| """Disassembler of Python byte code into mnemonics.""" |
| |
| import sys |
| import types |
| import collections |
| |
| from opcode import * |
| from opcode import __all__ as _opcodes_all |
| |
| __all__ = ["code_info", "dis", "disassemble", "distb", "disco", |
| "findlinestarts", "findlabels", "show_code", |
| "get_instructions", "Instruction", "Bytecode"] + _opcodes_all |
| del _opcodes_all |
| |
| _have_code = (types.MethodType, types.FunctionType, types.CodeType, type) |
| |
| def _try_compile(source, name): |
| """Attempts to compile the given source, first as an expression and |
| then as a statement if the first approach fails. |
| |
| Utility function to accept strings in functions that otherwise |
| expect code objects |
| """ |
| try: |
| c = compile(source, name, 'eval') |
| except SyntaxError: |
| c = compile(source, name, 'exec') |
| return c |
| |
| def dis(x=None, *, file=None): |
| """Disassemble classes, methods, functions, or code. |
| |
| With no argument, disassemble the last traceback. |
| |
| """ |
| if x is None: |
| distb() |
| return |
| if hasattr(x, '__func__'): # Method |
| x = x.__func__ |
| if hasattr(x, '__code__'): # Function |
| x = x.__code__ |
| if hasattr(x, '__dict__'): # Class or module |
| items = sorted(x.__dict__.items()) |
| for name, x1 in items: |
| if isinstance(x1, _have_code): |
| print("Disassembly of %s:" % name, file=file) |
| try: |
| dis(x1) |
| except TypeError as msg: |
| print("Sorry:", msg, file=file) |
| print(file=file) |
| elif hasattr(x, 'co_code'): # Code object |
| disassemble(x, file=file) |
| elif isinstance(x, (bytes, bytearray)): # Raw bytecode |
| _disassemble_bytes(x, file=file) |
| elif isinstance(x, str): # Source code |
| _disassemble_str(x, file=file) |
| else: |
| raise TypeError("don't know how to disassemble %s objects" % |
| type(x).__name__) |
| |
| def distb(tb=None, *, file=None): |
| """Disassemble a traceback (default: last traceback).""" |
| if tb is None: |
| try: |
| tb = sys.last_traceback |
| except AttributeError: |
| raise RuntimeError("no last traceback to disassemble") |
| while tb.tb_next: tb = tb.tb_next |
| disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file) |
| |
| # The inspect module interrogates this dictionary to build its |
| # list of CO_* constants. It is also used by pretty_flags to |
| # turn the co_flags field into a human readable list. |
| COMPILER_FLAG_NAMES = { |
| 1: "OPTIMIZED", |
| 2: "NEWLOCALS", |
| 4: "VARARGS", |
| 8: "VARKEYWORDS", |
| 16: "NESTED", |
| 32: "GENERATOR", |
| 64: "NOFREE", |
| } |
| |
| def pretty_flags(flags): |
| """Return pretty representation of code flags.""" |
| names = [] |
| for i in range(32): |
| flag = 1<<i |
| if flags & flag: |
| names.append(COMPILER_FLAG_NAMES.get(flag, hex(flag))) |
| flags ^= flag |
| if not flags: |
| break |
| else: |
| names.append(hex(flags)) |
| return ", ".join(names) |
| |
| def _get_code_object(x): |
| """Helper to handle methods, functions, strings and raw code objects""" |
| if hasattr(x, '__func__'): # Method |
| x = x.__func__ |
| if hasattr(x, '__code__'): # Function |
| x = x.__code__ |
| if isinstance(x, str): # Source code |
| x = _try_compile(x, "<disassembly>") |
| if hasattr(x, 'co_code'): # Code object |
| return x |
| raise TypeError("don't know how to disassemble %s objects" % |
| type(x).__name__) |
| |
| def code_info(x): |
| """Formatted details of methods, functions, or code.""" |
| return _format_code_info(_get_code_object(x)) |
| |
| def _format_code_info(co): |
| lines = [] |
| lines.append("Name: %s" % co.co_name) |
| lines.append("Filename: %s" % co.co_filename) |
