summaryrefslogtreecommitdiff
path: root/bdb/db/db_ret.c
blob: b1af7b4ffebe58ca14defba2b2b8cc65b3394856 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2002
 *	Sleepycat Software.  All rights reserved.
 */

#include "db_config.h"

#ifndef lint
static const char revid[] = "$Id: db_ret.c,v 11.21 2002/03/28 19:21:47 bostic Exp $";
#endif /* not lint */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <string.h>
#endif

#include "db_int.h"
#include "dbinc/db_page.h"
#include "dbinc/db_am.h"

/*
 * __db_ret --
 *	Build return DBT.
 *
 * PUBLIC: int __db_ret __P((DB *,
 * PUBLIC:    PAGE *, u_int32_t, DBT *, void **, u_int32_t *));
 */
int
__db_ret(dbp, h, indx, dbt, memp, memsize)
	DB *dbp;
	PAGE *h;
	u_int32_t indx;
	DBT *dbt;
	void **memp;
	u_int32_t *memsize;
{
	BKEYDATA *bk;
	HOFFPAGE ho;
	BOVERFLOW *bo;
	u_int32_t len;
	u_int8_t *hk;
	void *data;

	switch (TYPE(h)) {
	case P_HASH:
		hk = P_ENTRY(dbp, h, indx);
		if (HPAGE_PTYPE(hk) == H_OFFPAGE) {
			memcpy(&ho, hk, sizeof(HOFFPAGE));
			return (__db_goff(dbp, dbt,
			    ho.tlen, ho.pgno, memp, memsize));
		}
		len = LEN_HKEYDATA(dbp, h, dbp->pgsize, indx);
		data = HKEYDATA_DATA(hk);
		break;
	case P_LBTREE:
	case P_LDUP:
	case P_LRECNO:
		bk = GET_BKEYDATA(dbp, h, indx);
		if (B_TYPE(bk->type) == B_OVERFLOW) {
			bo = (BOVERFLOW *)bk;
			return (__db_goff(dbp, dbt,
			    bo->tlen, bo->pgno, memp, memsize));
		}
		len = bk->len;
		data = bk->data;
		break;
	default:
		return (__db_pgfmt(dbp->dbenv, h->pgno));
	}

	return (__db_retcopy(dbp->dbenv, dbt, data, len, memp, memsize));
}

/*
 * __db_retcopy --
 *	Copy the returned data into the user's DBT, handling special flags.
 *
 * PUBLIC: int __db_retcopy __P((DB_ENV *, DBT *,
 * PUBLIC:    void *, u_int32_t, void **, u_int32_t *));
 */
int
__db_retcopy(dbenv, dbt, data, len, memp, memsize)
	DB_ENV *dbenv;
	DBT *dbt;
	void *data;
	u_int32_t len;
	void **memp;
	u_int32_t *memsize;
{
	int ret;

	/* If returning a partial record, reset the length. */
	if (F_ISSET(dbt, DB_DBT_PARTIAL)) {
		data = (u_int8_t *)data + dbt->doff;
		if (len > dbt->doff) {
			len -= dbt->doff;
			if (len > dbt->dlen)
				len = dbt->dlen;
		} else
			len = 0;
	}

	/*
	 * Return the length of the returned record in the DBT size field.
	 * This satisfies the requirement that if we're using user memory
	 * and insufficient memory was provided, return the amount necessary
	 * in the size field.
	 */
	dbt->size = len;

	/*
	 * Allocate memory to be owned by the application: DB_DBT_MALLOC,
	 * DB_DBT_REALLOC.
	 *
	 * !!!
	 * We always allocate memory, even if we're copying out 0 bytes. This
	 * guarantees consistency, i.e., the application can always free memory
	 * without concern as to how many bytes of the record were requested.
	 *
	 * Use the memory specified by the application: DB_DBT_USERMEM.
	 *
	 * !!!
	 * If the length we're going to copy is 0, the application-supplied
	 * memory pointer is allowed to be NULL.
	 */
	if (F_ISSET(dbt, DB_DBT_MALLOC)) {
		if ((ret = __os_umalloc(dbenv, len, &dbt->data)) != 0)
			return (ret);
	} else if (F_ISSET(dbt, DB_DBT_REALLOC)) {
		if ((ret = __os_urealloc(dbenv, len, &dbt->data)) != 0)
			return (ret);
	} else if (F_ISSET(dbt, DB_DBT_USERMEM)) {
		if (len != 0 && (dbt->data == NULL || dbt->ulen < len))
			return (ENOMEM);
	} else if (memp == NULL || memsize == NULL) {
		return (EINVAL);
	} else {
		if (len != 0 && (*memsize == 0 || *memsize < len)) {
			if ((ret = __os_realloc(dbenv, len, memp)) != 0) {
				*memsize = 0;
				return (ret);
			}
			*memsize = len;
		}
		dbt->data = *memp;
	}

	if (len != 0)
		memcpy(dbt->data, data, len);
	return (0);
}