archie/berkdb/btree/bt_open.c
2024-05-27 16:13:40 +02:00

445 lines
11 KiB
C

/*-
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 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 */
/*
* 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 <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 <db.h>
#include "btree.h"
#ifdef DEBUG
#undef MINPSIZE
#define MINPSIZE 128
#endif
static int byteorder __P((void));
static int nroot __P((BTREE *));
static int tmp __P((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(fname, flags, mode, openinfo, dflags)
const char *fname;
int flags, mode, dflags;
const BTREEINFO *openinfo;
{
struct stat sb;
BTMETA m;
BTREE *t;
BTREEINFO b;
DB *dbp;
pgno_t ncache;
ssize_t nr;
int machine_lorder;
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 *)malloc(sizeof(BTREE))) == NULL)
goto err;
memset(t, 0, sizeof(BTREE));
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 *)malloc(sizeof(DB))) == NULL)
goto err;
memset(t->bt_dbp, 0, sizeof(DB));
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: if (t) {
if (t->bt_dbp)
free(t->bt_dbp);
if (t->bt_fd != -1)
(void)close(t->bt_fd);
free(t);
}
return (NULL);
}
/*
* NROOT -- Create the root of a new tree.
*
* Parameters:
* t: tree
*
* Returns:
* RET_ERROR, RET_SUCCESS
*/
static int
nroot(t)
BTREE *t;
{
PAGE *meta, *root;
pgno_t npg;
if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) {
mpool_put(t->bt_mp, meta, 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)) == NULL)
return (RET_ERROR);
if ((root = mpool_new(t->bt_mp, &npg)) == 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()
{
sigset_t set, oset;
int fd;
char *envtmp;
char path[MAXPATHLEN];
envtmp = getenv("TMPDIR");
(void)snprintf(path,
sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : "/tmp");
(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()
{
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(dbp)
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);
}