AFFS support

[Marco Gerards]

Hi,

Because I didn't immediately want to continue working on XFS support
and because Jaime (he's CC'ed) asked me about AFFS support, I wrote
AFFS support.

It was only tested using an image I found on the internet, but I
expect it works for any AFFS filesystem.  OFS filesystems are not
supported (yet), but that should be really easy to change.  AFAIK I
just used features that are also available for OFS.

If no one sees a problem in this code and no bugs are reported this
week, I will apply AFFS support this weekend.

As I normally do with filesystems, I didn't send in a patch, but just
the code.  If you want to test it, the easiest way to do so is
replacing some filesystem (jfs.c or so) with this code.

Both the SFS (if it is just as easy to implement as AFFS, I need it
for my pegasos) and XFS filesystem are on my short term to do list.

Thanks,
Marco


/* affs.c - Amiga Fast FileSystem.  */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 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>
#include <grub/fshelp.h>

/* The affs bootblock.  */
struct grub_affs_bblock
{
  grub_uint8_t type[3];
  grub_uint8_t flags;
  grub_uint32_t checksum;
  grub_uint32_t rootblock;
};

/* Set if the filesystem is a AFFS filesystem.  Otherwise this is an
   OFS filesystem.  */
#define GRUB_AFFS_FLAG_FFS      1

/* The affs rootblock.  */
struct grub_affs_rblock
{
  grub_uint8_t type[4];
  grub_uint8_t unused1[8];
  grub_uint32_t htsize;
  grub_uint32_t unused2;
  grub_uint32_t checksum;
  grub_uint32_t hashtable[1];
};

/* The second part of a file header block.  */
struct grub_affs_file
{
  grub_uint8_t unused1[12];
  grub_uint32_t size;
  grub_uint8_t unused2[104];
  grub_uint8_t namelen;
  grub_uint8_t name[30];
  grub_uint8_t unused3[33];
  grub_uint32_t next;
  grub_uint32_t parent;
  grub_uint32_t extension;
  grub_int32_t type;
};

/* The location of `struct grub_affs_file' relative to the end of a
   file header block.  */
#define GRUB_AFFS_FILE_LOCATION         200

/* The offset in both the rootblock and the file header block for the
   hashtable, symlink and block pointers (all synonyms).  */
#define GRUB_AFFS_HASHTABLE_OFFSET      24
#define GRUB_AFFS_BLOCKPTR_OFFSET       24
#define GRUB_AFFS_SYMLINK_OFFSET        24

#define GRUB_AFFS_SYMLINK_SIZE(blocksize) ((blocksize) - 225)

#define GRUB_AFFS_FILETYPE_DIR          -3
#define GRUB_AFFS_FILETYPE_REG          2
#define GRUB_AFFS_FILETYPE_SYMLINK      3


struct grub_fshelp_node
{
  struct grub_affs_data *data;
  int block;
  int size;
  int parent;
};

/* Information about a "mounted" affs filesystem.  */
struct grub_affs_data
{
  struct grub_affs_bblock bblock;
  struct grub_fshelp_node diropen;
  grub_disk_t disk;

  /* Blocksize in sectors.  */
  int blocksize;

  /* The number of entries in the hashtable.  */
  int htsize;
};

#ifndef GRUB_UTIL
static grub_dl_t my_mod;
#endif


static int
grub_affs_read_block (grub_fshelp_node_t node, int fileblock)
{
  int links;
  grub_uint32_t pos;
  int block = node->block;
  struct grub_affs_file file;
  struct grub_affs_data *data = node->data;

