1 /*
2  * Copyright (c) 1997-2000 by Sun Microsystems, Inc.
3  * All rights reserved.
4  */
5 
6 #ifndef _KRB5_BTREE_H
7 #define	_KRB5_BTREE_H
8 
9 #ifdef	__cplusplus
10 extern "C" {
11 #endif
12 
13 
14 /*-
15  * Copyright (c) 1991, 1993, 1994
16  *	The Regents of the University of California.  All rights reserved.
17  *
18  * This code is derived from software contributed to Berkeley by
19  * Mike Olson.
20  *
21  * Redistribution and use in source and binary forms, with or without
22  * modification, are permitted provided that the following conditions
23  * are met:
24  * 1. Redistributions of source code must retain the above copyright
25  *    notice, this list of conditions and the following disclaimer.
26  * 2. Redistributions in binary form must reproduce the above copyright
27  *    notice, this list of conditions and the following disclaimer in the
28  *    documentation and/or other materials provided with the distribution.
29  * 3. All advertising materials mentioning features or use of this software
30  *    must display the following acknowledgement:
31  *	This product includes software developed by the University of
32  *	California, Berkeley and its contributors.
33  * 4. Neither the name of the University nor the names of its contributors
34  *    may be used to endorse or promote products derived from this software
35  *    without specific prior written permission.
36  *
37  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
38  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
39  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
40  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
41  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
42  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
43  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
45  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
46  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
47  * SUCH DAMAGE.
48  *
49  *	@(#)btree.h	8.11 (Berkeley) 8/17/94
50  */
51 
52 /* Macros to set/clear/test flags. */
53 #define	F_SET(p, f)	(p)->flags |= (f)
54 #define	F_CLR(p, f)	(p)->flags &= ~(f)
55 #define	F_ISSET(p, f)	((p)->flags & (f))
56 
57 #include "mpool.h"
58 
59 #define	DEFMINKEYPAGE	(2)		/* Minimum keys per page */
60 #define	MINCACHE	(5)		/* Minimum cached pages */
61 #define	MINPSIZE	(512)		/* Minimum page size */
62 
63 /*
64  * Page 0 of a btree file contains a copy of the meta-data.  This page is also
65  * used as an out-of-band page, i.e. page pointers that point to nowhere point
66  * to page 0.  Page 1 is the root of the btree.
67  */
68 #define	P_INVALID	 0		/* Invalid tree page number. */
69 #define	P_META		 0		/* Tree metadata page number. */
70 #define	P_ROOT		 1		/* Tree root page number. */
71 
72 /*
73  * There are five page layouts in the btree: btree internal pages (BINTERNAL),
74  * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
75  * (RLEAF) and overflow pages.  All five page types have a page header (PAGE).
76  * This implementation requires that values within structures NOT be padded.
77  * (ANSI C permits random padding.)  If your compiler pads randomly you'll have
78  * to do some work to get this package to run.
79  */
80 typedef struct _page {
81 	db_pgno_t	pgno;			/* this page's page number */
82 	db_pgno_t	prevpg;			/* left sibling */
83 	db_pgno_t	nextpg;			/* right sibling */
84 
85 #define	P_BINTERNAL	0x01		/* btree internal page */
86 #define	P_BLEAF		0x02		/* leaf page */
87 #define	P_OVERFLOW	0x04		/* overflow page */
88 #define	P_RINTERNAL	0x08		/* recno internal page */
89 #define	P_RLEAF		0x10		/* leaf page */
90 #define P_TYPE		0x1f		/* type mask */
91 #define	P_PRESERVE	0x20		/* never delete this chain of pages */
92 	u_int32_t flags;
93 
94 	indx_t	lower;			/* lower bound of free space on page */
95 	indx_t	upper;			/* upper bound of free space on page */
96 	indx_t	linp[1];		/* indx_t-aligned VAR. LENGTH DATA */
97 } PAGE;
98 
99 /* First and next index. */
100 #define	BTDATAOFF							\
101 	(sizeof(db_pgno_t) + sizeof(db_pgno_t) + sizeof(db_pgno_t) +		\
102 	    sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t))
103 #define	NEXTINDEX(p)	(((p)->lower - BTDATAOFF) / sizeof(indx_t))
104 
105 /*
106  * For pages other than overflow pages, there is an array of offsets into the
107  * rest of the page immediately following the page header.  Each offset is to
108  * an item which is unique to the type of page.  The h_lower offset is just
109  * past the last filled-in index.  The h_upper offset is the first item on the
110  * page.  Offsets are from the beginning of the page.
