1 /*
2 * linux/fs/befs/btree.c
3 *
4 * Copyright (C) 2001-2002 Will Dyson <will_dyson@pobox.com>
5 *
6 * Licensed under the GNU GPL. See the file COPYING for details.
7 *
8 * 2002-02-05: Sergey S. Kostyliov added binary search within
9 * btree nodes.
10 *
11 * Many thanks to:
12 *
13 * Dominic Giampaolo, author of "Practical File System
14 * Design with the Be File System", for such a helpful book.
15 *
16 * Marcus J. Ranum, author of the b+tree package in
17 * comp.sources.misc volume 10. This code is not copied from that
18 * work, but it is partially based on it.
19 *
20 * Makoto Kato, author of the original BeFS for linux filesystem
21 * driver.
22 */
23
24 #include <linux/kernel.h>
25 #include <linux/string.h>
26 #include <linux/slab.h>
27 #include <linux/mm.h>
28 #include <linux/buffer_head.h>
29
30 #include "befs.h"
31 #include "btree.h"
32 #include "datastream.h"
33
34 /*
35 * The btree functions in this file are built on top of the
36 * datastream.c interface, which is in turn built on top of the
37 * io.c interface.
38 */
39
40 /* Befs B+tree structure:
41 *
42 * The first thing in the tree is the tree superblock. It tells you
43 * all kinds of useful things about the tree, like where the rootnode
44 * is located, and the size of the nodes (always 1024 with current version
45 * of BeOS).
46 *
47 * The rest of the tree consists of a series of nodes. Nodes contain a header
48 * (struct befs_btree_nodehead), the packed key data, an array of shorts
49 * containing the ending offsets for each of the keys, and an array of
50 * befs_off_t values. In interior nodes, the keys are the ending keys for
51 * the childnode they point to, and the values are offsets into the
52 * datastream containing the tree.
53 */
54
55 /* Note:
56 *
57 * The book states 2 confusing things about befs b+trees. First,
58 * it states that the overflow field of node headers is used by internal nodes
59 * to point to another node that "effectively continues this one". Here is what
60 * I believe that means. Each key in internal nodes points to another node that
61 * contains key values less than itself. Inspection reveals that the last key
62 * in the internal node is not the last key in the index. Keys that are
63 * greater than the last key in the internal node go into the overflow node.
64 * I imagine there is a performance reason for this.
65 *
66 * Second, it states that the header of a btree node is sufficient to
67 * distinguish internal nodes from leaf nodes. Without saying exactly how.
68 * After figuring out the first, it becomes obvious that internal nodes have
69 * overflow nodes and leafnodes do not.
70 */
71
72 /*
73 * Currently, this code is only good for directory B+trees.
74 * In order to be used for other BFS indexes, it needs to be extended to handle
75 * duplicate keys and non-string keytypes (int32, int64, float, double).
76 */
77
78 /*
79 * In memory structure of each btree node
80 */
81 struct befs_btree_node {
82 befs_host_btree_nodehead head; /* head of node converted to cpu byteorder */
83 struct buffer_head *bh;
84 befs_btree_nodehead *od_node; /* on disk node */
85 };
86
87 /* local constants */
88 static const befs_off_t BEFS_BT_INVAL = 0xffffffffffffffffULL;
89
90 /* local functions */
91 static int befs_btree_seekleaf(struct super_block *sb, const befs_data_stream *ds,
92 befs_btree_super * bt_super,
93 struct befs_btree_node *this_node,
94 befs_off_t * node_off);
95
96 static int befs_bt_read_super(struct super_block *sb, const befs_data_stream *ds,
97 befs_btree_super * sup);
98
99 static int befs_bt_read_node(struct super_block *sb, const befs_data_stream *ds,
100 struct befs_btree_node *node,
101 befs_off_t node_off);
102
103 static int befs_leafnode(struct befs_btree_node *node);
104
105 static fs16 *befs_bt_keylen_index(struct befs_btree_node *node);
106
107 static fs64 *befs_bt_valarray(struct befs_btree_node *node);
108
109 static char *befs_bt_keydata(struct befs_btree_node *node);
110
111 static int befs_find_key(struct super_block *sb,
112 struct befs_btree_node *node,
113 const char *findkey, befs_off_t * value);
114
115 static char *befs_bt_get_key(struct super_block *sb,
116 struct befs_btree_node *node,
117 int index, u16 * keylen);
118
119 static int befs_compare_strings(const void *key1, int keylen1,
120 const void *key2, int keylen2);
121
122 /**
123 * befs_bt_read_super() - read in btree superblock convert to cpu byteorder
124 * @sb: Filesystem superblock
125 * @ds: Datastream to read from
126 * @sup: Buffer in which to place the btree superblock
127 *
128 * Calls befs_read_datastream to read in the btree superblock and
129 * makes sure it is in cpu byteorder, byteswapping if necessary.
