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fs_reiserfs.c

/*
 *  fs_reiserfs.c - an implementation for the Reiser filesystem
 *
 *  Copyright (C) 2001 Jeffrey Mahoney (jeffm@suse.com)
 *
 *  Adapted from Grub
 *
 *  Copyright (C) 2000, 2001 Free Software Foundation, Inc.
 *
 *  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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include "types.h"
#include "ctype.h"
#include "string.h"
#include "stdlib.h"
#include "fs.h"
#include "errors.h"
#include "debug.h"
#include "reiserfs/reiserfs.h"

/* Exported in struct fs_t */
static int reiserfs_open( struct boot_file_t *file, const char *dev_name,
                    struct partition_t *part, const char *file_name );
static int reiserfs_read( struct boot_file_t *file, unsigned int size,

                    void *buffer );
static int reiserfs_seek( struct boot_file_t *file, unsigned int newpos );
static int reiserfs_close( struct boot_file_t *file );

struct fs_t reiserfs_filesystem = {
     name:"reiserfs",
     open:reiserfs_open,
     read:reiserfs_read,
     seek:reiserfs_seek,
     close:reiserfs_close
};

static int reiserfs_read_super( void );
static int reiserfs_open_file( char *dirname );
static int reiserfs_read_data( char *buf, __u32 len );


static struct reiserfs_state reiserfs;
static struct reiserfs_state *INFO = &reiserfs;

/* Adapted from GRUB: */
static char FSYS_BUF[FSYSREISER_CACHE_SIZE];
int errnum;


static int
reiserfs_open( struct boot_file_t *file, const char *dev_name,
               struct partition_t *part, const char *file_name )
{
     static char buffer[1024];

     DEBUG_ENTER;
     DEBUG_OPEN;

     memset( INFO, 0, sizeof(struct reiserfs_state) );
     INFO->file = file;

     if (part)
     {
        DEBUG_F( "Determining offset for partition %d\n", part->part_number );
        INFO->partition_offset = ((uint64_t)part->part_start) * part->blocksize;
        DEBUG_F( "%Lu = %lu * %hu\n", INFO->partition_offset,
               part->part_start,
               part->blocksize );
     }
     else
        INFO->partition_offset = 0;

     sprintf( buffer, "%s:%d", dev_name, 0 ); /* 0 is full disk in OF */
     file->of_device = prom_open( buffer );
     DEBUG_F( "Trying to open dev_name=%s; filename=%s; partition offset=%Lu\n",
            buffer, file_name, INFO->partition_offset );

     if ( file->of_device == PROM_INVALID_HANDLE || file->of_device == NULL )
     {
        DEBUG_F( "Can't open device %p\n", file->of_device );
        DEBUG_LEAVE(FILE_ERR_BADDEV);
        return FILE_ERR_BADDEV;
     }

     DEBUG_F("%p was successfully opened\n", file->of_device);

     if ( reiserfs_read_super() != 1 )
     {
        DEBUG_F( "Couldn't open ReiserFS @ %s/%Lu\n", buffer, INFO->partition_offset );
        prom_close( file->of_device );
        DEBUG_LEAVE(FILE_ERR_BAD_FSYS);
        return FILE_ERR_BAD_FSYS;
     }

     DEBUG_F( "Attempting to open %s\n", file_name );
     strcpy(buffer, file_name); /* reiserfs_open_file modifies argument */
     if (reiserfs_open_file(buffer) == 0)
     {
        DEBUG_F( "reiserfs_open_file failed. errnum = %d\n", errnum );
        prom_close( file->of_device );
        DEBUG_LEAVE_F(errnum);
        return errnum;
     }

     DEBUG_F( "Successfully opened %s\n", file_name );

     DEBUG_LEAVE(FILE_ERR_OK);
     DEBUG_SLEEP;
     return FILE_ERR_OK;
}

static int
reiserfs_read( struct boot_file_t *file, unsigned int size, void *buffer )
{
     return reiserfs_read_data( buffer, size );
}

static int
reiserfs_seek( struct boot_file_t *file, unsigned int newpos )
{
     file->pos = newpos;
     return FILE_ERR_OK;
}

static int
reiserfs_close( struct boot_file_t *file )
{
     if( file->of_device )
     {
        prom_close(file->of_device);
        file->of_device = 0;
        DEBUG_F("reiserfs_close called\n");
     }
     return FILE_ERR_OK;
}


