minivmac4ios/libhfs/btree.c

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2016-05-21 13:01:57 +00:00
/*
* libhfs - library for reading and writing Macintosh HFS volumes
* Copyright (C) 1996-1998 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.
*
* $Id: btree.c,v 1.10 1998/11/02 22:08:54 rob Exp $
*/
# ifdef HAVE_CONFIG_H
# include "config.h"
# endif
# include <stdlib.h>
# include <string.h>
# include <errno.h>
# include "libhfs.h"
# include "btree.h"
# include "data.h"
# include "file.h"
# include "block.h"
# include "node.h"
/*
* NAME: btree->getnode()
* DESCRIPTION: retrieve a numbered node from a B*-tree file
*/
int bt_getnode(node *np, btree *bt, unsigned long nnum)
{
block *bp = &np->data;
const byte *ptr;
int i;
np->bt = bt;
np->nnum = nnum;
# if 0
fprintf(stderr, "BTREE: GET vol \"%s\" btree \"%s\" node %lu\n",
bt->f.vol->mdb.drVN, bt->f.name, np->nnum);
# endif
/* verify the node exists and is marked as in-use */
if (nnum > 0 && nnum >= bt->hdr.bthNNodes)
ERROR(EIO, "read nonexistent b*-tree node");
else if (bt->map && ! BMTST(bt->map, nnum))
ERROR(EIO, "read unallocated b*-tree node");
if (f_getblock(&bt->f, nnum, bp) == -1)
goto fail;
ptr = *bp;
d_fetchul(&ptr, &np->nd.ndFLink);
d_fetchul(&ptr, &np->nd.ndBLink);
d_fetchsb(&ptr, &np->nd.ndType);
d_fetchsb(&ptr, &np->nd.ndNHeight);
d_fetchuw(&ptr, &np->nd.ndNRecs);
d_fetchsw(&ptr, &np->nd.ndResv2);
if (np->nd.ndNRecs > HFS_MAX_NRECS)
ERROR(EIO, "too many b*-tree node records");
i = np->nd.ndNRecs + 1;
ptr = *bp + HFS_BLOCKSZ - (2 * i);
while (i--)
d_fetchuw(&ptr, &np->roff[i]);
return 0;
fail:
return -1;
}
/*
* NAME: btree->putnode()
* DESCRIPTION: store a numbered node into a B*-tree file
*/
int bt_putnode(node *np)
{
btree *bt = np->bt;
block *bp = &np->data;
byte *ptr;
int i;
# if 0
fprintf(stderr, "BTREE: PUT vol \"%s\" btree \"%s\" node %lu\n",
bt->f.vol->mdb.drVN, bt->f.name, np->nnum);
# endif
/* verify the node exists and is marked as in-use */
if (np->nnum > 0 && np->nnum >= bt->hdr.bthNNodes)
ERROR(EIO, "write nonexistent b*-tree node");
else if (bt->map && ! BMTST(bt->map, np->nnum))
ERROR(EIO, "write unallocated b*-tree node");
ptr = *bp;
d_storeul(&ptr, np->nd.ndFLink);
d_storeul(&ptr, np->nd.ndBLink);
d_storesb(&ptr, np->nd.ndType);
d_storesb(&ptr, np->nd.ndNHeight);
d_storeuw(&ptr, np->nd.ndNRecs);
d_storesw(&ptr, np->nd.ndResv2);
if (np->nd.ndNRecs > HFS_MAX_NRECS)
ERROR(EIO, "too many b*-tree node records");
i = np->nd.ndNRecs + 1;
ptr = *bp + HFS_BLOCKSZ - (2 * i);
while (i--)
d_storeuw(&ptr, np->roff[i]);
return f_putblock(&bt->f, np->nnum, bp);
fail:
return -1;
}
/*
* NAME: btree->readhdr()
* DESCRIPTION: read the header node of a B*-tree
*/
int bt_readhdr(btree *bt)
{
const byte *ptr;
byte *map = 0;
int i;
unsigned long nnum;
if (bt_getnode(&bt->hdrnd, bt, 0) == -1)
goto fail;
if (bt->hdrnd.nd.ndType != ndHdrNode ||
bt->hdrnd.nd.ndNRecs != 3 ||
bt->hdrnd.roff[0] != 0x00e ||
bt->hdrnd.roff[1] != 0x078 ||
