grub/fs/jfs.c

/* jfs.c - JFS.  */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2004, 2005  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <grub/err.h>
#include <grub/file.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/disk.h>
#include <grub/dl.h>
#include <grub/types.h>

#define GRUB_JFS_MAX_SYMLNK_CNT	8
#define GRUB_JFS_FILETYPE_MASK	0170000
#define GRUB_JFS_FILETYPE_REG	0100000
#define GRUB_JFS_FILETYPE_LNK	0120000
#define GRUB_JFS_FILETYPE_DIR	0040000

#define GRUB_JFS_SBLOCK		64
#define GRUB_JFS_AGGR_INODE	2
#define GRUB_JFS_FS1_INODE_BLK	104

#define GRUB_JFS_TREE_LEAF	2

struct grub_jfs_sblock
{
  /* The magic for JFS.  It should contain the string "JFS1".  */
  grub_uint8_t magic[4];
  grub_uint32_t version;
  grub_uint64_t ag_size;
  
  /* The size of a filesystem block in bytes.  XXX: currently only
     4096 was tested.  */
  grub_uint32_t blksz;
  grub_uint16_t log2_blksz;
  
  grub_uint8_t unused[71];
  grub_uint8_t volname[11];  
};

struct grub_jfs_extent
{
  /* The length of the extent in filesystem blocks.  */
  grub_uint16_t length;
  grub_uint8_t length2;
  
  /* The physical offset of the first block on the disk.  */
  grub_uint8_t blk1;
  grub_uint32_t blk2;
} __attribute__ ((packed));

struct grub_jfs_iag
{
  grub_uint8_t unused[3072];
  struct grub_jfs_extent inodes[128];
} __attribute__ ((packed));


/* The head of the tree used to find extents.  */
struct grub_jfs_treehead
{
  grub_uint64_t next;
  grub_uint64_t prev;
  
  grub_uint8_t flags; 
  grub_uint8_t unused;
  
  grub_uint16_t count;
  grub_uint16_t max;
  grub_uint8_t unused2[10];
} __attribute__ ((packed));

/* A node in the extent tree.  */
struct grub_jfs_tree_extent
{
  grub_uint8_t flags;
  grub_uint16_t unused;

  /* The offset is the key used to lookup an extent.  */
  grub_uint8_t offset1;
  grub_uint32_t offset2;
  
  struct grub_jfs_extent extent;
} __attribute__ ((packed));

/* The tree of directory entries.  */
struct grub_jfs_tree_dir
{
  /* Pointers to the previous and next tree headers of other nodes on
     this level.  */
  grub_uint64_t nextb;
  grub_uint64_t prevb;
  
  grub_uint8_t flags;
  
  /* The amount of dirents in this node.  */
  grub_uint8_t count;
  grub_uint8_t freecnt;
  grub_uint8_t freelist;
  grub_uint8_t maxslot;
  
  /* The location of the sorted array of pointers to dirents.  */
  grub_uint8_t sindex;
  grub_uint8_t unused[10];
} __attribute__ ((packed));

/* An internal node in the dirents tree.  */
struct grub_jfs_internal_dirent
{
  struct grub_jfs_extent ex;
  grub_uint8_t next;
  grub_uint8_t len;
  grub_uint16_t namepart[11];
} __attribute__ ((packed));

/* A leaf node in the dirents tree.  */
struct grub_jfs_leaf_dirent
{
  /* The inode for this dirent.  */
  grub_uint32_t inode;
  grub_uint8_t next;

  /* The size of the name.  */
  grub_uint8_t len;
  grub_uint16_t namepart[11];
  grub_uint32_t index;
} __attribute__ ((packed));

/* A leaf in the dirents tree.  This one is used if the previously
   dirent was not big enough to store the name.  */
struct grub_jfs_leaf_next_dirent
{
  grub_uint8_t next;
  grub_uint8_t len;
  grub_uint16_t namepart[15];
} __attribute__ ((packed));

struct grub_jfs_inode
{
  grub_uint32_t stamp;
  grub_uint32_t fileset;
  grub_uint32_t inode;
  grub_uint8_t unused[12];
  grub_uint64_t size;
  grub_uint8_t unused2[20];
  grub_uint32_t mode;
  grub_uint8_t unused3[72];
  grub_uint8_t unused4[96];
  
  union
  {
    /* The tree describing the extents of the file.  */
    struct
    {
      struct grub_jfs_treehead tree;
      struct grub_jfs_tree_extent extents[16];
    } file __attribute__ ((packed));
    union
    {
      /* The tree describing the dirents.  */
      struct
      {
	grub_uint8_t unused[16];
	grub_uint8_t flags;
	