static __inline__ __u32
log2( __u32 word )
{
     int i = 0;
     while( word && (word & (1 << ++i)) == 0 );
     return i;
}

static __inline__ int
is_power_of_two( unsigned long word )
{
     return ( word & -word ) == word;
}

static int
read_disk_block( struct boot_file_t *file, __u32 block, __u32 start,
                 __u32 length, void *buf )
{
     __u16 fs_blocksize = INFO->blocksize == 0 ? REISERFS_OLD_BLOCKSIZE
        : INFO->blocksize;
     unsigned long long pos = (unsigned long long)block * (unsigned long long)fs_blocksize;
     pos += (unsigned long long)INFO->partition_offset + (unsigned long long)start;
     DEBUG_F( "Reading %u bytes, starting at block %u, disk offset %Lu\n",
            length, block, pos );
     if (!prom_lseek( file->of_device, pos )) {
        DEBUG_F("prom_lseek failed\n");
        return 0;
     }
     return prom_read( file->of_device, buf, length );
}


static int
journal_read( __u32 block, __u32 len, char *buffer )
{
     return read_disk_block( INFO->file,
                       (INFO->journal_block + block), 0,
                       len, buffer );
}

/* Read a block from ReiserFS file system, taking the journal into
 * account.  If the block nr is in the journal, the block from the
 * journal taken.  
 */
static int
block_read( __u32 blockNr, __u32 start, __u32 len, char *buffer )
{
     __u32 transactions = INFO->journal_transactions;
     __u32 desc_block = INFO->journal_first_desc;
     __u32 journal_mask = INFO->journal_block_count - 1;
     __u32 translatedNr = blockNr;
     __u32 *journal_table = JOURNAL_START;

//    DEBUG_F( "block_read( %u, %u, %u, ..)\n", blockNr, start, len );

     while ( transactions-- > 0 )
     {
        int i = 0;
        int j_len;

        if ( *journal_table != 0xffffffff )
        {
             /* Search for the blockNr in cached journal */
             j_len = le32_to_cpu(*journal_table++);
             while ( i++ < j_len )
             {
                if ( le32_to_cpu(*journal_table++) == blockNr )
                {
                   journal_table += j_len - i;
                   goto found;
                }
             }
        }
        else
        {
             /* This is the end of cached journal marker.  The remaining
            * transactions are still on disk. */
             struct reiserfs_journal_desc desc;
             struct reiserfs_journal_commit commit;

             if ( !journal_read( desc_block, sizeof(desc), (char *) &desc ) )
                return 0;

             j_len = le32_to_cpu(desc.j_len);
             while ( i < j_len && i < JOURNAL_TRANS_HALF )
                if ( le32_to_cpu(desc.j_realblock[i++]) == blockNr )
                   goto found;

             if ( j_len >= JOURNAL_TRANS_HALF )
             {
                int commit_block = ( desc_block + 1 + j_len ) & journal_mask;

                if ( !journal_read( commit_block,
                              sizeof(commit), (char *) &commit ) )
                   return 0;

                while ( i < j_len )
                   if ( le32_to_cpu(commit.j_realblock[i++ - JOURNAL_TRANS_HALF]) == blockNr )
                        goto found;
             }
        }
        goto not_found;

     found:
        translatedNr =
             INFO->journal_block + ( ( desc_block + i ) & journal_mask );

        DEBUG_F( "block_read: block %u is mapped to journal block %u.\n",
               blockNr, translatedNr - INFO->journal_block );

        /* We must continue the search, as this block may be overwritten in 
         * later transactions. */
     not_found:
        desc_block = (desc_block + 2 + j_len) & journal_mask;
     }

     return read_disk_block( INFO->file, translatedNr, start, len, buffer );
}

/* Init the journal data structure.  We try to cache as much as
 * possible in the JOURNAL_START-JOURNAL_END space, but if it is full
 * we can still read the rest from the disk on demand.
 *
 * The first number of valid transactions and the descriptor block of the
 * first valid transaction are held in INFO.  The transactions are all 
 * adjacent, but we must take care of the journal wrap around. 
 */
static int
journal_init( void )
{
     struct reiserfs_journal_header header;
     struct reiserfs_journal_desc desc;
     struct reiserfs_journal_commit commit;
     __u32 block_count = INFO->journal_block_count;
     __u32 desc_block;
     __u32 commit_block;
     __u32 next_trans_id;
     __u32 *journal_table = JOURNAL_START;

     journal_read( block_count, sizeof ( header ), ( char * ) &header );
     desc_block = le32_to_cpu(header.j_first_unflushed_offset);
     if ( desc_block >= block_count )
        return 0;

