file/map.py

   1 from bisect import bisect
   2 from struct import unpack
   3 from array import array
   4
   5 class map:
   6         "Object map"
   7         # This is the core idi's data structure, mapping the file and
   8         # slicing it to many "segments" of various types.
   9         #
  10         # Note that the segments may overlap. Also note that this is
  11         # TOTALLY different from executable format's notion of "segments".
  12         # Our segments are actually very tiny, typically spanning one
  13         # data item or a single instruction.
  14         def __init__(self, file):
  15                 self.file = file
  16                 self.segments = []
  17
  18         # Add new segment to the map.
  19         def new_segment(self, seg):
  20                 # Optimize for common case - appending
  21                 pos = len(self.segments)
  22                 if (seg.physofs < pos):
  23                         pos = bisect(self.segments, seg.physofs);
  24                 self.segments.insert(pos, seg)
  25
  26         # Public attributes:
  27         # file (class file.file.file)
  28         # segments ([class segment]) (ordered by offset)
  29
  30
  31 class segment:
  32         "Object map segment"
  33         # This is one segment in the file; that is, continuous part of the
  34         # file that is either code or data. There can be also zero-sized
  35         # comment-only segments.
  36         def __init__(self, map, memofs, physofs, len, comment = None):
  37                 self.map = map
  38                 self.memofs = memofs
  39                 self.physofs = physofs
  40                 self.len = len
  41                 self.comment = comment
  42
  43         # Public attributes:
  44         # map (class map)
  45         # memofs (int, offset in memory)
  46         # physofs (int, offset in file)
  47         # len (int)
  48         # comment (string, can be None)
  49         # name (string)
  50         #       Contains user-visible name of segment type; use __class__ for
  51         #       programmatic segment type inspection instead.
  52         name = 'Generic'
  53
  54
  55 # XXX: I don't quite like how comments are done now.
  56
  57
  58 class seg_code (segment):
  59         "Map segment - code instruction"
  60         # Code segment: single instruction
  61         #
  62         # TODO: This object is very rudimentary now, it will probably get
  63         # much richer over time - flow information for jump instructions,
  64         # register information, etc.
  65         #
  66         # len is length of the instruction's binary representation in octets
  67         # txt is the textual representation of the instruction
  68         #       (TODO: This should be richer - registers identified, etc.)
  69         # comment is optional comment, usually added by the user
  70         def __init__(self, map, memofs, physofs, len, comment, txt):
  71                 segment.__init__(self, map, memofs, physofs, len, comment)
  72                 self.txt = txt
  73
  74         # Public attributes:
  75         # txt (string)
  76         name = 'Code'
  77
  78
  79 # TODO: More FMT support
  80 FMT_HEX=0       # cellsize 0: whole segment in hex
  81 #FMT_DEC=1      # cellsize 0: N/A
  82 #FMT_OCT=2      # cellsize 0: whole segment in hex
  83 #FMT_FLOAT=3    # cellsize 0: N/A
  84 #FMT_ASCII=4    # cellsize 0: whole segment in quoted ascii
  85 #FMT_ZASCII=4   # cellsize!0: up to \0
  86 #FMT_PASCII=5   # cellsize!0: first char is len
  87 # ...
  88
  89 # Cell formatters:
  90
  91 def _fmt_1hex(num):
  92         return "%02x" % num
  93
  94 def _fmt_hex(data):
  95         return reduce(lambda a, b: a + _fmt_1hex(b) + ' ', array("B", data), '')
  96
  97 _fmts = [_fmt_hex];
  98
  99 class seg_data (segment):
 100         "Map segment - data"
 101         # Data segment
 102         # Consists of one or more cells of given size, formatted in
 103         # given way
 104
 105         # Convert given data to a string (assuming the data is contents
 106         # of this segment); returns array of strings, one per cell
 107         def string(self, data):
 108                 if self.cellsize > 0:
 109                         return filter(_fmts[self.format],
 110                                         [data[i:i + self.cellsize]
 111                                                 for i in range(0, len(data), self.cellsize)])
 112                 else:
 113                         return [_fmts[self.format](data)]
 114
 115         # Public attributes:
 116         # format (int: DATA_*)
 117         # cellsize (int; 0 is fmt specific)
 118         # TODO: endianity
 119         format = FMT_HEX
 120         cellsize = 0
 121
 122         name = 'Data'
 123
 124
 125 class seg_comment (segment):
 126         "Map segment - comment"
 127         # Comment (that is not bound with any code/data)
 128
 129         name = 'Comment'