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Cream of the Crop 1
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Cream of the Crop 1.iso
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PROGRAM
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CBASE102.ARJ
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BTSETCUR.C
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1991-09-23
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/* Copyright (c) 1989 Citadel */
/* All Rights Reserved */
/* #ident "@(#)btsetcur.c 1.5 - 91/09/23" */
#include <ansi.h>
/* ansi headers */
#include <errno.h>
#ifdef AC_STRING
#include <string.h>
#endif
/* library headers */
#include <blkio.h>
/* local headers */
#include "btree_.h"
/*man---------------------------------------------------------------------------
NAME
btsetcur - set btree cursor
SYNOPSIS
#include <btree.h>
int btsetcur(btp, btposp)
btree_t *btp;
const btpos_t *btposp;
DESCRIPTION
The btsetcur function sets the current cursor position for btree
btp to the value in btposp. btposp should point to a cursor
value saved previously with btgetcur. If btposp is the NULL
pointer, the cursor is set to null. It is important to remember
that a btree position is not valid after an insertion, deletion,
or unlock.
btsetcur will fail if one or more of the following is true:
[EINVAL] btp is not a valid btree pointer.
[BTELOCK] btp is not locked.
[BTENKEY] btposp points to an invalid cursor value.
[BTENOPEN] btp is not open.
SEE ALSO
btgetcur.
DIAGNOSTICS
Upon successful completion, a value of 0 is returned. Otherwise,
a value of -1 is returned, and errno set to indicate the error.
------------------------------------------------------------------------------*/
#ifdef AC_PROTO
int btsetcur(btree_t *btp, const btpos_t *btposp)
#else
int btsetcur(btp, btposp)
btree_t *btp;
const btpos_t *btposp;
#endif
{
/* validate arguments */
if (!bt_valid(btp)) {
errno = EINVAL;
return -1;
}
/* check if not open */
if (!(btp->flags & BTOPEN)) {
errno = BTENOPEN;
return -1;
}
/* check locks */
if (!(btp->flags & BTLOCKS)) {
errno = BTELOCK;
return -1;
}
/* set cursor */
if (btposp == NULL) {
btp->cbtpos.node = NIL; /* set cursor to null */
btp->cbtpos.key = 0;
} else {
memcpy(&btp->cbtpos, btposp, sizeof(btp->cbtpos));
}
/* read in new current node */
if (btp->cbtpos.node == NIL) {
bt_ndinit(btp, btp->cbtnp);
} else {
if (bt_ndget(btp, btp->cbtpos.node, btp->cbtnp) == -1) {
BTEPRINT;
if (errno == BEEOF) errno = BTENKEY;
return -1;
}
if (btp->cbtnp->n == 0) { /* check if block empty */
btp->cbtpos.node = NIL;
btp->cbtpos.key = 0;
bt_ndinit(btp, btp->cbtnp);
errno = BTENKEY;
return -1;
}
}
/* check if key number in range */
if (btp->cbtpos.key > btp->cbtnp->n) {
btp->cbtpos.node = NIL;
btp->cbtpos.key = 0;
bt_ndinit(btp, btp->cbtnp);
errno = BTENKEY;
return -1;
}
return 0;
}