/*-

 * 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	8.11 (Berkeley) 11/2/95";

#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 "k5-platform.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 "db-int.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;

	db_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 != DB_BIG_ENDIAN && b.lorder != DB_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 | O_BINARY, 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;

	db_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()

{

#ifdef SIG_BLOCK

	sigset_t set, oset;

#else

	int oset;

#endif

	int fd;

	char *envtmp;

	char path[MAXPATHLEN];

	static char fn[] = "/bt.XXXXXX";

	envtmp = getenv("TMPDIR");

	/* this used to be done with snprintf(), but since snprintf

	   isn't in most operating systems, and overflow checking in

	   this case is easy, this is what is done */

	if (envtmp && ((strlen(envtmp)+sizeof(fn)+1) > sizeof(path)))

	    return(-1);

	(void)snprintf(path, sizeof(path),

		       "%s%s", (envtmp ? envtmp : "/tmp"), fn);

#ifdef SIG_BLOCK

	(void)sigfillset(&set);

	(void)sigprocmask(SIG_BLOCK, &set, &oset);

#else

	oset = sigblock(~0);

#endif

	if ((fd = mkstemp(path)) != -1)

		(void)unlink(path);

	set_cloexec_fd(fd);

#ifdef SIG_BLOCK

	(void)sigprocmask(SIG_SETMASK, &oset, NULL);

#else

	sigsetmask(oset);

#endif

#ifdef __CYGWIN32__

      /* Ensure the fd is in binary mode. */

      setmode(fd, O_BINARY);

#endif /* __CYGWIN32__ */

	return(fd);

}

static int

byteorder()

{

	u_int32_t x;

	u_char *p;

	x = 0x01020304;

	p = (u_char *)&x;

	switch (*p) {

	case 1:

		return (DB_BIG_ENDIAN);

	case 4:

		return (DB_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);

}