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35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)bt_utils.c 8.8 (Berkeley) 7/20/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include <sys/param.h>
52 * Build return key/data pair.
56 * e: key/data pair to be returned
57 * key: user's key structure (NULL if not to be filled in)
58 * rkey: memory area to hold key
59 * data: user's data structure (NULL if not to be filled in)
60 * rdata: memory area to hold data
61 * copy: always copy the key/data item
64 * RET_SUCCESS, RET_ERROR.
67 __bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy)
72 bl = GETBLEAF(e->page, e->index);
75 * We must copy big keys/data to make them contigous. Otherwise,
76 * leave the page pinned and don't copy unless the user specified
82 if (bl->flags & P_BIGKEY) {
83 if (__ovfl_get(t, bl->bytes,
84 &key->size, &rkey->data, &rkey->size))
86 key->data = rkey->data;
87 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
88 if (bl->ksize > rkey->size) {
89 p = realloc(rkey->data, bl->ksize);
93 rkey->size = bl->ksize;
95 memmove(rkey->data, bl->bytes, bl->ksize);
96 key->size = bl->ksize;
97 key->data = rkey->data;
99 key->size = bl->ksize;
100 key->data = bl->bytes;
105 return (RET_SUCCESS);
107 if (bl->flags & P_BIGDATA) {
108 if (__ovfl_get(t, bl->bytes + bl->ksize,
109 &data->size, &rdata->data, &rdata->size))
111 data->data = rdata->data;
112 } else if (copy || F_ISSET(t, B_DB_LOCK)) {
113 /* Use +1 in case the first record retrieved is 0 length. */
114 if (bl->dsize + 1 > rdata->size) {
115 p = realloc(rdata->data, bl->dsize + 1);
119 rdata->size = bl->dsize + 1;
121 memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
122 data->size = bl->dsize;
123 data->data = rdata->data;
125 data->size = bl->dsize;
126 data->data = bl->bytes + bl->ksize;
129 return (RET_SUCCESS);
133 * __BT_CMP -- Compare a key to a given record.
137 * k1: DBT pointer of first arg to comparison
138 * e: pointer to EPG for comparison
141 * < 0 if k1 is < record
142 * = 0 if k1 is = record
143 * > 0 if k1 is > record
146 __bt_cmp(BTREE *t, const DBT *k1, EPG *e)
155 * The left-most key on internal pages, at any level of the tree, is
156 * guaranteed by the following code to be less than any user key.
157 * This saves us from having to update the leftmost key on an internal
158 * page when the user inserts a new key in the tree smaller than
159 * anything we've yet seen.
162 if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
166 if (h->flags & P_BLEAF) {
167 bl = GETBLEAF(h, e->index);
168 if (bl->flags & P_BIGKEY)
175 bi = GETBINTERNAL(h, e->index);
176 if (bi->flags & P_BIGKEY)
185 if (__ovfl_get(t, bigkey,
186 &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
188 k2.data = t->bt_rdata.data;
190 return ((*t->bt_cmp)(k1, &k2));
194 * __BT_DEFCMP -- Default comparison routine.
206 __bt_defcmp(const DBT *a, const DBT *b)
213 * If a size_t doesn't fit in an int, this routine can lose.
214 * What we need is an integral type which is guaranteed to be
215 * larger than a size_t, and there is no such thing.
217 len = MIN(a->size, b->size);
218 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
220 return ((int)*p1 - (int)*p2);
221 return ((int)a->size - (int)b->size);
225 * __BT_DEFPFX -- Default prefix routine.
232 * Number of bytes needed to distinguish b from a.
235 __bt_defpfx(const DBT *a, const DBT *b)
241 len = MIN(a->size, b->size);
242 for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
246 /* a->size must be <= b->size, or they wouldn't be in this order. */
247 return (a->size < b->size ? a->size + 1 : a->size);