Annotation of sys/kern/uipc_mbuf2.c, Revision 1.1.1.1
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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