	/* Amount of dirents in this node.  */
	grub_uint8_t count;
	grub_uint8_t freecnt;
	grub_uint8_t freelist;
	grub_uint32_t idotdot;
	grub_uint8_t sorted[8];
      } header;
      struct grub_jfs_leaf_dirent dirents[8];
    } dir __attribute__ ((packed));
    /* Fast symlink.  */
    struct
    {
      grub_uint8_t unused[32];
      grub_uint8_t path[128];
    } symlink;
  } __attribute__ ((packed));
} __attribute__ ((packed));

struct grub_jfs_data
{
  struct grub_jfs_sblock sblock;
  grub_disk_t disk;
  struct grub_jfs_inode fileset;
  struct grub_jfs_inode currinode;
  int pos;
  int linknest;
} __attribute__ ((packed));

struct grub_jfs_diropen
{
  int index;
  union
  {
    struct grub_jfs_tree_dir header;
    struct grub_jfs_leaf_dirent dirent[0];
    struct grub_jfs_leaf_next_dirent next_dirent[0];
    char sorted[0];
  } *dirpage __attribute__ ((packed));
  struct grub_jfs_data *data;
  struct grub_jfs_inode *inode;
  int count;
  char *sorted;
  struct grub_jfs_leaf_dirent *leaf;
  struct grub_jfs_leaf_next_dirent *next_leaf;
  
  /* The filename and inode of the last read dirent.  */
  char name[255];
  grub_uint32_t ino;
} __attribute__ ((packed));


#ifndef GRUB_UTIL
static grub_dl_t my_mod;
#endif

static grub_err_t grub_jfs_lookup_symlink (struct grub_jfs_data *data, int ino);

/* Get the block number for the block BLK in the node INODE in the
   mounted filesystem DATA.  */
static int
grub_jfs_blkno (struct grub_jfs_data *data, struct grub_jfs_inode *inode,
		unsigned int blk)
{
  auto int getblk (struct grub_jfs_treehead *treehead,
		   struct grub_jfs_tree_extent *extents);
  
  int getblk (struct grub_jfs_treehead *treehead,
	      struct grub_jfs_tree_extent *extents)
    {
      int found = -1;
      int i;
      
      for (i = 0; i < grub_le_to_cpu16 (treehead->count) - 2; i++)
	{
	  if (treehead->flags & GRUB_JFS_TREE_LEAF)
	    {
	      /* Read the leafnode.  */
	      if (grub_le_to_cpu32 (extents[i].offset2) <= blk 
		  && ((grub_le_to_cpu16 (extents[i].extent.length))
		      + (extents[i].extent.length2 << 8)
		      + grub_le_to_cpu32 (extents[i].offset2)) > blk)
		return (blk - grub_le_to_cpu32 (extents[i].offset2)
			+ grub_le_to_cpu32 (extents[i].extent.blk2));
	    }
	  else
	    if (blk >= grub_le_to_cpu32 (extents[i].offset2))
	      found = i;
	}
      
      if (found != -1)
	{
	  struct
	  {
	    struct grub_jfs_treehead treehead;
	    struct grub_jfs_tree_extent extents[254];
	  } tree;
	  	  
	  if (grub_disk_read (data->disk,
			      grub_le_to_cpu32 (extents[found].extent.blk2)
			      << (grub_le_to_cpu16 (data->sblock.log2_blksz)
				  - GRUB_DISK_SECTOR_BITS), 0,
			      sizeof (tree), (char *) &tree))
	    return -1;
	  
	  return getblk (&tree.treehead, &tree.extents[0]);
	}
      
      return -1;
    }
  
  return getblk (&inode->file.tree, &inode->file.extents[0]);
}


static grub_err_t
grub_jfs_read_inode (struct grub_jfs_data *data, int ino,
		     struct grub_jfs_inode *inode)
{
  struct grub_jfs_iag iag;
  int iagnum = ino / 4096;
  int inoext = (ino % 4096) / 32;
  int inonum = (ino % 4096) % 32;
  grub_uint32_t iagblk;
  grub_uint32_t inoblk;

  iagblk = grub_jfs_blkno (data, &data->fileset, iagnum + 1);
  if (grub_errno)
    return grub_errno;

