source: rtems-libbsd/freebsd-userspace/lib/libc/db/btree/bt_open.c @ e4e1746

#include "port_before.h"

/*-
 * Copyright (c) 1990, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bt_open.c   8.10 (Berkeley) 8/17/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * Implementation of btree access method for 4.4BSD.
 *
 * The design here was originally based on that of the btree access method
 * used in the Postgres database system at UC Berkeley.  This implementation
 * is wholly independent of the Postgres code.
 */

#include "namespace.h"
#include <sys/param.h>
#include <sys/stat.h>

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"

#include <db.h>
#include "btree.h"

#ifdef DEBUG
#undef  MINPSIZE
#define MINPSIZE        128
#endif

static int byteorder(void);
static int nroot(BTREE *);
static int tmp(void);

/*
 * __BT_OPEN -- Open a btree.
 *
 * Creates and fills a DB struct, and calls the routine that actually
 * opens the btree.
 *
 * Parameters:
 *      fname:  filename (NULL for in-memory trees)
 *      flags:  open flag bits
 *      mode:   open permission bits
 *      b:      BTREEINFO pointer
 *
 * Returns:
 *      NULL on failure, pointer to DB on success.
 *
 */
DB *
__bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, int dflags)
{
        struct stat sb;
        BTMETA m;
        BTREE *t;
        BTREEINFO b;
        DB *dbp;
        pgno_t ncache;
        ssize_t nr;
        int machine_lorder, saved_errno;

        t = NULL;

        /*
         * Intention is to make sure all of the user's selections are okay
         * here and then use them without checking.  Can't be complete, since
         * we don't know the right page size, lorder or flags until the backing
         * file is opened.  Also, the file's page size can cause the cachesize
         * to change.
         */
        machine_lorder = byteorder();
        if (openinfo) {
                b = *openinfo;

                /* Flags: R_DUP. */
                if (b.flags & ~(R_DUP))
                        goto einval;

                /*
                 * Page size must be indx_t aligned and >= MINPSIZE.  Default
                 * page size is set farther on, based on the underlying file
                 * transfer size.
                 */
                if (b.psize &&
                    (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
                    b.psize & (sizeof(indx_t) - 1) ))
                        goto einval;

                /* Minimum number of keys per page; absolute minimum is 2. */
                if (b.minkeypage) {
                        if (b.minkeypage < 2)
                                goto einval;
                } else
                        b.minkeypage = DEFMINKEYPAGE;

                /* If no comparison, use default comparison and prefix. */
                if (b.compare == NULL) {
                        b.compare = __bt_defcmp;
                        if (b.prefix == NULL)
                                b.prefix = __bt_defpfx;
                }

                if (b.lorder == 0)
                        b.lorder = machine_lorder;
        } else {
                b.compare = __bt_defcmp;
                b.cachesize = 0;
                b.flags = 0;
                b.lorder = machine_lorder;
                b.minkeypage = DEFMINKEYPAGE;
                b.prefix = __bt_defpfx;
                b.psize = 0;
        }

        /* Check for the ubiquitous PDP-11. */
        if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
                goto einval;

        /* Allocate and initialize DB and BTREE structures. */
        if ((t = (BTREE *)calloc(1, sizeof(BTREE))) == NULL)
                goto err;
        t->bt_fd = -1;                  /* Don't close unopened fd on error. */
        t->bt_lorder = b.lorder;
        t->bt_order = NOT;
        t->bt_cmp = b.compare;
        t->bt_pfx = b.prefix;
        t->bt_rfd = -1;

        if ((t->bt_dbp = dbp = (DB *)calloc(1, sizeof(DB))) == NULL)
                goto err;
        if (t->bt_lorder != machine_lorder)
                F_SET(t, B_NEEDSWAP);

        dbp->type = DB_BTREE;
        dbp->internal = t;
        dbp->close = __bt_close;
        dbp->del = __bt_delete;
        dbp->fd = __bt_fd;
        dbp->get = __bt_get;
        dbp->put = __bt_put;
        dbp->seq = __bt_seq;
        dbp->sync = __bt_sync;

