445 lines
11 KiB
C
445 lines
11 KiB
C
/*-
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* Copyright (c) 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Mike Olson.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)bt_open.c 8.10 (Berkeley) 8/17/94";
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#endif /* LIBC_SCCS and not lint */
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/*
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* Implementation of btree access method for 4.4BSD.
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*
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* The design here was originally based on that of the btree access method
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* used in the Postgres database system at UC Berkeley. This implementation
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* is wholly independent of the Postgres code.
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*/
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <db.h>
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#include "btree.h"
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#ifdef DEBUG
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#undef MINPSIZE
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#define MINPSIZE 128
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#endif
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static int byteorder __P((void));
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static int nroot __P((BTREE *));
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static int tmp __P((void));
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/*
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* __BT_OPEN -- Open a btree.
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*
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* Creates and fills a DB struct, and calls the routine that actually
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* opens the btree.
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*
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* Parameters:
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* fname: filename (NULL for in-memory trees)
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* flags: open flag bits
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* mode: open permission bits
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* b: BTREEINFO pointer
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*
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* Returns:
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* NULL on failure, pointer to DB on success.
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*
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*/
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DB *
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__bt_open(fname, flags, mode, openinfo, dflags)
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const char *fname;
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int flags, mode, dflags;
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const BTREEINFO *openinfo;
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{
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struct stat sb;
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BTMETA m;
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BTREE *t;
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BTREEINFO b;
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DB *dbp;
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pgno_t ncache;
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ssize_t nr;
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int machine_lorder;
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t = NULL;
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/*
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* Intention is to make sure all of the user's selections are okay
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* here and then use them without checking. Can't be complete, since
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* we don't know the right page size, lorder or flags until the backing
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* file is opened. Also, the file's page size can cause the cachesize
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* to change.
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*/
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machine_lorder = byteorder();
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if (openinfo) {
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b = *openinfo;
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/* Flags: R_DUP. */
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if (b.flags & ~(R_DUP))
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goto einval;
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/*
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* Page size must be indx_t aligned and >= MINPSIZE. Default
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* page size is set farther on, based on the underlying file
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* transfer size.
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*/
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if (b.psize &&
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(b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
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b.psize & sizeof(indx_t) - 1))
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goto einval;
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/* Minimum number of keys per page; absolute minimum is 2. */
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if (b.minkeypage) {
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if (b.minkeypage < 2)
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goto einval;
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} else
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b.minkeypage = DEFMINKEYPAGE;
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/* If no comparison, use default comparison and prefix. */
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if (b.compare == NULL) {
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b.compare = __bt_defcmp;
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if (b.prefix == NULL)
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b.prefix = __bt_defpfx;
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}
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if (b.lorder == 0)
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b.lorder = machine_lorder;
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} else {
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b.compare = __bt_defcmp;
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b.cachesize = 0;
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b.flags = 0;
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b.lorder = machine_lorder;
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b.minkeypage = DEFMINKEYPAGE;
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b.prefix = __bt_defpfx;
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b.psize = 0;
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}
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/* Check for the ubiquitous PDP-11. */
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if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
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goto einval;
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/* Allocate and initialize DB and BTREE structures. */
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if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL)
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goto err;
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memset(t, 0, sizeof(BTREE));
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t->bt_fd = -1; /* Don't close unopened fd on error. */
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t->bt_lorder = b.lorder;
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t->bt_order = NOT;
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t->bt_cmp = b.compare;
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t->bt_pfx = b.prefix;
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t->bt_rfd = -1;
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if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
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goto err;
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memset(t->bt_dbp, 0, sizeof(DB));
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if (t->bt_lorder != machine_lorder)
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F_SET(t, B_NEEDSWAP);
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dbp->type = DB_BTREE;
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dbp->internal = t;
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dbp->close = __bt_close;
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dbp->del = __bt_delete;
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dbp->fd = __bt_fd;
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dbp->get = __bt_get;
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dbp->put = __bt_put;
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dbp->seq = __bt_seq;
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dbp->sync = __bt_sync;
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/*
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* If no file name was supplied, this is an in-memory btree and we
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* open a backing temporary file. Otherwise, it's a disk-based tree.
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*/
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if (fname) {
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switch (flags & O_ACCMODE) {
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case O_RDONLY:
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F_SET(t, B_RDONLY);
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break;
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case O_RDWR:
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break;
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case O_WRONLY:
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default:
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goto einval;
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}
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if ((t->bt_fd = open(fname, flags, mode)) < 0)
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goto err;
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} else {
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if ((flags & O_ACCMODE) != O_RDWR)
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goto einval;
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if ((t->bt_fd = tmp()) == -1)
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goto err;
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F_SET(t, B_INMEM);
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}
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if (fcntl(t->bt_fd, F_SETFD, 1) == -1)
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goto err;
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if (fstat(t->bt_fd, &sb))
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goto err;
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if (sb.st_size) {
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if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
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goto err;
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if (nr != sizeof(BTMETA))
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goto eftype;
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/*
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* Read in the meta-data. This can change the notion of what
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* the lorder, page size and flags are, and, when the page size
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* changes, the cachesize value can change too. If the user
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* specified the wrong byte order for an existing database, we
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* don't bother to return an error, we just clear the NEEDSWAP
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* bit.
