--- /dev/null
+/*
+ * libhfs - library for reading and writing Macintosh HFS volumes
+ * The fucntions are used to handle the various forms of btrees
+ * found on HFS+ volumes.
+ *
+ * The fucntions are used to handle the various forms of btrees
+ * found on HFS+ volumes.
+ *
+ * Copyright (C) 2000 Klaus Halfmann <khalfmann@libra.de>
+ * Original 1996-1998 Robert Leslie <rob@mars.org>
+ * Additional work by Brad Boyer (flar@pants.nu)
+ *
+ * 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., 51 Franklin Street - Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ *
+ * $Id: btree.c,v 1.14 2000/10/25 05:43:04 hasi Exp $
+ */
+
+#include "config.h"
+#include "libhfsp.h"
+#include "volume.h"
+#include "btree.h"
+#include "record.h"
+#include "swab.h"
+
+/* Read the node from the given buffer and swap the bytes.
+ *
+ * return pointer after reading the structure
+ */
+static void* btree_readnode(btree_node_desc* node, void *p)
+{
+ node->next = bswabU32_inc(p);
+ node->prev = bswabU32_inc(p);
+ node->kind = bswabU8_inc(p);
+ node->height = bswabU8_inc(p);
+ node->num_rec = bswabU16_inc(p);
+ node->reserved = bswabU16_inc(p);
+ return p;
+}
+
+/* read a btree header from the given buffer and swap the bytes.
+ *
+ * return pointer after reading the structure
+ */
+static void* btree_readhead(btree_head* head, void *p)
+{
+ UInt32 *q;
+ head->depth = bswabU16_inc(p);
+ head->root = bswabU32_inc(p);
+ head->leaf_count = bswabU32_inc(p);
+ head->leaf_head = bswabU32_inc(p);
+ head->leaf_tail = bswabU32_inc(p);
+ head->node_size = bswabU16_inc(p);
+ head->max_key_len = bswabU16_inc(p);
+ head->node_count = bswabU32_inc(p);
+ head->free_nodes = bswabU32_inc(p);
+ head->reserved1 = bswabU16_inc(p);
+ head->clump_size = bswabU32_inc(p);
+ head->btree_type = bswabU8_inc(p);
+ head->reserved2 = bswabU8_inc(p);
+ head->attributes = bswabU32_inc(p);
+ // skip reserved bytes
+ q=((UInt32*) p);
+ // ((UInt32*) p) += 16;
+ q+=16;
+ return q;
+}
+
+/* Priority of the depth of the node compared to LRU value.
+ * Should be the average number of keys per node but these vary. */
+#define DEPTH_FACTOR 1000
+
+/* Cache size is height of tree + this value
+ * Really big numbers wont help in case of ls -R
+ */
+#define EXTRA_CACHESIZE 3
+
+/* Not in use by now ... */
+#define CACHE_DIRTY 0x0001
+
+/* Intialize cache with default cache Size,
+ * must call node_cache_close to deallocate memory */
+static int node_cache_init(node_cache* cache, btree* tree, int size)
+{
+ int nodebufsize;
+ char * buf;
+
+ cache->size = size;
+ cache->currindex = 0;
+ nodebufsize = tree->head.node_size + sizeof(node_buf);
+ buf = malloc(size *(sizeof(node_entry) + nodebufsize));
+ if (!buf)
+ return -1;
+ cache -> nodebufsize = nodebufsize;
+ cache -> entries = (node_entry*) buf;
+ cache -> buffers = (char*) &cache->entries[size];
+ bzero(cache->entries, size*sizeof(node_entry));
+ return 0;
+}
+
+/* Like cache->buffers[i], since size of node_buf is variable */
+static inline node_buf* node_buf_get(node_cache* cache, int i)
+{
+ return (node_buf*) (cache->buffers + (i * cache->nodebufsize));
+}
+
+/* flush the node at index */
+static void node_cache_flush_node(node_cache* cache, int index)
+{
+ // NYI
+ cache -> entries[index].index = 0; // invalidate entry
+}
+
+static void node_cache_close(node_cache* cache)
+{
+ if (!cache->entries) // not (fully) intialized ?