130 * Return: BEFS_OK on success and if *@sup contains the btree superblock in cpu
131 * byte order. Otherwise return BEFS_ERR on error.
132 */
133 static int
134 befs_bt_read_super(struct super_block *sb, const befs_data_stream *ds,
135 befs_btree_super * sup)
136 {
137 struct buffer_head *bh;
138 befs_disk_btree_super *od_sup;
139
140 befs_debug(sb, "---> %s", __func__);
141
142 bh = befs_read_datastream(sb, ds, 0, NULL);
143
144 if (!bh) {
145 befs_error(sb, "Couldn't read index header.");
146 goto error;
147 }
148 od_sup = (befs_disk_btree_super *) bh->b_data;
149 befs_dump_index_entry(sb, od_sup);
150
151 sup->magic = fs32_to_cpu(sb, od_sup->magic);
152 sup->node_size = fs32_to_cpu(sb, od_sup->node_size);
153 sup->max_depth = fs32_to_cpu(sb, od_sup->max_depth);
154 sup->data_type = fs32_to_cpu(sb, od_sup->data_type);
155 sup->root_node_ptr = fs64_to_cpu(sb, od_sup->root_node_ptr);
156
157 brelse(bh);
158 if (sup->magic != BEFS_BTREE_MAGIC) {
159 befs_error(sb, "Index header has bad magic.");
160 goto error;
161 }
162
163 befs_debug(sb, "<--- %s", __func__);
164 return BEFS_OK;
165
166 error:
167 befs_debug(sb, "<--- %s ERROR", __func__);
168 return BEFS_ERR;
169 }
170
171 /**
172 * befs_bt_read_node - read in btree node and convert to cpu byteorder
173 * @sb: Filesystem superblock
174 * @ds: Datastream to read from
175 * @node: Buffer in which to place the btree node
176 * @node_off: Starting offset (in bytes) of the node in @ds
177 *
178 * Calls befs_read_datastream to read in the indicated btree node and
179 * makes sure its header fields are in cpu byteorder, byteswapping if
180 * necessary.
181 * Note: node->bh must be NULL when this function is called the first time.
182 * Don't forget brelse(node->bh) after last call.
183 *
184 * On success, returns BEFS_OK and *@node contains the btree node that
185 * starts at @node_off, with the node->head fields in cpu byte order.
186 *
187 * On failure, BEFS_ERR is returned.