bt->hdrnd.roff[2] != 0x0f8 ||
bt->hdrnd.roff[3] != 0x1f8)
ERROR(EIO, "malformed b*-tree header node");
/* read header record */
ptr = HFS_NODEREC(bt->hdrnd, 0);
d_fetchuw(&ptr, &bt->hdr.bthDepth);
d_fetchul(&ptr, &bt->hdr.bthRoot);
d_fetchul(&ptr, &bt->hdr.bthNRecs);
d_fetchul(&ptr, &bt->hdr.bthFNode);
d_fetchul(&ptr, &bt->hdr.bthLNode);
d_fetchuw(&ptr, &bt->hdr.bthNodeSize);
d_fetchuw(&ptr, &bt->hdr.bthKeyLen);
d_fetchul(&ptr, &bt->hdr.bthNNodes);
d_fetchul(&ptr, &bt->hdr.bthFree);
for (i = 0; i < 76; ++i)
d_fetchsb(&ptr, &bt->hdr.bthResv[i]);
if (bt->hdr.bthNodeSize != HFS_BLOCKSZ)
ERROR(EINVAL, "unsupported b*-tree node size");
/* read map record; construct btree bitmap */
/* don't set bt->map until we're done, since getnode() checks it */
map = ALLOC(byte, HFS_MAP1SZ);
if (map == 0)
ERROR(ENOMEM, 0);
memcpy(map, HFS_NODEREC(bt->hdrnd, 2), HFS_MAP1SZ);
bt->mapsz = HFS_MAP1SZ;
/* read continuation map records, if any */
nnum = bt->hdrnd.nd.ndFLink;
while (nnum)
{
node n;
byte *newmap;
if (bt_getnode(&n, bt, nnum) == -1)
goto fail;
if (n.nd.ndType != ndMapNode ||
n.nd.ndNRecs != 1 ||
n.roff[0] != 0x00e ||
n.roff[1] != 0x1fa)
ERROR(EIO, "malformed b*-tree map node");
newmap = REALLOC(map, byte, bt->mapsz + HFS_MAPXSZ);
if (newmap == 0)
ERROR(ENOMEM, 0);
map = newmap;
memcpy(map + bt->mapsz, HFS_NODEREC(n, 0), HFS_MAPXSZ);
bt->mapsz += HFS_MAPXSZ;
nnum = n.nd.ndFLink;
}
bt->map = map;
return 0;
fail:
FREE(map);
return -1;
}
/*
* NAME: btree->writehdr()
* DESCRIPTION: write the header node of a B*-tree
*/
int bt_writehdr(btree *bt)
{
byte *ptr, *map;
unsigned long mapsz, nnum;
int i;
ASSERT(bt->hdrnd.bt == bt &&
bt->hdrnd.nnum == 0 &&
bt->hdrnd.nd.ndType == ndHdrNode &&
bt->hdrnd.nd.ndNRecs == 3);
ptr = HFS_NODEREC(bt->hdrnd, 0);
d_storeuw(&ptr, bt->hdr.bthDepth);
d_storeul(&ptr, bt->hdr.bthRoot);
d_storeul(&ptr, bt->hdr.bthNRecs);
d_storeul(&ptr, bt->hdr.bthFNode);
d_storeul(&ptr, bt->hdr.bthLNode);
d_storeuw(&ptr, bt->hdr.bthNodeSize);
d_storeuw(&ptr, bt->hdr.bthKeyLen);
d_storeul(&ptr, bt->hdr.bthNNodes);
d_storeul(&ptr, bt->hdr.bthFree);
for (i = 0; i < 76; ++i)
d_storesb(&ptr, bt->hdr.bthResv[i]);
memcpy(HFS_NODEREC(bt->hdrnd, 2), bt->map, HFS_MAP1SZ);
if (bt_putnode(&bt->hdrnd) == -1)
goto fail;
map = bt->map + HFS_MAP1SZ;
mapsz = bt->mapsz - HFS_MAP1SZ;
nnum = bt->hdrnd.nd.ndFLink;
while (mapsz)
{
node n;
if (nnum == 0)
ERROR(EIO, "truncated b*-tree map");
if (bt_getnode(&n, bt, nnum) == -1)
goto fail;
if (n.nd.ndType != ndMapNode ||
n.nd.ndNRecs != 1 ||
n.roff[0] != 0x00e ||
n.roff[1] != 0x1fa)
ERROR(EIO, "malformed b*-tree map node");
memcpy(HFS_NODEREC(n, 0), map, HFS_MAPXSZ);
if (bt_putnode(&n) == -1)
goto fail;
map += HFS_MAPXSZ;
mapsz -= HFS_MAPXSZ;
nnum = n.nd.ndFLink;
}
bt->flags &= ~HFS_BT_UPDATE_HDR;
return 0;
fail:
return -1;
}
/* High-Level B*-Tree Routines ============================================= */
/*
* NAME: btree->space()
