grub/grub-core/fs/sfs.c
2010-05-06 11:34:04 +05:30

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/* sfs.c - Amiga Smart FileSystem. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2005,2006,2007,2008,2009 Free Software Foundation, Inc.
*
* GRUB 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 3 of the License, or
* (at your option) any later version.
*
* GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#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 common header for a block. */
struct grub_sfs_bheader
{
grub_uint8_t magic[4];
grub_uint32_t chksum;
grub_uint32_t ipointtomyself;
} __attribute__ ((packed));
/* The sfs rootblock. */
struct grub_sfs_rblock
{
struct grub_sfs_bheader header;
grub_uint32_t version;
grub_uint8_t unused1[36];
grub_uint32_t blocksize;
grub_uint8_t unused2[40];
grub_uint8_t unused3[8];
grub_uint32_t rootobject;
grub_uint32_t btree;
} __attribute__ ((packed));
/* A SFS object container. */
struct grub_sfs_obj
{
grub_uint8_t unused1[4];
grub_uint32_t nodeid;
grub_uint8_t unused2[4];
union
{
struct
{
grub_uint32_t first_block;
grub_uint32_t size;
} file __attribute__ ((packed));
struct
{
grub_uint32_t hashtable;
grub_uint32_t dir_objc;
} dir __attribute__ ((packed));
} file_dir;
grub_uint8_t unused3[4];
grub_uint8_t type;
grub_uint8_t filename[1];
grub_uint8_t comment[1];
} __attribute__ ((packed));
#define GRUB_SFS_TYPE_DELETED 32
#define GRUB_SFS_TYPE_SYMLINK 64
#define GRUB_SFS_TYPE_DIR 128
/* A SFS object container. */
struct grub_sfs_objc
{
struct grub_sfs_bheader header;
grub_uint32_t parent;
grub_uint32_t next;
grub_uint32_t prev;
/* The amount of objects depends on the blocksize. */
struct grub_sfs_obj objects[1];
} __attribute__ ((packed));
struct grub_sfs_btree_node
{
grub_uint32_t key;
grub_uint32_t data;
} __attribute__ ((packed));
struct grub_sfs_btree_extent
{
grub_uint32_t key;
grub_uint32_t next;
grub_uint32_t prev;
grub_uint16_t size;
} __attribute__ ((packed));
struct grub_sfs_btree
{
struct grub_sfs_bheader header;
grub_uint16_t nodes;
grub_uint8_t leaf;
grub_uint8_t nodesize;
/* Normally this can be kind of node, but just extents are
supported. */
struct grub_sfs_btree_node node[1];
} __attribute__ ((packed));
struct grub_fshelp_node
{
struct grub_sfs_data *data;
int block;
int size;
};
/* Information about a "mounted" sfs filesystem. */
struct grub_sfs_data
{
struct grub_sfs_rblock rblock;
struct grub_fshelp_node diropen;
grub_disk_t disk;
/* Blocksize in sectors. */
unsigned int blocksize;
/* Label of the filesystem. */
char *label;
};
static grub_dl_t my_mod;
/* Lookup the extent starting with BLOCK in the filesystem described
by DATA. Return the extent size in SIZE and the following extent
in NEXTEXT. */
static grub_err_t
grub_sfs_read_extent (struct grub_sfs_data *data, unsigned int block,
int *size, int *nextext)
{
char *treeblock;
struct grub_sfs_btree *tree;
int i;
int next;
int prev;
treeblock = grub_malloc (data->blocksize);
if (!block)
return 0;
next = grub_be_to_cpu32 (data->rblock.btree);
tree = (struct grub_sfs_btree *) treeblock;
/* Handle this level in the btree. */
do
{
prev = 0;
grub_disk_read (data->disk, next, 0, data->blocksize, treeblock);
if (grub_errno)
{
grub_free (treeblock);
return grub_errno;
}
for (i = grub_be_to_cpu16 (tree->nodes) - 1; i >= 0; i--)
{
#define EXTNODE(tree, index) \
((struct grub_sfs_btree_node *) (((char *) &(tree)->node[0]) \
+ (index) * (tree)->nodesize))
/* Follow the tree down to the leaf level. */
if ((grub_be_to_cpu32 (EXTNODE(tree, i)->key) <= block)
&& !tree->leaf)
{
next = grub_be_to_cpu32 (EXTNODE (tree, i)->data);
break;
}
/* If the leaf level is reached, just find the correct extent. */
if (grub_be_to_cpu32 (EXTNODE (tree, i)->key) == block && tree->leaf)
{
struct grub_sfs_btree_extent *extent;
