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32 * @(#)bt_utils.c 8.8 (Berkeley) 7/20/94
33 * $FreeBSD: head/lib/libc/db/btree/bt_utils.c 189387 2009-03-05 00:57:01Z delphij $
36 #include <sys/param.h>
47 * Build return key/data pair.
51 * e: key/data pair to be returned
52 * key: user's key structure (NULL if not to be filled in)
53 * rkey: memory area to hold key
54 * data: user's data structure (NULL if not to be filled in)
55 * rdata: memory area to hold data
56 * copy: always copy the key/data item
59 * RET_SUCCESS, RET_ERROR.
62 __bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy)
67 bl = GETBLEAF(e->page, e->index);
70 * We must copy big keys/data to make them contigous. Otherwise,
71 * leave the page pinned and don't copy unless the user specified
77 if (bl->flags & P_BIGKEY) {
78 if (__ovfl_get(t, bl->bytes,
79 &key->size, &rkey->data, &rkey->size))
81 key->data = rkey->data;
82 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
83 if (bl->ksize > rkey->size) {
84 p = realloc(rkey->data, bl->ksize);
88 rkey->size = bl->ksize;
90 memmove(rkey->data, bl->bytes, bl->ksize);
91 key->size = bl->ksize;
92 key->data = rkey->data;
94 key->size = bl->ksize;
95 key->data = bl->bytes;
100 return (RET_SUCCESS);
102 if (bl->flags & P_BIGDATA) {
103 if (__ovfl_get(t, bl->bytes + bl->ksize,
104 &data->size, &rdata->data, &rdata->size))
106 data->data = rdata->data;
107 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
108 /* Use +1 in case the first record retrieved is 0 length. */
109 if (bl->dsize + 1 > rdata->size) {
110 p = realloc(rdata->data, bl->dsize + 1);
114 rdata->size = bl->dsize + 1;
116 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
117 data->size = bl->dsize;
118 data->data = rdata->data;
120 data->size = bl->dsize;
121 data->data = bl->bytes + bl->ksize;
124 return (RET_SUCCESS);
128 * __BT_CMP -- Compare a key to a given record.
132 * k1: DBT pointer of first arg to comparison
133 * e: pointer to EPG for comparison
136 * < 0 if k1 is < record
137 * = 0 if k1 is = record
138 * > 0 if k1 is > record
141 __bt_cmp(BTREE *t, const DBT *k1, EPG *e)
150 * The left-most key on internal pages, at any level of the tree, is
151 * guaranteed by the following code to be less than any user key.
152 * This saves us from having to update the leftmost key on an internal
153 * page when the user inserts a new key in the tree smaller than
154 * anything we've yet seen.
157 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
161 if (h->flags & P_BLEAF) {
162 bl = GETBLEAF(h, e->index);
163 if (bl->flags & P_BIGKEY)
170 bi = GETBINTERNAL(h, e->index);
171 if (bi->flags & P_BIGKEY)
180 if (__ovfl_get(t, bigkey,
181 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
183 k2.data = t->bt_rdata.data;
185 return ((*t->bt_cmp)(k1, &k2));
189 * __BT_DEFCMP -- Default comparison routine.
201 __bt_defcmp(const DBT *a, const DBT *b)
204 unsigned char *p1, *p2;
208 * If a size_t doesn't fit in an int, this routine can lose.
209 * What we need is an integral type which is guaranteed to be
210 * larger than a size_t, and there is no such thing.
212 len = MIN(a->size, b->size);
213 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
215 return ((int)*p1 - (int)*p2);
216 return ((int)a->size - (int)b->size);
220 * __BT_DEFPFX -- Default prefix routine.
227 * Number of bytes needed to distinguish b from a.
230 __bt_defpfx(const DBT *a, const DBT *b)
232 unsigned char *p1, *p2;
236 len = MIN(a->size, b->size);
237 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
241 /* a->size must be <= b->size, or they wouldn't be in this order. */
242 return (a->size < b->size ? a->size + 1 : a->size);