* DESCRIPTION: assert space for new records, or extend the file
*/
int bt_space(btree *bt, unsigned int nrecs)
{
unsigned int nnodes;
long space;
nnodes = nrecs * (bt->hdr.bthDepth + 1);
if (nnodes <= bt->hdr.bthFree)
goto done;
/* make sure the extents tree has room too */
if (bt != &bt->f.vol->ext)
{
if (bt_space(&bt->f.vol->ext, 1) == -1)
goto fail;
}
space = f_alloc(&bt->f);
if (space == -1)
goto fail;
nnodes = space * (bt->f.vol->mdb.drAlBlkSiz / bt->hdr.bthNodeSize);
bt->hdr.bthNNodes += nnodes;
bt->hdr.bthFree += nnodes;
bt->flags |= HFS_BT_UPDATE_HDR;
bt->f.vol->flags |= HFS_VOL_UPDATE_ALTMDB;
while (bt->hdr.bthNNodes > bt->mapsz * 8)
{
byte *newmap;
node mapnd;
/* extend tree map */
newmap = REALLOC(bt->map, byte, bt->mapsz + HFS_MAPXSZ);
if (newmap == 0)
ERROR(ENOMEM, 0);
memset(newmap + bt->mapsz, 0, HFS_MAPXSZ);
bt->map = newmap;
bt->mapsz += HFS_MAPXSZ;
n_init(&mapnd, bt, ndMapNode, 0);
if (n_new(&mapnd) == -1)
goto fail;
mapnd.nd.ndNRecs = 1;
mapnd.roff[1] = 0x1fa;
/* link the new map node */
if (bt->hdrnd.nd.ndFLink == 0)
{
bt->hdrnd.nd.ndFLink = mapnd.nnum;
mapnd.nd.ndBLink = 0;
}
else
{
node n;
unsigned long nnum;
nnum = bt->hdrnd.nd.ndFLink;
while (1)
{
if (bt_getnode(&n, bt, nnum) == -1)
goto fail;
if (n.nd.ndFLink == 0)
break;
nnum = n.nd.ndFLink;
}
n.nd.ndFLink = mapnd.nnum;
mapnd.nd.ndBLink = n.nnum;
if (bt_putnode(&n) == -1)
goto fail;
}
if (bt_putnode(&mapnd) == -1)
goto fail;
}
done:
return 0;
fail:
return -1;
}
/*
* NAME: insertx()
* DESCRIPTION: recursively locate a node and insert a record
*/
static
int insertx(node *np, byte *record, int *reclen)
{
node child;
byte *rec;
int result = 0;
if (n_search(np, record))
ERROR(EIO, "b*-tree record already exists");
switch (np->nd.ndType)
{
case ndIndxNode:
if (np->rnum == -1)
rec = HFS_NODEREC(*np, 0);
else
rec = HFS_NODEREC(*np, np->rnum);
if (bt_getnode(&child, np->bt, d_getul(HFS_RECDATA(rec))) == -1 ||
insertx(&child, record, reclen) == -1)
goto fail;
if (np->rnum == -1)
{
n_index(&child, rec, 0);
if (*reclen == 0)
{
result = bt_putnode(np);
goto done;
}
}
if (*reclen)
result = n_insert(np, record, reclen);
break;
case ndLeafNode:
result = n_insert(np, record, reclen);
break;
default:
ERROR(EIO, "unexpected b*-tree node");
}
done:
return result;
fail:
return -1;
}
/*
* NAME: btree->insert()
* DESCRIPTION: insert a new node record into a tree
*/
int bt_insert(btree *bt, const byte *record, unsigned int reclen)
{
node root;
byte newrec[HFS_MAX_RECLEN];
if (bt->hdr.bthRoot == 0)
{
/* create root node */
n_init(&root, bt, ndLeafNode, 1);
if (n_new(&root) == -1 ||
bt_putnode(&root) == -1)
goto fail;
bt->hdr.bthDepth = 1;
bt->hdr.bthRoot = root.nnum;
bt->hdr.bthFNode = root.nnum;
bt->hdr.bthLNode = root.nnum;
bt->flags |= HFS_BT_UPDATE_HDR;
}
else if (bt_getnode(&root, bt, bt->hdr.bthRoot) == -1)
goto fail;
memcpy(newrec, record, reclen);
if (insertx(&root, newrec, &reclen) == -1)
goto fail;
if (reclen)
{
byte oroot[HFS_MAX_RECLEN];
unsigned int orootlen;
