FreeBSD/Linux Kernel Cross Reference
sys/fs/hfs/btree.c

     /*
      * linux/fs/hfs/btree.c
      *
      * Copyright (C) 1995-1997  Paul H. Hargrove
      * This file may be distributed under the terms of the GNU General Public License.
      *
      * This file contains the code to manipulate the B-tree structure.
      * The catalog and extents files are both B-trees.
      *
     * "XXX" in a comment is a note to myself to consider changing something.
     *
     * In function preconditions the term "valid" applied to a pointer to
     * a structure means that the pointer is non-NULL and the structure it
     * points to has all fields initialized to consistent values.
     *
     * The code in this file initializes some structures which contain
     * pointers by calling memset(&foo, 0, sizeof(foo)).
     * This produces the desired behavior only due to the non-ANSI
     * assumption that the machine representation of NULL is all zeros.
     */
    
    #include "hfs_btree.h"
    
    /*================ File-local functions ================*/
    
    /*
     * hfs_bnode_ditch() 
     *
     * Description:
     *   This function deletes an entire linked list of bnodes, so it
     *   does not need to keep the linked list consistent as
     *   hfs_bnode_delete() does.
     *   Called by hfs_btree_init() for error cleanup and by hfs_btree_free().
     * Input Variable(s):
     *   struct hfs_bnode *bn: pointer to the first (struct hfs_bnode) in
     *    the linked list to be deleted.
     * Output Variable(s):
     *   NONE
     * Returns:
     *   void
     * Preconditions:
     *   'bn' is NULL or points to a "valid" (struct hfs_bnode) with a 'prev'
     *    field of NULL.
     * Postconditions:
     *   'bn' and all (struct hfs_bnode)s in the chain of 'next' pointers
     *   are deleted, freeing the associated memory and hfs_buffer_put()ing
     *   the associated buffer.
     */
    static void hfs_bnode_ditch(struct hfs_bnode *bn) {
            struct hfs_bnode *tmp;
    #if defined(DEBUG_BNODES) || defined(DEBUG_ALL)
            extern int bnode_count;
    #endif
    
            while (bn != NULL) {
                    tmp = bn->next;
    #if defined(DEBUG_BNODES) || defined(DEBUG_ALL)
                    hfs_warn("deleting node %d from tree %d with count %d\n",
                             bn->node, (int)ntohl(bn->tree->entry.cnid), bn->count);
                    --bnode_count;
    #endif
                    hfs_buffer_put(bn->buf); /* safe: checks for NULL argument */
    
                    /* free all but the header */
                    if (bn->node) {
                            HFS_DELETE(bn);
                    }
                    bn = tmp;
            }
    }
    
    /*================ Global functions ================*/
    
    /*
     * hfs_btree_free()
     *
     * Description:
     *   This function frees a (struct hfs_btree) obtained from hfs_btree_init().
     *   Called by hfs_put_super().
     * Input Variable(s):
     *   struct hfs_btree *bt: pointer to the (struct hfs_btree) to free
     * Output Variable(s):
     *   NONE
     * Returns:
     *   void
     * Preconditions:
     *   'bt' is NULL or points to a "valid" (struct hfs_btree)
     * Postconditions:
     *   If 'bt' points to a "valid" (struct hfs_btree) then all (struct
     *    hfs_bnode)s associated with 'bt' are freed by calling
     *    hfs_bnode_ditch() and the memory associated with the (struct
     *    hfs_btree) is freed.
     *   If 'bt' is NULL or not "valid" an error is printed and nothing
     *    is changed.
     */
    void hfs_btree_free(struct hfs_btree *bt)
    {
            int lcv;
    
           if (bt && (bt->magic == HFS_BTREE_MAGIC)) {
                   hfs_extent_free(&bt->entry.u.file.data_fork);
   
                   for (lcv=0; lcv<HFS_CACHELEN; ++lcv) {
   #if defined(DEBUG_BNODES) || defined(DEBUG_ALL)
                           hfs_warn("deleting nodes from bucket %d:\n", lcv);
   #endif
                           hfs_bnode_ditch(bt->cache[lcv]);
                   }
   
   #if defined(DEBUG_BNODES) || defined(DEBUG_ALL)
                   hfs_warn("deleting header and bitmap nodes\n");
   #endif
                   hfs_bnode_ditch(&bt->head);
   
   #if defined(DEBUG_BNODES) || defined(DEBUG_ALL)
                   hfs_warn("deleting root node\n");
   #endif
                   hfs_bnode_ditch(bt->root);
   