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*/
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if (m.magic == BTREEMAGIC)
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F_CLR(t, B_NEEDSWAP);
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else {
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F_SET(t, B_NEEDSWAP);
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M_32_SWAP(m.magic);
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M_32_SWAP(m.version);
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M_32_SWAP(m.psize);
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M_32_SWAP(m.free);
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M_32_SWAP(m.nrecs);
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M_32_SWAP(m.flags);
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}
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if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
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goto eftype;
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if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
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m.psize & sizeof(indx_t) - 1)
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goto eftype;
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if (m.flags & ~SAVEMETA)
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goto eftype;
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b.psize = m.psize;
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F_SET(t, m.flags);
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t->bt_free = m.free;
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t->bt_nrecs = m.nrecs;
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} else {
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/*
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* Set the page size to the best value for I/O to this file.
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* Don't overflow the page offset type.
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*/
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if (b.psize == 0) {
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b.psize = sb.st_blksize;
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if (b.psize < MINPSIZE)
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b.psize = MINPSIZE;
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if (b.psize > MAX_PAGE_OFFSET + 1)
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b.psize = MAX_PAGE_OFFSET + 1;
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}
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/* Set flag if duplicates permitted. */
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if (!(b.flags & R_DUP))
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F_SET(t, B_NODUPS);
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t->bt_free = P_INVALID;
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t->bt_nrecs = 0;
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F_SET(t, B_METADIRTY);
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}
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t->bt_psize = b.psize;
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/* Set the cache size; must be a multiple of the page size. */
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if (b.cachesize && b.cachesize & b.psize - 1)
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b.cachesize += (~b.cachesize & b.psize - 1) + 1;
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if (b.cachesize < b.psize * MINCACHE)
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b.cachesize = b.psize * MINCACHE;
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/* Calculate number of pages to cache. */
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ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
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/*
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* The btree data structure requires that at least two keys can fit on
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* a page, but other than that there's no fixed requirement. The user
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* specified a minimum number per page, and we translated that into the
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* number of bytes a key/data pair can use before being placed on an
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* overflow page. This calculation includes the page header, the size
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* of the index referencing the leaf item and the size of the leaf item
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* structure. Also, don't let the user specify a minkeypage such that
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* a key/data pair won't fit even if both key and data are on overflow
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* pages.
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*/
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t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
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(sizeof(indx_t) + NBLEAFDBT(0, 0));
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if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
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t->bt_ovflsize =
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NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
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/* Initialize the buffer pool. */
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if ((t->bt_mp =
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mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
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goto err;
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if (!F_ISSET(t, B_INMEM))
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mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
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/* Create a root page if new tree. */
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if (nroot(t) == RET_ERROR)
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goto err;
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/* Global flags. */
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if (dflags & DB_LOCK)
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F_SET(t, B_DB_LOCK);
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if (dflags & DB_SHMEM)
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F_SET(t, B_DB_SHMEM);
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if (dflags & DB_TXN)
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F_SET(t, B_DB_TXN);
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return (dbp);
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einval: errno = EINVAL;
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goto err;
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eftype: errno = EFTYPE;
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goto err;
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err: if (t) {
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if (t->bt_dbp)
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free(t->bt_dbp);
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if (t->bt_fd != -1)
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(void)close(t->bt_fd);
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free(t);
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}
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return (NULL);
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}
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/*
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* NROOT -- Create the root of a new tree.
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*
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* Parameters:
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* t: tree
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*
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* Returns:
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* RET_ERROR, RET_SUCCESS
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*/
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static int
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nroot(t)
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BTREE *t;
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{
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PAGE *meta, *root;
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pgno_t npg;
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if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) {
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mpool_put(t->bt_mp, meta, 0);
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return (RET_SUCCESS);
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}
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if (errno != EINVAL) /* It's OK to not exist. */
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return (RET_ERROR);
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errno = 0;
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if ((meta = mpool_new(t->bt_mp, &npg)) == NULL)
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return (RET_ERROR);
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if ((root = mpool_new(t->bt_mp, &npg)) == NULL)
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return (RET_ERROR);
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if (npg != P_ROOT)
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return (RET_ERROR);
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root->pgno = npg;
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root->prevpg = root->nextpg = P_INVALID;
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root->lower = BTDATAOFF;
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root->upper = t->bt_psize;
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root->flags = P_BLEAF;
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memset(meta, 0, t->bt_psize);
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mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
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mpool_put(t->bt_mp, root, MPOOL_DIRTY);
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return (RET_SUCCESS);
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}
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static int
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tmp()
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{
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sigset_t set, oset;
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int fd;
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char *envtmp;
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char path[MAXPATHLEN];
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envtmp = getenv("TMPDIR");
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(void)snprintf(path,
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sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : "/tmp");
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(void)sigfillset(&set);
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(void)sigprocmask(SIG_BLOCK, &set, &oset);
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if ((fd = mkstemp(path)) != -1)
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(void)unlink(path);
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(void)sigprocmask(SIG_SETMASK, &oset, NULL);
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return(fd);
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}
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static int
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byteorder()
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{
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u_int32_t x;
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u_char *p;
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x = 0x01020304;
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p = (u_char *)&x;
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switch (*p) {
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case 1:
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return (BIG_ENDIAN);
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case 4:
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return (LITTLE_ENDIAN);
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default:
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return (0);
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}
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}
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int
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__bt_fd(dbp)
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const DB *dbp;
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{
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BTREE *t;
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t = dbp->internal;
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/* Toss any page pinned across calls. */
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if (t->bt_pinned != NULL) {
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mpool_put(t->bt_mp, t->bt_pinned, 0);
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t->bt_pinned = NULL;
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}
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/* In-memory database can't have a file descriptor. */
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if (F_ISSET(t, B_INMEM)) {
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errno = ENOENT;
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return (-1);
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}
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return (t->bt_fd);
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}
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