  /* Read in the IAG.  */
  if (grub_disk_read (data->disk,
		      iagblk << (grub_le_to_cpu16 (data->sblock.log2_blksz)
				 - GRUB_DISK_SECTOR_BITS), 0,
		      sizeof (struct grub_jfs_iag), (char *) &iag))
    return grub_errno;
  
  inoblk = grub_le_to_cpu32 (iag.inodes[inoext].blk2);
  inoblk <<= (grub_le_to_cpu16 (data->sblock.log2_blksz)
	      - GRUB_DISK_SECTOR_BITS);
  inoblk += inonum;
  
  if (grub_disk_read (data->disk, inoblk, 0,
		      sizeof (struct grub_jfs_inode), (char *) inode))
    return grub_errno;

  return 0;
}


static struct grub_jfs_data *
grub_jfs_mount (grub_disk_t disk)
{
  struct grub_jfs_data *data = 0;

  data = grub_malloc (sizeof (struct grub_jfs_data));
  if (!data)
    return 0;

  /* Read the superblock.  */
  if (grub_disk_read (disk, GRUB_JFS_SBLOCK, 0,
		      sizeof (struct grub_jfs_sblock), (char *) &data->sblock))
    goto fail;
  
  if (grub_strncmp (data->sblock.magic, "JFS1", 4))
    {
      grub_error (GRUB_ERR_BAD_FS, "not a jfs filesystem");
      goto fail;
    }
  
  data->disk = disk;
  data->pos = 0;
  data->linknest = 0;

  /* Read the inode of the first fileset.  */
  if (grub_disk_read (data->disk, GRUB_JFS_FS1_INODE_BLK, 0,
		      sizeof (struct grub_jfs_inode), (char *) &data->fileset))
    goto fail;
  
  return data;
  
 fail:
  grub_free (data);
  
  if (grub_errno == GRUB_ERR_OUT_OF_RANGE)
    grub_error (GRUB_ERR_BAD_FS, "not a jfs filesystem");
  
  return 0;
}


static struct grub_jfs_diropen *
grub_jfs_opendir (struct grub_jfs_data *data, struct grub_jfs_inode *inode)
{
  struct grub_jfs_internal_dirent *de;
  struct grub_jfs_diropen *diro;
  int blk;
  
  de = (struct grub_jfs_internal_dirent *) inode->dir.dirents;
  
  if (!((grub_le_to_cpu32 (inode->mode)
	 & GRUB_JFS_FILETYPE_MASK) == GRUB_JFS_FILETYPE_DIR))
    {
      grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a directory");
      return 0;
    }
  
  diro = grub_malloc (sizeof (struct grub_jfs_diropen));
  if (!diro)
    return 0;
  
  diro->index = 0;
  diro->data = data;
  diro->inode = inode;

  /* Check if the entire tree is contained within the inode.  */
  if (inode->file.tree.flags & GRUB_JFS_TREE_LEAF)
    {
      diro->leaf = inode->dir.dirents;
      diro->next_leaf = (struct grub_jfs_leaf_next_dirent *) de;
      diro->sorted = inode->dir.header.sorted;
      diro->count = inode->dir.header.count;
      diro->dirpage = 0;

      return diro;
    }

  diro->dirpage = grub_malloc (grub_le_to_cpu32 (data->sblock.blksz));
  if (!diro->dirpage)
    {
      grub_free (diro);
      return 0;
    }
  
  blk = grub_le_to_cpu32 (de[inode->dir.header.sorted[0]].ex.blk2);
  blk <<= (grub_le_to_cpu16 (data->sblock.log2_blksz) - GRUB_DISK_SECTOR_BITS);
  