  /* Find the block that points to the fileblock we are looking up by
     following the chain until the right table is reached.  */
  for (links = fileblock / (data->htsize); links; links--)
    {
      grub_disk_read (data->disk, block + data->blocksize - 1,
                      data->blocksize * (GRUB_DISK_SECTOR_SIZE
                                         - GRUB_AFFS_FILE_LOCATION),
                      sizeof (file), (char *) &file);
      if (grub_errno)
        return 0;
          
      block = grub_be_to_cpu32 (file.extension);
    }

  /* Translate the fileblock to the block within the right table.  */
  fileblock = fileblock % (data->htsize);
  grub_disk_read (data->disk, block,
                  GRUB_AFFS_BLOCKPTR_OFFSET
                  + (data->htsize - fileblock - 1) * sizeof (pos),
                  sizeof (pos), (char *) &pos);
  if (grub_errno)
    return 0;
  
  return grub_be_to_cpu32 (pos);
}


/* 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_affs_read_file (grub_fshelp_node_t node,
                     void (*read_hook) (unsigned long sector,
                                        unsigned offset, unsigned length),
                     int pos, unsigned int len, char *buf)
{
  return grub_fshelp_read_file (node->data->disk, node, read_hook,
                                pos, len, buf, grub_affs_read_block,
                                node->size, 0);
}


static struct grub_affs_data *
grub_affs_mount (grub_disk_t disk)
{
  struct grub_affs_data *data;
  grub_uint32_t *rootblock = 0;
  struct grub_affs_rblock *rblock;

  int checksum = 0;
  int checksumr = 0;
  int blocksize = 0;

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

  /* Read the bootblock.  */
  grub_disk_read (disk, 0, 0, sizeof (struct grub_affs_bblock),
                  (char *) &data->bblock);
  if (grub_errno)
    goto fail;

  /* Make sure this is an affs filesystem.  */
  if (grub_strncmp (data->bblock.type, "DOS", 3))
    {
      grub_error (GRUB_ERR_BAD_FS, "not an affs filesystem");
      goto fail;
    }

  /* Test if the filesystem is a OFS filesystem.  */
  if (! (data->bblock.flags & GRUB_AFFS_FLAG_FFS))
    {
      grub_error (GRUB_ERR_BAD_FS, "ofs not yet supported");
      goto fail;
    }

  /* Read the bootblock.  */
  grub_disk_read (disk, 0, 0, sizeof (struct grub_affs_bblock),
                  (char *) &data->bblock);
  if (grub_errno)
    goto fail;

  /* No sane person uses more than 8KB for a block.  At least I hope
     for that person because in that case this won't work.  */
  rootblock = grub_malloc (GRUB_DISK_SECTOR_SIZE * 16);
  if (!rootblock)
    goto fail;

  rblock = (struct grub_affs_rblock *) rootblock;

  /* Read the rootblock.  */
  grub_disk_read (disk, (disk->total_sectors >> 1) + blocksize, 0,
                  GRUB_DISK_SECTOR_SIZE * 16, (char *) rootblock);
  if (grub_errno)
    goto fail;

  /* The filesystem blocksize is not stored anywhere in the filesystem
     itself.  One way to determine it is reading blocks for the
     rootblock until the checksum is correct.  */
  checksumr = grub_be_to_cpu32 (rblock->checksum);
  rblock->checksum = 0;
  for (blocksize = 0; blocksize < 8; blocksize++)
    {
      grub_uint32_t *currblock = rootblock + GRUB_DISK_SECTOR_SIZE * blocksize;
      unsigned int i;

      for (i = 0; i < GRUB_DISK_SECTOR_SIZE / sizeof (*currblock); i++)
        checksum += grub_be_to_cpu32 (currblock[i]);

      if (checksumr == -checksum)
        break;
    }
  if (-checksum != checksumr)
    {
      grub_error (GRUB_ERR_BAD_FS, "affs blocksize could not be determined");
      goto fail;
    }
  blocksize++;

  data->blocksize = blocksize;
  data->disk = disk;
  data->htsize = grub_be_to_cpu32 (rblock->htsize);
  data->diropen.data = data;
  data->diropen.block = (disk->total_sectors >> 1);

  grub_free (rootblock);

  return data;

 fail:
  grub_free (data);
  grub_free (rootblock);
  return 0;
}


static char *
grub_affs_read_symlink (grub_fshelp_node_t node)
{
  struct grub_affs_data *data = node->data;
  char *symlink;

  symlink = grub_malloc (GRUB_AFFS_SYMLINK_SIZE (data->blocksize));
  if (!symlink)
    return 0;