                   HFS_DELETE(bt);
           } else if (bt) {
                   hfs_warn("hfs_btree_free: corrupted hfs_btree.\n");
           }
   }
   
   /*
    * hfs_btree_init()
    *
    * Description:
    *   Given some vital information from the MDB (HFS superblock),
    *   initializes the fields of a (struct hfs_btree).
    * Input Variable(s):
    *   struct hfs_mdb *mdb: pointer to the MDB
    *   ino_t cnid: the CNID (HFS_CAT_CNID or HFS_EXT_CNID) of the B-tree
    *   hfs_u32 tsize: the size, in bytes, of the B-tree
    *   hfs_u32 csize: the size, in bytes, of the clump size for the B-tree
    * Output Variable(s):
    *   NONE
    * Returns:
    *   (struct hfs_btree *): pointer to the initialized hfs_btree on success,
    *    or NULL on failure
    * Preconditions:
    *   'mdb' points to a "valid" (struct hfs_mdb)
    * Postconditions:
    *   Assuming the inputs are what they claim to be, no errors occur
    *   reading from disk, and no inconsistencies are noticed in the data
    *   read from disk, the return value is a pointer to a "valid"
    *   (struct hfs_btree).  If there are errors reading from disk or
    *   inconsistencies are noticed in the data read from disk, then and
    *   all resources that were allocated are released and NULL is
    *   returned.  If the inputs are not what they claim to be or if they
    *   are unnoticed inconsistencies in the data read from disk then the
    *   returned hfs_btree is probably going to lead to errors when it is
    *   used in a non-trivial way.
    */
   struct hfs_btree * hfs_btree_init(struct hfs_mdb *mdb, ino_t cnid,
                                     hfs_byte_t ext[12],
                                     hfs_u32 tsize, hfs_u32 csize)
   {
           struct hfs_btree * bt;
           struct BTHdrRec * th;
           struct hfs_bnode * tmp;
           unsigned int next;
   #if defined(DEBUG_HEADER) || defined(DEBUG_ALL)
           unsigned char *p, *q;
   #endif
   
           if (!mdb || !ext || !HFS_NEW(bt)) {
                   goto bail3;
           }
   
           bt->magic = HFS_BTREE_MAGIC;
           bt->sys_mdb = mdb->sys_mdb;
           bt->reserved = 0;
           bt->lock = 0;
           hfs_init_waitqueue(&bt->wait);
           bt->dirt = 0;
           memset(bt->cache, 0, sizeof(bt->cache));
   
   #if 0   /* this is a fake entry. so we don't need to initialize it. */
           memset(&bt->entry, 0, sizeof(bt->entry));
           hfs_init_waitqueue(&bt->entry.wait);
           INIT_LIST_HEAD(&bt->entry.hash);
           INIT_LIST_HEAD(&bt->entry.list);
   #endif
   
           bt->entry.mdb = mdb;
           bt->entry.cnid = cnid;
           bt->entry.type = HFS_CDR_FIL;
           bt->entry.u.file.magic = HFS_FILE_MAGIC;
           bt->entry.u.file.clumpablks = (csize / mdb->alloc_blksz)
                                                   >> HFS_SECTOR_SIZE_BITS;
           bt->entry.u.file.data_fork.entry = &bt->entry;
           bt->entry.u.file.data_fork.lsize = tsize;
           bt->entry.u.file.data_fork.psize = tsize >> HFS_SECTOR_SIZE_BITS;
           bt->entry.u.file.data_fork.fork = HFS_FK_DATA;
           hfs_extent_in(&bt->entry.u.file.data_fork, ext);
   
           hfs_bnode_read(&bt->head, bt, 0, HFS_STICKY);
           if (!hfs_buffer_ok(bt->head.buf)) {
                   goto bail2;
           }
           th = (struct BTHdrRec *)((char *)hfs_buffer_data(bt->head.buf) +
                                                   sizeof(struct NodeDescriptor));
   