111  *
112  * If an item is too big to store on a single page, a flag is set and the item
113  * is a { page, size } pair such that the page is the first page of an overflow
114  * chain with size bytes of item.  Overflow pages are simply bytes without any
115  * external structure.
116  *
117  * The page number and size fields in the items are db_pgno_t-aligned so they can
118  * be manipulated without copying.  (This presumes that 32 bit items can be
119  * manipulated on this system.)
120  */
121 #define	LALIGN(n)	(((n) + sizeof(db_pgno_t) - 1) & ~(sizeof(db_pgno_t) - 1))
122 #define	NOVFLSIZE	(sizeof(db_pgno_t) + sizeof(u_int32_t))
123 
124 /*
125  * For the btree internal pages, the item is a key.  BINTERNALs are {key, pgno}
126  * pairs, such that the key compares less than or equal to all of the records
127  * on that page.  For a tree without duplicate keys, an internal page with two
128  * consecutive keys, a and b, will have all records greater than or equal to a
129  * and less than b stored on the page associated with a.  Duplicate keys are
130  * somewhat special and can cause duplicate internal and leaf page records and
131  * some minor modifications of the above rule.
132  */
133 typedef struct _binternal {
134 	u_int32_t ksize;		/* key size */
135 	db_pgno_t	pgno;			/* page number stored on */
136 #define	P_BIGDATA	0x01		/* overflow data */
137 #define	P_BIGKEY	0x02		/* overflow key */
138 	u_char	flags;
139 	char	bytes[1];		/* data */
140 } BINTERNAL;
141 
142 /* Get the page's BINTERNAL structure at index indx. */
143 #define	GETBINTERNAL(pg, indx)						\
144 	((BINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
145 
146 /* Get the number of bytes in the entry. */
147 #define NBINTERNAL(len)							\
148 	LALIGN(sizeof(u_int32_t) + sizeof(db_pgno_t) + sizeof(u_char) + (len))
149 
150 /* Copy a BINTERNAL entry to the page. */
151 #define	WR_BINTERNAL(p, size, pgno, flags) {				\
152 	*(u_int32_t *)p = size;						\
153 	p += sizeof(u_int32_t);						\
154 	*(db_pgno_t *)p = pgno;						\
155 	p += sizeof(db_pgno_t);						\
156 	*(u_char *)p = flags;						\
157 	p += sizeof(u_char);						\
158 }
159 
160 /*
161  * For the recno internal pages, the item is a page number with the number of
162  * keys found on that page and below.
163  */
164 typedef struct _rinternal {
165 	recno_t	nrecs;			/* number of records */
166 	db_pgno_t	pgno;			/* page number stored below */
167 } RINTERNAL;
168 
169 /* Get the page's RINTERNAL structure at index indx. */
170 #define	GETRINTERNAL(pg, indx)						\
171 	((RINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
172 
173 /* Get the number of bytes in the entry. */
174 #define NRINTERNAL							\
175 	LALIGN(sizeof(recno_t) + sizeof(db_pgno_t))
176 
177 /* Copy a RINTERAL entry to the page. */
178 #define	WR_RINTERNAL(p, nrecs, pgno) {					\
179 	*(recno_t *)p = nrecs;						\
180 	p += sizeof(recno_t);						\
181 	*(db_pgno_t *)p = pgno;						\
182 }
183 
184 /* For the btree leaf pages, the item is a key and data pair. */
185 typedef struct _bleaf {
186 	u_int32_t	ksize;		/* size of key */
187 	u_int32_t	dsize;		/* size of data */
188 	u_char	flags;			/* P_BIGDATA, P_BIGKEY */
189 	char	bytes[1];		/* data */
190 } BLEAF;
191 
192 /* Get the page's BLEAF structure at index indx. */
193 #define	GETBLEAF(pg, indx)						\
194 	((BLEAF *)((char *)(pg) + (pg)->linp[indx]))
195 
196 /* Get the number of bytes in the entry. */
197 #define NBLEAF(p)	NBLEAFDBT((p)->ksize, (p)->dsize)
198 
199 /* Get the number of bytes in the user's key/data pair. */
200 #define NBLEAFDBT(ksize, dsize)						\
201 	LALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) +	\
202 	    (ksize) + (dsize))
203 
204 /* Copy a BLEAF entry to the page. */
205 #define	WR_BLEAF(p, key, data, flags) {					\
206 	*(u_int32_t *)p = key->size;					\
207 	p += sizeof(u_int32_t);						\
208 	*(u_int32_t *)p = data->size;					\
209 	p += sizeof(u_int32_t);						\
