Annotation of sys/kern/uipc_mbuf2.c, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: uipc_mbuf2.c,v 1.28 2007/03/17 09:26:35 art Exp $ */
! 2: /* $KAME: uipc_mbuf2.c,v 1.29 2001/02/14 13:42:10 itojun Exp $ */
! 3: /* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */
! 4:
! 5: /*
! 6: * Copyright (C) 1999 WIDE Project.
! 7: * All rights reserved.
! 8: *
! 9: * Redistribution and use in source and binary forms, with or without
! 10: * modification, are permitted provided that the following conditions
! 11: * are met:
! 12: * 1. Redistributions of source code must retain the above copyright
! 13: * notice, this list of conditions and the following disclaimer.
! 14: * 2. Redistributions in binary form must reproduce the above copyright
! 15: * notice, this list of conditions and the following disclaimer in the
! 16: * documentation and/or other materials provided with the distribution.
! 17: * 3. Neither the name of the project nor the names of its contributors
! 18: * may be used to endorse or promote products derived from this software
! 19: * without specific prior written permission.
! 20: *
! 21: * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
! 22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 24: * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
! 25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 31: * SUCH DAMAGE.
! 32: */
! 33:
! 34: /*
! 35: * Copyright (c) 1982, 1986, 1988, 1991, 1993
! 36: * The Regents of the University of California. All rights reserved.
! 37: *
! 38: * Redistribution and use in source and binary forms, with or without
! 39: * modification, are permitted provided that the following conditions
! 40: * are met:
! 41: * 1. Redistributions of source code must retain the above copyright
! 42: * notice, this list of conditions and the following disclaimer.
! 43: * 2. Redistributions in binary form must reproduce the above copyright
! 44: * notice, this list of conditions and the following disclaimer in the
! 45: * documentation and/or other materials provided with the distribution.
! 46: * 3. Neither the name of the University nor the names of its contributors
! 47: * may be used to endorse or promote products derived from this software
! 48: * without specific prior written permission.
! 49: *
! 50: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 51: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 52: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 53: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 54: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 55: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 56: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 57: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 58: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 59: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 60: * SUCH DAMAGE.
! 61: *
! 62: * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
! 63: */
! 64:
! 65: #include <sys/param.h>
! 66: #include <sys/systm.h>
! 67: #include <sys/proc.h>
! 68: #include <sys/malloc.h>
! 69: #include <sys/mbuf.h>
! 70:
! 71: /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
! 72: static struct mbuf *m_dup1(struct mbuf *, int, int, int);
! 73:
! 74: /*
! 75: * ensure that [off, off + len] is contiguous on the mbuf chain "m".
! 76: * packet chain before "off" is kept untouched.
! 77: * if offp == NULL, the target will start at <retval, 0> on resulting chain.
! 78: * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
! 79: *
! 80: * on error return (NULL return value), original "m" will be freed.
! 81: *
! 82: * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
! 83: */
! 84: struct mbuf *
! 85: m_pulldown(struct mbuf *m, int off, int len, int *offp)
! 86: {
! 87: struct mbuf *n, *o;
! 88: int hlen, tlen, olen;
! 89: int sharedcluster;
! 90:
! 91: /* check invalid arguments. */
! 92: if (m == NULL)
! 93: panic("m == NULL in m_pulldown()");
! 94: if (len > MCLBYTES) {
! 95: m_freem(m);
! 96: return (NULL); /* impossible */
! 97: }
! 98:
! 99: n = m;
! 100: while (n != NULL && off > 0) {
! 101: if (n->m_len > off)
! 102: break;
! 103: off -= n->m_len;
! 104: n = n->m_next;
! 105: }
! 106: /* be sure to point non-empty mbuf */
! 107: while (n != NULL && n->m_len == 0)
! 108: n = n->m_next;
! 109: if (!n) {
! 110: m_freem(m);
! 111: return (NULL); /* mbuf chain too short */
! 112: }
! 113:
! 114: sharedcluster = M_READONLY(n);
! 115:
! 116: /*
! 117: * the target data is on <n, off>.
! 118: * if we got enough data on the mbuf "n", we're done.
! 119: */
! 120: if ((off == 0 || offp) && len <= n->m_len - off && !sharedcluster)
! 121: goto ok;
! 122:
! 123: /*
! 124: * when len <= n->m_len - off and off != 0, it is a special case.
