db/recno/FreeBSD/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 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/db/recno/rec_delete.c,v 1.2 2002/03/21 22:46:28 obrien Exp $");
  42
  43 #include <sys/types.h>
  44
  45 #include <errno.h>
  46 #include <stdio.h>
  47 #include <string.h>
  48
  49 #include <db.h>
  50 #include "recno.h"
  51
  52 static int rec_rdelete(BTREE *, recno_t);
  53
  54 /*
  55  * __REC_DELETE -- Delete the item(s) referenced by a key.
  56  *
  57  * Parameters:
  58  *      dbp:    pointer to access method
  59  *      key:    key to delete
  60  *      flags:  R_CURSOR if deleting what the cursor references
  61  *
  62  * Returns:
  63  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
  64  */
  65 int
  66 __rec_delete(dbp, key, flags)
  67         const DB *dbp;
  68         const DBT *key;
  69         u_int flags;
  70 {
  71         BTREE *t;
  72         recno_t nrec;
  73         int status;
  74
  75         t = dbp->internal;
  76
  77         /* Toss any page pinned across calls. */
  78         if (t->bt_pinned != NULL) {
  79                 mpool_put(t->bt_mp, t->bt_pinned, 0);
  80                 t->bt_pinned = NULL;
  81         }
  82
  83         switch(flags) {
  84         case 0:
  85                 if ((nrec = *(recno_t *)key->data) == 0)
  86                         goto einval;
  87                 if (nrec > t->bt_nrecs)
  88                         return (RET_SPECIAL);
  89                 --nrec;
  90                 status = rec_rdelete(t, nrec);
  91                 break;
  92         case R_CURSOR:
  93                 if (!F_ISSET(&t->bt_cursor, CURS_INIT))
  94                         goto einval;
  95                 if (t->bt_nrecs == 0)
  96                         return (RET_SPECIAL);
  97                 status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
  98                 if (status == RET_SUCCESS)
  99                         --t->bt_cursor.rcursor;
 100                 break;
 101         default:
 102 einval:         errno = EINVAL;
 103                 return (RET_ERROR);
 104         }
 105
 106         if (status == RET_SUCCESS)
 107                 F_SET(t, B_MODIFIED | R_MODIFIED);
 108         return (status);
 109 }
 110
 111 /*
 112  * REC_RDELETE -- Delete the data matching the specified key.
 113  *
 114  * Parameters:
 115  *      tree:   tree
 116  *      nrec:   record to delete
 117  *
 118  * Returns:
 119  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 120  */
 121 static int
 122 rec_rdelete(t, nrec)
 123         BTREE *t;
 124         recno_t nrec;
 125 {
 126         EPG *e;
 127         PAGE *h;
 128         int status;
 129
 130         /* Find the record; __rec_search pins the page. */
 131         if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
 132                 return (RET_ERROR);
 133
 134         /* Delete the record. */
 135         h = e->page;
 136         status = __rec_dleaf(t, h, e->index);
 137         if (status != RET_SUCCESS) {
 138                 mpool_put(t->bt_mp, h, 0);
 139                 return (status);
 140         }
 141         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 142         return (RET_SUCCESS);
 143 }
 144
 145 /*
 146  * __REC_DLEAF -- Delete a single record from a recno leaf page.
 147  *
 148  * Parameters:
 149  *      t:      tree
 150  *      index:  index on current page to delete
 151  *
 152  * Returns:
 153  *      RET_SUCCESS, RET_ERROR.
 154  */
 155 int
 156 __rec_dleaf(t, h, index)
 157         BTREE *t;
 158         PAGE *h;
 159         u_int32_t index;
 160 {
 161         RLEAF *rl;
 162         indx_t *ip, cnt, offset;
 163         u_int32_t nbytes;
 164         char *from;
 165         void *to;
 166
 167         /*
 168          * Delete a record from a recno leaf page.  Internal records are never
 169          * deleted from internal pages, regardless of the records that caused
 170          * them to be added being deleted.  Pages made empty by deletion are
 171          * not reclaimed.  They are, however, made available for reuse.
 172          *
 173          * Pack the remaining entries at the end of the page, shift the indices
 174          * down, overwriting the deleted record and its index.  If the record
 175          * uses overflow pages, make them available for reuse.
 176          */
 177         to = rl = GETRLEAF(h, index);
 178         if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
 179                 return (RET_ERROR);
 180         nbytes = NRLEAF(rl);
 181
 182         /*
 183          * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
 184          * offsets.  Reset the headers.
 185          */
 186         from = (char *)h + h->upper;
 187         memmove(from + nbytes, from, (char *)to - from);
 188         h->upper += nbytes;
 189
 190         offset = h->linp[index];
 191         for (cnt = &h->linp[index] - (ip = &h->linp[0]); cnt--; ++ip)
 192                 if (ip[0] < offset)
 193                         ip[0] += nbytes;
 194         for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
 195                 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
 196         h->lower -= sizeof(indx_t);
 197         --t->bt_nrecs;
 198         return (RET_SUCCESS);
 199 }