188 */
189
190 static int
191 befs_bt_read_node(struct super_block *sb, const befs_data_stream *ds,
192 struct befs_btree_node *node, befs_off_t node_off)
193 {
194 uint off = 0;
195
196 befs_debug(sb, "---> %s", __func__);
197
198 if (node->bh)
199 brelse(node->bh);
200
201 node->bh = befs_read_datastream(sb, ds, node_off, &off);
202 if (!node->bh) {
203 befs_error(sb, "%s failed to read "
204 "node at %llu", __func__, node_off);
205 befs_debug(sb, "<--- %s ERROR", __func__);
206
207 return BEFS_ERR;
208 }
209 node->od_node =
210 (befs_btree_nodehead *) ((void *) node->bh->b_data + off);
211
212 befs_dump_index_node(sb, node->od_node);
213
214 node->head.left = fs64_to_cpu(sb, node->od_node->left);
215 node->head.right = fs64_to_cpu(sb, node->od_node->right);
216 node->head.overflow = fs64_to_cpu(sb, node->od_node->overflow);
217 node->head.all_key_count =
218 fs16_to_cpu(sb, node->od_node->all_key_count);
219 node->head.all_key_length =
220 fs16_to_cpu(sb, node->od_node->all_key_length);
221
222 befs_debug(sb, "<--- %s", __func__);
223 return BEFS_OK;
224 }
225
226 /**
227 * befs_btree_find - Find a key in a befs B+tree
228 * @sb: Filesystem superblock
229 * @ds: Datastream containing btree
230 * @key: Key string to lookup in btree
231 * @value: Value stored with @key
232 *
233 * On success, returns BEFS_OK and sets *@value to the value stored
234 * with @key (usually the disk block number of an inode).
235 *
236 * On failure, returns BEFS_ERR or BEFS_BT_NOT_FOUND.
237 *
238 * Algorithm:
239 * Read the superblock and rootnode of the b+tree.
240 * Drill down through the interior nodes using befs_find_key().
241 * Once at the correct leaf node, use befs_find_key() again to get the
242 * actual value stored with the key.
243 */
244 int
245 befs_btree_find(struct super_block *sb, const befs_data_stream *ds,
246 const char *key, befs_off_t * value)
247 {
248 struct befs_btree_node *this_node;
249 befs_btree_super bt_super;
250 befs_off_t node_off;
251 int res;
252
253 befs_debug(sb, "---> %s Key: %s", __func__, key);
254
255 if (befs_bt_read_super(sb, ds, &bt_super) != BEFS_OK) {
256 befs_error(sb,
257 "befs_btree_find() failed to read index superblock");
258 goto error;
259 }
260
261 this_node = kmalloc(sizeof(struct befs_btree_node),
262 GFP_NOFS);
263 if (!this_node) {
264 befs_error(sb, "befs_btree_find() failed to allocate %zu "
265 "bytes of memory", sizeof(struct befs_btree_node));
266 goto error;
267 }
268
269 this_node->bh = NULL;
270
271 /* read in root node */
272 node_off = bt_super.root_node_ptr;
273 if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) {
274 befs_error(sb, "befs_btree_find() failed to read "
275 "node at %llu", node_off);
276 goto error_alloc;
277 }
278
279 while (!befs_leafnode(this_node)) {
280 res = befs_find_key(sb, this_node, key, &node_off);
281 /* if no key set, try the overflow node */
282 if (res == BEFS_BT_OVERFLOW)
283 node_off = this_node->head.overflow;
284 if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) {
285 befs_error(sb, "befs_btree_find() failed to read "
286 "node at %llu", node_off);
287 goto error_alloc;
288 }
289 }
290
291 /* at a leaf node now, check if it is correct */
292 res = befs_find_key(sb, this_node, key, value);
293
294 brelse(this_node->bh);
295 kfree(this_node);
296
297 if (res != BEFS_BT_MATCH) {
298 befs_error(sb, "<--- %s Key %s not found", __func__, key);
299 befs_debug(sb, "<--- %s ERROR", __func__);
300 *value = 0;
301 return BEFS_BT_NOT_FOUND;
302 }
303 befs_debug(sb, "<--- %s Found key %s, value %llu", __func__,
304 key, *value);
305 return BEFS_OK;
306
307 error_alloc:
308 kfree(this_node);
309 error:
310 *value = 0;
311 befs_debug(sb, "<--- %s ERROR", __func__);
312 return BEFS_ERR;
313 }
314
315 /**
316 * befs_find_key - Search for a key within a node
317 * @sb: Filesystem superblock
318 * @node: Node to find the key within
319 * @findkey: Keystring to search for
320 * @value: If key is found, the value stored with the key is put here
321 *
322 * Finds exact match if one exists, and returns BEFS_BT_MATCH.
