Class: Rex::OLE::FAT

Inherits:
DIFAT
  • Object
show all
Defined in:
lib/rex/ole/fat.rb

Instance Method Summary collapse

Methods inherited from DIFAT

#+, #<<, #[], #[]=, #each, #initialize, #length, #reset, #slice!, #to_s

Constructor Details

This class inherits a constructor from Rex::OLE::DIFAT

Instance Method Details

#allocate_sector(type = nil) ⇒ Object 



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# File 'lib/rex/ole/fat.rb', line 45

def allocate_sector(type=nil)
	idx = @entries.index(SECT_FREE)
	if (not idx)
		# add a sector worth
		idx = @entries.length
		@stg.header.idx_per_sect.times {
			@entries << SECT_FREE
		}
	end

	# mark the sector as in use
	if (type)
		@entries[idx] = type
	else
		# default normal sectors to end of chain
		@entries[idx] = SECT_END
	end
	idx
end

#read(difat) ⇒ Object

low-level functions



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# File 'lib/rex/ole/fat.rb', line 19

def read(difat)
	@entries = []
	cnt = left = @stg.header._csectFat
	difat.each { |fs|
		break if (left == 0)

		if (fs != SECT_FREE)
			buf = @stg.read_sector(fs, @stg.header.sector_size)
			arr = Util.get32array(buf)

			# hax!
			if (@entries[fs] == SECT_DIF)
				# chop the next ptr
				@entries += arr.slice!(0, arr.length - 1)
			else
				@entries += arr
			end
			left -= 1
		end
	}

	if (left != 0)
		raise RuntimeError, 'Only found %u of %u sectors' % [(cnt - left), cnt]
	end
end

#write(difat) ⇒ Object 



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# File 'lib/rex/ole/fat.rb', line 65

def write(difat)
	# we build the difat as we write these..
	difat.reset

	# allocate the sectors
	fat_sects = []
	left = @entries.length
	while (left > 0)
		if (left > @stg.header.idx_per_sect)
			left -= @stg.header.idx_per_sect
		else
			left = 0
		end
		fat_sects << allocate_sector(SECT_FAT)
	end

	# write the fat into the difat/allocated sectors
	copy = @entries.dup
	fat_sects.each { |fs|
		part = copy.slice!(0, @stg.header.idx_per_sect)
		sbuf = Util.pack32array(part)

		if (sbuf.length != @stg.header.sector_size)
			raise RuntimeError, 'Unsupported number of fat sectors (not multiple of idx per sect)'
		end

		@stg.write_sector_raw(fs, sbuf)
		difat << fs
	}
end