| lines.append("Argument count: %s" % co.co_argcount) |
| lines.append("Kw-only arguments: %s" % co.co_kwonlyargcount) |
| lines.append("Number of locals: %s" % co.co_nlocals) |
| lines.append("Stack size: %s" % co.co_stacksize) |
| lines.append("Flags: %s" % pretty_flags(co.co_flags)) |
| if co.co_consts: |
| lines.append("Constants:") |
| for i_c in enumerate(co.co_consts): |
| lines.append("%4d: %r" % i_c) |
| if co.co_names: |
| lines.append("Names:") |
| for i_n in enumerate(co.co_names): |
| lines.append("%4d: %s" % i_n) |
| if co.co_varnames: |
| lines.append("Variable names:") |
| for i_n in enumerate(co.co_varnames): |
| lines.append("%4d: %s" % i_n) |
| if co.co_freevars: |
| lines.append("Free variables:") |
| for i_n in enumerate(co.co_freevars): |
| lines.append("%4d: %s" % i_n) |
| if co.co_cellvars: |
| lines.append("Cell variables:") |
| for i_n in enumerate(co.co_cellvars): |
| lines.append("%4d: %s" % i_n) |
| return "\n".join(lines) |
| |
| def show_code(co, *, file=None): |
| """Print details of methods, functions, or code to *file*. |
| |
| If *file* is not provided, the output is printed on stdout. |
| """ |
| print(code_info(co), file=file) |
| |
| _Instruction = collections.namedtuple("_Instruction", |
| "opname opcode arg argval argrepr offset starts_line is_jump_target") |
| |
| class Instruction(_Instruction): |
| """Details for a bytecode operation |
| |
| Defined fields: |
| opname - human readable name for operation |
| opcode - numeric code for operation |
| arg - numeric argument to operation (if any), otherwise None |
| argval - resolved arg value (if known), otherwise same as arg |
| argrepr - human readable description of operation argument |
| offset - start index of operation within bytecode sequence |
| starts_line - line started by this opcode (if any), otherwise None |
| is_jump_target - True if other code jumps to here, otherwise False |
| """ |
| |
| def _disassemble(self, lineno_width=3, mark_as_current=False): |
| """Format instruction details for inclusion in disassembly output |
| |
| *lineno_width* sets the width of the line number field (0 omits it) |
| *mark_as_current* inserts a '-->' marker arrow as part of the line |
| """ |
| fields = [] |
| # Column: Source code line number |
| if lineno_width: |
| if self.starts_line is not None: |
| lineno_fmt = "%%%dd" % lineno_width |
| fields.append(lineno_fmt % self.starts_line) |
| else: |
| fields.append(' ' * lineno_width) |
| # Column: Current instruction indicator |
| if mark_as_current: |
| fields.append('-->') |
| else: |
| fields.append(' ') |
| # Column: Jump target marker |
| if self.is_jump_target: |
| fields.append('>>') |
| else: |
| fields.append(' ') |
| # Column: Instruction offset from start of code sequence |
| fields.append(repr(self.offset).rjust(4)) |
| # Column: Opcode name |
| fields.append(self.opname.ljust(20)) |
| # Column: Opcode argument |
| if self.arg is not None: |
| fields.append(repr(self.arg).rjust(5)) |
| # Column: Opcode argument details |
| if self.argrepr: |
| fields.append('(' + self.argrepr + ')') |
| return ' '.join(fields) |
| |
| |
| def get_instructions(x, *, line_offset=0): |
| """Iterator for the opcodes in methods, functions or code |
| |
| Generates a series of Instruction named tuples giving the details of |
| each operations in the supplied code. |
| |
| The given line offset is added to the 'starts_line' attribute of any |
| instructions that start a new line. |
| """ |
| co = _get_code_object(x) |
| cell_names = co.co_cellvars + co.co_freevars |
| linestarts = dict(findlinestarts(co)) |
| return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names, |
