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36 * @(#)bt_utils.c 8.8 (Berkeley) 7/20/94
37 * $DragonFly: src/lib/libc/db/btree/bt_utils.c,v 1.3 2004/10/25 19:38:01 drhodus Exp $
40 #include <sys/param.h>
51 * Build return key/data pair.
55 * e: key/data pair to be returned
56 * key: user's key structure (NULL if not to be filled in)
57 * rkey: memory area to hold key
58 * data: user's data structure (NULL if not to be filled in)
59 * rdata: memory area to hold data
60 * copy: always copy the key/data item
63 * RET_SUCCESS, RET_ERROR.
66 __bt_ret(t, e, key, rkey, data, rdata, copy)
69 DBT *key, *rkey, *data, *rdata;
75 bl = GETBLEAF(e->page, e->index);
78 * We must copy big keys/data to make them contigous. Otherwise,
79 * leave the page pinned and don't copy unless the user specified
85 if (bl->flags & P_BIGKEY) {
86 if (__ovfl_get(t, bl->bytes,
87 &key->size, &rkey->data, &rkey->size))
89 key->data = rkey->data;
90 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
91 if (bl->ksize > rkey->size) {
92 p = (void *)(rkey->data == NULL ?
93 malloc(bl->ksize) : realloc(rkey->data, bl->ksize));
97 rkey->size = bl->ksize;
99 memmove(rkey->data, bl->bytes, bl->ksize);
100 key->size = bl->ksize;
101 key->data = rkey->data;
103 key->size = bl->ksize;
104 key->data = bl->bytes;
109 return (RET_SUCCESS);
111 if (bl->flags & P_BIGDATA) {
112 if (__ovfl_get(t, bl->bytes + bl->ksize,
113 &data->size, &rdata->data, &rdata->size))
115 data->data = rdata->data;
116 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
117 /* Use +1 in case the first record retrieved is 0 length. */
118 if (bl->dsize + 1 > rdata->size) {
119 p = (void *)(rdata->data == NULL ?
120 malloc(bl->dsize + 1) :
121 realloc(rdata->data, bl->dsize + 1));
125 rdata->size = bl->dsize + 1;
127 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
128 data->size = bl->dsize;
129 data->data = rdata->data;
131 data->size = bl->dsize;
132 data->data = bl->bytes + bl->ksize;
135 return (RET_SUCCESS);
139 * __BT_CMP -- Compare a key to a given record.
143 * k1: DBT pointer of first arg to comparison
144 * e: pointer to EPG for comparison
147 * < 0 if k1 is < record
148 * = 0 if k1 is = record
149 * > 0 if k1 is > record
164 * The left-most key on internal pages, at any level of the tree, is
165 * guaranteed by the following code to be less than any user key.
166 * This saves us from having to update the leftmost key on an internal
167 * page when the user inserts a new key in the tree smaller than
168 * anything we've yet seen.
171 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
175 if (h->flags & P_BLEAF) {
176 bl = GETBLEAF(h, e->index);
177 if (bl->flags & P_BIGKEY)
184 bi = GETBINTERNAL(h, e->index);
185 if (bi->flags & P_BIGKEY)
194 if (__ovfl_get(t, bigkey,
195 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
197 k2.data = t->bt_rdata.data;
199 return ((*t->bt_cmp)(k1, &k2));
203 * __BT_DEFCMP -- Default comparison routine.
223 * If a size_t doesn't fit in an int, this routine can lose.
224 * What we need is a integral type which is guaranteed to be
225 * larger than a size_t, and there is no such thing.
227 len = MIN(a->size, b->size);
228 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
230 return ((int)*p1 - (int)*p2);
231 return ((int)a->size - (int)b->size);
235 * __BT_DEFPFX -- Default prefix routine.
242 * Number of bytes needed to distinguish b from a.
252 len = MIN(a->size, b->size);
253 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
257 /* a->size must be <= b->size, or they wouldn't be in this order. */
258 return (a->size < b->size ? a->size + 1 : a->size);