  /* Read in the nodes until we are on the leaf node level.  */
  do
    {
      int index;
      if (grub_disk_read (data->disk, blk, 0,
			  grub_le_to_cpu32 (data->sblock.blksz),
			  diro->dirpage->sorted))
	{
	  grub_free (diro->dirpage);
	  grub_free (diro);
	  return 0;
	}

      de = (struct grub_jfs_internal_dirent *) diro->dirpage->dirent;
      index = diro->dirpage->sorted[diro->dirpage->header.sindex * 32];
      blk = (grub_le_to_cpu32 (de[index].ex.blk2)
	     << (grub_le_to_cpu16 (data->sblock.log2_blksz)
		 - GRUB_DISK_SECTOR_BITS));
    } while (!(diro->dirpage->header.flags & GRUB_JFS_TREE_LEAF));

  diro->leaf = diro->dirpage->dirent;
  diro->next_leaf = diro->dirpage->next_dirent;
  diro->sorted = &diro->dirpage->sorted[diro->dirpage->header.sindex * 32];
  diro->count = diro->dirpage->header.count;
  
  return diro;
}


static void
grub_jfs_closedir (struct grub_jfs_diropen *diro)
{
  if (!diro)
    return;
  grub_free (diro->dirpage);
  grub_free (diro);
}


/* Read in the next dirent from the directory described by DIRO.  */
static grub_err_t
grub_jfs_getent (struct grub_jfs_diropen *diro)
{
  int strpos = 0;
  struct grub_jfs_leaf_dirent *leaf;
  struct grub_jfs_leaf_next_dirent *next_leaf;
  int len;
  int nextent;
  grub_uint16_t filename[255];
  
  auto void addstr (grub_uint16_t *uname, int ulen);
  
  /* Add the unicode string to the utf16 filename buffer.  */
  void addstr (grub_uint16_t *name, int ulen)
    {
      while (ulen--)
	filename[strpos++] = *(name++);
    }
  
  /* The last node, read in more.  */
  if (diro->index == diro->count)
    {
      unsigned int next;
      
      /* If the inode contains the entrie tree or if this was the last
	 node, there is nothing to read.  */
      if ((diro->inode->file.tree.flags & GRUB_JFS_TREE_LEAF)
	  || !grub_le_to_cpu64 (diro->dirpage->header.nextb))
	return GRUB_ERR_OUT_OF_RANGE;
      
      next = grub_le_to_cpu64 (diro->dirpage->header.nextb);
      next <<= (grub_le_to_cpu16 (diro->data->sblock.log2_blksz)
		- GRUB_DISK_SECTOR_BITS);
      
      if (grub_disk_read (diro->data->disk, next, 0,
			  grub_le_to_cpu32 (diro->data->sblock.blksz),
			  diro->dirpage->sorted))
	return grub_errno;

      diro->leaf = diro->dirpage->dirent;
      diro->next_leaf = diro->dirpage->next_dirent;
      diro->sorted = &diro->dirpage->sorted[diro->dirpage->header.sindex * 32];
      diro->count = diro->dirpage->header.count;
      diro->index = 0;
    }

  leaf = &diro->leaf[(int) diro->sorted[diro->index]];
  next_leaf = &diro->next_leaf[diro->index];
  
  len = leaf->len;
  if (!len)
    {
      diro->index++;
      return grub_jfs_getent (diro);
    }
  
  addstr (leaf->namepart, len < 11 ? len : 11);
  diro->ino = grub_le_to_cpu32 (leaf->inode);
  len -= 11;
  
  /* Move down to the leaf level.  */
  nextent = leaf->next;
  if (leaf->next != 255)
    do
      {
 	next_leaf = &diro->next_leaf[nextent];
	addstr (next_leaf->namepart, len < 15 ? len : 15 );
	
	len -= 15;
	nextent = next_leaf->next;
      } while (next_leaf->next != 255 && len > 0);

  diro->index++;

  /* Convert the temporary UTF16 filename to UTF8.  */
  *grub_utf16_to_utf8 (diro->name, filename, strpos) = '\0';
  
  return 0;
}


/* Read LEN bytes from the file described by DATA starting with byte
   POS.  Return the amount of read bytes in READ.  */
static grub_ssize_t
grub_jfs_read_file (struct grub_jfs_data *data,
		    void (*read_hook) (unsigned long sector,
				       unsigned offset, unsigned length),
		    int pos, unsigned int len, char *buf)
{
  int i;
  int blockcnt;

  /* Adjust len so it we can't read past the end of the file.  */
  if (len > data->currinode.size)
    len = data->currinode.size;

  blockcnt = ((len + pos + grub_le_to_cpu32 (data->sblock.blksz) - 1)
	      / grub_le_to_cpu32 (data->sblock.blksz));
  
  for (i = pos / grub_le_to_cpu32 (data->sblock.blksz); i < blockcnt; i++)
    {
      int blknr;
      int blockoff = pos % grub_le_to_cpu32 (data->sblock.blksz);
      int blockend = grub_le_to_cpu32 (data->sblock.blksz);
      
      int skipfirst = 0;
      
      blknr = grub_jfs_blkno (data, &data->currinode, i);
      if (grub_errno)
	return -1;

