diff options
Diffstat (limited to 'db/btree/bt_open.c')
| -rw-r--r-- | db/btree/bt_open.c | 444 |
1 files changed, 444 insertions, 0 deletions
diff --git a/db/btree/bt_open.c b/db/btree/bt_open.c new file mode 100644 index 0000000000..f052249777 --- /dev/null +++ b/db/btree/bt_open.c @@ -0,0 +1,444 @@ +/*- + * 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); +} |