! 125: * len bytes from <n, off> sits in single mbuf, but the caller does
! 126: * not like the starting position (off).
! 127: * chop the current mbuf into two pieces, set off to 0.
! 128: */
! 129: if (len <= n->m_len - off) {
! 130: struct mbuf *mlast;
! 131:
! 132: o = m_dup1(n, off, n->m_len - off, M_DONTWAIT);
! 133: if (o == NULL) {
! 134: m_freem(m);
! 135: return (NULL); /* ENOBUFS */
! 136: }
! 137: for (mlast = o; mlast->m_next != NULL; mlast = mlast->m_next)
! 138: ;
! 139: n->m_len = off;
! 140: mlast->m_next = n->m_next;
! 141: n->m_next = o;
! 142: n = o;
! 143: off = 0;
! 144: goto ok;
! 145: }
! 146:
! 147: /*
! 148: * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
! 149: * and construct contiguous mbuf with m_len == len.
! 150: * note that hlen + tlen == len, and tlen > 0.
! 151: */
! 152: hlen = n->m_len - off;
! 153: tlen = len - hlen;
! 154:
! 155: /*
! 156: * ensure that we have enough trailing data on mbuf chain.
! 157: * if not, we can do nothing about the chain.
! 158: */
! 159: olen = 0;
! 160: for (o = n->m_next; o != NULL; o = o->m_next)
! 161: olen += o->m_len;
! 162: if (hlen + olen < len) {
! 163: m_freem(m);
! 164: return (NULL); /* mbuf chain too short */
! 165: }
! 166:
! 167: /*
! 168: * easy cases first.
! 169: * we need to use m_copydata() to get data from <n->m_next, 0>.
! 170: */
! 171: if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
! 172: !sharedcluster) {
! 173: m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
! 174: n->m_len += tlen;
! 175: m_adj(n->m_next, tlen);
! 176: goto ok;
! 177: }
! 178: if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
! 179: !sharedcluster && n->m_next->m_len >= tlen) {
! 180: n->m_next->m_data -= hlen;
! 181: n->m_next->m_len += hlen;
! 182: bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
! 183: n->m_len -= hlen;
! 184: n = n->m_next;
! 185: off = 0;
! 186: goto ok;
! 187: }
! 188:
! 189: /*
! 190: * now, we need to do the hard way. don't m_copy as there's no room
! 191: * on both ends.
! 192: */
! 193: MGET(o, M_DONTWAIT, m->m_type);
! 194: if (o && len > MLEN) {
! 195: MCLGET(o, M_DONTWAIT);
! 196: if ((o->m_flags & M_EXT) == 0) {
! 197: m_free(o);
! 198: o = NULL;
! 199: }
! 200: }
! 201: if (!o) {
! 202: m_freem(m);
! 203: return (NULL); /* ENOBUFS */
! 204: }
! 205: /* get hlen from <n, off> into <o, 0> */
! 206: o->m_len = hlen;
! 207: bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
! 208: n->m_len -= hlen;
! 209: /* get tlen from <n->m_next, 0> into <o, hlen> */
! 210: m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
! 211: o->m_len += tlen;
! 212: m_adj(n->m_next, tlen);
! 213: o->m_next = n->m_next;
! 214: n->m_next = o;
! 215: n = o;
! 216: off = 0;
! 217:
! 218: ok:
! 219: if (offp)
! 220: *offp = off;
! 221: return (n);
! 222: }
! 223:
! 224: static struct mbuf *
! 225: m_dup1(struct mbuf *m, int off, int len, int wait)
! 226: {
! 227: struct mbuf *n;
! 228: int l;
! 229:
! 230: if (len > MCLBYTES)
! 231: return (NULL);
! 232: if (off == 0 && (m->m_flags & M_PKTHDR) != 0) {
! 233: MGETHDR(n, wait, m->m_type);
! 234: if (n == NULL)
! 235: return (NULL);
! 236: M_DUP_PKTHDR(n, m);
! 237: l = MHLEN;
! 238: } else {
! 239: MGET(n, wait, m->m_type);
! 240: l = MLEN;
! 241: }
! 242: if (n && len > l) {
! 243: MCLGET(n, wait);
! 244: if ((n->m_flags & M_EXT) == 0) {
! 245: m_free(n);
! 246: n = NULL;
! 247: }
! 248: }
! 249: if (!n)