     INFO->journal_transactions = 0;
     INFO->journal_first_desc = desc_block;
     next_trans_id = le32_to_cpu(header.j_last_flush_trans_id) + 1;

     DEBUG_F( "journal_init: last flushed %u\n", le32_to_cpu(header.j_last_flush_trans_id) );

     while ( 1 )
     {
        journal_read( desc_block, sizeof(desc), (char *) &desc );
        if ( strcmp( JOURNAL_DESC_MAGIC, desc.j_magic ) != 0
             || desc.j_trans_id != next_trans_id
             || desc.j_mount_id != header.j_mount_id )
             /* no more valid transactions */
             break;

        commit_block = ( desc_block + le32_to_cpu(desc.j_len) + 1 ) & ( block_count - 1 );
        journal_read( commit_block, sizeof(commit), (char *) &commit );
        if ( desc.j_trans_id != commit.j_trans_id
             || desc.j_len != commit.j_len )
             /* no more valid transactions */
             break;


        DEBUG_F( "Found valid transaction %u/%u at %u.\n",
               le32_to_cpu(desc.j_trans_id), le32_to_cpu(desc.j_mount_id),
               desc_block );


        next_trans_id++;
        if ( journal_table < JOURNAL_END )
        {
             if ( ( journal_table + 1 + le32_to_cpu(desc.j_len) ) >= JOURNAL_END )
             {
                /* The table is almost full; mark the end of the cached * *
                 * journal. */
                *journal_table = 0xffffffff;
                journal_table = JOURNAL_END;
             }
             else
             {
                int i;

                /* Cache the length and the realblock numbers in the table. * 
                 * The block number of descriptor can easily be computed. *
                 * and need not to be stored here. */
                *journal_table++ = desc.j_len;
                for ( i = 0; i < le32_to_cpu(desc.j_len) && i < JOURNAL_TRANS_HALF; i++ )
                {
                   *journal_table++ = desc.j_realblock[i];

                   DEBUG_F( "block %u is in journal %u.\n",
                          le32_to_cpu(desc.j_realblock[i]), desc_block );

                }
                for ( ; i < le32_to_cpu(desc.j_len); i++ )
                {
                   *journal_table++ =
                        commit.j_realblock[i - JOURNAL_TRANS_HALF];

                   DEBUG_F( "block %u is in journal %u.\n",
                          le32_to_cpu(commit.j_realblock[i - JOURNAL_TRANS_HALF]),
                          desc_block );

                }
             }
        }
        desc_block = (commit_block + 1) & (block_count - 1);
     }

     DEBUG_F( "Transaction %u/%u at %u isn't valid.\n",
            le32_to_cpu(desc.j_trans_id), le32_to_cpu(desc.j_mount_id),
            desc_block );


     INFO->journal_transactions
        = next_trans_id - le32_to_cpu(header.j_last_flush_trans_id) - 1;
     return (errnum == 0);
}

/* check filesystem types and read superblock into memory buffer */
static int
reiserfs_read_super( void )
{
     struct reiserfs_super_block super;
     __u64 superblock = REISERFS_SUPERBLOCK_BLOCK;

     if (read_disk_block(INFO->file, superblock, 0, sizeof(super), &super) != sizeof(super)) {
        DEBUG_F("read_disk_block failed!\n");
        return 0;
     }

     DEBUG_F( "Found super->magic: \"%s\"\n", super.s_magic );

     if( strcmp( REISER2FS_SUPER_MAGIC_STRING, super.s_magic ) != 0 &&
       strcmp( REISERFS_SUPER_MAGIC_STRING, super.s_magic ) != 0 )
     {
        /* Try old super block position */
        superblock = REISERFS_OLD_SUPERBLOCK_BLOCK;

        if (read_disk_block( INFO->file, superblock, 0, sizeof (super),  &super ) != sizeof(super)) {
             DEBUG_F("read_disk_block failed!\n");
             return 0;
        }

        if ( strcmp( REISER2FS_SUPER_MAGIC_STRING, super.s_magic ) != 0 &&
             strcmp( REISERFS_SUPER_MAGIC_STRING, super.s_magic ) != 0 )
        {
             /* pre journaling super block - untested */
             if ( strcmp( REISERFS_SUPER_MAGIC_STRING,
                      (char *) ((__u32) &super + 20 ) ) != 0 )
                return 0;

             super.s_blocksize = cpu_to_le16(REISERFS_OLD_BLOCKSIZE);
             super.s_journal_block = 0;
             super.s_version = 0;
        }
     }

