lib/libc/db/recno/rec_delete.c

   1 /*      $NetBSD: rec_delete.c,v 1.17 2008/09/11 12:58:00 joerg Exp $    */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Mike Olson.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #if HAVE_NBTOOL_CONFIG_H
  36 #include "nbtool_config.h"
  37 #endif
  38
  39 #include <sys/cdefs.h>
  40 __RCSID("$NetBSD: rec_delete.c,v 1.17 2008/09/11 12:58:00 joerg Exp $");
  41
  42 #include "namespace.h"
  43 #include <sys/types.h>
  44
  45 #include <assert.h>
  46 #include <errno.h>
  47 #include <stdio.h>
  48 #include <string.h>
  49
  50 #include <db.h>
  51 #include "recno.h"
  52
  53 static int rec_rdelete(BTREE *, recno_t);
  54
  55 /*
  56  * __REC_DELETE -- Delete the item(s) referenced by a key.
  57  *
  58  * Parameters:
  59  *      dbp:    pointer to access method
  60  *      key:    key to delete
  61  *      flags:  R_CURSOR if deleting what the cursor references
  62  *
  63  * Returns:
  64  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
  65  */
  66 int
  67 __rec_delete(const DB *dbp, const DBT *key, u_int flags)
  68 {
  69         BTREE *t;
  70         recno_t nrec;
  71         int status;
  72
  73         t = dbp->internal;
  74
  75         /* Toss any page pinned across calls. */
  76         if (t->bt_pinned != NULL) {
  77                 mpool_put(t->bt_mp, t->bt_pinned, 0);
  78                 t->bt_pinned = NULL;
  79         }
  80
  81         switch(flags) {
  82         case 0:
  83                 if ((nrec = *(recno_t *)key->data) == 0)
  84                         goto einval;
  85                 if (nrec > t->bt_nrecs)
  86                         return (RET_SPECIAL);
  87                 --nrec;
  88                 status = rec_rdelete(t, nrec);
  89                 break;
  90         case R_CURSOR:
  91                 if (!F_ISSET(&t->bt_cursor, CURS_INIT))
  92                         goto einval;
  93                 if (t->bt_nrecs == 0)
  94                         return (RET_SPECIAL);
  95                 status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
  96                 if (status == RET_SUCCESS)
  97                         --t->bt_cursor.rcursor;
  98                 break;
  99         default:
 100 einval:         errno = EINVAL;
 101                 return (RET_ERROR);
 102         }
 103
 104         if (status == RET_SUCCESS)
 105                 F_SET(t, B_MODIFIED | R_MODIFIED);
 106         return (status);
 107 }
 108
 109 /*
 110  * REC_RDELETE -- Delete the data matching the specified key.
 111  *
 112  * Parameters:
 113  *      tree:   tree
 114  *      nrec:   record to delete
 115  *
 116  * Returns:
 117  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 118  */
 119 static int
 120 rec_rdelete(BTREE *t, recno_t nrec)
 121 {
 122         EPG *e;
 123         PAGE *h;
 124         int status;
 125
 126         /* Find the record; __rec_search pins the page. */
 127         if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
 128                 return (RET_ERROR);
 129
 130         /* Delete the record. */
 131         h = e->page;
 132         status = __rec_dleaf(t, h, (uint32_t)e->index);
 133         if (status != RET_SUCCESS) {
 134                 mpool_put(t->bt_mp, h, 0);
 135                 return (status);
 136         }
 137         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 138         return (RET_SUCCESS);
 139 }
 140
 141 /*
 142  * __REC_DLEAF -- Delete a single record from a recno leaf page.
 143  *
 144  * Parameters:
 145  *      t:      tree
 146  *      index:  index on current page to delete
 147  *
 148  * Returns:
 149  *      RET_SUCCESS, RET_ERROR.
 150  */
 151 int
 152 __rec_dleaf(BTREE *t, PAGE *h, uint32_t idx)
 153 {
 154         RLEAF *rl;
 155         indx_t *ip, cnt, offset;
 156         uint32_t nbytes;
 157         char *from;
 158         void *to;
 159         size_t temp;
 160
 161         /*
 162          * Delete a record from a recno leaf page.  Internal records are never
 163          * deleted from internal pages, regardless of the records that caused
 164          * them to be added being deleted.  Pages made empty by deletion are
 165          * not reclaimed.  They are, however, made available for reuse.
 166          *
 167          * Pack the remaining entries at the end of the page, shift the indices
 168          * down, overwriting the deleted record and its index.  If the record
 169          * uses overflow pages, make them available for reuse.
 170          */
 171         to = rl = GETRLEAF(h, idx);
 172         if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
 173                 return (RET_ERROR);
 174         nbytes = NRLEAF(rl);
 175
 176         /*
 177          * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
 178          * offsets.  Reset the headers.
 179          */
 180         from = (char *)(void *)h + h->upper;
 181         memmove(from + nbytes, from, (size_t)((char *)to - from));
 182         h->upper += nbytes;
 183
 184         offset = h->linp[idx];
 185         temp = &h->linp[idx] - (ip = &h->linp[0]);
 186         _DBFIT(temp, uint16_t);
 187         for (cnt = (uint16_t)temp;  cnt--; ++ip)
 188                 if (ip[0] < offset)
 189                         ip[0] += nbytes;
 190         temp = &h->linp[NEXTINDEX(h)] - ip;
 191         _DBFIT(temp, uint16_t);
 192         for (cnt = (uint16_t)temp;  --cnt; ++ip)
 193                 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
 194         h->lower -= sizeof(indx_t);
 195         --t->bt_nrecs;
 196         return (RET_SUCCESS);
 197 }