2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
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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"
60 #include "libc_private.h"
70 static int byteorder(void);
71 static int nroot(BTREE *);
75 * __BT_OPEN -- Open a btree.
77 * Creates and fills a DB struct, and calls the routine that actually
81 * fname: filename (NULL for in-memory trees)
82 * flags: open flag bits
83 * mode: open permission bits
84 * b: BTREEINFO pointer
87 * NULL on failure, pointer to DB on success.
91 __bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, int dflags)
100 int machine_lorder, saved_errno;
105 * Intention is to make sure all of the user's selections are okay
106 * here and then use them without checking. Can't be complete, since
107 * we don't know the right page size, lorder or flags until the backing
108 * file is opened. Also, the file's page size can cause the cachesize
111 machine_lorder = byteorder();
116 if (b.flags & ~(R_DUP))
120 * Page size must be indx_t aligned and >= MINPSIZE. Default
121 * page size is set farther on, based on the underlying file
125 (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
126 b.psize & (sizeof(indx_t) - 1) ))
129 /* Minimum number of keys per page; absolute minimum is 2. */
131 if (b.minkeypage < 2)
134 b.minkeypage = DEFMINKEYPAGE;
136 /* If no comparison, use default comparison and prefix. */
137 if (b.compare == NULL) {
138 b.compare = __bt_defcmp;
139 if (b.prefix == NULL)
140 b.prefix = __bt_defpfx;
144 b.lorder = machine_lorder;
146 b.compare = __bt_defcmp;
149 b.lorder = machine_lorder;
150 b.minkeypage = DEFMINKEYPAGE;
151 b.prefix = __bt_defpfx;
155 /* Check for the ubiquitous PDP-11. */
156 if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
159 /* Allocate and initialize DB and BTREE structures. */
160 if ((t = (BTREE *)calloc(1, sizeof(BTREE))) == NULL)
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 *)calloc(1, sizeof(DB))) == NULL)
171 if (t->bt_lorder != machine_lorder)
172 F_SET(t, B_NEEDSWAP);
174 dbp->type = DB_BTREE;
176 dbp->close = __bt_close;
177 dbp->del = __bt_delete;
182 dbp->sync = __bt_sync;
185 * If no file name was supplied, this is an in-memory btree and we
186 * open a backing temporary file. Otherwise, it's a disk-based tree.
189 switch (flags & O_ACCMODE) {
200 if ((t->bt_fd = _open(fname, flags | O_CLOEXEC, mode)) < 0)
204 if ((flags & O_ACCMODE) != O_RDWR)
206 if ((t->bt_fd = tmp()) == -1)
211 if (_fstat(t->bt_fd, &sb))
214 if ((nr = _read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
216 if (nr != sizeof(BTMETA))
220 * Read in the meta-data. This can change the notion of what
221 * the lorder, page size and flags are, and, when the page size
222 * changes, the cachesize value can change too. If the user
223 * specified the wrong byte order for an existing database, we
224 * don't bother to return an error, we just clear the NEEDSWAP
227 if (m.magic == BTREEMAGIC)
228 F_CLR(t, B_NEEDSWAP);
230 F_SET(t, B_NEEDSWAP);
232 M_32_SWAP(m.version);
238 if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
240 if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
241 m.psize & (sizeof(indx_t) - 1) )
243 if (m.flags & ~SAVEMETA)
248 t->bt_nrecs = m.nrecs;
251 * Set the page size to the best value for I/O to this file.
252 * Don't overflow the page offset type.
255 b.psize = sb.st_blksize;
256 if (b.psize < MINPSIZE)
258 if (b.psize > MAX_PAGE_OFFSET + 1)
259 b.psize = MAX_PAGE_OFFSET + 1;
262 /* Set flag if duplicates permitted. */
263 if (!(b.flags & R_DUP))
266 t->bt_free = P_INVALID;
268 F_SET(t, B_METADIRTY);
271 t->bt_psize = b.psize;
273 /* Set the cache size; must be a multiple of the page size. */
274 if (b.cachesize && b.cachesize & (b.psize - 1) )
275 b.cachesize += (~b.cachesize & (b.psize - 1) ) + 1;
276 if (b.cachesize < b.psize * MINCACHE)
277 b.cachesize = b.psize * MINCACHE;
279 /* Calculate number of pages to cache. */
280 ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
283 * The btree data structure requires that at least two keys can fit on
284 * a page, but other than that there's no fixed requirement. The user
285 * specified a minimum number per page, and we translated that into the
286 * number of bytes a key/data pair can use before being placed on an
287 * overflow page. This calculation includes the page header, the size
288 * of the index referencing the leaf item and the size of the leaf item
289 * structure. Also, don't let the user specify a minkeypage such that
290 * a key/data pair won't fit even if both key and data are on overflow
293 t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
294 (sizeof(indx_t) + NBLEAFDBT(0, 0));
295 if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
297 NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
299 /* Initialize the buffer pool. */
301 mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
303 if (!F_ISSET(t, B_INMEM))
304 mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
306 /* Create a root page if new tree. */
307 if (nroot(t) == RET_ERROR)
311 if (dflags & DB_LOCK)
313 if (dflags & DB_SHMEM)
314 F_SET(t, B_DB_SHMEM);
320 einval: errno = EINVAL;
323 eftype: errno = EFTYPE;
326 err: saved_errno = errno;
331 (void)_close(t->bt_fd);
339 * NROOT -- Create the root of a new tree.
345 * RET_ERROR, RET_SUCCESS
353 if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
354 if (root->lower == 0 &&
356 root->linp[0] == 0) {
357 mpool_delete(t->bt_mp, root);
360 mpool_put(t->bt_mp, root, 0);
361 return (RET_SUCCESS);
364 if (errno != EINVAL) /* It's OK to not exist. */
368 if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
371 if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
377 root->prevpg = root->nextpg = P_INVALID;
378 root->lower = BTDATAOFF;
379 root->upper = t->bt_psize;
380 root->flags = P_BLEAF;
381 memset(meta, 0, t->bt_psize);
382 mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
383 mpool_put(t->bt_mp, root, MPOOL_DIRTY);
384 return (RET_SUCCESS);
393 char path[MAXPATHLEN];
395 if (issetugid() == 0)
396 envtmp = getenv("TMPDIR");
398 sizeof(path), "%s/bt.XXXXXXXXXX", envtmp ? envtmp : "/tmp");
399 if (len < 0 || len >= (int)sizeof(path)) {
400 errno = ENAMETOOLONG;
404 (void)sigfillset(&set);
405 (void)__libc_sigprocmask(SIG_BLOCK, &set, &oset);
406 if ((fd = mkostemp(path, O_CLOEXEC)) != -1)
408 (void)__libc_sigprocmask(SIG_SETMASK, &oset, NULL);
424 return (LITTLE_ENDIAN);
431 __bt_fd(const DB *dbp)
437 /* Toss any page pinned across calls. */
438 if (t->bt_pinned != NULL) {
439 mpool_put(t->bt_mp, t->bt_pinned, 0);
443 /* In-memory database can't have a file descriptor. */
444 if (F_ISSET(t, B_INMEM)) {