     DEBUG_F( "ReiserFS superblock data:\n" );
     DEBUG_F( "Block count: %u\n", le32_to_cpu(super.s_block_count) )
        DEBUG_F( "Free blocks: %u\n", le32_to_cpu(super.s_free_blocks) );
     DEBUG_F( "Journal block: %u\n", le32_to_cpu(super.s_journal_block) );
     DEBUG_F( "Journal size (in blocks): %u\n",
            le32_to_cpu(super.s_orig_journal_size) );
     DEBUG_F( "Root block: %u\n\n", le32_to_cpu(super.s_root_block) );


     INFO->version = le16_to_cpu(super.s_version);
     INFO->blocksize = le16_to_cpu(super.s_blocksize);
     INFO->blocksize_shift = log2( INFO->blocksize );

     INFO->journal_block = le32_to_cpu(super.s_journal_block);
     INFO->journal_block_count = le32_to_cpu(super.s_orig_journal_size);

     INFO->cached_slots = (FSYSREISER_CACHE_SIZE >> INFO->blocksize_shift) - 1;

     /* At this point, we've found a valid superblock. If we run into problems
      * mounting the FS, the user should probably know. */

     /* A few sanity checks ... */
     if ( INFO->version > REISERFS_MAX_SUPPORTED_VERSION )
     {
        prom_printf( "ReiserFS: Unsupported version field: %u\n",
                   INFO->version );
        return 0;
     }

     if ( INFO->blocksize < FSYSREISER_MIN_BLOCKSIZE
        || INFO->blocksize > FSYSREISER_MAX_BLOCKSIZE )
     {
        prom_printf( "ReiserFS: Unsupported block size: %u\n",
                   INFO->blocksize );
        return 0;
     }

     /* Setup the journal.. */
     if ( INFO->journal_block != 0 )
     {
        if ( !is_power_of_two( INFO->journal_block_count ) )
        {
             prom_printf( "ReiserFS: Unsupported journal size, "
                      "not a power of 2: %u\n",
                      INFO->journal_block_count );
             return 0;
        }

        journal_init();
        /* Read in super block again, maybe it is in the journal */
        block_read( superblock, 0, sizeof (struct reiserfs_super_block),
                  (char *) &super );
     }

     /* Read in the root block */
     if ( !block_read( le32_to_cpu(super.s_root_block), 0,
                   INFO->blocksize, ROOT ) )
     {
        prom_printf( "ReiserFS: Failed to read in root block\n" );
        return 0;
     }

     /* The root node is always the "deepest", so we can
      determine the hieght of the tree using it. */
     INFO->tree_depth = blkh_level(BLOCKHEAD(ROOT));


     DEBUG_F( "root read_in: block=%u, depth=%u\n",
            le32_to_cpu(super.s_root_block), INFO->tree_depth );

     if ( INFO->tree_depth >= REISERFS_MAX_TREE_HEIGHT )
     {
        prom_printf( "ReiserFS: Unsupported tree depth (too deep): %u\n",
                   INFO->tree_depth );
        return 0;
     }

     if ( INFO->tree_depth == BLKH_LEVEL_LEAF )
     {
        /* There is only one node in the whole filesystem, which is
           simultanously leaf and root */
        memcpy( LEAF, ROOT, INFO->blocksize );
     }
     return 1;
}

/***************** TREE ACCESSING METHODS *****************************/

/* I assume you are familiar with the ReiserFS tree, if not go to
 * http://devlinux.com/projects/reiserfs/
 *
 * My tree node cache is organized as following
 *   0   ROOT node
 *   1   LEAF node  (if the ROOT is also a LEAF it is copied here
 *   2-n other nodes on current path from bottom to top.  
 *       if there is not enough space in the cache, the top most are
 *       omitted.
 *
 * I have only two methods to find a key in the tree:
 *   search_stat(dir_id, objectid) searches for the stat entry (always
 *       the first entry) of an object.
 *   next_key() gets the next key in tree order.
 *
 * This means, that I can only sequential reads of files are
 * efficient, but this really doesn't hurt for grub.  
 */

