2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
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9 * modification, are permitted provided that the following conditions
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12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
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15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
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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
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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
32 * $FreeBSD: src/lib/libc/db/btree/bt_open.c,v 1.7.2.1 2000/11/02 10:30:07 kris Exp $
33 * $DragonFly: src/lib/libc/db/btree/bt_open.c,v 1.6 2005/11/12 23:01:54 swildner Exp $
35 * @(#)bt_open.c 8.10 (Berkeley) 8/17/94
39 * Implementation of btree access method for 4.4BSD.
41 * The design here was originally based on that of the btree access method
42 * used in the Postgres database system at UC Berkeley. This implementation
43 * is wholly independent of the Postgres code.
46 #include "namespace.h"
47 #include <sys/param.h>
58 #include "un-namespace.h"
68 static int byteorder (void);
69 static int nroot (BTREE
*);
70 static int tmp (void);
73 * __BT_OPEN -- Open a btree.
75 * Creates and fills a DB struct, and calls the routine that actually
79 * fname: filename (NULL for in-memory trees)
80 * flags: open flag bits
81 * mode: open permission bits
82 * b: BTREEINFO pointer
85 * NULL on failure, pointer to DB on success.
89 __bt_open(const char *fname
, int flags
, int mode
, const BTREEINFO
*openinfo
,
104 * Intention is to make sure all of the user's selections are okay
105 * here and then use them without checking. Can't be complete, since
106 * we don't know the right page size, lorder or flags until the backing
107 * file is opened. Also, the file's page size can cause the cachesize
110 machine_lorder
= byteorder();
115 if (b
.flags
& ~(R_DUP
))
119 * Page size must be indx_t aligned and >= MINPSIZE. Default
120 * page size is set farther on, based on the underlying file
124 (b
.psize
< MINPSIZE
|| b
.psize
> MAX_PAGE_OFFSET
+ 1 ||
125 b
.psize
& (sizeof(indx_t
) - 1) ))
128 /* Minimum number of keys per page; absolute minimum is 2. */
130 if (b
.minkeypage
< 2)
133 b
.minkeypage
= DEFMINKEYPAGE
;
135 /* If no comparison, use default comparison and prefix. */
136 if (b
.compare
== NULL
) {
137 b
.compare
= __bt_defcmp
;
138 if (b
.prefix
== NULL
)
139 b
.prefix
= __bt_defpfx
;
143 b
.lorder
= machine_lorder
;
145 b
.compare
= __bt_defcmp
;
148 b
.lorder
= machine_lorder
;
149 b
.minkeypage
= DEFMINKEYPAGE
;
150 b
.prefix
= __bt_defpfx
;
154 /* Check for the ubiquitous PDP-11. */
155 if (b
.lorder
!= BIG_ENDIAN
&& b
.lorder
!= LITTLE_ENDIAN
)
158 /* Allocate and initialize DB and BTREE structures. */
159 if ((t
= (BTREE
*)malloc(sizeof(BTREE
))) == NULL
)
161 memset(t
, 0, sizeof(BTREE
));
162 t
->bt_fd
= -1; /* Don't close unopened fd on error. */
163 t
->bt_lorder
= b
.lorder
;
165 t
->bt_cmp
= b
.compare
;
166 t
->bt_pfx
= b
.prefix
;
169 if ((t
->bt_dbp
= dbp
= (DB
*)malloc(sizeof(DB
))) == NULL
)
171 memset(t
->bt_dbp
, 0, sizeof(DB
));
172 if (t
->bt_lorder
!= machine_lorder
)
173 F_SET(t
, B_NEEDSWAP
);
175 dbp
->type
= DB_BTREE
;
177 dbp
->close
= __bt_close
;
178 dbp
->del
= __bt_delete
;
183 dbp
->sync
= __bt_sync
;
186 * If no file name was supplied, this is an in-memory btree and we
187 * open a backing temporary file. Otherwise, it's a disk-based tree.
190 switch (flags
& O_ACCMODE
) {
201 if ((t
->bt_fd
= _open(fname
, flags
, mode
)) < 0)
205 if ((flags
& O_ACCMODE
) != O_RDWR
)
207 if ((t
->bt_fd
= tmp()) == -1)
212 if (_fcntl(t
->bt_fd
, F_SETFD
, 1) == -1)
215 if (_fstat(t
->bt_fd
, &sb
))
218 if ((nr
= _read(t
->bt_fd
, &m
, sizeof(BTMETA
))) < 0)
220 if (nr
!= sizeof(BTMETA
))
224 * Read in the meta-data. This can change the notion of what
225 * the lorder, page size and flags are, and, when the page size
226 * changes, the cachesize value can change too. If the user
227 * specified the wrong byte order for an existing database, we
228 * don't bother to return an error, we just clear the NEEDSWAP
231 if (m
.magic
== BTREEMAGIC
)
232 F_CLR(t
, B_NEEDSWAP
);
234 F_SET(t
, B_NEEDSWAP
);
236 M_32_SWAP(m
.version
);
242 if (m
.magic
!= BTREEMAGIC
|| m
.version
!= BTREEVERSION
)
244 if (m
.psize
< MINPSIZE
|| m
.psize
> MAX_PAGE_OFFSET
+ 1 ||
245 m
.psize
& (sizeof(indx_t
) - 1) )
247 if (m
.flags
& ~SAVEMETA
)
252 t
->bt_nrecs
= m
.nrecs
;
255 * Set the page size to the best value for I/O to this file.