/* root node was split; create a new root */
n_index(&root, oroot, &orootlen);
n_init(&root, bt, ndIndxNode, root.nd.ndNHeight + 1);
if (n_new(&root) == -1)
goto fail;
++bt->hdr.bthDepth;
bt->hdr.bthRoot = root.nnum;
bt->flags |= HFS_BT_UPDATE_HDR;
/* insert index records for new root */
n_search(&root, oroot);
n_insertx(&root, oroot, orootlen);
n_search(&root, newrec);
n_insertx(&root, newrec, reclen);
if (bt_putnode(&root) == -1)
goto fail;
}
++bt->hdr.bthNRecs;
bt->flags |= HFS_BT_UPDATE_HDR;
return 0;
fail:
return -1;
}
/*
* NAME: deletex()
* DESCRIPTION: recursively locate a node and delete a record
*/
static
int deletex(node *np, const byte *key, byte *record, int *flag)
{
node child;
byte *rec;
int found, result = 0;
found = n_search(np, key);
switch (np->nd.ndType)
{
case ndIndxNode:
if (np->rnum == -1)
ERROR(EIO, "b*-tree record not found");
rec = HFS_NODEREC(*np, np->rnum);
if (bt_getnode(&child, np->bt, d_getul(HFS_RECDATA(rec))) == -1 ||
deletex(&child, key, rec, flag) == -1)
goto fail;
if (*flag)
{
*flag = 0;
if (HFS_RECKEYLEN(rec) == 0)
{
result = n_delete(np, record, flag);
break;
}
if (np->rnum == 0)
{
/* propagate index record change into parent */
n_index(np, record, 0);
*flag = 1;
}
result = bt_putnode(np);
}
break;
case ndLeafNode:
if (found == 0)
ERROR(EIO, "b*-tree record not found");
result = n_delete(np, record, flag);
break;
default:
ERROR(EIO, "unexpected b*-tree node");
}
return result;
fail:
return -1;
}
/*
* NAME: btree->delete()
* DESCRIPTION: remove a node record from a tree
*/
int bt_delete(btree *bt, const byte *key)
{
node root;
byte record[HFS_MAX_RECLEN];
int flag = 0;
if (bt->hdr.bthRoot == 0)
ERROR(EIO, "empty b*-tree");
if (bt_getnode(&root, bt, bt->hdr.bthRoot) == -1 ||
deletex(&root, key, record, &flag) == -1)
goto fail;
if (bt->hdr.bthDepth > 1 && root.nd.ndNRecs == 1)
{
const byte *rec;
/* root only has one record; eliminate it and decrease the tree depth */
rec = HFS_NODEREC(root, 0);
--bt->hdr.bthDepth;
bt->hdr.bthRoot = d_getul(HFS_RECDATA(rec));
if (n_free(&root) == -1)
goto fail;
}
else if (bt->hdr.bthDepth == 1 && root.nd.ndNRecs == 0)
{
/* root node was deleted */
bt->hdr.bthDepth = 0;
bt->hdr.bthRoot = 0;
}
--bt->hdr.bthNRecs;
bt->flags |= HFS_BT_UPDATE_HDR;
return 0;
fail:
return -1;
}
/*
* NAME: btree->search()
* DESCRIPTION: locate a data record given a search key
*/
int bt_search(btree *bt, const byte *key, node *np)
{
int found = 0;
unsigned long nnum;
nnum = bt->hdr.bthRoot;
if (nnum == 0)
ERROR(ENOENT, 0);
while (1)
{
const byte *rec;
if (bt_getnode(np, bt, nnum) == -1)
{
found = -1;
goto fail;
}
found = n_search(np, key);
switch (np->nd.ndType)
{
case ndIndxNode:
if (np->rnum == -1)
ERROR(ENOENT, 0);
rec = HFS_NODEREC(*np, np->rnum);
nnum = d_getul(HFS_RECDATA(rec));
break;
case ndLeafNode:
if (! found)
ERROR(ENOENT, 0);
goto done;
default:
found = -1;
ERROR(EIO, "unexpected b*-tree node");
}
}
done:
fail:
return found;
}