323 * If there is no match and node's value array is too small for key, return
324 * BEFS_BT_OVERFLOW.
325 * If no match and node should countain this key, return BEFS_BT_NOT_FOUND.
326 *
327 * Uses binary search instead of a linear.
328 */
329 static int
330 befs_find_key(struct super_block *sb, struct befs_btree_node *node,
331 const char *findkey, befs_off_t * value)
332 {
333 int first, last, mid;
334 int eq;
335 u16 keylen;
336 int findkey_len;
337 char *thiskey;
338 fs64 *valarray;
339
340 befs_debug(sb, "---> %s %s", __func__, findkey);
341
342 findkey_len = strlen(findkey);
343
344 /* if node can not contain key, just skip this node */
345 last = node->head.all_key_count - 1;
346 thiskey = befs_bt_get_key(sb, node, last, &keylen);
347
348 eq = befs_compare_strings(thiskey, keylen, findkey, findkey_len);
349 if (eq < 0) {
350 befs_debug(sb, "<--- node can't contain %s", findkey);
351 return BEFS_BT_OVERFLOW;
352 }
353
354 valarray = befs_bt_valarray(node);
355
356 /* simple binary search */
357 first = 0;
358 mid = 0;
359 while (last >= first) {
360 mid = (last + first) / 2;
361 befs_debug(sb, "first: %d, last: %d, mid: %d", first, last,
362 mid);
363 thiskey = befs_bt_get_key(sb, node, mid, &keylen);
364 eq = befs_compare_strings(thiskey, keylen, findkey,
365 findkey_len);
366
367 if (eq == 0) {
368 befs_debug(sb, "<--- %s found %s at %d",
369 __func__, thiskey, mid);
370
371 *value = fs64_to_cpu(sb, valarray[mid]);
372 return BEFS_BT_MATCH;
373 }
374 if (eq > 0)
375 last = mid - 1;
376 else
377 first = mid + 1;
378 }
379
380 /* return an existing value so caller can arrive to a leaf node */
381 if (eq < 0)
382 *value = fs64_to_cpu(sb, valarray[mid + 1]);
383 else
384 *value = fs64_to_cpu(sb, valarray[mid]);
385 befs_error(sb, "<--- %s %s not found", __func__, findkey);
386 befs_debug(sb, "<--- %s ERROR", __func__);
387 return BEFS_BT_NOT_FOUND;
388 }
389
390 /**
391 * befs_btree_read - Traverse leafnodes of a btree
392 * @sb: Filesystem superblock
393 * @ds: Datastream containing btree
394 * @key_no: Key number (alphabetical order) of key to read
395 * @bufsize: Size of the buffer to return key in
396 * @keybuf: Pointer to a buffer to put the key in
397 * @keysize: Length of the returned key
398 * @value: Value stored with the returned key
399 *
400 * Here's how it works: Key_no is the index of the key/value pair to
401 * return in keybuf/value.
402 * Bufsize is the size of keybuf (BEFS_NAME_LEN+1 is a good size). Keysize is
403 * the number of characters in the key (just a convenience).
404 *
405 * Algorithm:
406 * Get the first leafnode of the tree. See if the requested key is in that
407 * node. If not, follow the node->right link to the next leafnode. Repeat
408 * until the (key_no)th key is found or the tree is out of keys.
