1#pragma ident	"%Z%%M%	%I%	%E% SMI"
2
3/*-
4 * Copyright (c) 1990, 1993, 1994
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Mike Olson.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the University of
21 *	California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39#if defined(LIBC_SCCS) && !defined(lint)
40static char sccsid[] = "@(#)bt_open.c	8.11 (Berkeley) 11/2/95";
41#endif /* LIBC_SCCS and not lint */
42
43/*
44 * Implementation of btree access method for 4.4BSD.
45 *
46 * The design here was originally based on that of the btree access method
47 * used in the Postgres database system at UC Berkeley.  This implementation
48 * is wholly independent of the Postgres code.
49 */
50
51#include <sys/param.h>
52#include <sys/stat.h>
53
54#include <errno.h>
55#include <fcntl.h>
56#include <limits.h>
57#include <signal.h>
58#include <stdio.h>
59#include <stdlib.h>
60#include <string.h>
61#include <unistd.h>
62
63#include "db-int.h"
64#include "btree.h"
65
66#ifdef DEBUG
67#undef	MINPSIZE
68#define	MINPSIZE	128
69#endif
70
71static int byteorder __P((void));
72static int nroot __P((BTREE *));
73static int tmp __P((void));
74
75/*
76 * __BT_OPEN -- Open a btree.
77 *
78 * Creates and fills a DB struct, and calls the routine that actually
79 * opens the btree.
80 *
81 * Parameters:
82 *	fname:	filename (NULL for in-memory trees)
83 *	flags:	open flag bits
84 *	mode:	open permission bits
85 *	b:	BTREEINFO pointer
86 *
87 * Returns:
88 *	NULL on failure, pointer to DB on success.
89 *
90 */
91DB *
92__bt_open(fname, flags, mode, openinfo, dflags)
93	const char *fname;
94	int flags, mode, dflags;
95	const BTREEINFO *openinfo;
96{
97	struct stat sb;
98	BTMETA m;
99	BTREE *t;
100	BTREEINFO b;
101	DB *dbp;
102	db_pgno_t ncache;
103	ssize_t nr;
104	int machine_lorder;
105
106	t = NULL;
107
108	/*
109	 * Intention is to make sure all of the user's selections are okay
110	 * here and then use them without checking.  Can't be complete, since
111	 * we don't know the right page size, lorder or flags until the backing
112	 * file is opened.  Also, the file's page size can cause the cachesize
113	 * to change.
114	 */
115	machine_lorder = byteorder();
116	if (openinfo) {
117		b = *openinfo;
118
119		/* Flags: R_DUP. */
120		if (b.flags & ~(R_DUP))
121			goto einval;
122
123		/*
124		 * Page size must be indx_t aligned and >= MINPSIZE.  Default
125		 * page size is set farther on, based on the underlying file
126		 * transfer size.
127		 */
128		if (b.psize &&
129		    (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
130		    b.psize & (sizeof(indx_t) - 1)))
131			goto einval;
132
133		/* Minimum number of keys per page; absolute minimum is 2. */
134		if (b.minkeypage) {
135			if (b.minkeypage < 2)
136				goto einval;
137		} else
138			b.minkeypage = DEFMINKEYPAGE;
139
140		/* If no comparison, use default comparison and prefix. */
141		if (b.compare == NULL) {
142			b.compare = __bt_defcmp;
143			if (b.prefix == NULL)
144				b.prefix = __bt_defpfx;
145		}
146
147		if (b.lorder == 0)
148			b.lorder = machine_lorder;
149	} else {
150		b.compare = __bt_defcmp;
151		b.cachesize = 0;
152		b.flags = 0;
153		b.lorder = machine_lorder;
154		b.minkeypage = DEFMINKEYPAGE;
155		b.prefix = __bt_defpfx;
156		b.psize = 0;
157	}
158
159	/* Check for the ubiquitous PDP-11. */
160	if (b.lorder != DB_BIG_ENDIAN && b.lorder != DB_LITTLE_ENDIAN)
161		goto einval;
162
163	/* Allocate and initialize DB and BTREE structures. */
164	if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL)
165		goto err;
166	memset(t, 0, sizeof(BTREE));
167	t->bt_fd = -1;			/* Don't close unopened fd on error. */
168	t->bt_lorder = b.lorder;
169	t->bt_order = NOT;
170	t->bt_cmp = b.compare;
171	t->bt_pfx = b.prefix;
172	t->bt_rfd = -1;
173
174	if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
175		goto err;
176	memset(t->bt_dbp, 0, sizeof(DB));
177	if (t->bt_lorder != machine_lorder)
178		F_SET(t, B_NEEDSWAP);
179
180	dbp->type = DB_BTREE;
181	dbp->internal = t;
182	dbp->close = __bt_close;
183	dbp->del = __bt_delete;
184	dbp->fd = __bt_fd;
185	dbp->get = __bt_get;
186	dbp->put = __bt_put;
187	dbp->seq = __bt_seq;
188	dbp->sync = __bt_sync;
189
190	/*
191	 * If no file name was supplied, this is an in-memory btree and we
192	 * open a backing temporary file.  Otherwise, it's a disk-based tree.