! 250: return (NULL);
! 251:
! 252: m_copydata(m, off, len, mtod(n, caddr_t));
! 253: n->m_len = len;
! 254:
! 255: return (n);
! 256: }
! 257:
! 258: /* Get a packet tag structure along with specified data following. */
! 259: struct m_tag *
! 260: m_tag_get(int type, int len, int wait)
! 261: {
! 262: struct m_tag *t;
! 263:
! 264: if (len < 0)
! 265: return (NULL);
! 266: t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
! 267: if (t == NULL)
! 268: return (NULL);
! 269: t->m_tag_id = type;
! 270: t->m_tag_len = len;
! 271: return (t);
! 272: }
! 273:
! 274: /* Prepend a packet tag. */
! 275: void
! 276: m_tag_prepend(struct mbuf *m, struct m_tag *t)
! 277: {
! 278: SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
! 279: }
! 280:
! 281: /* Unlink and free a packet tag. */
! 282: void
! 283: m_tag_delete(struct mbuf *m, struct m_tag *t)
! 284: {
! 285: SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
! 286: free(t, M_PACKET_TAGS);
! 287: }
! 288:
! 289: /* Unlink and free a packet tag chain. */
! 290: void
! 291: m_tag_delete_chain(struct mbuf *m)
! 292: {
! 293: struct m_tag *p;
! 294:
! 295: while ((p = SLIST_FIRST(&m->m_pkthdr.tags)) != NULL) {
! 296: SLIST_REMOVE_HEAD(&m->m_pkthdr.tags, m_tag_link);
! 297: free(p, M_PACKET_TAGS);
! 298: }
! 299: }
! 300:
! 301: /* Find a tag, starting from a given position. */
! 302: struct m_tag *
! 303: m_tag_find(struct mbuf *m, int type, struct m_tag *t)
! 304: {
! 305: struct m_tag *p;
! 306:
! 307: if (t == NULL)
! 308: p = SLIST_FIRST(&m->m_pkthdr.tags);
! 309: else
! 310: p = SLIST_NEXT(t, m_tag_link);
! 311: while (p != NULL) {
! 312: if (p->m_tag_id == type)
! 313: return (p);
! 314: p = SLIST_NEXT(p, m_tag_link);
! 315: }
! 316: return (NULL);
! 317: }
! 318:
! 319: /* Copy a single tag. */
! 320: struct m_tag *
! 321: m_tag_copy(struct m_tag *t)
! 322: {
! 323: struct m_tag *p;
! 324:
! 325: p = m_tag_get(t->m_tag_id, t->m_tag_len, M_NOWAIT);
! 326: if (p == NULL)
! 327: return (NULL);
! 328: bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
! 329: return (p);
! 330: }
! 331:
! 332: /*
! 333: * Copy two tag chains. The destination mbuf (to) loses any attached
! 334: * tags even if the operation fails. This should not be a problem, as
! 335: * m_tag_copy_chain() is typically called with a newly-allocated
! 336: * destination mbuf.
! 337: */
! 338: int
! 339: m_tag_copy_chain(struct mbuf *to, struct mbuf *from)
! 340: {
! 341: struct m_tag *p, *t, *tprev = NULL;
! 342:
! 343: m_tag_delete_chain(to);
! 344: SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
! 345: t = m_tag_copy(p);
! 346: if (t == NULL) {
! 347: m_tag_delete_chain(to);
! 348: return (0);
! 349: }
! 350: if (tprev == NULL)
! 351: SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
! 352: else
! 353: SLIST_INSERT_AFTER(tprev, t, m_tag_link);
! 354: tprev = t;
! 355: }
! 356: return (1);
! 357: }
! 358:
! 359: /* Initialize tags on an mbuf. */
! 360: void
! 361: m_tag_init(struct mbuf *m)
! 362: {
! 363: SLIST_INIT(&m->m_pkthdr.tags);
! 364: }
! 365:
! 366: /* Get first tag in chain. */
! 367: struct m_tag *
! 368: m_tag_first(struct mbuf *m)
! 369: {
! 370: return (SLIST_FIRST(&m->m_pkthdr.tags));
! 371: }
! 372:
! 373: /* Get next tag in chain. */
! 374: struct m_tag *
! 375: m_tag_next(struct mbuf *m, struct m_tag *t)
! 376: {
! 377: return (SLIST_NEXT(t, m_tag_link));
! 378: }
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