           /* read in the bitmap nodes (if any) */
           tmp = &bt->head;
           while ((next = tmp->ndFLink)) {
                   if (!HFS_NEW(tmp->next)) {
                           goto bail2;
                   }
                   hfs_bnode_read(tmp->next, bt, next, HFS_STICKY);
                   if (!hfs_buffer_ok(tmp->next->buf)) {
                           goto bail2;
                   }
                   tmp->next->prev = tmp;
                   tmp = tmp->next;
           }
   
           if (hfs_get_ns(th->bthNodeSize) != htons(HFS_SECTOR_SIZE)) {
                   hfs_warn("hfs_btree_init: bthNodeSize!=512 not supported\n");
                   goto bail2;
           }
   
           if (cnid == htonl(HFS_CAT_CNID)) {
                   bt->compare = (hfs_cmpfn)hfs_cat_compare;
           } else if (cnid == htonl(HFS_EXT_CNID)) {
                   bt->compare = (hfs_cmpfn)hfs_ext_compare;
           } else {
                   goto bail2;
           }
           bt->bthDepth  = hfs_get_hs(th->bthDepth);
           bt->bthRoot   = hfs_get_hl(th->bthRoot);
           bt->bthNRecs  = hfs_get_hl(th->bthNRecs);
           bt->bthFNode  = hfs_get_hl(th->bthFNode);
           bt->bthLNode  = hfs_get_hl(th->bthLNode);
           bt->bthNNodes = hfs_get_hl(th->bthNNodes);
           bt->bthFree   = hfs_get_hl(th->bthFree);
           bt->bthKeyLen = hfs_get_hs(th->bthKeyLen);
   
   #if defined(DEBUG_HEADER) || defined(DEBUG_ALL)
           hfs_warn("bthDepth %d\n", bt->bthDepth);
           hfs_warn("bthRoot %d\n", bt->bthRoot);
           hfs_warn("bthNRecs %d\n", bt->bthNRecs);
           hfs_warn("bthFNode %d\n", bt->bthFNode);
           hfs_warn("bthLNode %d\n", bt->bthLNode);
           hfs_warn("bthKeyLen %d\n", bt->bthKeyLen);
           hfs_warn("bthNNodes %d\n", bt->bthNNodes);
           hfs_warn("bthFree %d\n", bt->bthFree);
           p = (unsigned char *)hfs_buffer_data(bt->head.buf);
           q = p + HFS_SECTOR_SIZE;
           while (p < q) {
                   hfs_warn("%02x %02x %02x %02x %02x %02x %02x %02x "
                            "%02x %02x %02x %02x %02x %02x %02x %02x\n",
                            *p++, *p++, *p++, *p++, *p++, *p++, *p++, *p++,
                            *p++, *p++, *p++, *p++, *p++, *p++, *p++, *p++);
           }
   #endif
   
           /* Read in the root if it exists.
              The header always exists, but the root exists only if the
              tree is non-empty */
           if (bt->bthDepth && bt->bthRoot) {
                   if (!HFS_NEW(bt->root)) {
                           goto bail2;
                   }
                   hfs_bnode_read(bt->root, bt, bt->bthRoot, HFS_STICKY);
                   if (!hfs_buffer_ok(bt->root->buf)) {
                           goto bail1;
                   }
           } else {
                   bt->root = NULL;
           }
   
           return bt;
   
    bail1:
           hfs_bnode_ditch(bt->root);
    bail2:
           hfs_bnode_ditch(&bt->head);
           HFS_DELETE(bt);
    bail3:
           return NULL;
   }
   
   /*
    * hfs_btree_commit()
    *
    * Called to write a possibly dirty btree back to disk.
    */
   void hfs_btree_commit(struct hfs_btree *bt, hfs_byte_t ext[12], hfs_lword_t size)
   {
           if (bt->dirt) {
                   struct BTHdrRec *th;
                   th = (struct BTHdrRec *)((char *)hfs_buffer_data(bt->head.buf) +
                                                    sizeof(struct NodeDescriptor));
   
                   hfs_put_hs(bt->bthDepth,  th->bthDepth);
                   hfs_put_hl(bt->bthRoot,   th->bthRoot);
                   hfs_put_hl(bt->bthNRecs,  th->bthNRecs);
                   hfs_put_hl(bt->bthFNode,  th->bthFNode);
                   hfs_put_hl(bt->bthLNode,  th->bthLNode);
                   hfs_put_hl(bt->bthNNodes, th->bthNNodes);
                   hfs_put_hl(bt->bthFree,   th->bthFree);
                   hfs_buffer_dirty(bt->head.buf);
   
                   /*
                    * Commit the bnodes which are not cached.
                    * The map nodes don't need to be committed here because
                    * they are committed every time they are changed.
                    */
                   hfs_bnode_commit(&bt->head);
                   if (bt->root) {
                           hfs_bnode_commit(bt->root);
                   }
   
           
                   hfs_put_hl(bt->bthNNodes << HFS_SECTOR_SIZE_BITS, size);
                   hfs_extent_out(&bt->entry.u.file.data_fork, ext);
                   /* hfs_buffer_dirty(mdb->buf); (Done by caller) */
   
                   bt->dirt = 0;
           }
   }

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