1/*-
2 * See the file LICENSE for redistribution information.
3 *
4 * Copyright (c) 1996,2008 Oracle.  All rights reserved.
5 *
6 * $Id: db_dup.c,v 12.14 2008/01/08 20:58:10 bostic Exp $
7 */
8
9#include "db_config.h"
10
11#include "db_int.h"
12#include "dbinc/db_page.h"
13#include "dbinc/mp.h"
14#include "dbinc/db_am.h"
15
16/*
17 * __db_ditem --
18 *	Remove an item from a page.
19 *
20 * PUBLIC:  int __db_ditem __P((DBC *, PAGE *, u_int32_t, u_int32_t));
21 */
22int
23__db_ditem(dbc, pagep, indx, nbytes)
24	DBC *dbc;
25	PAGE *pagep;
26	u_int32_t indx, nbytes;
27{
28	DB *dbp;
29	DBT ldbt;
30	db_indx_t cnt, *inp, offset;
31	int ret;
32	u_int8_t *from;
33
34	dbp = dbc->dbp;
35	DB_ASSERT(dbp->env, IS_DIRTY(pagep));
36	DB_ASSERT(dbp->env, indx < NUM_ENT(pagep));
37
38	if (DBC_LOGGING(dbc)) {
39		ldbt.data = P_ENTRY(dbp, pagep, indx);
40		ldbt.size = nbytes;
41		if ((ret = __db_addrem_log(dbp, dbc->txn,
42		    &LSN(pagep), 0, DB_REM_DUP, PGNO(pagep),
43		    (u_int32_t)indx, nbytes, &ldbt, NULL, &LSN(pagep))) != 0)
44			return (ret);
45	} else
46		LSN_NOT_LOGGED(LSN(pagep));
47
48	/*
49	 * If there's only a single item on the page, we don't have to
50	 * work hard.
51	 */
52	if (NUM_ENT(pagep) == 1) {
53		NUM_ENT(pagep) = 0;
54		HOFFSET(pagep) = dbp->pgsize;
55		return (0);
56	}
57
58	inp = P_INP(dbp, pagep);
59	/*
60	 * Pack the remaining key/data items at the end of the page.  Use
61	 * memmove(3), the regions may overlap.
62	 */
63	from = (u_int8_t *)pagep + HOFFSET(pagep);
64	DB_ASSERT(dbp->env, inp[indx] >= HOFFSET(pagep));
65	memmove(from + nbytes, from, inp[indx] - HOFFSET(pagep));
66	HOFFSET(pagep) += nbytes;
67
68	/* Adjust the indices' offsets. */
69	offset = inp[indx];
70	for (cnt = 0; cnt < NUM_ENT(pagep); ++cnt)
71		if (inp[cnt] < offset)
72			inp[cnt] += nbytes;
73
74	/* Shift the indices down. */
75	--NUM_ENT(pagep);
76	if (indx != NUM_ENT(pagep))
77		memmove(&inp[indx], &inp[indx + 1],
78		    sizeof(db_indx_t) * (NUM_ENT(pagep) - indx));
79
80	return (0);
81}
82
83/*
84 * __db_pitem --
85 *	Put an item on a page.
86 *
87 * PUBLIC: int __db_pitem
88 * PUBLIC:     __P((DBC *, PAGE *, u_int32_t, u_int32_t, DBT *, DBT *));
89 */
90int
91__db_pitem(dbc, pagep, indx, nbytes, hdr, data)
92	DBC *dbc;
93	PAGE *pagep;
94	u_int32_t indx;
95	u_int32_t nbytes;
96	DBT *hdr, *data;
97{
98	BKEYDATA bk;
99	DB *dbp;
100	DBT thdr;
101	db_indx_t *inp;
102	int ret;
103	u_int8_t *p;
104
105	dbp = dbc->dbp;
106	DB_ASSERT(dbp->env, IS_DIRTY(pagep));
107
108	if (nbytes > P_FREESPACE(dbp, pagep)) {
109		DB_ASSERT(dbp->env, nbytes <= P_FREESPACE(dbp, pagep));
110		return (EINVAL);
111	}
112	/*
113	 * Put a single item onto a page.  The logic figuring out where to
114	 * insert and whether it fits is handled in the caller.  All we do
115	 * here is manage the page shuffling.  We cheat a little bit in that
116	 * we don't want to copy the dbt on a normal put twice.  If hdr is
117	 * NULL, we create a BKEYDATA structure on the page, otherwise, just
118	 * copy the caller's information onto the page.
119	 *
120	 * This routine is also used to put entries onto the page where the
121	 * entry is pre-built, e.g., during recovery.  In this case, the hdr
122	 * will point to the entry, and the data argument will be NULL.
123	 *
124	 * !!!
125	 * There's a tremendous potential for off-by-one errors here, since
126	 * the passed in header sizes must be adjusted for the structure's
127	 * placeholder for the trailing variable-length data field.
128	 */
129	if (DBC_LOGGING(dbc)) {
130		if ((ret = __db_addrem_log(dbp, dbc->txn,
131		    &LSN(pagep), 0, DB_ADD_DUP, PGNO(pagep),
132		    (u_int32_t)indx, nbytes, hdr, data, &LSN(pagep))) != 0)
133			return (ret);
134	} else
135		LSN_NOT_LOGGED(LSN(pagep));
136
137	if (hdr == NULL) {
138		B_TSET(bk.type, B_KEYDATA);
139		bk.len = data == NULL ? 0 : data->size;
140
141		thdr.data = &bk;
142		thdr.size = SSZA(BKEYDATA, data);
143		hdr = &thdr;
144	}
145	inp = P_INP(dbp, pagep);
146
147	/* Adjust the index table, then put the item on the page. */
148	if (indx != NUM_ENT(pagep))
149		memmove(&inp[indx + 1], &inp[indx],
150		    sizeof(db_indx_t) * (NUM_ENT(pagep) - indx));
151	HOFFSET(pagep) -= nbytes;
152	inp[indx] = HOFFSET(pagep);
153	++NUM_ENT(pagep);
154
155	p = P_ENTRY(dbp, pagep, indx);
156	memcpy(p, hdr->data, hdr->size);
157	if (data != NULL)
158		memcpy(p + hdr->size, data->data, data->size);
159
160	return (0);
161}
162