db.1.85/recno/rec_delete.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Mike Olson.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)rec_delete.c        8.7 (Berkeley) 7/14/94";
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include <sys/types.h>
  42
  43 #include <errno.h>
  44 #include <stdio.h>
  45 #include <string.h>
  46
  47 #include <db.h>
  48 #include "recno.h"
  49
  50 static int rec_rdelete __P((BTREE *, recno_t));
  51
  52 /*
  53  * __REC_DELETE -- Delete the item(s) referenced by a key.
  54  *
  55  * Parameters:
  56  *      dbp:    pointer to access method
  57  *      key:    key to delete
  58  *      flags:  R_CURSOR if deleting what the cursor references
  59  *
  60  * Returns:
  61  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
  62  */
  63 int
  64 __rec_delete(dbp, key, flags)
  65         const DB *dbp;
  66         const DBT *key;
  67         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(t, nrec)
 121         BTREE *t;
 122         recno_t nrec;
 123 {
 124         EPG *e;
 125         PAGE *h;
 126         int status;
 127
 128         /* Find the record; __rec_search pins the page. */
 129         if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
 130                 return (RET_ERROR);
 131
 132         /* Delete the record. */
 133         h = e->page;
 134         status = __rec_dleaf(t, h, e->index);
 135         if (status != RET_SUCCESS) {
 136                 mpool_put(t->bt_mp, h, 0);
 137                 return (status);
 138         }
 139         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 140         return (RET_SUCCESS);
 141 }
 142
 143 /*
 144  * __REC_DLEAF -- Delete a single record from a recno leaf page.
 145  *
 146  * Parameters:
 147  *      t:      tree
 148  *      index:  index on current page to delete
 149  *
 150  * Returns:
 151  *      RET_SUCCESS, RET_ERROR.
 152  */
 153 int
 154 __rec_dleaf(t, h, index)
 155         BTREE *t;
 156         PAGE *h;
 157         u_int32_t index;
 158 {
 159         RLEAF *rl;
 160         indx_t *ip, cnt, offset;
 161         u_int32_t nbytes;
 162         char *from;
 163         void *to;
 164
 165         /*
 166          * Delete a record from a recno leaf page.  Internal records are never
 167          * deleted from internal pages, regardless of the records that caused
 168          * them to be added being deleted.  Pages made empty by deletion are
 169          * not reclaimed.  They are, however, made available for reuse.
 170          *
 171          * Pack the remaining entries at the end of the page, shift the indices
 172          * down, overwriting the deleted record and its index.  If the record
 173          * uses overflow pages, make them available for reuse.
 174          */
 175         to = rl = GETRLEAF(h, index);
 176         if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
 177                 return (RET_ERROR);
 178         nbytes = NRLEAF(rl);
 179
 180         /*
 181          * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
 182          * offsets.  Reset the headers.
 183          */
 184         from = (char *)h + h->upper;
 185         memmove(from + nbytes, from, (char *)to - from);
 186         h->upper += nbytes;
 187
 188         offset = h->linp[index];
 189         for (cnt = &h->linp[index] - (ip = &h->linp[0]); cnt--; ++ip)
 190                 if (ip[0] < offset)
 191                         ip[0] += nbytes;
 192         for (cnt = &h->linp[NEXTINDEX(h)] - ip; --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 }