409 */
410 int
411 befs_btree_read(struct super_block *sb, const befs_data_stream *ds,
412 loff_t key_no, size_t bufsize, char *keybuf, size_t * keysize,
413 befs_off_t * value)
414 {
415 struct befs_btree_node *this_node;
416 befs_btree_super bt_super;
417 befs_off_t node_off;
418 int cur_key;
419 fs64 *valarray;
420 char *keystart;
421 u16 keylen;
422 int res;
423
424 uint key_sum = 0;
425
426 befs_debug(sb, "---> %s", __func__);
427
428 if (befs_bt_read_super(sb, ds, &bt_super) != BEFS_OK) {
429 befs_error(sb,
430 "befs_btree_read() failed to read index superblock");
431 goto error;
432 }
433
434 this_node = kmalloc(sizeof(struct befs_btree_node), GFP_NOFS);
435 if (this_node == NULL) {
436 befs_error(sb, "befs_btree_read() failed to allocate %zu "
437 "bytes of memory", sizeof(struct befs_btree_node));
438 goto error;
439 }
440
441 node_off = bt_super.root_node_ptr;
442 this_node->bh = NULL;
443
444 /* seeks down to first leafnode, reads it into this_node */
445 res = befs_btree_seekleaf(sb, ds, &bt_super, this_node, &node_off);
446 if (res == BEFS_BT_EMPTY) {
447 brelse(this_node->bh);
448 kfree(this_node);
449 *value = 0;
450 *keysize = 0;
451 befs_debug(sb, "<--- %s Tree is EMPTY", __func__);
452 return BEFS_BT_EMPTY;
453 } else if (res == BEFS_ERR) {
454 goto error_alloc;
455 }
456
457 /* find the leaf node containing the key_no key */
458
459 while (key_sum + this_node->head.all_key_count <= key_no) {
460
461 /* no more nodes to look in: key_no is too large */
462 if (this_node->head.right == BEFS_BT_INVAL) {
463 *keysize = 0;
464 *value = 0;
465 befs_debug(sb,
466 "<--- %s END of keys at %llu", __func__,
467 (unsigned long long)
468 key_sum + this_node->head.all_key_count);
469 brelse(this_node->bh);
470 kfree(this_node);
471 return BEFS_BT_END;
472 }
473
474 key_sum += this_node->head.all_key_count;
475 node_off = this_node->head.right;
476
477 if (befs_bt_read_node(sb, ds, this_node, node_off) != BEFS_OK) {
478 befs_error(sb, "%s failed to read node at %llu",
479 __func__, (unsigned long long)node_off);
480 goto error_alloc;
481 }
482 }
483
484 /* how many keys into this_node is key_no */
485 cur_key = key_no - key_sum;
486
487 /* get pointers to datastructures within the node body */
488 valarray = befs_bt_valarray(this_node);
489
490 keystart = befs_bt_get_key(sb, this_node, cur_key, &keylen);
491
492 befs_debug(sb, "Read [%llu,%d]: keysize %d",
493 (long long unsigned int)node_off, (int)cur_key,
494 (int)keylen);
495
496 if (bufsize < keylen + 1) {
497 befs_error(sb, "%s keybuf too small (%zu) "
498 "for key of size %d", __func__, bufsize, keylen);
499 brelse(this_node->bh);
500 goto error_alloc;
501 }
502
503 strscpy(keybuf, keystart, keylen + 1);
504 *value = fs64_to_cpu(sb, valarray[cur_key]);
505 *keysize = keylen;
506
507 befs_debug(sb, "Read [%llu,%d]: Key \"%.*s\", Value %llu", node_off,
508 cur_key, keylen, keybuf, *value);
509
510 brelse(this_node->bh);
511 kfree(this_node);
512
513 befs_debug(sb, "<--- %s", __func__);
514
515 return BEFS_OK;
516
517 error_alloc:
518 kfree(this_node);
519
520 error:
521 *keysize = 0;
522 *value = 0;
523 befs_debug(sb, "<--- %s ERROR", __func__);
524 return BEFS_ERR;
525 }
526
527 /**
528 * befs_btree_seekleaf - Find the first leafnode in the btree
529 * @sb: Filesystem superblock
530 * @ds: Datastream containing btree
531 * @bt_super: Pointer to the superblock of the btree
532 * @this_node: Buffer to return the leafnode in
533 * @node_off: Pointer to offset of current node within datastream. Modified
534 * by the function.
535 *
536 * Helper function for btree traverse. Moves the current position to the
537 * start of the first leaf node.
538 *
539 * Also checks for an empty tree. If there are no keys, returns BEFS_BT_EMPTY.
