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175 lines
6.8 KiB
Python
175 lines
6.8 KiB
Python
"""
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ReiserFS file system version 3 parser (other version have not been tested).
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Author: Frederic Weisbecker
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Creation date: 8 december 2006
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Sources:
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- http://p-nand-q.com/download/rfstool/reiserfs_docs.html
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- http://homes.cerias.purdue.edu/~florian/reiser/reiserfs.php
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- file://usr/src/linux-2.6.16.19/include/linux/reiserfs_fs.h
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NOTES:
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The most part of the description of the structures, their fields and their
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comments decribed here comes from the file include/linux/reiserfs_fs.h
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- written by Hans reiser - located in the Linux kernel 2.6.16.19 and from
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the Reiserfs explanations in
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http://p-nand-q.com/download/rfstool/reiserfs_docs.html written by Gerson
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Kurz.
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"""
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from hachoir.parser import Parser
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from hachoir.field import (FieldSet, Enum,
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UInt16, UInt32, String, RawBytes, NullBytes, SeekableFieldSet, Bit)
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from hachoir.core.endian import LITTLE_ENDIAN
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class BlockState(Bit):
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"""The state (used/free) of a ReiserFs Block"""
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STATE = {
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True: "used",
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False: "free"
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}
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block_nb = 0
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def __init__(self, parent, name, nb_block):
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"""@param nb_block: Number of the block concerned"""
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Bit.__init__(self, parent, name)
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self.block_nb = self.__class__.block_nb
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self.__class__.block_nb += 1
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def createDescription(self):
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return "State of the block %d" % self.block_nb
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def createDisplay(self):
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return self.STATE[Bit.createValue(self)]
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class BitmapBlock(SeekableFieldSet):
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""" The bitmap blocks are Reiserfs blocks where each byte contains
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the state of 8 blocks in the filesystem. So each bit will describe
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the state of a block to tell if it is used or not.
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"""
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def createFields(self):
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block_size = self["/superblock/blocksize"].value
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for i in range(0, block_size * 8):
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yield BlockState(self, "block[]", i)
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class BitmapBlockGroup(SeekableFieldSet):
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"""The group that manages the Bitmap Blocks"""
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def createFields(self):
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block_size = self["/superblock/blocksize"].value
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nb_bitmap_block = self["/superblock/bmap_nr"].value
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# Position of the first bitmap block
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self.seekByte(REISER_FS.SUPERBLOCK_OFFSET + block_size, relative=False)
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yield BitmapBlock(self, "BitmapBlock[]", "Bitmap blocks tells for each block if it is used")
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# The other bitmap blocks
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for i in range(1, nb_bitmap_block):
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self.seekByte((block_size**2) * 8 * i, relative=False)
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yield BitmapBlock(self, "BitmapBlock[]", "Bitmap blocks tells for each block if it is used")
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class Journal_params(FieldSet):
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static_size = 32 * 8
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def createFields(self):
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yield UInt32(self, "1st_block", "Journal 1st block number")
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yield UInt32(self, "dev", "Journal device number")
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yield UInt32(self, "size", "Size of the journal")
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yield UInt32(self, "trans_max", "Max number of blocks in a transaction")
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# TODO: Must be explained: it was sb_journal_block_count
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yield UInt32(self, "magic", "Random value made on fs creation.")
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yield UInt32(self, "max_batch", "Max number of blocks to batch into a trans")
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yield UInt32(self, "max_commit_age", "In seconds, how old can an async commit be")
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yield UInt32(self, "max_trans_age", "In seconds, how old can a transaction be")
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def createDescription(self):
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return "Parameters of the journal"
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class SuperBlock(FieldSet):
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# static_size = 204*8
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UMOUNT_STATE = {1: "unmounted", 2: "not unmounted"}
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HASH_FUNCTIONS = {
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0: "UNSET_HASH",
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1: "TEA_HASH",
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2: "YURA_HASH",
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3: "R5_HASH"
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}
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def createFields(self):
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# TODO: This structure is normally divided in two parts:
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# _reiserfs_super_block_v1
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# _reiserfs_super_block
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# It will be divided later to easily support older version of the first
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# part
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yield UInt32(self, "block_count", "Number of blocks")
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yield UInt32(self, "free_blocks", "Number of free blocks")
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yield UInt32(self, "root_block", "Root block number")
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yield Journal_params(self, "Journal parameters")
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yield UInt16(self, "blocksize", "Size of a block")
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yield UInt16(self, "oid_maxsize", "Max size of object id array")
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yield UInt16(self, "oid_cursize", "Current size of object id array")
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yield Enum(UInt16(self, "umount_state", "Filesystem umounted or not"), self.UMOUNT_STATE)
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yield String(self, "magic", 10, "Magic string", strip="\0")
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# TODO: change the type of s_fs_state in Enum to have more details
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# about this fsck state
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yield UInt16(self, "fs_state", "Rebuilding phase of fsck ")
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yield Enum(UInt32(self, "hash_function", "Hash function to sort names in a directory"), self.HASH_FUNCTIONS)
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yield UInt16(self, "tree_height", "Height of disk tree")
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yield UInt16(self, "bmap_nr", "Amount of bitmap blocks needed to address each block of file system")
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# TODO: find a good description for this field
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yield UInt16(self, "version", "Field only reliable on filesystem with non-standard journal")
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yield UInt16(self, "reserved_for_journal", "Size in blocks of journal area on main device")
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# TODO: same as above
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yield UInt32(self, "inode_generation", "No description")
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# TODO: same as above and should be an enum field
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yield UInt32(self, "flags", "No description")
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# TODO: Create a special Type to format this id
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yield RawBytes(self, "uuid", 16, "Filesystem unique identifier")
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yield String(self, "label", 16, "Filesystem volume label", strip="\0")
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yield NullBytes(self, "unused", 88)
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yield NullBytes(self, "Bytes before end of the block", self["blocksize"].value - 204)
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def createDescription(self):
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return "Superblock: ReiserFs Filesystem"
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class REISER_FS(Parser):
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PARSER_TAGS = {
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"id": "reiserfs",
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"category": "file_system",
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# 130 blocks before the journal +
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# Minimal size of journal (513 blocks) +
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# 1 block for the rest
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# And The Minimal size of a block is 512 bytes
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"min_size": (130 + 513 + 1) * (512 * 8),
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"description": "ReiserFS file system"
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}
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endian = LITTLE_ENDIAN
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# Offsets (in bytes) of important information
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SUPERBLOCK_OFFSET = 64 * 1024
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MAGIC_OFFSET = SUPERBLOCK_OFFSET + 52
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def validate(self):
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# Let's look at the magic field in the superblock
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magic = self.stream.readBytes(self.MAGIC_OFFSET * 8, 9).rstrip(b"\0")
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if magic in (b"ReIsEr3Fs", b"ReIsErFs", b"ReIsEr2Fs"):
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return True
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return "Invalid magic string"
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def createFields(self):
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yield NullBytes(self, "padding[]", self.SUPERBLOCK_OFFSET)
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yield SuperBlock(self, "superblock")
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yield BitmapBlockGroup(self, "Group of bitmap blocks")
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