193	 */
194	if (fname) {
195		switch (flags & O_ACCMODE) {
196		case O_RDONLY:
197			F_SET(t, B_RDONLY);
198			break;
199		case O_RDWR:
200			break;
201		case O_WRONLY:
202		default:
203			goto einval;
204		}
205
206		if ((t->bt_fd = open(fname, flags | O_BINARY, mode)) < 0)
207			goto err;
208
209	} else {
210		if ((flags & O_ACCMODE) != O_RDWR)
211			goto einval;
212		if ((t->bt_fd = tmp()) == -1)
213			goto err;
214		F_SET(t, B_INMEM);
215	}
216
217	if (fcntl(t->bt_fd, F_SETFD, 1) == -1)
218		goto err;
219
220	if (fstat(t->bt_fd, &sb))
221		goto err;
222	if (sb.st_size) {
223		if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
224			goto err;
225		if (nr != sizeof(BTMETA))
226			goto eftype;
227
228		/*
229		 * Read in the meta-data.  This can change the notion of what
230		 * the lorder, page size and flags are, and, when the page size
231		 * changes, the cachesize value can change too.  If the user
232		 * specified the wrong byte order for an existing database, we
233		 * don't bother to return an error, we just clear the NEEDSWAP
234		 * bit.
235		 */
236		if (m.magic == BTREEMAGIC)
237			F_CLR(t, B_NEEDSWAP);
238		else {
239			F_SET(t, B_NEEDSWAP);
240			M_32_SWAP(m.magic);
241			M_32_SWAP(m.version);
242			M_32_SWAP(m.psize);
243			M_32_SWAP(m.free);
244			M_32_SWAP(m.nrecs);
245			M_32_SWAP(m.flags);
246		}
247		if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
248			goto eftype;
249		if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
250		    m.psize & (sizeof(indx_t) - 1))
251			goto eftype;
252		if (m.flags & ~SAVEMETA)
253			goto eftype;
254		b.psize = m.psize;
255		F_SET(t, m.flags);
256		t->bt_free = m.free;
257		t->bt_nrecs = m.nrecs;
258	} else {
259		/*
260		 * Set the page size to the best value for I/O to this file.
261		 * Don't overflow the page offset type.
262		 */
263		if (b.psize == 0) {
264			b.psize = sb.st_blksize;
265			if (b.psize < MINPSIZE)
266				b.psize = MINPSIZE;
267			if (b.psize > MAX_PAGE_OFFSET + 1)
268				b.psize = MAX_PAGE_OFFSET + 1;
269		}
270
271		/* Set flag if duplicates permitted. */
272		if (!(b.flags & R_DUP))
273			F_SET(t, B_NODUPS);
274
275		t->bt_free = P_INVALID;
276		t->bt_nrecs = 0;
277		F_SET(t, B_METADIRTY);
278	}
279
280	t->bt_psize = b.psize;
281
282	/* Set the cache size; must be a multiple of the page size. */
283	if (b.cachesize && b.cachesize & (b.psize - 1))
284		b.cachesize += (~b.cachesize & (b.psize - 1)) + 1;
285	if (b.cachesize < b.psize * MINCACHE)
286		b.cachesize = b.psize * MINCACHE;
287
288	/* Calculate number of pages to cache. */
289	ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
290
291	/*
292	 * The btree data structure requires that at least two keys can fit on
293	 * a page, but other than that there's no fixed requirement.  The user
294	 * specified a minimum number per page, and we translated that into the
295	 * number of bytes a key/data pair can use before being placed on an
296	 * overflow page.  This calculation includes the page header, the size
297	 * of the index referencing the leaf item and the size of the leaf item
298	 * structure.  Also, don't let the user specify a minkeypage such that
299	 * a key/data pair won't fit even if both key and data are on overflow
300	 * pages.