  grub_disk_read (data->disk, node->block, GRUB_AFFS_SYMLINK_OFFSET,
                  GRUB_AFFS_SYMLINK_SIZE (data->blocksize), symlink);
  if (grub_errno)
    {
      grub_free (symlink);
      return 0;
    }
  grub_printf ("Symlink: `%s'\n", symlink);
  return symlink;
}


static int
grub_affs_iterate_dir (grub_fshelp_node_t dir,
                       int NESTED_FUNC_ATTR
                       (*hook) (const char *filename,
                                enum grub_fshelp_filetype filetype,
                                grub_fshelp_node_t node))
{
  int i;
  struct grub_affs_file file;
  struct grub_fshelp_node *node = 0;
  struct grub_affs_data *data = dir->data;
  grub_uint32_t *hashtable;

  auto int NESTED_FUNC_ATTR grub_affs_create_node (const char *name, int block,
                                                   int size, int type);

  int NESTED_FUNC_ATTR grub_affs_create_node (const char *name, int block,
                                              int size, int type)
    {
      node = grub_malloc (sizeof (*node));
      if (!node)
        {
          grub_free (hashtable);
          return 1;
        }

      node->data = data;
      node->size = size;
      node->block = block;
      node->parent = grub_be_to_cpu32 (file.parent);

      if (hook (name, type, node))
        {
          grub_free (hashtable);
          return 1;
        }
      return 0;
    }

  hashtable = grub_malloc (data->htsize * sizeof (*hashtable));
  if (!hashtable)
    return 1;

  grub_disk_read (data->disk, dir->block, GRUB_AFFS_HASHTABLE_OFFSET,
                  data->htsize * sizeof (*hashtable), (char *) hashtable);
  if (grub_errno)
    goto fail;

  /* Create the directory entries for `.' and `..'.  */
  if (grub_affs_create_node (".", dir->block, dir->size, GRUB_FSHELP_DIR))
    return 1;
  if (grub_affs_create_node ("..", dir->parent ? dir->parent : dir->block,
                             dir->size, GRUB_FSHELP_DIR))
    return 1;

  for (i = 0; i < data->htsize; i++)
    {
      enum grub_fshelp_filetype type;
      grub_uint64_t next;

      if (!hashtable[i])
        continue;

      /* Every entry in the hashtable can be chained.  Read the entire
         chain.  */
      next = grub_be_to_cpu32 (hashtable[i]);

      while (next)
        {
          grub_disk_read (data->disk, next + data->blocksize - 1,
                          data->blocksize * GRUB_DISK_SECTOR_SIZE
                          - GRUB_AFFS_FILE_LOCATION,
                          sizeof (file), (char *) &file);
          if (grub_errno)
            goto fail;
          
          file.name[file.namelen] = '\0';

          if ((int) grub_be_to_cpu32 (file.type) == GRUB_AFFS_FILETYPE_DIR)
            type = GRUB_FSHELP_REG;
          else if (grub_be_to_cpu32 (file.type) == GRUB_AFFS_FILETYPE_REG)
            type = GRUB_FSHELP_DIR;
          else if (grub_be_to_cpu32 (file.type) == GRUB_AFFS_FILETYPE_SYMLINK)
            type = GRUB_FSHELP_SYMLINK;
          else
            type = GRUB_FSHELP_UNKNOWN;

          if (grub_affs_create_node (file.name, next,
                                     grub_be_to_cpu32 (file.size), type))
            return 1;

          next = grub_be_to_cpu32 (file.next);
        }      
    }

  grub_free (hashtable);
  return 0;

 fail:
  grub_free (node);
  grub_free (hashtable);
  return 1;
}


/* Open a file named NAME and initialize FILE.  */
static grub_err_t
grub_affs_open (struct grub_file *file, const char *name)
{
  struct grub_affs_data *data;
  struct grub_fshelp_node *fdiro = 0;
  
#ifndef GRUB_UTIL
  grub_dl_ref (my_mod);
#endif
  
  data = grub_affs_mount (file->device->disk);
  if (!data)
    goto fail;
  
  grub_fshelp_find_file (name, &data->diropen, &fdiro, grub_affs_iterate_dir,
                         grub_affs_read_symlink, GRUB_FSHELP_REG);
  if (grub_errno)
    goto fail;
  
  file->size = fdiro->size;
  data->diropen = *fdiro;
  grub_free (fdiro);

  file->data = data;
  file->offset = 0;

  return 0;

 fail:
  if (data && fdiro != &data->diropen)
    grub_free (fdiro);
  grub_free (data);
  