/* Read in the node at the current path and depth into the node cache.
 * You must set INFO->blocks[depth] before.
 */
static char *
read_tree_node( __u32 blockNr, __u16 depth )
{
     char *cache = CACHE(depth);
     int num_cached = INFO->cached_slots;
     errnum = 0;

     if ( depth < num_cached )
     {
        /* This is the cached part of the path.
           Check if same block is needed. */
        if ( blockNr == INFO->blocks[depth] )
             return cache;
     }
     else
        cache = CACHE(num_cached);

     DEBUG_F( "  next read_in: block=%u (depth=%u)\n", blockNr, depth );

     if ( !block_read( blockNr, 0, INFO->blocksize, cache ) )
     {
        DEBUG_F( "block_read failed\n" );
        return 0;
     }

     DEBUG_F( "FOUND: blk_level=%u, blk_nr_item=%u, blk_free_space=%u\n",
            blkh_level(BLOCKHEAD(cache)),
            blkh_nr_item(BLOCKHEAD(cache)),
            le16_to_cpu(BLOCKHEAD(cache)->blk_free_space) );

     /* Make sure it has the right node level */
     if ( blkh_level(BLOCKHEAD(cache)) != depth )
     {
        DEBUG_F( "depth = %u != %u\n", blkh_level(BLOCKHEAD(cache)), depth );
        DEBUG_LEAVE(FILE_ERR_BAD_FSYS);
        errnum = FILE_ERR_BAD_FSYS;
        return 0;
     }

     INFO->blocks[depth] = blockNr;
     return cache;
}

/* Get the next key, i.e. the key following the last retrieved key in
 * tree order.  INFO->current_ih and 
 * INFO->current_info are adapted accordingly.  */
static int
next_key( void )
{
     __u16 depth;
     struct item_head *ih = INFO->current_ih + 1;
     char *cache;


     DEBUG_F( "next_key:\n  old ih: key %u:%u:%u:%u version:%u\n",
            le32_to_cpu(INFO->current_ih->ih_key.k_dir_id),
            le32_to_cpu(INFO->current_ih->ih_key.k_objectid),
            le32_to_cpu(INFO->current_ih->ih_key.u.k_offset_v1.k_offset),
            le32_to_cpu(INFO->current_ih->ih_key.u.k_offset_v1.k_uniqueness),
            ih_version(INFO->current_ih) );


     if ( ih == &ITEMHEAD[blkh_nr_item(BLOCKHEAD( LEAF ))] )
     {
        depth = BLKH_LEVEL_LEAF;
        /* The last item, was the last in the leaf node. * Read in the next
         * * block */
        do
        {
             if ( depth == INFO->tree_depth )
             {
                /* There are no more keys at all. * Return a dummy item with
                 * * MAX_KEY */
                ih =
                   ( struct item_head * )
                   &BLOCKHEAD( LEAF )->blk_right_delim_key;
                goto found;
             }
             depth++;

             DEBUG_F( "  depth=%u, i=%u\n", depth, INFO->next_key_nr[depth] );

        }
        while ( INFO->next_key_nr[depth] == 0 );

        if ( depth == INFO->tree_depth )
             cache = ROOT;
        else if ( depth <= INFO->cached_slots )
             cache = CACHE( depth );
        else
        {
             cache = read_tree_node( INFO->blocks[depth], --depth );
             if ( !cache )
                return 0;
        }

        do
        {
             __u16 nr_item = blkh_nr_item(BLOCKHEAD( cache ));
             int key_nr = INFO->next_key_nr[depth]++;


             DEBUG_F( "  depth=%u, i=%u/%u\n", depth, key_nr, nr_item );

             if ( key_nr == nr_item )
                /* This is the last item in this block, set the next_key_nr * 
                 * to 0 */
                INFO->next_key_nr[depth] = 0;

             cache =
                read_tree_node( dc_block_number( &(DC( cache )[key_nr])),
                            --depth );
             if ( !cache )
                return 0;
        }
        while ( depth > BLKH_LEVEL_LEAF );

        ih = ITEMHEAD;
     }
found:
     INFO->current_ih = ih;
     INFO->current_item = &LEAF[ih_location(ih)];