210 	*(u_char *)p = flags;						\
211 	p += sizeof(u_char);						\
212 	memmove(p, key->data, key->size);				\
213 	p += key->size;							\
214 	memmove(p, data->data, data->size);				\
215 }
216 
217 /* For the recno leaf pages, the item is a data entry. */
218 typedef struct _rleaf {
219 	u_int32_t	dsize;		/* size of data */
220 	u_char	flags;			/* P_BIGDATA */
221 	char	bytes[1];
222 } RLEAF;
223 
224 /* Get the page's RLEAF structure at index indx. */
225 #define	GETRLEAF(pg, indx)						\
226 	((RLEAF *)((char *)(pg) + (pg)->linp[indx]))
227 
228 /* Get the number of bytes in the entry. */
229 #define NRLEAF(p)	NRLEAFDBT((p)->dsize)
230 
231 /* Get the number of bytes from the user's data. */
232 #define	NRLEAFDBT(dsize)						\
233 	LALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize))
234 
235 /* Copy a RLEAF entry to the page. */
236 #define	WR_RLEAF(p, data, flags) {					\
237 	*(u_int32_t *)p = data->size;					\
238 	p += sizeof(u_int32_t);						\
239 	*(u_char *)p = flags;						\
240 	p += sizeof(u_char);						\
241 	memmove(p, data->data, data->size);				\
242 }
243 
244 /*
245  * A record in the tree is either a pointer to a page and an index in the page
246  * or a page number and an index.  These structures are used as a cursor, stack
247  * entry and search returns as well as to pass records to other routines.
248  *
249  * One comment about searches.  Internal page searches must find the largest
250  * record less than key in the tree so that descents work.  Leaf page searches
251  * must find the smallest record greater than key so that the returned index
252  * is the record's correct position for insertion.
253  */
254 typedef struct _epgno {
255 	db_pgno_t	pgno;			/* the page number */
256 	indx_t	index;			/* the index on the page */
257 } EPGNO;
258 
259 typedef struct _epg {
260 	PAGE	*page;			/* the (pinned) page */
261 	indx_t	 index;			/* the index on the page */
262 } EPG;
263 
264 /*
265  * About cursors.  The cursor (and the page that contained the key/data pair
266  * that it referenced) can be deleted, which makes things a bit tricky.  If
267  * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
268  * or there simply aren't any duplicates of the key) we copy the key that it
269  * referenced when it's deleted, and reacquire a new cursor key if the cursor
270  * is used again.  If there are duplicates keys, we move to the next/previous
271  * key, and set a flag so that we know what happened.  NOTE: if duplicate (to
272  * the cursor) keys are added to the tree during this process, it is undefined
273  * if they will be returned or not in a cursor scan.
274  *
275  * The flags determine the possible states of the cursor:
276  *
277  * CURS_INIT	The cursor references *something*.
278  * CURS_ACQUIRE	The cursor was deleted, and a key has been saved so that
279  *		we can reacquire the right position in the tree.
280  * CURS_AFTER, CURS_BEFORE
281  *		The cursor was deleted, and now references a key/data pair
282  *		that has not yet been returned, either before or after the
283  *		deleted key/data pair.
284  * XXX
285  * This structure is broken out so that we can eventually offer multiple
286  * cursors as part of the DB interface.
287  */
288 typedef struct _cursor {
289 	EPGNO	 pg;			/* B: Saved tree reference. */
290 	DBT	 key;			/* B: Saved key, or key.data == NULL. */
291 	recno_t	 rcursor;		/* R: recno cursor (1-based) */
292 
293 #define	CURS_ACQUIRE	0x01		/*  B: Cursor needs to be reacquired. */
294 #define	CURS_AFTER	0x02		/*  B: Unreturned cursor after key. */
295 #define	CURS_BEFORE	0x04		/*  B: Unreturned cursor before key. */
296 #define	CURS_INIT	0x08		/* RB: Cursor initialized. */
297 	u_int8_t flags;
298 } CURSOR;
299 
300 /*
301  * The metadata of the tree.  The nrecs field is used only by the RECNO code.
302  * This is because the btree doesn't really need it and it requires that every
303  * put or delete call modify the metadata.
