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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)) {