#ifndef GRUB_UTIL
  grub_dl_unref (my_mod);
#endif

  return grub_errno;
}


static grub_err_t
grub_affs_close (grub_file_t file)
{
  grub_free (file->data);

#ifndef GRUB_UTIL
  grub_dl_unref (my_mod);
#endif

  return GRUB_ERR_NONE;
}


/* Read LEN bytes data from FILE into BUF.  */
static grub_ssize_t
grub_affs_read (grub_file_t file, char *buf, grub_ssize_t len)
{
  struct grub_affs_data *data = 
    (struct grub_affs_data *) file->data;

  int size = grub_affs_read_file (&data->diropen, file->read_hook,
                              file->offset, len, buf);

  return size;
}


static grub_err_t
grub_affs_dir (grub_device_t device, const char *path, 
               int (*hook) (const char *filename, int dir))
{
  struct grub_affs_data *data = 0;
  struct grub_fshelp_node *fdiro = 0;
  
  auto int NESTED_FUNC_ATTR iterate (const char *filename,
                                     enum grub_fshelp_filetype filetype,
                                     grub_fshelp_node_t node);

  int NESTED_FUNC_ATTR iterate (const char *filename,
                                enum grub_fshelp_filetype filetype,
                                grub_fshelp_node_t node)
    {
      grub_free (node);
      
      if (filetype == GRUB_FSHELP_DIR)
        return hook (filename, 1);
      else 
        return hook (filename, 0);
      
      return 0;
    }

#ifndef GRUB_UTIL
  grub_dl_ref (my_mod);
#endif
  
  data = grub_affs_mount (device->disk);
  if (!data)
    goto fail;
  
  grub_fshelp_find_file (path, &data->diropen, &fdiro, grub_affs_iterate_dir,
                         grub_affs_read_symlink, GRUB_FSHELP_DIR);
  if (grub_errno)
    goto fail;

  grub_affs_iterate_dir (fdiro, iterate);
  
 fail:
  if (data && fdiro != &data->diropen)
    grub_free (fdiro);
  grub_free (data);

#ifndef GRUB_UTIL
  grub_dl_unref (my_mod);
#endif

  return grub_errno;
}


static grub_err_t
grub_affs_label (grub_device_t device, char **label)
{
  struct grub_affs_data *data;
  struct grub_affs_file file;
  grub_disk_t disk = device->disk;

#ifndef GRUB_UTIL
  grub_dl_ref (my_mod);
#endif

  data = grub_affs_mount (disk);
  if (data)
    {
      /* The rootblock maps quite well on a file header block, it's
         something we can use here.  */
      grub_disk_read (data->disk, disk->total_sectors >> 1,
                      data->blocksize * (GRUB_DISK_SECTOR_SIZE
                                         - GRUB_AFFS_FILE_LOCATION),
                      sizeof (file), (char *) &file);
      if (grub_errno)
        return 0;

      *label = grub_strndup (file.name, file.namelen);
    }
  else
    *label = 0;

#ifndef GRUB_UTIL
  grub_dl_unref (my_mod);
#endif

  grub_free (data);

  return grub_errno;
}


static struct grub_fs grub_affs_fs =
  {
    .name = "affs",
    .dir = grub_affs_dir,
    .open = grub_affs_open,
    .read = grub_affs_read,
    .close = grub_affs_close,
    .label = grub_affs_label,
    .next = 0
  };

#ifdef GRUB_UTIL
void
grub_affs_init (void)
{
  grub_fs_register (&grub_affs_fs);
}

void
grub_affs_fini (void)
{
  grub_fs_unregister (&grub_affs_fs);
}
#else /* ! GRUB_UTIL */
GRUB_MOD_INIT
{
  grub_fs_register (&grub_affs_fs);
  my_mod = mod;
}

GRUB_MOD_FINI
{
  grub_fs_unregister (&grub_affs_fs);
}
#endif /* ! GRUB_UTIL */