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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33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char sccsid[] = "@(#)bt_open.c 8.10 (Berkeley) 8/17/94";
35 #endif /* LIBC_SCCS and not lint */
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
40 * Implementation of btree access method for 4.4BSD.
42 * The design here was originally based on that of the btree access method
43 * used in the Postgres database system at UC Berkeley. This implementation
44 * is wholly independent of the Postgres code.
47 #include "namespace.h"
48 #include <sys/param.h>
59 #include "un-namespace.h"
69 static int byteorder(void);
70 static int nroot(BTREE *);
74 * __BT_OPEN -- Open a btree.
76 * Creates and fills a DB struct, and calls the routine that actually
80 * fname: filename (NULL for in-memory trees)
81 * flags: open flag bits
82 * mode: open permission bits
83 * b: BTREEINFO pointer
86 * NULL on failure, pointer to DB on success.
90 __bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, int dflags)
99 int machine_lorder, saved_errno;
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 *)calloc(1, sizeof(BTREE))) == NULL)
161 t->bt_fd = -1; /* Don't close unopened fd on error. */
162 t->bt_lorder = b.lorder;
164 t->bt_cmp = b.compare;
165 t->bt_pfx = b.prefix;
168 if ((t->bt_dbp = dbp = (DB *)calloc(1, sizeof(DB))) == NULL)
170 if (t->bt_lorder != machine_lorder)
171 F_SET(t, B_NEEDSWAP);
173 dbp->type = DB_BTREE;
175 dbp->close = __bt_close;
176 dbp->del = __bt_delete;
181 dbp->sync = __bt_sync;
184 * If no file name was supplied, this is an in-memory btree and we
185 * open a backing temporary file. Otherwise, it's a disk-based tree.
188 switch (flags & O_ACCMODE) {
199 if ((t->bt_fd = _open(fname, flags, mode)) < 0)
203 if ((flags & O_ACCMODE) != O_RDWR)
205 if ((t->bt_fd = tmp()) == -1)
210 if (_fcntl(t->bt_fd, F_SETFD, 1) == -1)
213 if (_fstat(t->bt_fd, &sb))
216 if ((nr = _read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
218 if (nr != sizeof(BTMETA))
222 * Read in the meta-data. This can change the notion of what
223 * the lorder, page size and flags are, and, when the page size
224 * changes, the cachesize value can change too. If the user
225 * specified the wrong byte order for an existing database, we
226 * don't bother to return an error, we just clear the NEEDSWAP
229 if (m.magic == BTREEMAGIC)
230 F_CLR(t, B_NEEDSWAP);
232 F_SET(t, B_NEEDSWAP);
234 M_32_SWAP(m.version);
240 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
242 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
243 m.psize & (sizeof(indx_t) - 1) )
245 if (m.flags & ~SAVEMETA)
250 t->bt_nrecs = m.nrecs;
253 * Set the page size to the best value for I/O to this file.
254 * Don't overflow the page offset type.
257 b.psize = sb.st_blksize;
258 if (b.psize < MINPSIZE)
260 if (b.psize > MAX_PAGE_OFFSET + 1)
261 b.psize = MAX_PAGE_OFFSET + 1;
264 /* Set flag if duplicates permitted. */
265 if (!(b.flags & R_DUP))
268 t->bt_free = P_INVALID;
270 F_SET(t, B_METADIRTY);
273 t->bt_psize = b.psize;
275 /* Set the cache size; must be a multiple of the page size. */
276 if (b.cachesize && b.cachesize & (b.psize - 1) )
277 b.cachesize += (~b.cachesize & (b.psize - 1) ) + 1;
278 if (b.cachesize < b.psize * MINCACHE)
279 b.cachesize = b.psize * MINCACHE;
281 /* Calculate number of pages to cache. */
282 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
285 * The btree data structure requires that at least two keys can fit on
286 * a page, but other than that there's no fixed requirement. The user
287 * specified a minimum number per page, and we translated that into the
288 * number of bytes a key/data pair can use before being placed on an
289 * overflow page. This calculation includes the page header, the size
290 * of the index referencing the leaf item and the size of the leaf item
291 * structure. Also, don't let the user specify a minkeypage such that
292 * a key/data pair won't fit even if both key and data are on overflow
295 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
296 (sizeof(indx_t) + NBLEAFDBT(0, 0));
297 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
299 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
301 /* Initialize the buffer pool. */
303 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
305 if (!F_ISSET(t, B_INMEM))
306 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
308 /* Create a root page if new tree. */
309 if (nroot(t) == RET_ERROR)
313 if (dflags & DB_LOCK)
315 if (dflags & DB_SHMEM)
316 F_SET(t, B_DB_SHMEM);
322 einval: errno = EINVAL;
325 eftype: errno = EFTYPE;
328 err: saved_errno = errno;
333 (void)_close(t->bt_fd);
341 * NROOT -- Create the root of a new tree.
347 * RET_ERROR, RET_SUCCESS
355 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
356 if (root->lower == 0 &&
358 root->linp[0] == 0) {
359 mpool_delete(t->bt_mp, root);
362 mpool_put(t->bt_mp, root, 0);
363 return (RET_SUCCESS);
366 if (errno != EINVAL) /* It's OK to not exist. */
370 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
373 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
379 root->prevpg = root->nextpg = P_INVALID;
380 root->lower = BTDATAOFF;
381 root->upper = t->bt_psize;
382 root->flags = P_BLEAF;
383 memset(meta, 0, t->bt_psize);
384 mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
385 mpool_put(t->bt_mp, root, MPOOL_DIRTY);
386 return (RET_SUCCESS);
395 char path[MAXPATHLEN];
397 if (issetugid() == 0)
398 envtmp = getenv("TMPDIR");
400 sizeof(path), "%s/bt.XXXXXXXXXX", envtmp ? envtmp : "/tmp");
401 if (len < 0 || len >= (int)sizeof(path)) {
402 errno = ENAMETOOLONG;
406 (void)sigfillset(&set);
407 (void)_sigprocmask(SIG_BLOCK, &set, &oset);
408 if ((fd = mkstemp(path)) != -1)
410 (void)_sigprocmask(SIG_SETMASK, &oset, NULL);
426 return (LITTLE_ENDIAN);
433 __bt_fd(const DB *dbp)
439 /* Toss any page pinned across calls. */
440 if (t->bt_pinned != NULL) {
441 mpool_put(t->bt_mp, t->bt_pinned, 0);
445 /* In-memory database can't have a file descriptor. */
446 if (F_ISSET(t, B_INMEM)) {