540 */
541 static int
542 befs_btree_seekleaf(struct super_block *sb, const befs_data_stream *ds,
543 befs_btree_super *bt_super,
544 struct befs_btree_node *this_node,
545 befs_off_t * node_off)
546 {
547
548 befs_debug(sb, "---> %s", __func__);
549
550 if (befs_bt_read_node(sb, ds, this_node, *node_off) != BEFS_OK) {
551 befs_error(sb, "%s failed to read "
552 "node at %llu", __func__, *node_off);
553 goto error;
554 }
555 befs_debug(sb, "Seekleaf to root node %llu", *node_off);
556
557 if (this_node->head.all_key_count == 0 && befs_leafnode(this_node)) {
558 befs_debug(sb, "<--- %s Tree is EMPTY", __func__);
559 return BEFS_BT_EMPTY;
560 }
561
562 while (!befs_leafnode(this_node)) {
563
564 if (this_node->head.all_key_count == 0) {
565 befs_debug(sb, "%s encountered "
566 "an empty interior node: %llu. Using Overflow "
567 "node: %llu", __func__, *node_off,
568 this_node->head.overflow);
569 *node_off = this_node->head.overflow;
570 } else {
571 fs64 *valarray = befs_bt_valarray(this_node);
572 *node_off = fs64_to_cpu(sb, valarray[0]);
573 }
574 if (befs_bt_read_node(sb, ds, this_node, *node_off) != BEFS_OK) {
575 befs_error(sb, "%s failed to read "
576 "node at %llu", __func__, *node_off);
577 goto error;
578 }
579
580 befs_debug(sb, "Seekleaf to child node %llu", *node_off);
581 }
582 befs_debug(sb, "Node %llu is a leaf node", *node_off);
583
584 return BEFS_OK;
585
586 error:
587 befs_debug(sb, "<--- %s ERROR", __func__);
588 return BEFS_ERR;
589 }
590
591 /**
592 * befs_leafnode - Determine if the btree node is a leaf node or an
593 * interior node
594 * @node: Pointer to node structure to test
595 *
596 * Return 1 if leaf, 0 if interior
597 */
598 static int
599 befs_leafnode(struct befs_btree_node *node)
600 {
601 /* all interior nodes (and only interior nodes) have an overflow node */
602 if (node->head.overflow == BEFS_BT_INVAL)
603 return 1;
604 else
605 return 0;
606 }
607
608 /**
609 * befs_bt_keylen_index - Finds start of keylen index in a node
610 * @node: Pointer to the node structure to find the keylen index within
611 *
612 * Returns a pointer to the start of the key length index array
613 * of the B+tree node *@node
614 *
615 * "The length of all the keys in the node is added to the size of the
616 * header and then rounded up to a multiple of four to get the beginning
617 * of the key length index" (p.88, practical filesystem design).
618 *
619 * Except that rounding up to 8 works, and rounding up to 4 doesn't.
620 */
621 static fs16 *
622 befs_bt_keylen_index(struct befs_btree_node *node)
623 {
624 const int keylen_align = 8;
625 unsigned long int off =
626 (sizeof (befs_btree_nodehead) + node->head.all_key_length);
627 ulong tmp = off % keylen_align;
628
629 if (tmp)
630 off += keylen_align - tmp;
631
632 return (fs16 *) ((void *) node->od_node + off);
633 }
634
635 /**
636 * befs_bt_valarray - Finds the start of value array in a node
637 * @node: Pointer to the node structure to find the value array within
638 *
639 * Returns a pointer to the start of the value array
640 * of the node pointed to by the node header
641 */
642 static fs64 *
643 befs_bt_valarray(struct befs_btree_node *node)
644 {
645 void *keylen_index_start = (void *) befs_bt_keylen_index(node);
646 size_t keylen_index_size = node->head.all_key_count * sizeof (fs16);
647
648 return (fs64 *) (keylen_index_start + keylen_index_size);
649 }
650
651 /**
652 * befs_bt_keydata - Finds start of keydata array in a node
653 * @node: Pointer to the node structure to find the keydata array within
654 *
655 * Returns a pointer to the start of the keydata array
656 * of the node pointed to by the node header
657 */
658 static char *
659 befs_bt_keydata(struct befs_btree_node *node)
660 {
661 return (char *) ((void *) node->od_node + sizeof (befs_btree_nodehead));
662 }
663
664 /**
665 * befs_bt_get_key - returns a pointer to the start of a key
666 * @sb: filesystem superblock
667 * @node: node in which to look for the key
668 * @index: the index of the key to get
669 * @keylen: modified to be the length of the key at @index
670 *
671 * Returns a valid pointer into @node on success.