301	 */
302	t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
303	    (sizeof(indx_t) + NBLEAFDBT(0, 0));
304	if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
305		t->bt_ovflsize =
306		    NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
307
308	/* Initialize the buffer pool. */
309	if ((t->bt_mp =
310	    mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
311		goto err;
312	if (!F_ISSET(t, B_INMEM))
313		mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
314
315	/* Create a root page if new tree. */
316	if (nroot(t) == RET_ERROR)
317		goto err;
318
319	/* Global flags. */
320	if (dflags & DB_LOCK)
321		F_SET(t, B_DB_LOCK);
322	if (dflags & DB_SHMEM)
323		F_SET(t, B_DB_SHMEM);
324	if (dflags & DB_TXN)
325		F_SET(t, B_DB_TXN);
326
327	return (dbp);
328
329einval:	errno = EINVAL;
330	goto err;
331
332eftype:	errno = EFTYPE;
333	goto err;
334
335err:	if (t) {
336		if (t->bt_dbp)
337			free(t->bt_dbp);
338		if (t->bt_fd != -1)
339			(void)close(t->bt_fd);
340		free(t);
341	}
342	return (NULL);
343}
344
345/*
346 * NROOT -- Create the root of a new tree.
347 *
348 * Parameters:
349 *	t:	tree
350 *
351 * Returns:
352 *	RET_ERROR, RET_SUCCESS
353 */
354static int
355nroot(t)
356	BTREE *t;
357{
358	PAGE *meta, *root;
359	db_pgno_t npg;
360
361	if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
362		if (root->lower == 0 &&
363		    root->pgno == 0 &&
364		    root->linp[0] == 0) {
365			mpool_delete(t->bt_mp, root);
366			errno = EINVAL;
367		} else {
368			mpool_put(t->bt_mp, root, 0);
369			return (RET_SUCCESS);
370		}
371	}
372	if (errno != EINVAL)		/* It's OK to not exist. */
373		return (RET_ERROR);
374	errno = 0;
375
376	if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
377		return (RET_ERROR);
378
379	if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
380		return (RET_ERROR);
381
382	if (npg != P_ROOT)
383		return (RET_ERROR);
384	root->pgno = npg;
385	root->prevpg = root->nextpg = P_INVALID;
386	root->lower = BTDATAOFF;
387	root->upper = t->bt_psize;
388	root->flags = P_BLEAF;
389	memset(meta, 0, t->bt_psize);
390	mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
391	mpool_put(t->bt_mp, root, MPOOL_DIRTY);
392	return (RET_SUCCESS);
393}
394
395static int
396tmp()
397{
398#ifdef SIG_BLOCK
399	sigset_t set, oset;
400#else
401	int oset;
402#endif
403	int fd;
404	char *envtmp;
405	char path[MAXPATHLEN];
406	static char fn[] = "/bt.XXXXXX";
407
408	envtmp = getenv("TMPDIR");
409
410	/* this used to be done with snprintf(), but since snprintf
411	   isn't in most operating systems, and overflow checking in
412	   this case is easy, this is what is done */
413
414	if (envtmp && ((strlen(envtmp)+sizeof(fn)+1) > sizeof(path)))
415	    return(-1);
416
417	(void)sprintf(path, "%s%s", (envtmp ? envtmp : "/tmp"), fn);
418
419#ifdef SIG_BLOCK
420	(void)sigfillset(&set);
421	(void)sigprocmask(SIG_BLOCK, &set, &oset);
422#else
423	oset = sigblock(~0);
424#endif
425	if ((fd = mkstemp(path)) != -1)
426		(void)unlink(path);
427#ifdef SIG_BLOCK
428	(void)sigprocmask(SIG_SETMASK, &oset, NULL);
429#else
430	sigsetmask(oset);
431#endif
432#ifdef __CYGWIN32__
433      /* Ensure the fd is in binary mode. */
434      setmode(fd, O_BINARY);
435#endif /* __CYGWIN32__ */
436
437	return(fd);
438}
439
440static int
441byteorder()
442{
443	u_int32_t x;
444	u_char *p;
445
446	x = 0x01020304;
447	p = (u_char *)&x;
448	switch (*p) {
449	case 1:
450		return (DB_BIG_ENDIAN);
451	case 4:
452		return (DB_LITTLE_ENDIAN);
453	default:
454		return (0);
455	}
456}
457
458int
459__bt_fd(dbp)
460        const DB *dbp;
461{
462	BTREE *t;
463
464	t = dbp->internal;
465
466	/* Toss any page pinned across calls. */
467	if (t->bt_pinned != NULL) {
468		mpool_put(t->bt_mp, t->bt_pinned, 0);
469		t->bt_pinned = NULL;
470	}
471
472	/* In-memory database can't have a file descriptor. */
473	if (F_ISSET(t, B_INMEM)) {
474		errno = ENOENT;
475		return (-1);
476	}
477	return (t->bt_fd);
478}
479