     DEBUG_F( "  new ih: key %u:%u:%u:%u version:%u\n",
            le32_to_cpu(INFO->current_ih->ih_key.k_dir_id),
            le32_to_cpu(INFO->current_ih->ih_key.k_objectid),
            le32_to_cpu(INFO->current_ih->ih_key.u.k_offset_v1.k_offset),
            le32_to_cpu(INFO->current_ih->ih_key.u.k_offset_v1.k_uniqueness),
            ih_version(INFO->current_ih) );

     return 1;
}

/* preconditions: reiserfs_read_super already executed, therefore 
 *   INFO block is valid
 * returns: 0 if error (errnum is set), 
 *   nonzero iff we were able to find the key successfully.
 * postconditions: on a nonzero return, the current_ih and 
 *   current_item fields describe the key that equals the
 *   searched key.  INFO->next_key contains the next key after
 *   the searched key.
 * side effects: messes around with the cache.
 */
static int
search_stat( __u32 dir_id, __u32 objectid )
{
     char *cache;
     int depth;
     int nr_item;
     int i;
     struct item_head *ih;
     errnum = 0;

     DEBUG_F( "search_stat:\n  key %u:%u:0:0\n", le32_to_cpu(dir_id),
            le32_to_cpu(objectid) );


     depth = INFO->tree_depth;
     cache = ROOT;

     DEBUG_F( "depth = %d\n", depth );
     while ( depth > BLKH_LEVEL_LEAF )
     {
        struct key *key;

        nr_item = blkh_nr_item(BLOCKHEAD( cache ));

        key = KEY( cache );

        for ( i = 0; i < nr_item; i++ )
        {
             if (le32_to_cpu(key->k_dir_id) > le32_to_cpu(dir_id)
               || (key->k_dir_id == dir_id
                   && (le32_to_cpu(key->k_objectid) > le32_to_cpu(objectid)
                     || (key->k_objectid == objectid
                         && (key->u.k_offset_v1.k_offset
                           | key->u.k_offset_v1.k_uniqueness) > 0))))
                break;
             key++;
        }


        DEBUG_F( "  depth=%d, i=%d/%d\n", depth, i, nr_item );

        INFO->next_key_nr[depth] = ( i == nr_item ) ? 0 : i + 1;
        cache = read_tree_node( dc_block_number(&(DC(cache)[i])), --depth );
        if ( !cache )
             return 0;
     }

     /* cache == LEAF */
     nr_item = blkh_nr_item(BLOCKHEAD(LEAF));
     ih = ITEMHEAD;
     DEBUG_F( "nr_item = %d\n", nr_item );
     for ( i = 0; i < nr_item; i++ )
     {
        if ( ih->ih_key.k_dir_id == dir_id
             && ih->ih_key.k_objectid == objectid
             && ih->ih_key.u.k_offset_v1.k_offset == 0
             && ih->ih_key.u.k_offset_v1.k_uniqueness == 0 )
        {

             DEBUG_F( "  depth=%d, i=%d/%d\n", depth, i, nr_item );

             INFO->current_ih = ih;
             INFO->current_item = &LEAF[ih_location(ih)];

             return 1;
        }

        ih++;
     }

     DEBUG_LEAVE(FILE_ERR_BAD_FSYS);
     errnum = FILE_ERR_BAD_FSYS;
     return 0;
}

static int
reiserfs_read_data( char *buf, __u32 len )
{
     __u32 blocksize;
     __u32 offset;
     __u32 to_read;
     char *prev_buf = buf;
     errnum = 0;

     DEBUG_F( "reiserfs_read_data: INFO->file->pos=%Lu len=%u, offset=%Lu\n",
            INFO->file->pos, len, (__u64) IH_KEY_OFFSET(INFO->current_ih) - 1 );


     if ( INFO->current_ih->ih_key.k_objectid != INFO->fileinfo.k_objectid
        || IH_KEY_OFFSET( INFO->current_ih ) > INFO->file->pos + 1 )
     {
        search_stat( INFO->fileinfo.k_dir_id, INFO->fileinfo.k_objectid );
        goto get_next_key;
     }

     while ( errnum == 0 )
     {
        if ( INFO->current_ih->ih_key.k_objectid != INFO->fileinfo.k_objectid )
             break;

        offset = INFO->file->pos - IH_KEY_OFFSET( INFO->current_ih ) + 1;
        blocksize = ih_item_len(INFO->current_ih);