| co.co_consts, cell_names, linestarts, |
| line_offset) |
| |
| def _get_const_info(const_index, const_list): |
| """Helper to get optional details about const references |
| |
| Returns the dereferenced constant and its repr if the constant |
| list is defined. |
| Otherwise returns the constant index and its repr(). |
| """ |
| argval = const_index |
| if const_list is not None: |
| argval = const_list[const_index] |
| return argval, repr(argval) |
| |
| def _get_name_info(name_index, name_list): |
| """Helper to get optional details about named references |
| |
| Returns the dereferenced name as both value and repr if the name |
| list is defined. |
| Otherwise returns the name index and its repr(). |
| """ |
| argval = name_index |
| if name_list is not None: |
| argval = name_list[name_index] |
| argrepr = argval |
| else: |
| argrepr = repr(argval) |
| return argval, argrepr |
| |
| |
| def _get_instructions_bytes(code, varnames=None, names=None, constants=None, |
| cells=None, linestarts=None, line_offset=0): |
| """Iterate over the instructions in a bytecode string. |
| |
| Generates a sequence of Instruction namedtuples giving the details of each |
| opcode. Additional information about the code's runtime environment |
| (e.g. variable names, constants) can be specified using optional |
| arguments. |
| |
| """ |
| labels = findlabels(code) |
| extended_arg = 0 |
| starts_line = None |
| free = None |
| # enumerate() is not an option, since we sometimes process |
| # multiple elements on a single pass through the loop |
| n = len(code) |
| i = 0 |
| while i < n: |
| op = code[i] |
| offset = i |
| if linestarts is not None: |
| starts_line = linestarts.get(i, None) |
| if starts_line is not None: |
| starts_line += line_offset |
| is_jump_target = i in labels |
| i = i+1 |
| arg = None |
| argval = None |
| argrepr = '' |
| if op >= HAVE_ARGUMENT: |
| arg = code[i] + code[i+1]*256 + extended_arg |
| extended_arg = 0 |
| i = i+2 |
| if op == EXTENDED_ARG: |
| extended_arg = arg*65536 |
| # Set argval to the dereferenced value of the argument when |
| # availabe, and argrepr to the string representation of argval. |
| # _disassemble_bytes needs the string repr of the |
| # raw name index for LOAD_GLOBAL, LOAD_CONST, etc. |
| argval = arg |
| if op in hasconst: |
| argval, argrepr = _get_const_info(arg, constants) |
| elif op in hasname: |
| argval, argrepr = _get_name_info(arg, names) |
| elif op in hasjrel: |
| argval = i + arg |
| argrepr = "to " + repr(argval) |
| elif op in haslocal: |
| argval, argrepr = _get_name_info(arg, varnames) |
| elif op in hascompare: |
| argval = cmp_op[arg] |
| argrepr = argval |
| elif op in hasfree: |
| argval, argrepr = _get_name_info(arg, cells) |
| elif op in hasnargs: |
| argrepr = "%d positional, %d keyword pair" % (code[i-2], code[i-1]) |
| yield Instruction(opname[op], op, |
| arg, argval, argrepr, |
| offset, starts_line, is_jump_target) |
| |
| def disassemble(co, lasti=-1, *, file=None): |
| """Disassemble a code object.""" |
| cell_names = co.co_cellvars + co.co_freevars |
| linestarts = dict(findlinestarts(co)) |
| _disassemble_bytes(co.co_code, lasti, co.co_varnames, co.co_names, |
| co.co_consts, cell_names, linestarts, file=file) |
| |
| def _disassemble_bytes(code, lasti=-1, varnames=None, names=None, |
| constants=None, cells=None, linestarts=None, |
| *, file=None): |
| # Omit the line number column entirely if we have no line number info |
| show_lineno = linestarts is not None |
| # TODO?: Adjust width upwards if max(linestarts.values()) >= 1000? |
| lineno_width = 3 if show_lineno else 0 |
| for instr in _get_instructions_bytes(code, varnames, names, |