      /* Last block.  */
      if (i == blockcnt - 1)
	{
	  blockend = (len + pos) % grub_le_to_cpu32 (data->sblock.blksz);
	  
	  if (!blockend)
	    blockend = grub_le_to_cpu32 (data->sblock.blksz);
	}
      
      /* First block.  */
      if (i == (pos / (int) grub_le_to_cpu32 (data->sblock.blksz)))
	{
	  skipfirst = blockoff;
	  blockend -= skipfirst;
	}
      
      data->disk->read_hook = read_hook;
      grub_disk_read (data->disk,
		      blknr << (grub_le_to_cpu16 (data->sblock.log2_blksz)
				- GRUB_DISK_SECTOR_BITS),
		      skipfirst, blockend, buf);
      
      data->disk->read_hook = 0;
      if (grub_errno)
	return -1;
      
      buf += grub_le_to_cpu32 (data->sblock.blksz) - skipfirst;
    }
  
  return len;
}


/* Find the file with the pathname PATH on the filesystem described by
   DATA.  */
static grub_err_t
grub_jfs_find_file (struct grub_jfs_data *data, const char *path)
{
  char fpath[grub_strlen (path)];
  char *name = fpath;
  char *next;
  unsigned int pos = 0;
  struct grub_jfs_diropen *diro;
  
  grub_strncpy (fpath, path, grub_strlen (path) + 1);
  
  if (grub_jfs_read_inode (data, GRUB_JFS_AGGR_INODE, &data->currinode))
    return grub_errno;

  /* Skip the first slash.  */
  if (name[0] == '/')
    {
      name++;
      if (!*name)
	return 0;
    }

  /* Extract the actual part from the pathname.  */
  next = grub_strchr (name, '/');
  if (next)
    {
      next[0] = '\0';
      next++;
    }
  
  diro = grub_jfs_opendir (data, &data->currinode);
  if (!diro)
    return grub_errno;
    
  for (;;)
    {
      if (grub_strlen (name) == 0)
	return GRUB_ERR_NONE;
      
      if (grub_jfs_getent (diro) == GRUB_ERR_OUT_OF_RANGE)
	break;
      
      /* Check if the current direntry matches the current part of the
	 pathname.  */
      if (!grub_strcmp (name, diro->name))
	{
	  int ino = diro->ino;
	  int dirino = grub_le_to_cpu32 (data->currinode.inode);
	  
	  grub_jfs_closedir (diro);
	  diro = 0;
	  
	  if (grub_jfs_read_inode (data, ino, &data->currinode))
	    break;
	  
	  /* Check if this is a symlink.  */
	  if ((grub_le_to_cpu32 (data->currinode.mode)
	       & GRUB_JFS_FILETYPE_MASK) == GRUB_JFS_FILETYPE_LNK)
	    {
	      grub_jfs_lookup_symlink (data, dirino);
	      if (grub_errno)
		return grub_errno;
	    }
	  
	  if (!next)
	    return 0;

	  pos = 0;
	  
	  name = next;
	  next = grub_strchr (name, '/');
	  if (next)
	    {
	      next[0] = '\0';
	      next++;
	    }
	  
	  /* Open this directory for reading dirents.  */
	  diro = grub_jfs_opendir (data, &data->currinode);
	  if (!diro)
	    return grub_errno;
	  
	  continue;
	}
    }

  grub_jfs_closedir (diro);
  grub_error (GRUB_ERR_FILE_NOT_FOUND, "file not found");
  return grub_errno;
}


static grub_err_t
grub_jfs_lookup_symlink (struct grub_jfs_data *data, int ino)
{
  int size = grub_le_to_cpu64 (data->currinode.size);
  char symlink[size + 1];

  if (++data->linknest > GRUB_JFS_MAX_SYMLNK_CNT)
    return grub_error (GRUB_ERR_SYMLINK_LOOP, "too deep nesting of symlinks");
  
  if (size <= 128)
    grub_strncpy (symlink, data->currinode.symlink.path, 128);
  else if (grub_jfs_read_file (data, 0, 0, size, symlink) < 0)
    return grub_errno;

  symlink[size] = '\0';
  
