tools/lldbmacros/structanalyze.py

   1 import lldb
   2 from xnu import *
   3
   4 def _showStructPacking(symbol, prefix, begin_offset=0, typedef=None):
   5   """
   6      recursively parse the field members of structure.
   7      params : symbol (lldb.SBType) reference to symbol in binary
   8               prefix (string)      string to be prefixed for each line of output. Useful for recursive struct parsing.
   9      returns: string containing lines of output.
  10   """
  11   ctype = "unknown type"
  12   if symbol.GetTypeClass() == lldb.eTypeClassUnion :
  13     ctype = "union"
  14   if symbol.GetTypeClass() == lldb.eTypeClassStruct :
  15     ctype = "struct"
  16
  17   if typedef:
  18     outstr =  "[%4d] (%s) (%s) %s { " % (symbol.GetByteSize(), typedef, ctype, symbol.GetName()) + "\n"
  19   else :
  20     outstr =  "[%4d] (%s) %s { " % (symbol.GetByteSize(), ctype, symbol.GetName()) + "\n"
  21   numFields = symbol.GetNumberOfFields()
  22   _has_memory_hole = False
  23   _compact_size = 0    # asuming the struct is perfectly packed
  24   _compact_offset = begin_offset
  25   _previous_bit_offset = 0
  26   for i in range(numFields):
  27     member = symbol.GetFieldAtIndex(i)
  28     m_offset = member.GetOffsetInBytes() + begin_offset
  29     m_offset_bits = member.GetOffsetInBits()
  30     m_type = member.GetType()
  31     m_name = member.GetName()
  32     m_size = m_type.GetByteSize()
  33     warningstr = ""
  34     debugstr = "" # + str((m_size, m_offset , m_offset_bits, _previous_bit_offset, _compact_offset, begin_offset))
  35     if _compact_offset != m_offset and (m_offset_bits -  _previous_bit_offset) > m_size*8 :
  36       _has_memory_hole = True
  37       warningstr = "   *** Possible memory hole ***"
  38       _compact_offset = m_offset
  39     _compact_offset += m_size
  40
  41     _type_class = m_type.GetTypeClass()
  42     _canonical_type = m_type.GetCanonicalType()
  43     _canonical_type_class = m_type.GetCanonicalType().GetTypeClass()
  44
  45     if _type_class == lldb.eTypeClassTypedef and (_canonical_type_class == lldb.eTypeClassStruct or _canonical_type_class == lldb.eTypeClassUnion) :
  46       outstr += prefix + ("*%4d," % m_offset) + _showStructPacking(_canonical_type, prefix+"    ", m_offset, str(m_type)) + warningstr + debugstr + "\n"
  47     elif _type_class == lldb.eTypeClassStruct or _type_class == lldb.eTypeClassUnion :
  48       outstr += prefix + ("*%4d," % m_offset) + _showStructPacking(m_type, prefix+"    ", m_offset) + warningstr + debugstr + "\n"
  49     else:
  50       outstr += prefix + ("+%4d,[%4d] (%s) %s" % (m_offset, m_size, m_type.GetName(), m_name)) + warningstr + debugstr + "\n"
  51     if i > 0 :
  52       _previous_bit_offset = m_offset_bits
  53   outstr += prefix + "}"
  54   if _has_memory_hole == True :
  55     outstr += "   *** Warning: Struct layout leaves memory hole *** "
  56   return outstr
  57
  58 @lldb_command('showstructpacking')
  59 def showStructInfo(cmd_args=None):
  60   """Show how a structure is packed in the binary. The format is
  61      +<offset>, [<size_of_member>] (<type>) <name>
  62      For example:
  63       (lldb) script lldbmacros.showStructInfo("pollfd")
  64       [  8] (struct) pollfd {
  65       +  0,[  4] (int) fd
  66       +  4,[  2] (short) events
  67       +  6,[  2] (short) revents
  68       }
  69     syntax: showstructpacking task
  70   """
  71   if not cmd_args:
  72     raise ArgumentError("Please provide a type name.")
  73
  74   sym = gettype(cmd_args[0])
  75   if sym == None:
  76     print "No such struct found"
  77   if sym.GetTypeClass() == lldb.eTypeClassTypedef:
  78       sym = sym.GetCanonicalType()
  79   if sym.GetTypeClass() != lldb.eTypeClassStruct:
  80     print "%s is not a structure" % cmd_args[0]
  81   else:
  82     print _showStructPacking(sym,"", 0)
  83
  84 # EndMacro: showstructinto