xref: /netbsd-src/lib/libc/db/btree/bt_open.c (revision aae80e6be7bf8e6ad43f8b63d296d2d3923c4ee5)
1*aae80e6bSchristos /*	$NetBSD: bt_open.c,v 1.29 2016/09/24 21:31:25 christos Exp $	*/
2a954b078Scgd 
39f0aa214Scgd /*-
4a6d14e36Scgd  * Copyright (c) 1990, 1993, 1994
59f0aa214Scgd  *	The Regents of the University of California.  All rights reserved.
69f0aa214Scgd  *
79f0aa214Scgd  * This code is derived from software contributed to Berkeley by
89f0aa214Scgd  * Mike Olson.
99f0aa214Scgd  *
109f0aa214Scgd  * Redistribution and use in source and binary forms, with or without
119f0aa214Scgd  * modification, are permitted provided that the following conditions
129f0aa214Scgd  * are met:
139f0aa214Scgd  * 1. Redistributions of source code must retain the above copyright
149f0aa214Scgd  *    notice, this list of conditions and the following disclaimer.
159f0aa214Scgd  * 2. Redistributions in binary form must reproduce the above copyright
169f0aa214Scgd  *    notice, this list of conditions and the following disclaimer in the
179f0aa214Scgd  *    documentation and/or other materials provided with the distribution.
18eb7c1594Sagc  * 3. Neither the name of the University nor the names of its contributors
199f0aa214Scgd  *    may be used to endorse or promote products derived from this software
209f0aa214Scgd  *    without specific prior written permission.
219f0aa214Scgd  *
229f0aa214Scgd  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
239f0aa214Scgd  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
249f0aa214Scgd  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
259f0aa214Scgd  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
269f0aa214Scgd  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
279f0aa214Scgd  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
289f0aa214Scgd  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
299f0aa214Scgd  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
309f0aa214Scgd  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
319f0aa214Scgd  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
329f0aa214Scgd  * SUCH DAMAGE.
339f0aa214Scgd  */
349f0aa214Scgd 
35d3595ddfSjoerg #if HAVE_NBTOOL_CONFIG_H
36d3595ddfSjoerg #include "nbtool_config.h"
37d3595ddfSjoerg #endif
38d3595ddfSjoerg 
3900ae392dSchristos #include <sys/cdefs.h>
40*aae80e6bSchristos __RCSID("$NetBSD: bt_open.c,v 1.29 2016/09/24 21:31:25 christos Exp $");
419f0aa214Scgd 
429f0aa214Scgd /*
439f0aa214Scgd  * Implementation of btree access method for 4.4BSD.
449f0aa214Scgd  *
459f0aa214Scgd  * The design here was originally based on that of the btree access method
469f0aa214Scgd  * used in the Postgres database system at UC Berkeley.  This implementation
479f0aa214Scgd  * is wholly independent of the Postgres code.
489f0aa214Scgd  */
499f0aa214Scgd 
5043fa6fe3Sjtc #include "namespace.h"
519f0aa214Scgd #include <sys/stat.h>
529f0aa214Scgd 
53cb9daf8fSchristos #include <assert.h>
549f0aa214Scgd #include <errno.h>
559f0aa214Scgd #include <fcntl.h>
569f0aa214Scgd #include <limits.h>
579f0aa214Scgd #include <signal.h>
589f0aa214Scgd #include <stdio.h>
599f0aa214Scgd #include <stdlib.h>
609f0aa214Scgd #include <string.h>
619f0aa214Scgd #include <unistd.h>
625f062167Sfair #include <paths.h>
639f0aa214Scgd 
649f0aa214Scgd #include <db.h>
659f0aa214Scgd #include "btree.h"
669f0aa214Scgd 
6724420c01Scgd #ifdef DEBUG
6824420c01Scgd #undef	MINPSIZE
6924420c01Scgd #define	MINPSIZE	128
7024420c01Scgd #endif
7124420c01Scgd 
72cb9daf8fSchristos static int byteorder(void);
73cb9daf8fSchristos static int nroot(BTREE *);
749f0aa214Scgd 
759f0aa214Scgd /*
769f0aa214Scgd  * __BT_OPEN -- Open a btree.