+ return;
+ free(cache->entries);
+}
+
+/* Load the cach node indentified by index with
+ * the node identified by node_index */
+
+static node_buf* node_cache_load_buf
+ (btree* bt, node_cache* cache, int index, UInt16 node_index)
+{
+ node_buf *result = node_buf_get(cache ,index);
+ UInt32 blkpernode = bt->blkpernode;
+ UInt32 block = node_index * blkpernode;
+ void* p = volume_readfromfork(bt->vol, result->node, bt->fork,
+ block, blkpernode, HFSP_EXTENT_DATA, bt->cnid);
+ node_entry *e = &cache->entries[index];
+
+ if (!p)
+ return NULL; // evil ...
+
+ result->index = node_index;
+ btree_readnode(&result->desc, p);
+
+ e -> priority = result->desc.height * DEPTH_FACTOR;
+ e -> index = node_index;
+ return result;
+}
+
+/* Read node at given index, using cache.
+ */
+node_buf* btree_node_by_index(btree* bt, UInt16 index)
+{
+ node_cache* cache = &bt->cache;
+ int oldindex, lruindex;
+ int currindex = cache->currindex;
+ UInt32 prio;
+ node_entry *e;
+
+ // Shortcut acces to current node, will not change priorities
+ if (cache->entries[currindex].index == index)
+ return node_buf_get(cache ,currindex);
+ oldindex = currindex;
+ if (currindex == 0)
+ currindex = cache->size;
+ currindex--;
+ lruindex = oldindex; // entry to be flushed when needed
+ prio = 0; // current priority
+ while (currindex != oldindex) // round robin
+ {
+ e = &cache->entries[currindex];
+ if (e->index == index) // got it
+ {
+ if (e->priority != 0) // already top, uuh
+ e->priority--;
+ cache->currindex = currindex;
+ return node_buf_get(cache ,currindex);
+ }
+ else
+ {
+ if (!e->index)
+ {
+ lruindex = currindex;
+ break; // empty entry, load it
+ }
+ if (e->priority != UINT_MAX) // already least, uuh
+ e->priority++;
+ }
+ if (prio < e->priority)
+ {
+ lruindex = currindex;
+ prio = e->priority;
+ }
+ if (currindex == 0)
+ currindex = cache->size;
+ currindex--;
+ }
+ e = &cache->entries[lruindex];
+ cache->currindex = lruindex;
+ if (e->flags & CACHE_DIRTY)
+ node_cache_flush_node( cache, lruindex);
+ return node_cache_load_buf (bt, cache, lruindex, index);
+}
+
+/** intialize the btree with the first entry in the fork */
+static int btree_init(btree* bt, volume* vol, hfsp_fork_raw* fork)
+{
+ void *p;
+ char buf[vol->blksize];
+ UInt16 node_size;
+ btree_node_desc node;
+
+ bt->vol = vol;
+ bt->fork = fork;
+ p = volume_readfromfork(vol, buf, fork, 0, 1,
+ HFSP_EXTENT_DATA, bt->cnid);
+ if (!p)
+ return -1;
+ p = btree_readnode(&node, p);
+ if (node.kind != HFSP_NODE_HEAD)
+ return -1; // should not happen ?
+ btree_readhead(&bt->head, p);
+
+ node_size = bt->head.node_size;
+ bt->blkpernode = node_size / vol->blksize;
+
+ if (bt->blkpernode == 0 || vol->blksize *
+ bt->blkpernode != node_size)
+ return -1; // should never happen ...
+
+ node_cache_init(&bt->cache, bt, bt->head.depth + EXTRA_CACHESIZE);
+
+ // Allocate buffer
+ // bt->buf = malloc(node_size);
+ // if (!bt->buf)
+ // return ENOMEM;
+
+ return 0;
+}
+
+/** Intialize catalog btree, so that btree_close can safely be called. */
+void btree_reset(btree* bt)
+{
+ bt->cache.entries = NULL;
+}
+
+/** Intialize catalog btree */
+int btree_init_cat(btree* bt, volume* vol, hfsp_fork_raw* fork)
+{
+ int result = btree_init(bt,vol,fork); // super (...)
+ bt->cnid = HFSP_CAT_CNID;
+ bt->kcomp = record_key_compare;
+ bt->kread = record_readkey;
+ return result;
+}
+
+/** Intialize catalog btree */
+int btree_init_extent(btree* bt, volume* vol, hfsp_fork_raw* fork)
+{
+ int result = btree_init(bt,vol,fork); // super (...)