extent = (struct grub_sfs_btree_extent *) EXTNODE (tree, i);
/* We found a correct leaf. */
*size = grub_be_to_cpu16 (extent->size);
*nextext = grub_be_to_cpu32 (extent->next);
grub_free (treeblock);
return 0;
}
#undef EXTNODE
}
} while (!tree->leaf);
grub_free (treeblock);
return grub_error (GRUB_ERR_FILE_READ_ERROR, "SFS extent not found");
}
static grub_disk_addr_t
grub_sfs_read_block (grub_fshelp_node_t node, grub_disk_addr_t fileblock)
{
int blk = node->block;
int size = 0;
int next = 0;
while (blk)
{
grub_err_t err;
/* In case of the first block we don't have to lookup the
extent, the minimum size is always 1. */
if (fileblock == 0)
return blk;
err = grub_sfs_read_extent (node->data, blk, &size, &next);
if (err)
return 0;
if (fileblock < (unsigned int) size)
return fileblock + blk;
fileblock -= size;
blk = next;
}
grub_error (GRUB_ERR_FILE_READ_ERROR,
"reading a SFS block outside the extent");
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_sfs_read_file (grub_fshelp_node_t node,
void NESTED_FUNC_ATTR (*read_hook) (grub_disk_addr_t sector,
unsigned offset, unsigned length),
int pos, grub_size_t len, char *buf)
{
return grub_fshelp_read_file (node->data->disk, node, read_hook,
pos, len, buf, grub_sfs_read_block,
node->size, 0);
}
static struct grub_sfs_data *
grub_sfs_mount (grub_disk_t disk)
{
struct grub_sfs_data *data;
struct grub_sfs_objc *rootobjc;
char *rootobjc_data = 0;
unsigned int blk;
data = grub_malloc (sizeof (*data));
if (!data)
return 0;
/* Read the rootblock. */
grub_disk_read (disk, 0, 0, sizeof (struct grub_sfs_rblock),
&data->rblock);
if (grub_errno)
goto fail;
/* Make sure this is a sfs filesystem. */
if (grub_strncmp ((char *) (data->rblock.header.magic), "SFS", 4))
{
grub_error (GRUB_ERR_BAD_FS, "not a SFS filesystem");
goto fail;
}
data->blocksize = grub_be_to_cpu32 (data->rblock.blocksize);
rootobjc_data = grub_malloc (data->blocksize);
if (! rootobjc_data)
goto fail;
/* Read the root object container. */
grub_disk_read (disk, grub_be_to_cpu32 (data->rblock.rootobject), 0,
data->blocksize, rootobjc_data);
if (grub_errno)
goto fail;
rootobjc = (struct grub_sfs_objc *) rootobjc_data;
blk = grub_be_to_cpu32 (rootobjc->objects[0].file_dir.dir.dir_objc);
data->diropen.size = 0;
data->diropen.block = blk;
data->diropen.data = data;
data->disk = disk;
data->label = grub_strdup ((char *) (rootobjc->objects[0].filename));
return data;
fail:
if (grub_errno == GRUB_ERR_OUT_OF_RANGE)
grub_error (GRUB_ERR_BAD_FS, "not an SFS filesystem");
grub_free (data);
grub_free (rootobjc_data);
return 0;
}
static char *
grub_sfs_read_symlink (grub_fshelp_node_t node)
{
struct grub_sfs_data *data = node->data;
char *symlink;
char *block;
block = grub_malloc (data->blocksize);
if (!block)
return 0;
grub_disk_read (data->disk, node->block, 0, data->blocksize, block);
if (grub_errno)
{
grub_free (block);
return 0;
}
/* This is just a wild guess, but it always worked for me. How the
SLNK block looks like is not documented in the SFS docs. */
symlink = grub_strdup (&block[24]);
grub_free (block);
if (!symlink)
return 0;
return symlink;
}
static int
grub_sfs_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))
{
struct grub_fshelp_node *node = 0;
struct grub_sfs_data *data = dir->data;
char *objc_data;
struct grub_sfs_objc *objc;
unsigned int next = dir->block;
int pos;
auto int NESTED_FUNC_ATTR grub_sfs_create_node (const char *name, int block,
int size, int type);
int NESTED_FUNC_ATTR grub_sfs_create_node (const char *name, int block,
int size, int type)
{
node = grub_malloc (sizeof (*node));
if (!node)
return 1;
node->data = data;
node->size = size;
node->block = block;
return hook (name, type, node);
}
objc_data = grub_malloc (data->blocksize);
if (!objc_data)
goto fail;