779f0aa214Scgd  *
789f0aa214Scgd  * Creates and fills a DB struct, and calls the routine that actually
799f0aa214Scgd  * opens the btree.
809f0aa214Scgd  *
819f0aa214Scgd  * Parameters:
829f0aa214Scgd  *	fname:	filename (NULL for in-memory trees)
839f0aa214Scgd  *	flags:	open flag bits
849f0aa214Scgd  *	mode:	open permission bits
859f0aa214Scgd  *	b:	BTREEINFO pointer
869f0aa214Scgd  *
879f0aa214Scgd  * Returns:
889f0aa214Scgd  *	NULL on failure, pointer to DB on success.
899f0aa214Scgd  *
909f0aa214Scgd  */
919f0aa214Scgd DB *
__bt_open(const char * fname,int flags,mode_t mode,const BTREEINFO * openinfo,int dflags)92cb9daf8fSchristos __bt_open(const char *fname, int flags, mode_t mode, const BTREEINFO *openinfo,
93cb9daf8fSchristos     int dflags)
949f0aa214Scgd {
95a6d14e36Scgd 	struct stat sb;
969f0aa214Scgd 	BTMETA m;
979f0aa214Scgd 	BTREE *t;
989f0aa214Scgd 	BTREEINFO b;
999f0aa214Scgd 	DB *dbp;
1009f0aa214Scgd 	pgno_t ncache;
101a6d14e36Scgd 	ssize_t nr;
102cb9daf8fSchristos 	size_t temp;
103a6d14e36Scgd 	int machine_lorder;
1049f0aa214Scgd 
1059f0aa214Scgd 	t = NULL;
1069f0aa214Scgd 
1079f0aa214Scgd 	/*
1089f0aa214Scgd 	 * Intention is to make sure all of the user's selections are okay
1099f0aa214Scgd 	 * here and then use them without checking.  Can't be complete, since
1109f0aa214Scgd 	 * we don't know the right page size, lorder or flags until the backing
1119f0aa214Scgd 	 * file is opened.  Also, the file's page size can cause the cachesize
1129f0aa214Scgd 	 * to change.
1139f0aa214Scgd 	 */
1149f0aa214Scgd 	machine_lorder = byteorder();
1159f0aa214Scgd 	if (openinfo) {
1169f0aa214Scgd 		b = *openinfo;
1179f0aa214Scgd 
1189f0aa214Scgd 		/* Flags: R_DUP. */
1199f0aa214Scgd 		if (b.flags & ~(R_DUP))
1209f0aa214Scgd 			goto einval;
1219f0aa214Scgd 
1229f0aa214Scgd 		/*
1239f0aa214Scgd 		 * Page size must be indx_t aligned and >= MINPSIZE.  Default
1249f0aa214Scgd 		 * page size is set farther on, based on the underlying file
1259f0aa214Scgd 		 * transfer size.
1269f0aa214Scgd 		 */
1279f0aa214Scgd 		if (b.psize &&
1289f0aa214Scgd 		    (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
12900ae392dSchristos 		    b.psize & (sizeof(indx_t) - 1)))
1309f0aa214Scgd 			goto einval;
1319f0aa214Scgd 
1329f0aa214Scgd 		/* Minimum number of keys per page; absolute minimum is 2. */
1339f0aa214Scgd 		if (b.minkeypage) {
1349f0aa214Scgd 			if (b.minkeypage < 2)
1359f0aa214Scgd 				goto einval;
1369f0aa214Scgd 		} else
1379f0aa214Scgd 			b.minkeypage = DEFMINKEYPAGE;
1389f0aa214Scgd 
1399f0aa214Scgd 		/* If no comparison, use default comparison and prefix. */
1409f0aa214Scgd 		if (b.compare == NULL) {
1419f0aa214Scgd 			b.compare = __bt_defcmp;
1429f0aa214Scgd 			if (b.prefix == NULL)
1439f0aa214Scgd 				b.prefix = __bt_defpfx;
1449f0aa214Scgd 		}
1459f0aa214Scgd 
1469f0aa214Scgd 		if (b.lorder == 0)
1479f0aa214Scgd 			b.lorder = machine_lorder;
1489f0aa214Scgd 	} else {
1499f0aa214Scgd 		b.compare = __bt_defcmp;
1509f0aa214Scgd 		b.cachesize = 0;
1519f0aa214Scgd 		b.flags = 0;
1529f0aa214Scgd 		b.lorder = machine_lorder;
