make CURSOR of recno 0 do the right thing; copy the key out, too

[unix-history] / usr / src / lib / libc / db / recno / rec_seq.c

/*-
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*/

#ifndef lint
static char sccsid[] = "@(#)rec_seq.c   5.3 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <errno.h>
#include <db.h>
#include <limits.h>
#include <stdio.h>
#include "recno.h"

/*
* __REC_SEQ -- Recno sequential scan interface.
*
* Parameters:
*      dbp:    pointer to access method
*      key:    key for positioning and return value
*      data:   data return value
*      flags:  R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
*
* Returns:
*      RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
*/
int
__rec_seq(dbp, key, data, flags)
       const DB *dbp;
       DBT *key, *data;
       u_int flags;
{
       BTREE *t;
       EPG *e;
       recno_t nrec;
       int status;

       t = dbp->internal;
       switch(flags) {
       case R_CURSOR:
               if ((nrec = *(recno_t *)key->data) == 0) {
                       errno = EINVAL;
                       return (RET_ERROR);
               }
               break;
       case R_NEXT:
               if (ISSET(t, BTF_SEQINIT)) {
                       nrec = t->bt_rcursor + 1;
                       break;
               }
               /* FALLTHROUGH */
       case R_FIRST:
               nrec = 1;
               break;
       case R_PREV:
               if (ISSET(t, BTF_SEQINIT)) {
                       if ((nrec = t->bt_rcursor - 1) == 0) {
                               errno = EINVAL;
                               return (RET_ERROR);
                       }
                       break;
               }
               /* FALLTHROUGH */
       case R_LAST:
               if (t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
                       return (RET_ERROR);
               nrec = t->bt_nrecs;
               break;
       default:
               errno = EINVAL;
               return (RET_ERROR);
       }
       
       if (t->bt_nrecs == 0 || nrec > t->bt_nrecs) {
               if ((status = t->bt_irec(t, nrec)) != RET_SUCCESS)
                       return (status);
               if (t->bt_nrecs == 0 || nrec > t->bt_nrecs)
                       return (RET_SPECIAL);
       }

       if ((e = __rec_search(t, nrec - 1, SEARCH)) == NULL)
               return (RET_ERROR);

       if ((status = __rec_ret(t, e, data)) == RET_SUCCESS) {
               key->size = sizeof(recno_t);
               bcopy(&nrec, key->data, sizeof(recno_t));
               t->bt_rcursor = nrec;
               SET(t, BTF_SEQINIT);
               UNSET(t, BTF_DELCRSR);
       }
       mpool_put(t->bt_mp, e->page, 0);
       return (status);
}