/*
* hfsutils - tools for reading and writing Macintosh HFS volumes
* Copyright (C) 1996, 1997 Robert Leslie
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
# include <stdlib.h>
# include <string.h>
# include <errno.h>
# include "internal.h"
# include "data.h"
# include "btree.h"
# include "node.h"
# define NODESPACE(n) \
(HFS_BLOCKSZ - (n).roff[(n).nd.ndNRecs] - 2 * ((n).nd.ndNRecs + 1))
/*
* NAME: node->init()
* DESCRIPTION: construct an empty node
*/
void n_init(node *np, btree *bt, int type, int height)
{
np->bt = bt;
np->nnum = -1;
np->nd.ndFLink = 0;
np->nd.ndBLink = 0;
np->nd.ndType = type;
np->nd.ndNHeight = height;
np->nd.ndNRecs = 0;
np->nd.ndResv2 = 0;
np->rnum = -1;
np->roff[0] = 0x00e;
memset(np->data, 0, sizeof(np->data));
}
/*
* NAME: node->new()
* DESCRIPTION: allocate a new b*-tree node
*/
int n_new(node *np)
{
btree *bt = np->bt;
unsigned long num;
if (bt->hdr.bthFree == 0)
{
ERROR(EIO, "b*-tree full");
return -1;
}
num = 0;
while (num < bt->hdr.bthNNodes && BMTST(bt->map, num))
++num;
if (num == bt->hdr.bthNNodes)
{
ERROR(EIO, "free b*-tree node not found");
return -1;
}
np->nnum = num;
BMSET(bt->map, num);
--bt->hdr.bthFree;
bt->flags |= HFS_UPDATE_BTHDR;
return 0;
}
/*
* NAME: node->free()
* DESCRIPTION: deallocate a b*-tree node
*/
void n_free(node *np)
{
btree *bt = np->bt;
BMCLR(bt->map, np->nnum);
++bt->hdr.bthFree;
bt->flags |= HFS_UPDATE_BTHDR;
}
/*
* NAME: node->compact()
* DESCRIPTION: clean up a node, removing deleted records
*/
void n_compact(node *np)
{
unsigned char *ptr;
int offset, nrecs, i;
offset = 0x00e;
ptr = np->data + offset;
nrecs = 0;
for (i = 0; i < np->nd.ndNRecs; ++i)
{
unsigned char *rec;
int reclen;
rec = HFS_NODEREC(*np, i);
reclen = np->roff[i + 1] - np->roff[i];
if (HFS_RECKEYLEN(rec) > 0)
{
np->roff[nrecs++] = offset;
offset += reclen;
if (ptr == rec)
ptr += reclen;
else
{
while (reclen--)
*ptr++ = *rec++;
}
}
}
np->roff[nrecs] = offset;
np->nd.ndNRecs = nrecs;
}
/*
* NAME: node->search()
* DESCRIPTION: locate a record in a node, or the record it should follow
*/
int n_search(node *np, unsigned char *key)
{
btree *bt = np->bt;
int i, comp = -1;
for (i = np->nd.ndNRecs; i--; )
{
unsigned char *rec;
rec = HFS_NODEREC(*np, i);
if (HFS_RECKEYLEN(rec) == 0)
continue; /* deleted record */
comp = bt->compare(rec, key);
if (comp <= 0)
break;
}
np->rnum = i;
return comp == 0;
}
/*
* NAME: node->index()
* DESCRIPTION: create an index record from a key and node pointer
*/
void n_index(btree *bt, unsigned char *key, unsigned long nnum,
unsigned char *record, int *reclen)
{
if (bt == &bt->f.vol->cat)
{
/* force the key length to be 0x25 */
HFS_RECKEYLEN(record) = 0x25;
memset(record + 1, 0, 0x25);
memcpy(record + 1, key + 1, HFS_RECKEYLEN(key));
}
else
memcpy(record, key, HFS_RECKEYSKIP(key));
d_putl(HFS_RECDATA(record), nnum);
if (reclen)
*reclen = HFS_RECKEYSKIP(record) + 4;
}
/*
* NAME: node->split()
* DESCRIPTION: divide a node into two and insert a record
*/
int n_split(node *left, unsigned char *record, int *reclen)
{
node right;
int nrecs, i, mid;
unsigned char *rec;
right = *left;
right.nd.ndBLink = left->nnum;
if (n_new(&right) < 0)
return -1;
left->nd.ndFLink = right.nnum;
nrecs = left->nd.ndNRecs;
/*
* Ensure node split leaves enough room for new record.
* The size calculations used are based on the NODESPACE() macro, but
* I don't know what the extra 2's and 1's are needed for.
