1import lldb 2from xnu import * 3 4_UnionStructClass = [ lldb.eTypeClassStruct, lldb.eTypeClassClass, lldb.eTypeClassUnion ] 5 6def _get_offset_formatter(ctx, fmt_hex, fmt_dec): 7 """ Returns a formatter of struct member offsets and sizes. 8 9 params: 10 ctx - configuration context 11 fmt_hex - hexadecimal format 12 fmt_dec - decimal format 13 returns: 14 offset formatter 15 """ 16 O = ctx[0] 17 use_hex = ctx[1] 18 if use_hex: 19 fmt = fmt_hex 20 else: 21 fmt = fmt_dec 22 return lambda o, s: O.format(fmt, o, s) 23 24def _get_num_formatter(ctx, fmt_hex, fmt_dec): 25 """ Returns a number formatter. 26 27 params: 28 ctx - configuration context 29 fmt_hex - hexadecimal format 30 fmt_dec - decimal format 31 returns: 32 number formatter 33 """ 34 O = ctx[0] 35 use_hex = ctx[1] 36 if use_hex: 37 fmt = fmt_hex 38 else: 39 fmt = fmt_dec 40 return lambda n: O.format(fmt, n) 41 42def _showStructPacking(ctx, symbol, begin_offset=0, symsize=0, typedef=None, outerSize=0, memberName=None): 43 """ Recursively parse the field members of structure. 44 45 params : 46 ctx - context containing configuration settings and the output formatter (standard.py) symbol (lldb.SBType) reference to symbol in binary 47 returns: 48 string containing lines of output. 49 """ 50 51 O = ctx[0] 52 format_offset = _get_offset_formatter(ctx, "{:#06x},[{:#6x}]", "{:04d},[{:4d}]") 53 format_num = _get_num_formatter(ctx, "{:#04x}", "{:2d}") 54 55 ctype = "unknown type" 56 is_union = False 57 is_class = False 58 union_size = None 59 sym_size = symbol.GetByteSize() 60 61 if symbol.GetTypeClass() == lldb.eTypeClassUnion: 62 ctype = "union" 63 is_union = True 64 union_size = sym_size 65 if symbol.GetTypeClass() == lldb.eTypeClassStruct: 66 ctype = "struct" 67 if symbol.GetTypeClass() == lldb.eTypeClassClass: 68 ctype = "class" 69 is_class = True 70 71 if not outerSize or outerSize == sym_size: 72 outstr = format_offset(begin_offset, sym_size) 73 elif outerSize < sym_size: # happens with c++ inheritance 74 outstr = format_offset(begin_offset, outerSize) 75 else: 76 outstr = O.format("{:s}{VT.DarkRed}{{{:s}}}{VT.Default}", 77 format_offset(begin_offset, sym_size), 78 format_num(outerSize - sym_size)) 79 80 if typedef: 81 outstr += O.format(" {0}", typedef) 82 if symbol.IsAnonymousType(): 83 outstr += O.format(" ({VT.DarkMagenta}anonymous {0}{VT.Default})", ctype) 84 else: 85 outstr += O.format(" ({VT.DarkMagenta}{0} {1}{VT.Default})", ctype, symbol.GetName()) 86 if memberName: 87 outstr += O.format(" {0} {{", memberName) 88 else: 89 outstr += ") {" 90 91 print outstr 92 93 with O.indent(): 94 _previous_size = 0 95 _packed_bit_offset = 0 96 _nfields = symbol.GetNumberOfFields() 97 98 if is_class: 99 _next_offset_in_bits = 0 100 _nclasses = symbol.GetNumberOfDirectBaseClasses() 101 102 for i in range(_nclasses): 103 member = symbol.GetDirectBaseClassAtIndex(i) 104 if i < _nclasses - 1: 105 m_size_bits = symbol.GetDirectBaseClassAtIndex(i + 1).GetOffsetInBits() 106 elif _nfields: 107 m_size_bits = symbol.GetFieldAtIndex(0).GetOffsetInBits() 108 else: 109 m_size_bits = symbol.GetByteSize() * 8 110 111 m_offset = member.GetOffsetInBytes() + begin_offset 112 m_type = member.GetType() 113 m_name = member.GetName() 114 m_size = m_size_bits / 8 115 116 _previous_size = m_size 117 _packed_bit_offset = member.GetOffsetInBits() + m_size_bits 118 119 _showStructPacking(ctx, m_type, m_offset, str(m_type), outerSize=m_size, memberName=m_name) 120 121 for i in range(_nfields): 122 member = symbol.GetFieldAtIndex(i) 123 m_offset = member.GetOffsetInBytes() + begin_offset 124 