db/recno/rec_delete.c

   1 /*
   2  * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*-
  26  * Copyright (c) 1990, 1993, 1994
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * This code is derived from software contributed to Berkeley by
  30  * Mike Olson.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61 #if defined(LIBC_SCCS) && !defined(lint)
  62 static char sccsid[] = "@(#)rec_delete.c        8.7 (Berkeley) 7/14/94";
  63 #endif /* LIBC_SCCS and not lint */
  64 #include <sys/cdefs.h>
  65
  66 #include <sys/types.h>
  67
  68 #include <errno.h>
  69 #include <stdio.h>
  70 #include <string.h>
  71
  72 #include <db.h>
  73 #include "recno.h"
  74
  75 static int rec_rdelete(BTREE *, recno_t);
  76
  77 /*
  78  * __REC_DELETE -- Delete the item(s) referenced by a key.
  79  *
  80  * Parameters:
  81  *      dbp:    pointer to access method
  82  *      key:    key to delete
  83  *      flags:  R_CURSOR if deleting what the cursor references
  84  *
  85  * Returns:
  86  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
  87  */
  88 int
  89 __rec_delete(dbp, key, flags)
  90         const DB *dbp;
  91         const DBT *key;
  92         u_int flags;
  93 {
  94         BTREE *t;
  95         recno_t nrec;
  96         int status;
  97
  98         t = dbp->internal;
  99
 100         /* Toss any page pinned across calls. */
 101         if (t->bt_pinned != NULL) {
 102                 mpool_put(t->bt_mp, t->bt_pinned, 0);
 103                 t->bt_pinned = NULL;
 104         }
 105
 106         switch(flags) {
 107         case 0:
 108                 if ((nrec = *(recno_t *)key->data) == 0)
 109                         goto einval;
 110                 if (nrec > t->bt_nrecs)
 111                         return (RET_SPECIAL);
 112                 --nrec;
 113                 status = rec_rdelete(t, nrec);
 114                 break;
 115         case R_CURSOR:
 116                 if (!F_ISSET(&t->bt_cursor, CURS_INIT))
 117                         goto einval;
 118                 if (t->bt_nrecs == 0)
 119                         return (RET_SPECIAL);
 120                 status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
 121                 if (status == RET_SUCCESS)
 122                         --t->bt_cursor.rcursor;
 123                 break;
 124         default:
 125 einval:         errno = EINVAL;
 126                 return (RET_ERROR);
 127         }
 128
 129         if (status == RET_SUCCESS)
 130                 F_SET(t, B_MODIFIED | R_MODIFIED);
 131         return (status);
 132 }
 133
 134 /*
 135  * REC_RDELETE -- Delete the data matching the specified key.
 136  *
 137  * Parameters:
 138  *      tree:   tree
 139  *      nrec:   record to delete
 140  *
 141  * Returns:
 142  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 143  */
 144 static int
 145 rec_rdelete(t, nrec)
 146         BTREE *t;
 147         recno_t nrec;
 148 {
 149         EPG *e;
 150         PAGE *h;
 151         int status;
 152
 153         /* Find the record; __rec_search pins the page. */
 154         if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
 155                 return (RET_ERROR);
 156
 157         /* Delete the record. */
 158         h = e->page;
 159         status = __rec_dleaf(t, h, e->index);
 160         if (status != RET_SUCCESS) {
 161                 mpool_put(t->bt_mp, h, 0);
 162                 return (status);
 163         }
 164         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 165         return (RET_SUCCESS);
 166 }
 167
 168 /*
 169  * __REC_DLEAF -- Delete a single record from a recno leaf page.
 170  *
 171  * Parameters:
 172  *      t:      tree
 173  *      index:  index on current page to delete
 174  *
 175  * Returns:
 176  *      RET_SUCCESS, RET_ERROR.
 177  */
 178 int
 179 __rec_dleaf(t, h, index)
 180         BTREE *t;
 181         PAGE *h;
 182         u_int32_t index;
 183 {
 184         RLEAF *rl;
 185         indx_t *ip, cnt, offset;
 186         u_int32_t nbytes;
 187         char *from;
 188         void *to;
 189
 190         /*
 191          * Delete a record from a recno leaf page.  Internal records are never
 192          * deleted from internal pages, regardless of the records that caused
 193          * them to be added being deleted.  Pages made empty by deletion are
 194          * not reclaimed.  They are, however, made available for reuse.
 195          *
 196          * Pack the remaining entries at the end of the page, shift the indices
 197          * down, overwriting the deleted record and its index.  If the record
 198          * uses overflow pages, make them available for reuse.
 199          */
 200         to = rl = GETRLEAF(h, index);
 201         if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
 202                 return (RET_ERROR);
 203         nbytes = NRLEAF(rl);
 204
 205         /*
 206          * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
 207          * offsets.  Reset the headers.
 208          */
 209         from = (char *)h + h->upper;
 210         memmove(from + nbytes, from, (char *)to - from);
 211         h->upper += nbytes;
 212
 213         offset = h->linp[index];
 214         for (cnt = &h->linp[index] - (ip = &h->linp[0]); cnt--; ++ip)
 215                 if (ip[0] < offset)
 216                         ip[0] += nbytes;
 217         for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
 218                 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
 219         h->lower -= sizeof(indx_t);
 220         --t->bt_nrecs;
 221         return (RET_SUCCESS);
 222 }