256 * Don't overflow the page offset type.
259 b
.psize
= sb
.st_blksize
;
260 if (b
.psize
< MINPSIZE
)
262 if (b
.psize
> MAX_PAGE_OFFSET
+ 1)
263 b
.psize
= MAX_PAGE_OFFSET
+ 1;
266 /* Set flag if duplicates permitted. */
267 if (!(b
.flags
& R_DUP
))
270 t
->bt_free
= P_INVALID
;
272 F_SET(t
, B_METADIRTY
);
275 t
->bt_psize
= b
.psize
;
277 /* Set the cache size; must be a multiple of the page size. */
278 if (b
.cachesize
&& b
.cachesize
& (b
.psize
- 1) )
279 b
.cachesize
+= (~b
.cachesize
& (b
.psize
- 1) ) + 1;
280 if (b
.cachesize
< b
.psize
* MINCACHE
)
281 b
.cachesize
= b
.psize
* MINCACHE
;
283 /* Calculate number of pages to cache. */
284 ncache
= (b
.cachesize
+ t
->bt_psize
- 1) / t
->bt_psize
;
287 * The btree data structure requires that at least two keys can fit on
288 * a page, but other than that there's no fixed requirement. The user
289 * specified a minimum number per page, and we translated that into the
290 * number of bytes a key/data pair can use before being placed on an
291 * overflow page. This calculation includes the page header, the size
292 * of the index referencing the leaf item and the size of the leaf item
293 * structure. Also, don't let the user specify a minkeypage such that
294 * a key/data pair won't fit even if both key and data are on overflow
297 t
->bt_ovflsize
= (t
->bt_psize
- BTDATAOFF
) / b
.minkeypage
-
298 (sizeof(indx_t
) + NBLEAFDBT(0, 0));
299 if (t
->bt_ovflsize
< NBLEAFDBT(NOVFLSIZE
, NOVFLSIZE
) + sizeof(indx_t
))
301 NBLEAFDBT(NOVFLSIZE
, NOVFLSIZE
) + sizeof(indx_t
);
303 /* Initialize the buffer pool. */
305 mpool_open(NULL
, t
->bt_fd
, t
->bt_psize
, ncache
)) == NULL
)
307 if (!F_ISSET(t
, B_INMEM
))
308 mpool_filter(t
->bt_mp
, __bt_pgin
, __bt_pgout
, t
);
310 /* Create a root page if new tree. */
311 if (nroot(t
) == RET_ERROR
)
315 if (dflags
& DB_LOCK
)
317 if (dflags
& DB_SHMEM
)
318 F_SET(t
, B_DB_SHMEM
);
324 einval
: errno
= EINVAL
;
327 eftype
: errno
= EFTYPE
;
341 * NROOT -- Create the root of a new tree.
347 * RET_ERROR, RET_SUCCESS
355 if ((meta
= mpool_get(t
->bt_mp
, 0, 0)) != NULL
) {
356 mpool_put(t
->bt_mp
, meta
, 0);
357 return (RET_SUCCESS
);
359 if (errno
!= EINVAL
) /* It's OK to not exist. */
363 if ((meta
= mpool_new(t
->bt_mp
, &npg
)) == NULL
)
366 if ((root
= mpool_new(t
->bt_mp
, &npg
)) == NULL
)
372 root
->prevpg
= root
->nextpg
= P_INVALID
;
373 root
->lower
= BTDATAOFF
;
374 root
->upper
= t
->bt_psize
;
375 root
->flags
= P_BLEAF
;
376 memset(meta
, 0, t
->bt_psize
);
377 mpool_put(t
->bt_mp
, meta
, MPOOL_DIRTY
);
378 mpool_put(t
->bt_mp
, root
, MPOOL_DIRTY
);
379 return (RET_SUCCESS
);
388 char path
[MAXPATHLEN
];
390 if (issetugid() == 0)
391 envtmp
= getenv("TMPDIR");
393 sizeof(path
), "%s/bt.XXXXXXXXXX", envtmp
? envtmp
: "/tmp");
396 _sigprocmask(SIG_BLOCK
, &set
, &oset
);
397 if ((fd
= mkstemp(path
)) != -1)
399 _sigprocmask(SIG_SETMASK
, &oset
, NULL
);
415 return (LITTLE_ENDIAN
);
422 __bt_fd(const DB
*dbp
)
428 /* Toss any page pinned across calls. */
429 if (t
->bt_pinned
!= NULL
) {
430 mpool_put(t
->bt_mp
, t
->bt_pinned
, 0);
434 /* In-memory database can't have a file descriptor. */
435 if (F_ISSET(t
, B_INMEM
)) {