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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)rec_delete.c        8.7 (Berkeley) 7/14/94";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/db/recno/rec_delete.c,v 1.5 2009/03/03 02:16:12 delphij Exp $");
  38
  39 #include <sys/types.h>
  40
  41 #include <errno.h>
  42 #include <stdio.h>
  43 #include <string.h>
  44
  45 #include <db.h>
  46 #include "recno.h"
  47
  48 static int rec_rdelete(BTREE *, recno_t);
  49
  50 /*
  51  * __REC_DELETE -- Delete the item(s) referenced by a key.
  52  *
  53  * Parameters:
  54  *      dbp:    pointer to access method
  55  *      key:    key to delete
  56  *      flags:  R_CURSOR if deleting what the cursor references
  57  *
  58  * Returns:
  59  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
  60  */
  61 int
  62 __rec_delete(const DB *dbp, const DBT *key, u_int flags)
  63 {
  64         BTREE *t;
  65         recno_t nrec;
  66         int status;
  67
  68         t = dbp->internal;
  69
  70         /* Toss any page pinned across calls. */
  71         if (t->bt_pinned != NULL) {
  72                 mpool_put(t->bt_mp, t->bt_pinned, 0);
  73                 t->bt_pinned = NULL;
  74         }
  75
  76         switch(flags) {
  77         case 0:
  78                 if ((nrec = *(recno_t *)key->data) == 0)
  79                         goto einval;
  80                 if (nrec > t->bt_nrecs)
  81                         return (RET_SPECIAL);
  82                 --nrec;
  83                 status = rec_rdelete(t, nrec);
  84                 break;
  85         case R_CURSOR:
  86                 if (!F_ISSET(&t->bt_cursor, CURS_INIT))
  87                         goto einval;
  88                 if (t->bt_nrecs == 0)
  89                         return (RET_SPECIAL);
  90                 status = rec_rdelete(t, t->bt_cursor.rcursor - 1);
  91                 if (status == RET_SUCCESS)
  92                         --t->bt_cursor.rcursor;
  93                 break;
  94         default:
  95 einval:         errno = EINVAL;
  96                 return (RET_ERROR);
  97         }
  98
  99         if (status == RET_SUCCESS)
 100                 F_SET(t, B_MODIFIED | R_MODIFIED);
 101         return (status);
 102 }
 103
 104 /*
 105  * REC_RDELETE -- Delete the data matching the specified key.
 106  *
 107  * Parameters:
 108  *      tree:   tree
 109  *      nrec:   record to delete
 110  *
 111  * Returns:
 112  *      RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 113  */
 114 static int
 115 rec_rdelete(BTREE *t, recno_t nrec)
 116 {
 117         EPG *e;
 118         PAGE *h;
 119         int status;
 120
 121         /* Find the record; __rec_search pins the page. */
 122         if ((e = __rec_search(t, nrec, SDELETE)) == NULL)
 123                 return (RET_ERROR);
 124
 125         /* Delete the record. */
 126         h = e->page;
 127         status = __rec_dleaf(t, h, e->index);
 128         if (status != RET_SUCCESS) {
 129                 mpool_put(t->bt_mp, h, 0);
 130                 return (status);
 131         }
 132         mpool_put(t->bt_mp, h, MPOOL_DIRTY);
 133         return (RET_SUCCESS);
 134 }
 135
 136 /*
 137  * __REC_DLEAF -- Delete a single record from a recno leaf page.
 138  *
 139  * Parameters:
 140  *      t:      tree
 141  *      idx:    index on current page to delete
 142  *
 143  * Returns:
 144  *      RET_SUCCESS, RET_ERROR.
 145  */
 146 int
 147 __rec_dleaf(BTREE *t, PAGE *h, u_int32_t idx)
 148 {
 149         RLEAF *rl;
 150         indx_t *ip, cnt, offset;
 151         u_int32_t nbytes;
 152         char *from;
 153         void *to;
 154
 155         /*
 156          * Delete a record from a recno leaf page.  Internal records are never
 157          * deleted from internal pages, regardless of the records that caused
 158          * them to be added being deleted.  Pages made empty by deletion are
 159          * not reclaimed.  They are, however, made available for reuse.
 160          *
 161          * Pack the remaining entries at the end of the page, shift the indices
 162          * down, overwriting the deleted record and its index.  If the record
 163          * uses overflow pages, make them available for reuse.
 164          */
 165         to = rl = GETRLEAF(h, idx);
 166         if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
 167                 return (RET_ERROR);
 168         nbytes = NRLEAF(rl);
 169
 170         /*
 171          * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
 172          * offsets.  Reset the headers.
 173          */
 174         from = (char *)h + h->upper;
 175         memmove(from + nbytes, from, (char *)to - from);
 176         h->upper += nbytes;
 177
 178         offset = h->linp[idx];
 179         for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip)
 180                 if (ip[0] < offset)
 181                         ip[0] += nbytes;
 182         for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
 183                 ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
 184         h->lower -= sizeof(indx_t);
 185         --t->bt_nrecs;
 186         return (RET_SUCCESS);
 187 }