Apply FreeBSD-SA-09:07.libc - fix information leak in db(3)
[dragonfly.git] / lib / libc / db / hash / hash_buf.c
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1/*-
2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Margo Seltzer.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
cbebfd39 16 * 3. Neither the name of the University nor the names of its contributors
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17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $FreeBSD: src/lib/libc/db/hash/hash_buf.c,v 1.4.8.1 2001/03/05 07:38:05 obrien Exp $
17d47efc 33 * $DragonFly: src/lib/libc/db/hash/hash_buf.c,v 1.7 2005/11/19 20:46:32 swildner Exp $
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34 *
35 * @(#)hash_buf.c 8.5 (Berkeley) 7/15/94
984263bc 36 */
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37
38/*
39 * PACKAGE: hash
40 *
41 * DESCRIPTION:
42 * Contains buffer management
43 *
44 * ROUTINES:
45 * External
46 * __buf_init
47 * __get_buf
48 * __buf_free
49 * __reclaim_buf
50 * Internal
51 * newbuf
52 */
53
54#include <sys/param.h>
55
56#include <stddef.h>
57#include <stdio.h>
58#include <stdlib.h>
7895edcd 59#include <string.h>
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60
61#ifdef DEBUG
62#include <assert.h>
63#endif
64
65#include <db.h>
66#include "hash.h"
67#include "page.h"
68#include "extern.h"
69
064e1fb3 70static BUFHEAD *newbuf (HTAB *, u_int32_t, BUFHEAD *);
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71
72/* Unlink B from its place in the lru */
73#define BUF_REMOVE(B) { \
74 (B)->prev->next = (B)->next; \
75 (B)->next->prev = (B)->prev; \
76}
77
78/* Insert B after P */
79#define BUF_INSERT(B, P) { \
80 (B)->next = (P)->next; \
81 (B)->prev = (P); \
82 (P)->next = (B); \
83 (B)->next->prev = (B); \
84}
85
86#define MRU hashp->bufhead.next
87#define LRU hashp->bufhead.prev
88
89#define MRU_INSERT(B) BUF_INSERT((B), &hashp->bufhead)
90#define LRU_INSERT(B) BUF_INSERT((B), LRU)
91
92/*
93 * We are looking for a buffer with address "addr". If prev_bp is NULL, then
94 * address is a bucket index. If prev_bp is not NULL, then it points to the
95 * page previous to an overflow page that we are trying to find.
96 *
97 * CAVEAT: The buffer header accessed via prev_bp's ovfl field may no longer
98 * be valid. Therefore, you must always verify that its address matches the
99 * address you are seeking.
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100 *
101 * Parameters:
102 * newpage: If prev_bp set, indicates a new overflow page
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103 */
104extern BUFHEAD *
17d47efc 105__get_buf(HTAB *hashp, u_int32_t addr, BUFHEAD *prev_bp, int newpage)
984263bc 106{
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107 BUFHEAD *bp;
108 u_int32_t is_disk_mask;
109 int is_disk, segment_ndx;
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110 SEGMENT segp;
111
112 is_disk = 0;
113 is_disk_mask = 0;
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114 segment_ndx = 0;
115 segp = NULL;
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116 if (prev_bp) {
117 bp = prev_bp->ovfl;
118 if (!bp || (bp->addr != addr))
119 bp = NULL;
120 if (!newpage)
121 is_disk = BUF_DISK;
122 } else {
123 /* Grab buffer out of directory */
124 segment_ndx = addr & (hashp->SGSIZE - 1);
125
126 /* valid segment ensured by __call_hash() */
127 segp = hashp->dir[addr >> hashp->SSHIFT];
128#ifdef DEBUG
129 assert(segp != NULL);
130#endif
131 bp = PTROF(segp[segment_ndx]);
132 is_disk_mask = ISDISK(segp[segment_ndx]);
133 is_disk = is_disk_mask || !hashp->new_file;
134 }
135
136 if (!bp) {
137 bp = newbuf(hashp, addr, prev_bp);
138 if (!bp ||
139 __get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0))
140 return (NULL);
141 if (!prev_bp)
142 segp[segment_ndx] =
143 (BUFHEAD *)((ptrdiff_t)bp | is_disk_mask);
144 } else {
145 BUF_REMOVE(bp);
146 MRU_INSERT(bp);
147 }
148 return (bp);
149}
150
151/*
152 * We need a buffer for this page. Either allocate one, or evict a resident
153 * one (if we have as many buffers as we're allowed) and put this one in.
154 *
155 * If newbuf finds an error (returning NULL), it also sets errno.
156 */
157static BUFHEAD *
c9fbf0d3 158newbuf(HTAB *hashp, u_int32_t addr, BUFHEAD *prev_bp)
984263bc 159{
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160 BUFHEAD *bp; /* The buffer we're going to use */
161 BUFHEAD *xbp; /* Temp pointer */
162 BUFHEAD *next_xbp;
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163 SEGMENT segp;
164 int segment_ndx;
165 u_int16_t oaddr, *shortp;
166
167 oaddr = 0;
168 bp = LRU;
169 /*
170 * If LRU buffer is pinned, the buffer pool is too small. We need to
171 * allocate more buffers.