| constants, cells, linestarts): |
| new_source_line = (show_lineno and |
| instr.starts_line is not None and |
| instr.offset > 0) |
| if new_source_line: |
| print(file=file) |
| is_current_instr = instr.offset == lasti |
| print(instr._disassemble(lineno_width, is_current_instr), file=file) |
| |
| def _disassemble_str(source, *, file=None): |
| """Compile the source string, then disassemble the code object.""" |
| disassemble(_try_compile(source, '<dis>'), file=file) |
| |
| disco = disassemble # XXX For backwards compatibility |
| |
| def findlabels(code): |
| """Detect all offsets in a byte code which are jump targets. |
| |
| Return the list of offsets. |
| |
| """ |
| labels = [] |
| # enumerate() is not an option, since we sometimes process |
| # multiple elements on a single pass through the loop |
| n = len(code) |
| i = 0 |
| while i < n: |
| op = code[i] |
| i = i+1 |
| if op >= HAVE_ARGUMENT: |
| arg = code[i] + code[i+1]*256 |
| i = i+2 |
| label = -1 |
| if op in hasjrel: |
| label = i+arg |
| elif op in hasjabs: |
| label = arg |
| if label >= 0: |
| if label not in labels: |
| labels.append(label) |
| return labels |
| |
| def findlinestarts(code): |
| """Find the offsets in a byte code which are start of lines in the source. |
| |
| Generate pairs (offset, lineno) as described in Python/compile.c. |
| |
| """ |
| byte_increments = list(code.co_lnotab[0::2]) |
| line_increments = list(code.co_lnotab[1::2]) |
| |
| lastlineno = None |
| lineno = code.co_firstlineno |
| addr = 0 |
| for byte_incr, line_incr in zip(byte_increments, line_increments): |
| if byte_incr: |
| if lineno != lastlineno: |
| yield (addr, lineno) |
| lastlineno = lineno |
| addr += byte_incr |
| lineno += line_incr |
| if lineno != lastlineno: |
| yield (addr, lineno) |
| |
| class Bytecode: |
| """The bytecode operations of a piece of code |
| |
| Instantiate this with a function, method, string of code, or a code object |
| (as returned by compile()). |
| |
| Iterating over this yields the bytecode operations as Instruction instances. |
| """ |
| def __init__(self, x): |
| self.codeobj = _get_code_object(x) |
| self.cell_names = self.codeobj.co_cellvars + self.codeobj.co_freevars |
| self.linestarts = dict(findlinestarts(self.codeobj)) |
| self.line_offset = 0 |
| self.original_object = x |
| |
| def __iter__(self): |
| co = self.codeobj |
| return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names, |
| co.co_consts, self.cell_names, |
| self.linestarts, self.line_offset) |
| |
| def __repr__(self): |
| return "{}({!r})".format(self.__class__.__name__, self.original_object) |
| |
| def info(self): |
| """Return formatted information about the code object.""" |
| return _format_code_info(self.codeobj) |
| |
| def show_info(self, *, file=None): |
| """Print the information about the code object as returned by info().""" |
| print(self.info(), file=file) |
| |
| def display_code(self, *, file=None): |
| """Print a formatted view of the bytecode operations. |
| """ |
| co = self.codeobj |
| return _disassemble_bytes(co.co_code, varnames=co.co_varnames, |
| names=co.co_names, constants=co.co_consts, |
| cells=self.cell_names, |
| linestarts=self.linestarts, |
| file=file |
| ) |
| |
| |
| def _test(): |
| """Simple test program to disassemble a file.""" |
| import argparse |
| |
| parser = argparse.ArgumentParser() |
| parser.add_argument('infile', type=argparse.FileType(), nargs='?', default='-') |
| args = parser.parse_args() |
| with args.infile as infile: |
| source = infile.read() |
| code = compile(source, args.infile.name, "exec") |
| dis(code) |
| |
| if __name__ == "__main__": |
| _test() |