        /*
         * If no file name was supplied, this is an in-memory btree and we
         * open a backing temporary file.  Otherwise, it's a disk-based tree.
         */
        if (fname) {
                switch (flags & O_ACCMODE) {
                case O_RDONLY:
                        F_SET(t, B_RDONLY);
                        break;
                case O_RDWR:
                        break;
                case O_WRONLY:
                default:
                        goto einval;
                }

                if ((t->bt_fd = _open(fname, flags, mode)) < 0)
                        goto err;

        } else {
                if ((flags & O_ACCMODE) != O_RDWR)
                        goto einval;
                if ((t->bt_fd = tmp()) == -1)
                        goto err;
                F_SET(t, B_INMEM);
        }

        if (_fcntl(t->bt_fd, F_SETFD, 1) == -1)
                goto err;

        if (_fstat(t->bt_fd, &sb))
                goto err;
        if (sb.st_size) {
                if ((nr = _read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
                        goto err;
                if (nr != sizeof(BTMETA))
                        goto eftype;

                /*
                 * Read in the meta-data.  This can change the notion of what
                 * the lorder, page size and flags are, and, when the page size
                 * changes, the cachesize value can change too.  If the user
                 * specified the wrong byte order for an existing database, we
                 * don't bother to return an error, we just clear the NEEDSWAP
                 * bit.
                 */
                if (m.magic == BTREEMAGIC)
                        F_CLR(t, B_NEEDSWAP);
                else {
                        F_SET(t, B_NEEDSWAP);
                        M_32_SWAP(m.magic);
                        M_32_SWAP(m.version);
                        M_32_SWAP(m.psize);
                        M_32_SWAP(m.free);
                        M_32_SWAP(m.nrecs);
                        M_32_SWAP(m.flags);
                }
                if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
                        goto eftype;
                if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
                    m.psize & (sizeof(indx_t) - 1) )
                        goto eftype;
                if (m.flags & ~SAVEMETA)
                        goto eftype;
                b.psize = m.psize;
                F_SET(t, m.flags);
                t->bt_free = m.free;
                t->bt_nrecs = m.nrecs;
        } else {
                /*
                 * Set the page size to the best value for I/O to this file.
                 * Don't overflow the page offset type.
                 */
                if (b.psize == 0) {
                        b.psize = sb.st_blksize;
                        if (b.psize < MINPSIZE)
                                b.psize = MINPSIZE;
                        if (b.psize > MAX_PAGE_OFFSET + 1)
                                b.psize = MAX_PAGE_OFFSET + 1;
                }

                /* Set flag if duplicates permitted. */
                if (!(b.flags & R_DUP))
                        F_SET(t, B_NODUPS);

                t->bt_free = P_INVALID;
                t->bt_nrecs = 0;
                F_SET(t, B_METADIRTY);
        }

        t->bt_psize = b.psize;

        /* Set the cache size; must be a multiple of the page size. */
        if (b.cachesize && b.cachesize & (b.psize - 1) )
                b.cachesize += (~b.cachesize & (b.psize - 1) ) + 1;
        if (b.cachesize < b.psize * MINCACHE)
                b.cachesize = b.psize * MINCACHE;

        /* Calculate number of pages to cache. */
        ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;

        /*
         * The btree data structure requires that at least two keys can fit on
         * a page, but other than that there's no fixed requirement.  The user
         * specified a minimum number per page, and we translated that into the
         * number of bytes a key/data pair can use before being placed on an
         * overflow page.  This calculation includes the page header, the size
         * of the index referencing the leaf item and the size of the leaf item
         * structure.  Also, don't let the user specify a minkeypage such that
         * a key/data pair won't fit even if both key and data are on overflow
         * pages.
         */
        t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
            (sizeof(indx_t) + NBLEAFDBT(0, 0));
        if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
                t->bt_ovflsize =
                    NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);

