metasploit-framework/lib/rex/ole/fat.rb

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##
# $Id$
# Version: $Revision$
##
##
# Rex::OLE - an OLE implementation
# written in 2010 by Joshua J. Drake <jduck [at] metasploit.com>
##
module Rex
module OLE
class FAT < DIFAT
#
# low-level functions
#
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
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
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
end
end
end