined(PULLDOWN_STAT) && defined(INET6)
+ ip6stat.ip6s_pulldown++;
+#endif
+
+#ifdef PULLDOWN_DEBUG
+ {
+ struct mbuf *t;
+ printf("before:");
+ for (t = m; t; t = t->m_next)
+ printf(" %d", t->m_len);
+ printf("\n");
+ }
+#endif
+ n = m;
+ while (n != NULL && off > 0) {
+ if (n->m_len > off)
+ break;
+ off -= n->m_len;
+ n = n->m_next;
+ }
+ if (!n) {
+ m_freem(m);
+ return NULL; /* mbuf chain too short */
+ }
+
+ /*
+ * the target data is on <n, off>.
+ * if we got enough data on the mbuf "n", we're done.
+ */
+ if ((off == 0 || offp) && len <= n->m_len - off)
+ goto ok;
+
+#if defined(PULLDOWN_STAT) && defined(INET6)
+ ip6stat.ip6s_pulldown_copy++;
+#endif
+
+ /*
+ * when len < n->m_len - off and off != 0, it is a special case.
+ * len bytes from <n, off> sits in single mbuf, but the caller does
+ * not like the starting position (off).
+ * chop the current mbuf into two pieces, set off to 0.
+ */
+ if (len < n->m_len - off) {
+ o = m_copym(n, off, n->m_len - off, M_DONTWAIT);
+ if (o == NULL) {
+ m_freem(m);
+ return NULL; /* ENOBUFS */
+ }
+ n->m_len = off;
+ o->m_next = n->m_next;
+ n->m_next = o;
+ n = n->m_next;
+ off = 0;
+ goto ok;
+ }
+
+ /*
+ * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
+ * and construct contiguous mbuf with m_len == len.
+ * note that hlen + tlen == len, and tlen > 0.
+ */
+ hlen = n->m_len - off;
+ tlen = len - hlen;
+
+ /*
+ * ensure that we have enough trailing data on mbuf chain.
+ * if not, we can do nothing about the chain.
+ */
+ olen = 0;
+ for (o = n->m_next; o != NULL; o = o->m_next)
+ olen += o->m_len;
+ if (hlen + olen < len) {
+ m_freem(m);
+ return NULL; /* mbuf chain too short */
+ }
+
+ /*
+ * easy cases first.
+ * we need to use m_copydata() to get data from <n->m_next, 0>.
+ */
+ if ((n->m_flags & M_EXT) == 0)
+ sharedcluster = 0;
+ else {
+#ifdef __bsdi__
+ if (n->m_ext.ext_func)
+#else
+ if (n->m_ext.ext_free)
+#endif
+ sharedcluster = 1;
+#ifdef __NetBSD__
+ else if (MCLISREFERENCED(n))
+#else
+ else if (mclrefcnt[mtocl(n->m_ext.ext_buf)] > 1)
+#endif
+ sharedcluster = 1;
+ else
+ sharedcluster = 0;
+ }
+ if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
+ && !sharedcluster) {
+ m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
+ n->m_len += tlen;
+ m_adj(n->m_next, tlen);
+ goto ok;
+ }
+ if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
+ && !sharedcluster) {
+ n->m_next->m_data -= hlen;
+ n->m_next->m_len += hlen;
+ bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
+ n->m_len -= hlen;
+ n = n->m_next;
+ off = 0;
+ goto ok;
+ }
+
+ /*
+ * now, we need to do the hard way. don't m_copy as there's no room
+ * on both end.
+ */
+#if defined(PULLDOWN_STAT) && defined(INET6)
+ ip6stat.ip6s_pulldown_alloc++;
+#endif
+ MGET(o, M_DONTWAIT, m->m_type);
+ if (o == NULL) {
+ m_freem(m);
+ return NULL; /* ENOBUFS */
+ }
+ if (len > MHLEN) { /* use MHLEN just for safety */
+ MCLGET(o, M_DONTWAIT);
+ if ((o->m_flags & M_EXT) == 0) {
+ m_freem(m);
+ m_free(o);
+ return NULL; /* ENOBUFS */
+ }
+ }
+ /* get hlen from <n, off> into <o, 0> */
+ o->m_len = hlen;
+ bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
+ n->m_len -= hlen;
+ /* get tlen from <n->m_next, 0> into <o, hlen> */
+ m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
+ o->m_len += tlen;
+ m_adj(n->m_next, tlen);
+ o->m_next = n->m_next;
+ n->m_next = o;
+ n = o;
+ off = 0;
+
+ok:
+#ifdef PULLDOWN_DEBUG
+ {
+ struct mbuf *t;
+ printf("after:");
+ for (t = m; t; t = t->m_next)
+ printf("%c%d", t == n ? '*' : ' ', t->m_len);
+ printf(" (off=%d)\n", off);
+ }
+#endif
+ if (offp)
+ *offp = off;
+ return n;
+}
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