        /* Initialize the buffer pool. */
        if ((t->bt_mp =
            mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
                goto err;
        if (!F_ISSET(t, B_INMEM))
                mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);

        /* Create a root page if new tree. */
        if (nroot(t) == RET_ERROR)
                goto err;

        /* Global flags. */
        if (dflags & DB_LOCK)
                F_SET(t, B_DB_LOCK);
        if (dflags & DB_SHMEM)
                F_SET(t, B_DB_SHMEM);
        if (dflags & DB_TXN)
                F_SET(t, B_DB_TXN);

        return (dbp);

einval: errno = EINVAL;
        goto err;

eftype: errno = EFTYPE;
        goto err;

err:    saved_errno = errno;
        if (t) {
                if (t->bt_dbp)
                        free(t->bt_dbp);
                if (t->bt_fd != -1)
                        (void)_close(t->bt_fd);
                free(t);
        }
        errno = saved_errno;
        return (NULL);
}

/*
 * NROOT -- Create the root of a new tree.
 *
 * Parameters:
 *      t:      tree
 *
 * Returns:
 *      RET_ERROR, RET_SUCCESS
 */
static int
nroot(BTREE *t)
{
        PAGE *meta, *root;
        pgno_t npg;

        if ((root = mpool_get(t->bt_mp, 1, 0)) != NULL) {
                if (root->lower == 0 &&
                    root->pgno == 0 &&
                    root->linp[0] == 0) {
                        mpool_delete(t->bt_mp, root);
                        errno = EINVAL;
                } else {
                        mpool_put(t->bt_mp, root, 0);
                        return (RET_SUCCESS);
                }
        }
        if (errno != EINVAL)            /* It's OK to not exist. */
                return (RET_ERROR);
        errno = 0;

        if ((meta = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
                return (RET_ERROR);

        if ((root = mpool_new(t->bt_mp, &npg, MPOOL_PAGE_NEXT)) == NULL)
                return (RET_ERROR);

        if (npg != P_ROOT)
                return (RET_ERROR);
        root->pgno = npg;
        root->prevpg = root->nextpg = P_INVALID;
        root->lower = BTDATAOFF;
        root->upper = t->bt_psize;
        root->flags = P_BLEAF;
        memset(meta, 0, t->bt_psize);
        mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
        mpool_put(t->bt_mp, root, MPOOL_DIRTY);
        return (RET_SUCCESS);
}

static int
tmp(void)
{
        sigset_t set, oset;
        int fd, len;
        char *envtmp = NULL;
        char path[MAXPATHLEN];

        if (issetugid() == 0)
                envtmp = getenv("TMPDIR");
        len = snprintf(path,
            sizeof(path), "%s/bt.XXXXXXXXXX", envtmp ? envtmp : "/tmp");
        if (len < 0 || len >= (int)sizeof(path)) {
                errno = ENAMETOOLONG;
                return(-1);
        }

        (void)sigfillset(&set);
        (void)_sigprocmask(SIG_BLOCK, &set, &oset);
        if ((fd = mkstemp(path)) != -1)
                (void)unlink(path);
        (void)_sigprocmask(SIG_SETMASK, &oset, NULL);
        return(fd);
}

static int
byteorder(void)
{
        u_int32_t x;
        u_char *p;

        x = 0x01020304;
        p = (u_char *)&x;
        switch (*p) {
        case 1:
                return (BIG_ENDIAN);
        case 4:
                return (LITTLE_ENDIAN);
        default:
                return (0);
        }
}

int
__bt_fd(const DB *dbp)
{
        BTREE *t;

        t = dbp->internal;

        /* Toss any page pinned across calls. */
        if (t->bt_pinned != NULL) {
                mpool_put(t->bt_mp, t->bt_pinned, 0);
                t->bt_pinned = NULL;
        }

        /* In-memory database can't have a file descriptor. */
        if (F_ISSET(t, B_INMEM)) {
                errno = ENOENT;
                return (-1);
        }
        return (t->bt_fd);
}