172 */
173 if (hashp->nbufs || (bp->flags & BUF_PIN)) {
174 /* Allocate a new one */
7895edcd 175 if ((bp = (BUFHEAD *)calloc(1, sizeof(BUFHEAD))) == NULL)
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176 return (NULL);
177#ifdef PURIFY
178 memset(bp, 0xff, sizeof(BUFHEAD));
179#endif
7895edcd 180 if ((bp->page = (char *)calloc(1, hashp->BSIZE)) == NULL) {
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181 free(bp);
182 return (NULL);
183 }
184#ifdef PURIFY
185 memset(bp->page, 0xff, hashp->BSIZE);
186#endif
187 if (hashp->nbufs)
188 hashp->nbufs--;
189 } else {
190 /* Kick someone out */
191 BUF_REMOVE(bp);
192 /*
193 * If this is an overflow page with addr 0, it's already been
194 * flushed back in an overflow chain and initialized.
195 */
196 if ((bp->addr != 0) || (bp->flags & BUF_BUCKET)) {
197 /*
198 * Set oaddr before __put_page so that you get it
199 * before bytes are swapped.
200 */
201 shortp = (u_int16_t *)bp->page;
202 if (shortp[0])
203 oaddr = shortp[shortp[0] - 1];
204 if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page,
205 bp->addr, (int)IS_BUCKET(bp->flags), 0))
206 return (NULL);
207 /*
208 * Update the pointer to this page (i.e. invalidate it).
209 *
210 * If this is a new file (i.e. we created it at open
211 * time), make sure that we mark pages which have been
212 * written to disk so we retrieve them from disk later,
213 * rather than allocating new pages.
214 */
215 if (IS_BUCKET(bp->flags)) {
216 segment_ndx = bp->addr & (hashp->SGSIZE - 1);
217 segp = hashp->dir[bp->addr >> hashp->SSHIFT];
218#ifdef DEBUG
219 assert(segp != NULL);
220#endif
221
222 if (hashp->new_file &&
223 ((bp->flags & BUF_MOD) ||
224 ISDISK(segp[segment_ndx])))
225 segp[segment_ndx] = (BUFHEAD *)BUF_DISK;
226 else
227 segp[segment_ndx] = NULL;
228 }
229 /*
230 * Since overflow pages can only be access by means of
231 * their bucket, free overflow pages associated with
232 * this bucket.
233 */
234 for (xbp = bp; xbp->ovfl;) {
235 next_xbp = xbp->ovfl;
236 xbp->ovfl = 0;
237 xbp = next_xbp;
238
239 /* Check that ovfl pointer is up date. */
240 if (IS_BUCKET(xbp->flags) ||
241 (oaddr != xbp->addr))
242 break;
243
244 shortp = (u_int16_t *)xbp->page;
245 if (shortp[0])
246 /* set before __put_page */
247 oaddr = shortp[shortp[0] - 1];
248 if ((xbp->flags & BUF_MOD) && __put_page(hashp,
249 xbp->page, xbp->addr, 0, 0))
250 return (NULL);
251 xbp->addr = 0;
252 xbp->flags = 0;
253 BUF_REMOVE(xbp);
254 LRU_INSERT(xbp);
255 }
256 }
257 }
258
259 /* Now assign this buffer */
260 bp->addr = addr;
261#ifdef DEBUG1
c9fbf0d3 262 fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n",
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263 bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0);
264#endif
265 bp->ovfl = NULL;
266 if (prev_bp) {
267 /*
268 * If prev_bp is set, this is an overflow page, hook it in to
269 * the buffer overflow links.
270 */
271#ifdef DEBUG1
c9fbf0d3 272 fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n",
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273 prev_bp->addr, (prev_bp->ovfl ? bp->ovfl->addr : 0),
274 (bp ? bp->addr : 0));
275#endif
276 prev_bp->ovfl = bp;
277 bp->flags = 0;
278 } else
279 bp->flags = BUF_BUCKET;
280 MRU_INSERT(bp);
281 return (bp);
282}
283
284extern void
c9fbf0d3 285__buf_init(HTAB *hashp, int nbytes)
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286{
287 BUFHEAD *bfp;
288 int npages;
289
290 bfp = &(hashp->bufhead);
291 npages = (nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT;
292 npages = MAX(npages, MIN_BUFFERS);
293
294 hashp->nbufs = npages;
295 bfp->next = bfp;
296 bfp->prev = bfp;
297 /*
298 * This space is calloc'd so these are already null.
299 *
300 * bfp->ovfl = NULL;
301 * bfp->flags = 0;
302 * bfp->page = NULL;
303 * bfp->addr = 0;
304 */
305}
306
307extern int
c9fbf0d3 308__buf_free(HTAB *hashp, int do_free, int to_disk)
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309{
310 BUFHEAD *bp;
311
312 /* Need to make sure that buffer manager has been initialized */
313 if (!LRU)
314 return (0);
315 for (bp = LRU; bp != &hashp->bufhead;) {
316 /* Check that the buffer is valid */
317 if (bp->addr || IS_BUCKET(bp->flags)) {
318 if (to_disk && (bp->flags & BUF_MOD) &&
319 __put_page(hashp, bp->page,
320 bp->addr, IS_BUCKET(bp->flags), 0))
321 return (-1);
322 }
323 /* Check if we are freeing stuff */
324 if (do_free) {
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325 if (bp->page) {
326 memset(bp->page, 0, hashp->BSIZE);
984263bc 327 free(bp->page);
7895edcd 328 }
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329 BUF_REMOVE(bp);
330 free(bp);
331 bp = LRU;
332 } else
333 bp = bp->prev;
334 }
335 return (0);
336}
337
338extern void
c9fbf0d3 339__reclaim_buf(HTAB *hashp, BUFHEAD *bp)
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340{
341 bp->ovfl = 0;
342 bp->addr = 0;
343 bp->flags = 0;
344 BUF_REMOVE(bp);
345 LRU_INSERT(bp);
346}