m_offset_bits = member.GetOffsetInBits() 125 126 m_type = member.GetType() 127 m_name = member.GetName() 128 m_size = m_type.GetByteSize() 129 130 if member.IsBitfield(): 131 m_is_bitfield = True 132 m_size_bits = member.GetBitfieldSizeInBits() 133 else: 134 m_is_bitfield = False 135 m_size_bits = m_size * 8 136 137 if not is_union and _packed_bit_offset < m_offset_bits: 138 m_previous_offset = begin_offset + _packed_bit_offset / 8 139 m_hole_bits = m_offset_bits - _packed_bit_offset 140 if _packed_bit_offset % 8 == 0: 141 print O.format("{:s} ({VT.DarkRed}*** padding ***{VT.Default})", 142 format_offset(m_previous_offset, m_hole_bits / 8)) 143 else: 144 print O.format("{:s} ({VT.Brown}*** padding : {:s} ***{VT.Default})", 145 format_offset(m_previous_offset, _previous_size), 146 format_num(m_hole_bits)) 147 148 _previous_size = m_size 149 _packed_bit_offset = m_offset_bits + m_size_bits 150 151 _type_class = m_type.GetTypeClass() 152 _canonical_type = m_type.GetCanonicalType() 153 _canonical_type_class = m_type.GetCanonicalType().GetTypeClass() 154 155 if _type_class == lldb.eTypeClassTypedef and _canonical_type_class in _UnionStructClass: 156 _showStructPacking(ctx, _canonical_type, m_offset, str(m_type), outerSize=union_size, memberName=m_name) 157 elif _type_class in _UnionStructClass: 158 _showStructPacking(ctx, m_type, m_offset, outerSize=union_size, memberName=m_name) 159 else: 160 outstr = format_offset(m_offset, m_size) 161 if is_union and union_size != m_size_bits / 8: 162 outstr += O.format("{VT.DarkRed}{{{:s}}}{VT.Default}", 163 format_num(union_size - m_size_bits / 8)) 164 if m_is_bitfield: 165 outstr += O.format(" ({VT.DarkGreen}{:s} : {:s}{VT.Default}) {:s}", 166 m_type.GetName(), 167 format_num(m_size_bits), 168 m_name) 169 else: 170 outstr += O.format(" ({VT.DarkGreen}{:s}{VT.Default}) {:s}", 171 m_type.GetName(), m_name) 172 print outstr 173 174 referenceSize = min(outerSize, sym_size) or sym_size 175 if not is_union and _packed_bit_offset < referenceSize * 8: 176 m_previous_offset = begin_offset + _packed_bit_offset / 8 177 m_hole_bits = referenceSize * 8 - _packed_bit_offset 178 if _packed_bit_offset % 8 == 0: 179 print O.format("{:s} ({VT.DarkRed}*** padding ***{VT.Default})", 180 format_offset(m_previous_offset, m_hole_bits / 8)) 181 else: 182 print O.format("{:s} ({VT.Brown}padding : {:s}{VT.Default})\n", 183 format_offset(m_previous_offset, _previous_size), 184 format_num(m_hole_bits)) 185 186 print "}" 187 188@lldb_command('showstructpacking', "X" , fancy=True) 189def showStructInfo(cmd_args=None, cmd_options={}, O=None): 190 """ Show how a structure is packed in the binary. 191 192 Usage: showstructpacking [-X] <type name> 193 -X : prints struct members offsets and sizes in a hexadecimal format (decimal is default) 194 195 The format is: 196 <offset>, [<size_of_member>] (<type>) <name> 197 198 Example: 199 (lldb) showstructpacking pollfd 200 0,[ 8] struct pollfd { 201 0,[ 4] (int) fd 202 4,[ 2] (short) events 203 6,[ 2] (short) revents 204 } 205 """ 206 if not cmd_args: 207 raise ArgumentError("Please provide a type name.") 208 209 ty_name = cmd_args[0] 210 try: 211 sym = gettype(ty_name) 212 except NameError: 213 return O.error("Cannot find type named {0}", ty_name) 214 215 if sym.GetTypeClass() == lldb.eTypeClassTypedef: 216 sym = sym.GetCanonicalType() 217 218 if sym.GetTypeClass() not in _UnionStructClass: 219 return O.error("{0} is not a structure/union/class type", ty_name) 220 221 ctx = (O, "-X" in cmd_options) 222 223 _showStructPacking(ctx, sym, 0) 224 225# EndMacro: showstructinto 226