        DEBUG_F( "  loop: INFO->file->pos=%Lu len=%u, offset=%u blocksize=%u\n",
               INFO->file->pos, len, offset, blocksize );


        if ( IH_KEY_ISTYPE( INFO->current_ih, TYPE_DIRECT )
             && offset < blocksize )
        {
             to_read = blocksize - offset;
             if ( to_read > len )
                to_read = len;

             memcpy( buf, INFO->current_item + offset, to_read );
             goto update_buf_len;
        }
        else if ( IH_KEY_ISTYPE( INFO->current_ih, TYPE_INDIRECT ) )
        {
             blocksize = ( blocksize >> 2 ) << INFO->blocksize_shift;

             while ( offset < blocksize )
             {
                __u32 blocknr = le32_to_cpu(((__u32 *)
                                     INFO->current_item)[offset >> INFO->blocksize_shift]);

                int blk_offset = offset & (INFO->blocksize - 1);

                to_read = INFO->blocksize - blk_offset;
                if ( to_read > len )
                   to_read = len;

                /* Journal is only for meta data.
                   Data blocks can be read directly without using block_read */
                read_disk_block( INFO->file, blocknr, blk_offset, to_read,
                             buf );

             update_buf_len:
                len -= to_read;
                buf += to_read;
                offset += to_read;
                INFO->file->pos += to_read;
                if ( len == 0 )
                   goto done;
             }
        }
     get_next_key:
        next_key();
     }
done:
     return (errnum != 0) ? 0 : buf - prev_buf;
}


/* preconditions: reiserfs_read_super already executed, therefore 
 *   INFO block is valid
 * returns: 0 if error, nonzero iff we were able to find the file successfully
 * postconditions: on a nonzero return, INFO->fileinfo contains the info
 *   of the file we were trying to look up, filepos is 0 and filemax is 
 *   the size of the file.
 */
static int
reiserfs_open_file( char *dirname )
{
     struct reiserfs_de_head *de_head;
     char *rest, ch;
     __u32 dir_id, objectid, parent_dir_id = 0, parent_objectid = 0;

     char linkbuf[PATH_MAX];  /* buffer for following symbolic links */
     int link_count = 0;
     int mode;
     errnum = 0;

     dir_id = cpu_to_le32(REISERFS_ROOT_PARENT_OBJECTID);
     objectid = cpu_to_le32(REISERFS_ROOT_OBJECTID);

     while ( 1 )
     {

        DEBUG_F( "dirname=%s\n", dirname );

        /* Search for the stat info first. */
        if ( !search_stat( dir_id, objectid ) )
             return 0;


        DEBUG_F( "sd_mode=0%o sd_size=%Lu\n",
               sd_mode((struct stat_data *) INFO->current_item ),
               sd_size(INFO->current_ih, INFO->current_item ));


        mode = sd_mode((struct stat_data *)INFO->current_item);

        /* If we've got a symbolic link, then chase it. */
        if ( S_ISLNK( mode ) )
        {
             int len = 0;

             DEBUG_F("link count = %d\n", link_count);
             DEBUG_SLEEP;
             if ( ++link_count > MAX_LINK_COUNT )
             {
                DEBUG_F("Symlink loop\n");
                errnum = FILE_ERR_SYMLINK_LOOP;
                return 0;
             }

             /* Get the symlink size. */
             INFO->file->len = sd_size(INFO->current_ih, INFO->current_item);

             /* Find out how long our remaining name is. */
             while ( dirname[len] && !isspace( dirname[len] ) )
                len++;

             if ( INFO->file->len + len > sizeof ( linkbuf ) - 1 )
             {
                errnum = FILE_ERR_LENGTH;
                return 0;
             }

             /* Copy the remaining name to the end of the symlink data. Note * 
            * that DIRNAME and LINKBUF may overlap! */
             memmove( linkbuf + INFO->file->len, dirname, len + 1 );

             INFO->fileinfo.k_dir_id = dir_id;
             INFO->fileinfo.k_objectid = objectid;
             INFO->file->pos = 0;
             if ( !next_key()
                || reiserfs_read_data( linkbuf, INFO->file->len ) != INFO->file->len ) {
                DEBUG_F("reiserfs_open_file - if !next_key || reiserfs_read_data\n");
                DEBUG_SLEEP;
                errnum = FILE_IOERR;
                return 0;
             }