+ bt->cnid = HFSP_EXT_CNID;
+ bt->kcomp = record_extent_key_compare;
+ bt->kread = record_extent_readkey;
+ return result;
+}
+
+/** close the btree and free any resources */
+void btree_close(btree* bt)
+{
+ node_cache_close(&bt->cache);
+ // free(bt->buf);
+}
+
+/* returns pointer to key given by index in current node.
+ *
+ * Assumes that current node is not NODE_HEAD ...
+ */
+void* btree_key_by_index(btree* bt, node_buf* buf, UInt16 index)
+{
+ UInt16 node_size = bt->head.node_size;
+ // The offsets are found at the end of the node ...
+ UInt16 off_pos = node_size - (index +1) * sizeof(btree_record_offset);
+ // position of offset at end of node
+ btree_record_offset* offset =
+ (btree_record_offset*) (buf->node + off_pos);
+
+ // now we have the offset and can read the key ...
+#ifdef CONFIG_LITTLE_ENDIAN
+ return buf->node + bswabU16(*offset);
+#else
+ return buf->node + *offset;
+#endif
+}
+
+
+#ifdef DEBUG
+
+/* print btree header node information */
+void btree_printhead(btree_head* head)
+{
+ UInt32 attr;
+ printf(" depth : %#X\n", head->depth);
+ printf(" root : %#lX\n", head->root);
+ printf(" leaf_count : %#lX\n", head->leaf_count);
+ printf(" leaf_head : %#lX\n", head->leaf_head);
+ printf(" leaf_tail : %#lX\n", head->leaf_tail);
+ printf(" node_size : %#X\n", head->node_size);
+ printf(" max_key_len : %#X\n", head->max_key_len);
+ printf(" node_count : %#lX\n", head->node_count);
+ printf(" free_nodes : %#lX\n", head->free_nodes);
+ printf(" reserved1 : %#X\n", head->reserved1);
+ printf(" clump_size : %#lX\n", head->clump_size);
+ printf(" btree_type : %#X\n", head->btree_type);
+ attr = head->attributes;
+ printf(" reserved2 : %#X\n", head->reserved2);
+ if (attr & HFSPLUS_BAD_CLOSE)
+ printf(" HFSPLUS_BAD_CLOSE *** ");
+ else
+ printf(" !HFSPLUS_BAD_CLOSE");
+ if (attr & HFSPLUS_TREE_BIGKEYS)
+ printf(" HFSPLUS_TREE_BIGKEYS ");
+ else
+ printf(" !HFSPLUS_TREE_BIGKEYS");
+ if (attr & HFSPLUS_TREE_VAR_NDXKEY_SIZE)
+ printf(" HFSPLUS_TREE_VAR_NDXKEY_SIZE");
+ else
+ printf(" !HFSPLUS_TREE_VAR_NDXKEY_SIZE");
+ if (attr & HFSPLUS_TREE_UNUSED)
+ printf(" HFSPLUS_TREE_UNUSED ***\n");
+ printf("\n");
+}
+
+/* Dump all the node information to stdout */
+void btree_print(btree* bt)
+{
+ btree_node_desc* node;
+
+ btree_printhead(&bt->head);
+
+ node = &bt->node;
+ printf("next : %#lX\n", node->next);
+ printf("prev : %#lX\n", node->prev);
+ printf("height : %#X\n", node->height);
+ printf("num_rec : %#X\n", node->num_rec);
+ printf("reserved : %#X\n", node->reserved);
+ printf("height : %#X\n", node->height); switch(node->kind)
+ {
+ case HFSP_NODE_NDX :
+ printf("HFSP_NODE_NDX\n");
+ break;
+ case HFSP_NODE_HEAD :
+ printf("HFSP_NODE_HEAD\n");
+ break;
+ case HFSP_NODE_MAP :
+ printf("HFSP_NODE_MAP\n");
+ break;
+ case HFSP_NODE_LEAF :
+ printf("HFSP_NODE_LEAF\n");
+ break;
+ default:
+ printf("*** Unknown Node type ***\n");
+ }
+}
+
+#endif
Code Review / kvmfornfv.git / blobdiff