672 * Returns NULL on failure (bad input) and sets *@keylen = 0
673 */
674 static char *
675 befs_bt_get_key(struct super_block *sb, struct befs_btree_node *node,
676 int index, u16 * keylen)
677 {
678 int prev_key_end;
679 char *keystart;
680 fs16 *keylen_index;
681
682 if (index < 0 || index > node->head.all_key_count) {
683 *keylen = 0;
684 return NULL;
685 }
686
687 keystart = befs_bt_keydata(node);
688 keylen_index = befs_bt_keylen_index(node);
689
690 if (index == 0)
691 prev_key_end = 0;
692 else
693 prev_key_end = fs16_to_cpu(sb, keylen_index[index - 1]);
694
695 *keylen = fs16_to_cpu(sb, keylen_index[index]) - prev_key_end;
696
697 return keystart + prev_key_end;
698 }
699
700 /**
701 * befs_compare_strings - compare two strings
702 * @key1: pointer to the first key to be compared
703 * @keylen1: length in bytes of key1
704 * @key2: pointer to the second key to be compared
705 * @keylen2: length in bytes of key2
706 *
707 * Returns 0 if @key1 and @key2 are equal.
708 * Returns >0 if @key1 is greater.
709 * Returns <0 if @key2 is greater.
710 */
711 static int
712 befs_compare_strings(const void *key1, int keylen1,
713 const void *key2, int keylen2)
714 {
715 int len = min_t(int, keylen1, keylen2);
716 int result = strncmp(key1, key2, len);
717 if (result == 0)
718 result = keylen1 - keylen2;
719 return result;
720 }
721
722 /* These will be used for non-string keyed btrees */
723 #if 0
724 static int
725 btree_compare_int32(cont void *key1, int keylen1, const void *key2, int keylen2)
726 {
727 return *(int32_t *) key1 - *(int32_t *) key2;
728 }
729
730 static int
731 btree_compare_uint32(cont void *key1, int keylen1,
732 const void *key2, int keylen2)
733 {
734 if (*(u_int32_t *) key1 == *(u_int32_t *) key2)
735 return 0;
736 else if (*(u_int32_t *) key1 > *(u_int32_t *) key2)
737 return 1;
738
739 return -1;
740 }
741 static int
742 btree_compare_int64(cont void *key1, int keylen1, const void *key2, int keylen2)
743 {
744 if (*(int64_t *) key1 == *(int64_t *) key2)
745 return 0;
746 else if (*(int64_t *) key1 > *(int64_t *) key2)
747 return 1;
748
749 return -1;
750 }
751
752 static int
753 btree_compare_uint64(cont void *key1, int keylen1,
754 const void *key2, int keylen2)
755 {
756 if (*(u_int64_t *) key1 == *(u_int64_t *) key2)
757 return 0;
758 else if (*(u_int64_t *) key1 > *(u_int64_t *) key2)
759 return 1;
760
761 return -1;
762 }
763
764 static int
765 btree_compare_float(cont void *key1, int keylen1, const void *key2, int keylen2)
766 {
767 float result = *(float *) key1 - *(float *) key2;
768 if (result == 0.0f)
769 return 0;
770
771 return (result < 0.0f) ? -1 : 1;
772 }
773
774 static int
775 btree_compare_double(cont void *key1, int keylen1,
776 const void *key2, int keylen2)
777 {
778 double result = *(double *) key1 - *(double *) key2;
779 if (result == 0.0)
780 return 0;
781
782 return (result < 0.0) ? -1 : 1;
783 }
784 #endif //
785
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.