* John Witford <jwitford@hutch.com.au>
*/
n_search(&right, record);
mid = nrecs/2;
for(;;)
{
if (right.rnum < mid)
{
if ( mid > 0
&& left->roff[mid] + *reclen + 2 > HFS_BLOCKSZ - 2 * (mid + 1))
{
--mid;
if (mid > 0)
continue;
}
}
else
{
if ( mid < nrecs
&& right.roff[nrecs] - right.roff[mid] + left->roff[0] + *reclen + 2 > HFS_BLOCKSZ - 2 * (mid + 1))
{
++mid;
if (mid < nrecs)
continue;
}
}
break;
}
for (i = 0; i < nrecs; ++i)
{
if (i < mid)
rec = HFS_NODEREC(right, i);
else
rec = HFS_NODEREC(*left, i);
HFS_RECKEYLEN(rec) = 0;
}
/* original code ...
for (i = 0; i < nrecs; ++i)
{
if (i < nrecs / 2)
rec = HFS_NODEREC(right, i);
else
rec = HFS_NODEREC(*left, i);
HFS_RECKEYLEN(rec) = 0;
}
*/
n_compact(left);
n_compact(&right);
n_search(&right, record);
if (right.rnum >= 0)
n_insertx(&right, record, *reclen);
else
{
n_search(left, record);
n_insertx(left, record, *reclen);
}
/* store the new/modified nodes */
if (bt_putnode(left) < 0 ||
bt_putnode(&right) < 0)
return -1;
/* create an index record for the new node in the parent */
n_index(right.bt, HFS_NODEREC(right, 0), right.nnum, record, reclen);
/* update link pointers */
if (left->bt->hdr.bthLNode == left->nnum)
{
left->bt->hdr.bthLNode = right.nnum;
left->bt->flags |= HFS_UPDATE_BTHDR;
}
if (right.nd.ndFLink)
{
node n;
n.bt = right.bt;
n.nnum = right.nd.ndFLink;
if (bt_getnode(&n) < 0)
return -1;
n.nd.ndBLink = right.nnum;
if (bt_putnode(&n) < 0)
return -1;
}
return 0;
}
/*
* NAME: node->insertx()
* DESCRIPTION: insert a record into a node (which must already have room)
*/
void n_insertx(node *np, unsigned char *record, int reclen)
{
int rnum, i;
unsigned char *ptr;
rnum = np->rnum + 1;
/* push other records down to make room */
for (ptr = HFS_NODEREC(*np, np->nd.ndNRecs) + reclen;
ptr > HFS_NODEREC(*np, rnum) + reclen; --ptr)
*(ptr - 1) = *(ptr - 1 - reclen);
++np->nd.ndNRecs;
for (i = np->nd.ndNRecs; i > rnum; --i)
np->roff[i] = np->roff[i - 1] + reclen;
/* write the new record */
memcpy(HFS_NODEREC(*np, rnum), record, reclen);
}
/*
* NAME: node->insert()
* DESCRIPTION: insert a new record into a node; return a record for parent
*/
int n_insert(node *np, unsigned char *record, int *reclen)
{
n_compact(np);
/* check for free space */
if (np->nd.ndNRecs >= HFS_MAXRECS ||
*reclen + 2 > NODESPACE(*np))
return n_split(np, record, reclen);
n_insertx(np, record, *reclen);
*reclen = 0;
return bt_putnode(np);
}
/*
* NAME: node->merge()
* DESCRIPTION: combine two nodes into a single node
*/
int n_merge(node *right, node *left, unsigned char *record, int *flag)
{
int i, offset;
/* copy records and offsets */
memcpy(HFS_NODEREC(*left, left->nd.ndNRecs), HFS_NODEREC(*right, 0),
right->roff[right->nd.ndNRecs] - right->roff[0]);
offset = left->roff[left->nd.ndNRecs] - right->roff[0];
for (i = 1; i <= right->nd.ndNRecs; ++i)
left->roff[++left->nd.ndNRecs] = offset + right->roff[i];
/* update link pointers */
left->nd.ndFLink = right->nd.ndFLink;
if (bt_putnode(left) < 0)
return -1;
if (right->bt->hdr.bthLNode == right->nnum)
{
right->bt->hdr.bthLNode = left->nnum;
right->bt->flags |= HFS_UPDATE_BTHDR;
}
if (right->nd.ndFLink)
{
node n;
n.bt = right->bt;
n.nnum = right->nd.ndFLink;
if (bt_getnode(&n) < 0)
return -1;
n.nd.ndBLink = left->nnum;
if (bt_putnode(&n) < 0)
return -1;
}
n_free(right);
HFS_RECKEYLEN(record) = 0;
*flag = 1;
return 0;
}
/*
* NAME: node->delete()
* DESCRIPTION: remove a record from a node
*/
int n_delete(node *np, unsigned char *record, int *flag)
{
node left;
unsigned char *rec;
rec = HFS_NODEREC(*np, np->rnum);
HFS_RECKEYLEN(rec) = 0;
n_compact(np);
/* see if we can merge with our left sibling */
left.bt = np->bt;
left.nnum = np->nd.ndBLink;
if (left.nnum > 0)
{
if (bt_getnode(&left) < 0)
return -1;
if (np->nd.ndNRecs + left.nd.ndNRecs <= HFS_MAXRECS &&
np->roff[np->nd.ndNRecs] - np->roff[0] +
2 * np->nd.ndNRecs <= NODESPACE(left))
return n_merge(np, &left, record, flag);
}
if (np->rnum == 0)
{
/* special case: first record changed; update parent record key */
n_index(np->bt, HFS_NODEREC(*np, 0), np->nnum, record, 0);
*flag = 1;
}
return bt_putnode(np);
}