1539f0aa214Scgd 		b.minkeypage = DEFMINKEYPAGE;
1549f0aa214Scgd 		b.prefix = __bt_defpfx;
1559f0aa214Scgd 		b.psize = 0;
1569f0aa214Scgd 	}
1579f0aa214Scgd 
1589f0aa214Scgd 	/* Check for the ubiquitous PDP-11. */
1599f0aa214Scgd 	if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
1609f0aa214Scgd 		goto einval;
1619f0aa214Scgd 
1629f0aa214Scgd 	/* Allocate and initialize DB and BTREE structures. */
163b605a13bSchristos 	if ((t = malloc(sizeof(*t))) == NULL)
1649f0aa214Scgd 		goto err;
16565aeeefbScgd 	memset(t, 0, sizeof(BTREE));
16665aeeefbScgd 	t->bt_fd = -1;			/* Don't close unopened fd on error. */
1679f0aa214Scgd 	t->bt_lorder = b.lorder;
1689f0aa214Scgd 	t->bt_order = NOT;
1699f0aa214Scgd 	t->bt_cmp = b.compare;
1709f0aa214Scgd 	t->bt_pfx = b.prefix;
17165aeeefbScgd 	t->bt_rfd = -1;
17265aeeefbScgd 
173b605a13bSchristos 	if ((t->bt_dbp = dbp = malloc(sizeof(*dbp))) == NULL)
17465aeeefbScgd 		goto err;
17524420c01Scgd 	memset(t->bt_dbp, 0, sizeof(DB));
1769f0aa214Scgd 	if (t->bt_lorder != machine_lorder)
17724420c01Scgd 		F_SET(t, B_NEEDSWAP);
1789f0aa214Scgd 
1799f0aa214Scgd 	dbp->type = DB_BTREE;
1809f0aa214Scgd 	dbp->internal = t;
1819f0aa214Scgd 	dbp->close = __bt_close;
1829f0aa214Scgd 	dbp->del = __bt_delete;
1839f0aa214Scgd 	dbp->fd = __bt_fd;
1849f0aa214Scgd 	dbp->get = __bt_get;
1859f0aa214Scgd 	dbp->put = __bt_put;
1869f0aa214Scgd 	dbp->seq = __bt_seq;
1879f0aa214Scgd 	dbp->sync = __bt_sync;
1889f0aa214Scgd 
1899f0aa214Scgd 	/*
1909f0aa214Scgd 	 * If no file name was supplied, this is an in-memory btree and we
1919f0aa214Scgd 	 * open a backing temporary file.  Otherwise, it's a disk-based tree.
1929f0aa214Scgd 	 */
1939f0aa214Scgd 	if (fname) {
1949f0aa214Scgd 		switch (flags & O_ACCMODE) {
1959f0aa214Scgd 		case O_RDONLY:
19624420c01Scgd 			F_SET(t, B_RDONLY);
1979f0aa214Scgd 			break;
1989f0aa214Scgd 		case O_RDWR:
1999f0aa214Scgd 			break;
2009f0aa214Scgd 		case O_WRONLY:
2019f0aa214Scgd 		default:
2029f0aa214Scgd 			goto einval;
2039f0aa214Scgd 		}
204b605a13bSchristos 		if ((t->bt_fd = __dbopen(fname, flags, mode, &sb)) == -1)
205b7e6351cSmycroft 			goto err;
2069f0aa214Scgd 	} else {
2079f0aa214Scgd 		if ((flags & O_ACCMODE) != O_RDWR)
2089f0aa214Scgd 			goto einval;
209b605a13bSchristos 		if ((t->bt_fd = __dbtemp("bt.", &sb)) == -1)
2109f0aa214Scgd 			goto err;
21124420c01Scgd 		F_SET(t, B_INMEM);
2129f0aa214Scgd 	}
2139f0aa214Scgd 
2149f0aa214Scgd 
2159f0aa214Scgd 	if (sb.st_size) {
216a6d14e36Scgd 		if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
2179f0aa214Scgd 			goto err;
2189f0aa214Scgd 		if (nr != sizeof(BTMETA))
2199f0aa214Scgd 			goto eftype;
2209f0aa214Scgd 
2219f0aa214Scgd 		/*
2229f0aa214Scgd 		 * Read in the meta-data.  This can change the notion of what
2239f0aa214Scgd 		 * the lorder, page size and flags are, and, when the page size
2249f0aa214Scgd 		 * changes, the cachesize value can change too.  If the user
2259f0aa214Scgd 		 * specified the wrong byte order for an existing database, we
2269f0aa214Scgd 		 * don't bother to return an error, we just clear the NEEDSWAP
2279f0aa214Scgd 		 * bit.