304  */
305 typedef struct _btmeta {
306 	u_int32_t	magic;		/* magic number */
307 	u_int32_t	version;	/* version */
308 	u_int32_t	psize;		/* page size */
309 	u_int32_t	free;		/* page number of first free page */
310 	u_int32_t	nrecs;		/* R: number of records */
311 
312 #define	SAVEMETA	(B_NODUPS | R_RECNO)
313 	u_int32_t	flags;		/* bt_flags & SAVEMETA */
314 } BTMETA;
315 
316 /* The in-memory btree/recno data structure. */
317 typedef struct _btree {
318 	MPOOL	 *bt_mp;		/* memory pool cookie */
319 
320 	DB	 *bt_dbp;		/* pointer to enclosing DB */
321 
322 	EPG	  bt_cur;		/* current (pinned) page */
323 	PAGE	 *bt_pinned;		/* page pinned across calls */
324 
325 	CURSOR	  bt_cursor;		/* cursor */
326 
327 #define	BT_PUSH(t, p, i) {						\
328 	t->bt_sp->pgno = p; 						\
329 	t->bt_sp->index = i; 						\
330 	++t->bt_sp;							\
331 }
332 #define	BT_POP(t)	(t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
333 #define	BT_CLR(t)	(t->bt_sp = t->bt_stack)
334 	EPGNO	  bt_stack[50];		/* stack of parent pages */
335 	EPGNO	 *bt_sp;		/* current stack pointer */
336 
337 	DBT	  bt_rkey;		/* returned key */
338 	DBT	  bt_rdata;		/* returned data */
339 
340 	int	  bt_fd;		/* tree file descriptor */
341 
342 	db_pgno_t	  bt_free;		/* next free page */
343 	u_int32_t bt_psize;		/* page size */
344 	indx_t	  bt_ovflsize;		/* cut-off for key/data overflow */
345 	int	  bt_lorder;		/* byte order */
346 					/* sorted order */
347 	enum { NOT, BACK, FORWARD } bt_order;
348 	EPGNO	  bt_last;		/* last insert */
349 
350 					/* B: key comparison function */
351 	int	(*bt_cmp) __P((const DBT *, const DBT *));
352 					/* B: prefix comparison function */
353 	size_t	(*bt_pfx) __P((const DBT *, const DBT *));
354 					/* R: recno input function */
355 	int	(*bt_irec) __P((struct _btree *, recno_t));
356 
357 	FILE	 *bt_rfp;		/* R: record FILE pointer */
358 	int	  bt_rfd;		/* R: record file descriptor */
359 
360 	caddr_t	  bt_cmap;		/* R: current point in mapped space */
361 	caddr_t	  bt_smap;		/* R: start of mapped space */
362 	caddr_t   bt_emap;		/* R: end of mapped space */
363 	size_t	  bt_msize;		/* R: size of mapped region. */
364 
365 	recno_t	  bt_nrecs;		/* R: number of records */
366 	size_t	  bt_reclen;		/* R: fixed record length */
367 	u_char	  bt_bval;		/* R: delimiting byte/pad character */
368 
369 /*
370  * NB:
371  * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
372  */
373 #define	B_INMEM		0x00001		/* in-memory tree */
374 #define	B_METADIRTY	0x00002		/* need to write metadata */
375 #define	B_MODIFIED	0x00004		/* tree modified */
376 #define	B_NEEDSWAP	0x00008		/* if byte order requires swapping */
377 #define	B_RDONLY	0x00010		/* read-only tree */
378 
379 #define	B_NODUPS	0x00020		/* no duplicate keys permitted */
380 #define	R_RECNO		0x00080		/* record oriented tree */
381 
382 #define	R_CLOSEFP	0x00040		/* opened a file pointer */
383 #define	R_EOF		0x00100		/* end of input file reached. */
384 #define	R_FIXLEN	0x00200		/* fixed length records */
385 #define	R_MEMMAPPED	0x00400		/* memory mapped file. */
386 #define	R_INMEM		0x00800		/* in-memory file */
387 #define	R_MODIFIED	0x01000		/* modified file */
388 #define	R_RDONLY	0x02000		/* read-only file */
389 
390 #define	B_DB_LOCK	0x04000		/* DB_LOCK specified. */
391 #define	B_DB_SHMEM	0x08000		/* DB_SHMEM specified. */
392 #define	B_DB_TXN	0x10000		/* DB_TXN specified. */
393 	u_int32_t flags;
394 } BTREE;
395 
396 #include "extern.h"
397 
398 #ifdef	__cplusplus
399 }
400 #endif
401 
402 #endif	/* !_KRB5_BTREE_H */
403