FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf2.c

     /*      $FreeBSD: src/sys/kern/uipc_mbuf2.c,v 1.2.2.5 2003/01/23 21:06:44 sam Exp $     */
     /*      $DragonFly: src/sys/kern/uipc_mbuf2.c,v 1.15 2007/10/20 10:28:44 sephe Exp $    */
     /*      $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $     */
     /*      $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. 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_DEBUG*/
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/proc.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    
    MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information");
    
    /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
    static struct mbuf *m_dup1 (struct mbuf *, int, int, int);
    
    /*
     * 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(struct mbuf *m, int off, int 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 */
           }
   
   #ifdef PULLDOWN_DEBUG
       {
           struct mbuf *t;
           kprintf("before:");
           for (t = m; t; t = t->m_next)
                   kprintf(" %d", t->m_len);
           kprintf("\n");
       }
   #endif
           n = m;
           while (n != NULL && off > 0) {
                   if (n->m_len > off)
                           break;
                   off -= n->m_len;
                   n = n->m_next;
           }
           /* be sure to point non-empty mbuf */
           while (n != NULL && n->m_len == 0)
                   n = n->m_next;
           if (!n) {
                   m_freem(m);
                   return NULL;    /* mbuf chain too short */
           }
   
           sharedcluster = (m_sharecount(n) > 1);
   
           /*
            * 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 && !sharedcluster)
                   goto ok;
   
           /*
            * 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_dup1(n, off, n->m_len - off, MB_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 ((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.
            */
           o = m_getl(len, MB_DONTWAIT, m->m_type, 0, NULL);
           if (!o) {
                   m_freem(m);
                   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;
           kprintf("after:");
           for (t = m; t; t = t->m_next)
                   kprintf("%c%d", t == n ? '*' : ' ', t->m_len);
           kprintf(" (off=%d)\n", off);
       }
   #endif
           if (offp)
                   *offp = off;
           return n;
   }
   
   static struct mbuf *
   m_dup1(struct mbuf *m, int off, int len, int wait)
   {
           struct mbuf *n;
   
           if (len > MCLBYTES)
                   return NULL;
           n = m_getl(len, wait, m->m_type, m->m_flags, NULL);
           if (!n)
                   return NULL;
           if (off == 0 && (m->m_flags & M_PKTHDR) && !m_dup_pkthdr(n, m, wait)) {
                   m_free(n);
                   return NULL;
           }
           m_copydata(m, off, len, mtod(n, caddr_t));
           return n;
   }
   
   /* Get a packet tag structure along with specified data following. */
   struct m_tag *
   m_tag_alloc(uint32_t cookie, int type, int len, int wait)
   {
           struct m_tag *t;
   
           if (len < 0)
                   return NULL;
           t = kmalloc(len + sizeof(struct m_tag), M_PACKET_TAGS, MBTOM(wait));
           if (t == NULL)
                   return NULL;
           t->m_tag_id = type;
           t->m_tag_len = len;
           t->m_tag_cookie = cookie;
           return t;
   }
   
   
   /* Free a packet tag. */
   void
   m_tag_free(struct m_tag *t)
   {
           kfree(t, M_PACKET_TAGS);
   }
   
   /* Prepend a packet tag. */
   void
   m_tag_prepend(struct mbuf *m, struct m_tag *t)
   {
           KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t));
           KASSERT(m->m_flags & M_PKTHDR, ("m_tag_prepend: mbuf %p non-header", m));
           SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
   }
   
   /* Unlink a packet tag. */
   void
   m_tag_unlink(struct mbuf *m, struct m_tag *t)
   {
           KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t));
           KASSERT(m->m_flags & M_PKTHDR, ("m_tag_unlink: mbuf %p non-header", m));
           SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
   }
   
   /* Unlink and free a packet tag. */
   void
   m_tag_delete(struct mbuf *m, struct m_tag *t)
   {
           KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
           KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete: mbuf %p non-header", m));
           m_tag_unlink(m, t);
           m_tag_free(t);
   }
   
   /* Unlink and free a packet tag chain, starting from given tag. */
   void
   m_tag_delete_chain(struct mbuf *m)
   {
           struct m_tag *p, *q;
   
           KASSERT(m, ("m_tag_delete_chain: null mbuf"));
           KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete_chain: mbuf %p non-header", m));
           p = SLIST_FIRST(&m->m_pkthdr.tags);
           if (p == NULL)
                   return;
           while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
                   m_tag_delete(m, q);
           m_tag_delete(m, p);
   }
   
   /* Find a tag, starting from a given position. */
   struct m_tag *
   m_tag_locate(struct mbuf *m, uint32_t cookie, int type, struct m_tag *t)
   {
           struct m_tag *p;
   
           KASSERT(m, ("m_tag_find: null mbuf"));
           if (t == NULL)
                   p = SLIST_FIRST(&m->m_pkthdr.tags);
           else
                   p = SLIST_NEXT(t, m_tag_link);
           while (p != NULL) {
                   if (p->m_tag_cookie == cookie && p->m_tag_id == type)
                           return p;
                   p = SLIST_NEXT(p, m_tag_link);
           }
           return NULL;
   }
   
   /* Copy a single tag. */
   struct m_tag *
   m_tag_copy(struct m_tag *t, int how)
   {
           struct m_tag *p;
   
           KASSERT(t, ("m_tag_copy: null tag"));
           p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
           if (p == NULL)
                   return (NULL);
           bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
           return p;
   }
   
   /*
    * Copy two tag chains. The destination mbuf (to) loses any attached
    * tags even if the operation fails. This should not be a problem, as
    * m_tag_copy_chain() is typically called with a newly-allocated
    * destination mbuf.
    */
   int
   m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how)
   {
           struct m_tag *p, *t, *tprev = NULL;
   
           KASSERT(to && from,
                   ("m_tag_copy: null argument, to %p from %p", to, from));
           m_tag_delete_chain(to);
           SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
                   t = m_tag_copy(p, how);
                   if (t == NULL) {
                           m_tag_delete_chain(to);
                           return 0;
                   }
                   if (tprev == NULL)
                           SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
                   else {
                           SLIST_INSERT_AFTER(tprev, t, m_tag_link);
                           tprev = t;
                   }
           }
           return 1;
   }
   
   /* Initialize tags on an mbuf. */
   void
   m_tag_init(struct mbuf *m)
   {
           SLIST_INIT(&m->m_pkthdr.tags);
   }
   
   /* Get first tag in chain. */
   struct m_tag *
   m_tag_first(struct mbuf *m)
   {
           return SLIST_FIRST(&m->m_pkthdr.tags);
   }
   
   /* Get next tag in chain. */
   struct m_tag *
   m_tag_next(struct mbuf *m, struct m_tag *t)
   {
           return SLIST_NEXT(t, m_tag_link);
   }

Cache object: 2b1954795c90829a5acebaa5fbec4cff