2289f0aa214Scgd 		 */
22924420c01Scgd 		if (m.magic == BTREEMAGIC)
23024420c01Scgd 			F_CLR(t, B_NEEDSWAP);
2319f0aa214Scgd 		else {
23224420c01Scgd 			F_SET(t, B_NEEDSWAP);
23324420c01Scgd 			M_32_SWAP(m.magic);
23424420c01Scgd 			M_32_SWAP(m.version);
23524420c01Scgd 			M_32_SWAP(m.psize);
23624420c01Scgd 			M_32_SWAP(m.free);
23724420c01Scgd 			M_32_SWAP(m.nrecs);
23824420c01Scgd 			M_32_SWAP(m.flags);
2399f0aa214Scgd 		}
24024420c01Scgd 		if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
2419f0aa214Scgd 			goto eftype;
24224420c01Scgd 		if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
24300ae392dSchristos 		    m.psize & (sizeof(indx_t) - 1))
2449f0aa214Scgd 			goto eftype;
24524420c01Scgd 		if (m.flags & ~SAVEMETA)
2469f0aa214Scgd 			goto eftype;
24724420c01Scgd 		b.psize = m.psize;
24824420c01Scgd 		F_SET(t, m.flags);
24924420c01Scgd 		t->bt_free = m.free;
25024420c01Scgd 		t->bt_nrecs = m.nrecs;
2519f0aa214Scgd 	} else {
2529f0aa214Scgd 		/*
2539f0aa214Scgd 		 * Set the page size to the best value for I/O to this file.
2549f0aa214Scgd 		 * Don't overflow the page offset type.
2559f0aa214Scgd 		 */
2569f0aa214Scgd 		if (b.psize == 0) {
2579f0aa214Scgd 			b.psize = sb.st_blksize;
2589f0aa214Scgd 			if (b.psize < MINPSIZE)
2599f0aa214Scgd 				b.psize = MINPSIZE;
2609f0aa214Scgd 			if (b.psize > MAX_PAGE_OFFSET + 1)
2619f0aa214Scgd 				b.psize = MAX_PAGE_OFFSET + 1;
2629f0aa214Scgd 		}
2639f0aa214Scgd 
2649f0aa214Scgd 		/* Set flag if duplicates permitted. */
2659f0aa214Scgd 		if (!(b.flags & R_DUP))
26624420c01Scgd 			F_SET(t, B_NODUPS);
2679f0aa214Scgd 
2689f0aa214Scgd 		t->bt_free = P_INVALID;
2699f0aa214Scgd 		t->bt_nrecs = 0;
27024420c01Scgd 		F_SET(t, B_METADIRTY);
2719f0aa214Scgd 	}
2729f0aa214Scgd 
2739f0aa214Scgd 	t->bt_psize = b.psize;
2749f0aa214Scgd 
2759f0aa214Scgd 	/* Set the cache size; must be a multiple of the page size. */
27600ae392dSchristos 	if (b.cachesize && b.cachesize & (b.psize - 1))
27700ae392dSchristos 		b.cachesize += (~b.cachesize & (b.psize - 1)) + 1;
2789f0aa214Scgd 	if (b.cachesize < b.psize * MINCACHE)
2799f0aa214Scgd 		b.cachesize = b.psize * MINCACHE;
2809f0aa214Scgd 
2819f0aa214Scgd 	/* Calculate number of pages to cache. */
2829f0aa214Scgd 	ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
2839f0aa214Scgd 
2849f0aa214Scgd 	/*
2859f0aa214Scgd 	 * The btree data structure requires that at least two keys can fit on
2869f0aa214Scgd 	 * a page, but other than that there's no fixed requirement.  The user
2879f0aa214Scgd 	 * specified a minimum number per page, and we translated that into the
2889f0aa214Scgd 	 * number of bytes a key/data pair can use before being placed on an
2899f0aa214Scgd 	 * overflow page.  This calculation includes the page header, the size
2909f0aa214Scgd 	 * of the index referencing the leaf item and the size of the leaf item
2919f0aa214Scgd 	 * structure.  Also, don't let the user specify a minkeypage such that
2929f0aa214Scgd 	 * a key/data pair won't fit even if both key and data are on overflow
2939f0aa214Scgd 	 * pages.
