b.psize & sizeof(indx_t) - 1))
b.psize & (sizeof(indx_t) - 1) ))
__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);}