             DEBUG_F( "symlink=%s\n", linkbuf );
             DEBUG_SLEEP;

             dirname = linkbuf;
             if ( *dirname == '/' )
             {
                /* It's an absolute link, so look it up in root. */
                dir_id = cpu_to_le32(REISERFS_ROOT_PARENT_OBJECTID);
                objectid = cpu_to_le32(REISERFS_ROOT_OBJECTID);
             }
             else
             {
                /* Relative, so look it up in our parent directory. */
                dir_id = parent_dir_id;
                objectid = parent_objectid;
             }

             /* Now lookup the new name. */
             continue;
        }

        /* if we have a real file (and we're not just printing *
         * possibilities), then this is where we want to exit */

        if ( !*dirname || isspace( *dirname ) )
        {
             if ( !S_ISREG( mode ) )
             {
                errnum = FILE_ERR_BAD_TYPE;
                return 0;
             }

             INFO->file->pos = 0;
             INFO->file->len = sd_size(INFO->current_ih, INFO->current_item);

             INFO->fileinfo.k_dir_id = dir_id;
             INFO->fileinfo.k_objectid = objectid;
             return next_key();
        }

        /* continue with the file/directory name interpretation */
        while ( *dirname == '/' )
             dirname++;
        if ( !S_ISDIR( mode ) )
        {
             errnum = FILE_ERR_NOTDIR;
             return 0;
        }
        for ( rest = dirname; ( ch = *rest ) && !isspace( ch ) && ch != '/';
            rest++ ) ;
        *rest = 0;

        while ( 1 )
        {
             char *name_end;
             int num_entries;

             if ( !next_key() )
                return 0;

             if ( INFO->current_ih->ih_key.k_objectid != objectid )
                break;

             name_end = INFO->current_item + ih_item_len(INFO->current_ih);
             de_head = ( struct reiserfs_de_head * ) INFO->current_item;
             num_entries = ih_entry_count(INFO->current_ih);
             while ( num_entries > 0 )
             {
                char *filename = INFO->current_item + deh_location(de_head);
                char tmp = *name_end;

                if( deh_state(de_head) & (1 << DEH_Visible))
                {
                   int cmp;

                   /* Directory names in ReiserFS are not null * terminated. 
                    * We write a temporary 0 behind it. * NOTE: that this
                    * may overwrite the first block in * the tree cache.
                    * That doesn't hurt as long as we * don't call next_key
                    * () in between. */
                   *name_end = 0;
                   cmp = strcmp( dirname, filename );
                   *name_end = tmp;
                   if ( cmp == 0 )
                        goto found;
                }
                /* The beginning of this name marks the end of the next name. 
                 */
                name_end = filename;
                de_head++;
                num_entries--;
             }
        }

        errnum = FILE_ERR_NOTFOUND;
        *rest = ch;
        return 0;

     found:
        *rest = ch;
        dirname = rest;

        parent_dir_id = dir_id;
        parent_objectid = objectid;
        dir_id = de_head->deh_dir_id; /* LE */
        objectid = de_head->deh_objectid; /* LE */
     }
}



#ifndef __LITTLE_ENDIAN
typedef union {
     struct offset_v2 offset_v2;
     __u64 linear;
} offset_v2_esafe_overlay;

inline __u16
offset_v2_k_type( struct offset_v2 *v2 )
{
     offset_v2_esafe_overlay tmp = *(offset_v2_esafe_overlay *)v2;
     tmp.linear = le64_to_cpu( tmp.linear );
     return tmp.offset_v2.k_type;
}
 
inline loff_t
offset_v2_k_offset( struct offset_v2 *v2 )
{
     offset_v2_esafe_overlay tmp = *(offset_v2_esafe_overlay *)v2;
     tmp.linear = le64_to_cpu( tmp.linear );
     return tmp.offset_v2.k_offset;
}
#endif

inline int
uniqueness2type (__u32 uniqueness)
{
     switch (uniqueness) {
     case V1_SD_UNIQUENESS: return TYPE_STAT_DATA;
     case V1_INDIRECT_UNIQUENESS: return TYPE_INDIRECT;
     case V1_DIRECT_UNIQUENESS: return TYPE_DIRECT;
     case V1_DIRENTRY_UNIQUENESS: return TYPE_DIRENTRY;
     }
     return TYPE_ANY;
}

/* 
 * Local variables:
 * c-file-style: "k&r"
 * c-basic-offset: 5
 * End:
 */

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