2949f0aa214Scgd 	 */
295cb9daf8fSchristos 	temp = (t->bt_psize - BTDATAOFF) / b.minkeypage -
2969f0aa214Scgd 	    (sizeof(indx_t) + NBLEAFDBT(0, 0));
297cb9daf8fSchristos 	_DBFIT(temp, indx_t);
298cb9daf8fSchristos 	t->bt_ovflsize = (indx_t)temp;
299c5e820caSchristos 	if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t)) {
300c5e820caSchristos 		size_t l = NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
301c5e820caSchristos 		_DBFIT(l, indx_t);
302c5e820caSchristos 		t->bt_ovflsize = (indx_t)l;
303c5e820caSchristos 	}
3049f0aa214Scgd 
3059f0aa214Scgd 	/* Initialize the buffer pool. */
3069f0aa214Scgd 	if ((t->bt_mp =
3079f0aa214Scgd 	    mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
3089f0aa214Scgd 		goto err;
30924420c01Scgd 	if (!F_ISSET(t, B_INMEM))
3109f0aa214Scgd 		mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
3119f0aa214Scgd 
3129f0aa214Scgd 	/* Create a root page if new tree. */
3139f0aa214Scgd 	if (nroot(t) == RET_ERROR)
3149f0aa214Scgd 		goto err;
3159f0aa214Scgd 
31645e27c80Scgd 	/* Global flags. */
31745e27c80Scgd 	if (dflags & DB_LOCK)
31824420c01Scgd 		F_SET(t, B_DB_LOCK);
31945e27c80Scgd 	if (dflags & DB_SHMEM)
32024420c01Scgd 		F_SET(t, B_DB_SHMEM);
32145e27c80Scgd 	if (dflags & DB_TXN)
32224420c01Scgd 		F_SET(t, B_DB_TXN);
32345e27c80Scgd 
3249f0aa214Scgd 	return (dbp);
3259f0aa214Scgd 
3269f0aa214Scgd einval:	errno = EINVAL;
3279f0aa214Scgd 	goto err;
3289f0aa214Scgd 
3299f0aa214Scgd eftype:	errno = EFTYPE;
3309f0aa214Scgd 	goto err;
3319f0aa214Scgd 
3329f0aa214Scgd err:	if (t) {
3339f0aa214Scgd 		if (t->bt_dbp)
3349f0aa214Scgd 			free(t->bt_dbp);
3359f0aa214Scgd 		if (t->bt_fd != -1)
3369f0aa214Scgd 			(void)close(t->bt_fd);
3379f0aa214Scgd 		free(t);
3389f0aa214Scgd 	}
3399f0aa214Scgd 	return (NULL);
3409f0aa214Scgd }
3419f0aa214Scgd 
3429f0aa214Scgd /*
3439f0aa214Scgd  * NROOT -- Create the root of a new tree.