  /* The symlink is an absolute path, go back to the root inode.  */
  if (symlink[0] == '/')
    ino = 2;
  
  /* Now load in the old inode.  */
  if (grub_jfs_read_inode (data, ino, &data->currinode))
    return grub_errno;
  
  grub_jfs_find_file (data, symlink);
  if (grub_errno)
    grub_error (grub_errno, "Can not follow symlink `%s'.", symlink);
  
  return grub_errno;
}


static grub_err_t
grub_jfs_dir (grub_device_t device, const char *path, 
	      int (*hook) (const char *filename, int dir))
{
  struct grub_jfs_data *data = 0;
  struct grub_jfs_diropen *diro = 0;

#ifndef GRUB_UTIL
  grub_dl_ref (my_mod);
#endif

  data = grub_jfs_mount (device->disk);
  if (!data)
    goto fail;

  if (grub_jfs_find_file (data, path))
    goto fail;
  
  diro = grub_jfs_opendir (data, &data->currinode);
  if (!diro)
    goto fail;

  /* Iterate over the dirents in the directory that was found.  */
  while (grub_jfs_getent (diro) != GRUB_ERR_OUT_OF_RANGE)
    {
      struct grub_jfs_inode inode;
      int isdir;
      
      if (grub_jfs_read_inode (data, diro->ino, &inode))
	goto fail;
      
      isdir = (grub_le_to_cpu32 (inode.mode)
	       & GRUB_JFS_FILETYPE_MASK) == GRUB_JFS_FILETYPE_DIR;
      if (hook (diro->name, isdir))
	goto fail;
    }
  
  /* XXX: GRUB_ERR_OUT_OF_RANGE is used for the last dirent.  */
  if (grub_errno == GRUB_ERR_OUT_OF_RANGE)
    grub_errno = 0;

 fail:
  grub_jfs_closedir (diro);
  grub_free (data);

#ifndef GRUB_UTIL
  grub_dl_unref (my_mod);
#endif

  return grub_errno;
}


/* Open a file named NAME and initialize FILE.  */
static grub_err_t
grub_jfs_open (struct grub_file *file, const char *name)
{
  struct grub_jfs_data *data;

#ifndef GRUB_UTIL
  grub_dl_ref (my_mod);
#endif

  data = grub_jfs_mount (file->device->disk);
  if (!data)
    goto fail;
  
  grub_jfs_find_file (data, name);
  if (grub_errno)
    goto fail;
  
  /* It is only possible for open regular files.  */
  if (! ((grub_le_to_cpu32 (data->currinode.mode)
	  & GRUB_JFS_FILETYPE_MASK) == GRUB_JFS_FILETYPE_REG))
    {
      grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a regular file");
      goto fail;
    }
  
  file->data = data;
  file->size = grub_le_to_cpu64 (data->currinode.size);
  
  return 0;
  
 fail:

#ifndef GRUB_UTIL
  grub_dl_unref (my_mod);
#endif
  
  grub_free (data);
  
  return grub_errno;;
}


static grub_ssize_t
grub_jfs_read (grub_file_t file, char *buf, grub_ssize_t len)
{
  struct grub_jfs_data *data = 
    (struct grub_jfs_data *) file->data;
  
  return grub_jfs_read_file (data, file->read_hook, file->offset, len, buf);
}


static grub_err_t
grub_jfs_close (grub_file_t file)
{
  grub_free (file->data);
  
#ifndef GRUB_UTIL
  grub_dl_unref (my_mod);
#endif
  
  return GRUB_ERR_NONE;
}


static grub_err_t
grub_jfs_label (grub_device_t device, char **label)
{
  struct grub_jfs_data *data;
  data = grub_jfs_mount (device->disk);
  
  if (data)
    *label = grub_strndup (data->sblock.volname, 11);
  else
    *label = 0;
  
  return grub_errno;
}


static struct grub_fs grub_jfs_fs =
  {
    .name = "jfs",
    .dir = grub_jfs_dir,
    .open = grub_jfs_open,
    .read = grub_jfs_read,
    .close = grub_jfs_close,
    .label = grub_jfs_label,
    .next = 0
  };

GRUB_MOD_INIT(jfs)
{
  grub_fs_register (&grub_jfs_fs);
#ifndef GRUB_UTIL
  my_mod = mod;
#endif
}

GRUB_MOD_FINI(jfs)
{
  grub_fs_unregister (&grub_jfs_fs);
}