/* The Object container can consist of multiple blocks, iterate over
every block. */
while (next)
{
grub_disk_read (data->disk, next, 0, data->blocksize, objc_data);
if (grub_errno)
goto fail;
objc = (struct grub_sfs_objc *) objc_data;
pos = (char *) &objc->objects[0] - (char *) objc;
/* Iterate over all entries in this block. */
while (pos + sizeof (struct grub_sfs_obj) < data->blocksize)
{
struct grub_sfs_obj *obj;
obj = (struct grub_sfs_obj *) ((char *) objc + pos);
char *filename = (char *) (obj->filename);
int len;
enum grub_fshelp_filetype type;
unsigned int block;
/* The filename and comment dynamically increase the size of
the object. */
len = grub_strlen (filename);
len += grub_strlen (filename + len + 1);
pos += sizeof (*obj) + len;
/* Round up to a multiple of two bytes. */
pos = ((pos + 1) >> 1) << 1;
if (grub_strlen (filename) == 0)
continue;
/* First check if the file was not deleted. */
if (obj->type & GRUB_SFS_TYPE_DELETED)
continue;
else if (obj->type & GRUB_SFS_TYPE_SYMLINK)
type = GRUB_FSHELP_SYMLINK;
else if (obj->type & GRUB_SFS_TYPE_DIR)
type = GRUB_FSHELP_DIR;
else
type = GRUB_FSHELP_REG;
if (type == GRUB_FSHELP_DIR)
block = grub_be_to_cpu32 (obj->file_dir.dir.dir_objc);
else
block = grub_be_to_cpu32 (obj->file_dir.file.first_block);
if (grub_sfs_create_node (filename, block,
grub_be_to_cpu32 (obj->file_dir.file.size),
type))
{
grub_free (objc_data);
return 1;
}
}
next = grub_be_to_cpu32 (objc->next);
}
fail:
grub_free (objc_data);
return 0;
}
/* Open a file named NAME and initialize FILE. */
static grub_err_t
grub_sfs_open (struct grub_file *file, const char *name)
{
struct grub_sfs_data *data;
struct grub_fshelp_node *fdiro = 0;
grub_dl_ref (my_mod);
data = grub_sfs_mount (file->device->disk);
if (!data)
goto fail;
grub_fshelp_find_file (name, &data->diropen, &fdiro, grub_sfs_iterate_dir,
grub_sfs_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);
if (data)
grub_free (data->label);
grub_free (data);
grub_dl_unref (my_mod);
return grub_errno;
}
static grub_err_t
grub_sfs_close (grub_file_t file)
{
grub_free (file->data);
grub_dl_unref (my_mod);
return GRUB_ERR_NONE;
}
/* Read LEN bytes data from FILE into BUF. */
static grub_ssize_t
grub_sfs_read (grub_file_t file, char *buf, grub_size_t len)
{
struct grub_sfs_data *data = (struct grub_sfs_data *) file->data;
int size = grub_sfs_read_file (&data->diropen, file->read_hook,
file->offset, len, buf);
return size;
}
static grub_err_t
grub_sfs_dir (grub_device_t device, const char *path,
int (*hook) (const char *filename,
const struct grub_dirhook_info *info))
{
struct grub_sfs_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)
{
struct grub_dirhook_info info;
grub_memset (&info, 0, sizeof (info));
info.dir = ((filetype & GRUB_FSHELP_TYPE_MASK) == GRUB_FSHELP_DIR);
grub_free (node);
return hook (filename, &info);
}
grub_dl_ref (my_mod);
data = grub_sfs_mount (device->disk);
if (!data)
goto fail;
grub_fshelp_find_file (path, &data->diropen, &fdiro, grub_sfs_iterate_dir,
grub_sfs_read_symlink, GRUB_FSHELP_DIR);
if (grub_errno)
goto fail;
grub_sfs_iterate_dir (fdiro, iterate);
fail:
if (data && fdiro != &data->diropen)
grub_free (fdiro);
if (data)
grub_free (data->label);
grub_free (data);
grub_dl_unref (my_mod);
return grub_errno;
}
static grub_err_t
grub_sfs_label (grub_device_t device, char **label)
{
struct grub_sfs_data *data;
grub_disk_t disk = device->disk;
data = grub_sfs_mount (disk);
if (data)
*label = data->label;
grub_free (data);
return grub_errno;
}
static struct grub_fs grub_sfs_fs =
{
.name = "sfs",
.dir = grub_sfs_dir,
.open = grub_sfs_open,
.read = grub_sfs_read,
.close = grub_sfs_close,
.label = grub_sfs_label,
.next = 0
};
GRUB_MOD_INIT(sfs)
{
grub_fs_register (&grub_sfs_fs);
my_mod = mod;
}
GRUB_MOD_FINI(sfs)
{
grub_fs_unregister (&grub_sfs_fs);
}