3449f0aa214Scgd  *
3459f0aa214Scgd  * Parameters:
3469f0aa214Scgd  *	t:	tree
3479f0aa214Scgd  *
3489f0aa214Scgd  * Returns:
3499f0aa214Scgd  *	RET_ERROR, RET_SUCCESS
3509f0aa214Scgd  */
3519f0aa214Scgd static int
nroot(BTREE * t)352cb9daf8fSchristos nroot(BTREE *t)
3539f0aa214Scgd {
3549f0aa214Scgd 	PAGE *meta, *root;
3559f0aa214Scgd 	pgno_t npg;
3569f0aa214Scgd 
357*aae80e6bSchristos 	if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
35886147b1cSchristos 		if (root->lower == 0 &&
35986147b1cSchristos 		    root->pgno == 0 &&
36086147b1cSchristos 		    root->linp[0] == 0) {
36186147b1cSchristos 			mpool_delete(t->bt_mp, root);
36286147b1cSchristos 			errno = EINVAL;
36386147b1cSchristos 		} else {
36486147b1cSchristos 			mpool_put(t->bt_mp, root, 0);
36586147b1cSchristos 			return RET_SUCCESS;
36686147b1cSchristos 		}
3679f0aa214Scgd 	}
368a6d14e36Scgd 	if (errno != EINVAL)		/* It's OK to not exist. */
3699f0aa214Scgd 		return (RET_ERROR);
370a6d14e36Scgd 	errno = 0;
3719f0aa214Scgd 
37286147b1cSchristos 	if ((meta = mpool_newf(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
3739f0aa214Scgd 		return (RET_ERROR);
3749f0aa214Scgd 
37586147b1cSchristos 	if ((root = mpool_newf(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
3769f0aa214Scgd 		return (RET_ERROR);
3779f0aa214Scgd 
3789f0aa214Scgd 	if (npg != P_ROOT)
3799f0aa214Scgd 		return (RET_ERROR);
3809f0aa214Scgd 	root->pgno = npg;
3819f0aa214Scgd 	root->prevpg = root->nextpg = P_INVALID;
3829f0aa214Scgd 	root->lower = BTDATAOFF;
3839f0aa214Scgd 	root->upper = t->bt_psize;
3849f0aa214Scgd 	root->flags = P_BLEAF;
3859f0aa214Scgd 	memset(meta, 0, t->bt_psize);
3869f0aa214Scgd 	mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
3879f0aa214Scgd 	mpool_put(t->bt_mp, root, MPOOL_DIRTY);
3889f0aa214Scgd 	return (RET_SUCCESS);
3899f0aa214Scgd }
3909f0aa214Scgd 
3919f0aa214Scgd static int
byteorder(void)392cb9daf8fSchristos byteorder(void)
3939f0aa214Scgd {
39440b37a3bSjoerg 	uint32_t x;
39540b37a3bSjoerg 	uint8_t *p;
3969f0aa214Scgd 
3979f0aa214Scgd 	x = 0x01020304;
39840b37a3bSjoerg 	p = (uint8_t *)(void *)&x;
3999f0aa214Scgd 	switch (*p) {
4009f0aa214Scgd 	case 1:
4019f0aa214Scgd 		return (BIG_ENDIAN);
4029f0aa214Scgd 	case 4:
4039f0aa214Scgd 		return (LITTLE_ENDIAN);
4049f0aa214Scgd 	default:
4059f0aa214Scgd 		return (0);
4069f0aa214Scgd 	}
4079f0aa214Scgd }
4089f0aa214Scgd 
4099f0aa214Scgd int
__bt_fd(const DB * dbp)410cb9daf8fSchristos __bt_fd(const DB *dbp)
4119f0aa214Scgd {
4129f0aa214Scgd 	BTREE *t;
4139f0aa214Scgd 
4149f0aa214Scgd 	t = dbp->internal;
4159f0aa214Scgd 
41645e27c80Scgd 	/* Toss any page pinned across calls. */
41745e27c80Scgd 	if (t->bt_pinned != NULL) {
41845e27c80Scgd 		mpool_put(t->bt_mp, t->bt_pinned, 0);
41945e27c80Scgd 		t->bt_pinned = NULL;
42045e27c80Scgd 	}
42145e27c80Scgd 
42245e27c80Scgd 	/* In-memory database can't have a file descriptor. */
42324420c01Scgd 	if (F_ISSET(t, B_INMEM)) {
4249f0aa214Scgd 		errno = ENOENT;
4259f0aa214Scgd 		return (-1);
4269f0aa214Scgd 	}
4279f0aa214Scgd 	return (t->bt_fd);
4289f0aa214Scgd }
429