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dis.py20.1 KB · 554 lines
"""Disassembler of Python byte code into mnemonics.""" import sysimport typesimport collectionsimport io 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_alldel _opcodes_all _have_code = (types.MethodType, types.FunctionType, types.CodeType,              classmethod, staticmethod, type) FORMAT_VALUE = opmap['FORMAT_VALUE']FORMAT_VALUE_CONVERTERS = (    (None, ''),    (str, 'str'),    (repr, 'repr'),    (ascii, 'ascii'),)MAKE_FUNCTION = opmap['MAKE_FUNCTION']MAKE_FUNCTION_FLAGS = ('defaults', 'kwdefaults', 'annotations', 'closure')  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, depth=None):    """Disassemble classes, methods, functions, and other compiled objects.     With no argument, disassemble the last traceback.     Compiled objects currently include generator objects, async generator    objects, and coroutine objects, all of which store their code object    in a special attribute.    """    if x is None:        distb(file=file)        return    # Extract functions from methods.    if hasattr(x, '__func__'):        x = x.__func__    # Extract compiled code objects from...    if hasattr(x, '__code__'):  # ...a function, or        x = x.__code__    elif hasattr(x, 'gi_code'):  #...a generator object, or        x = x.gi_code    elif hasattr(x, 'ag_code'):  #...an asynchronous generator object, or        x = x.ag_code    elif hasattr(x, 'cr_code'):  #...a coroutine.        x = x.cr_code    # Perform the disassembly.    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, file=file, depth=depth)                except TypeError as msg:                    print("Sorry:", msg, file=file)                print(file=file)    elif hasattr(x, 'co_code'): # Code object        _disassemble_recursive(x, file=file, depth=depth)    elif isinstance(x, (bytes, bytearray)): # Raw bytecode        _disassemble_bytes(x, file=file)    elif isinstance(x, str):    # Source code        _disassemble_str(x, file=file, depth=depth)    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") from None        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",   128: "COROUTINE",   256: "ITERABLE_COROUTINE",   512: "ASYNC_GENERATOR",} 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, compiled or raw code objects, and strings."""    # Extract functions from methods.    if hasattr(x, '__func__'):        x = x.__func__    # Extract compiled code objects from...    if hasattr(x, '__code__'):  # ...a function, or        x = x.__code__    elif hasattr(x, 'gi_code'):  #...a generator object, or        x = x.gi_code    elif hasattr(x, 'ag_code'):  #...an asynchronous generator object, or        x = x.ag_code    elif hasattr(x, 'cr_code'):  #...a coroutine.        x = x.cr_code    # Handle source code.    if isinstance(x, str):        x = _try_compile(x, "<disassembly>")    # By now, if we don't have a code object, we can't disassemble x.    if hasattr(x, 'co_code'):        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("Positional-only arguments: %s" % co.co_posonlyargcount)    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") _Instruction.opname.__doc__ = "Human readable name for operation"_Instruction.opcode.__doc__ = "Numeric code for operation"_Instruction.arg.__doc__ = "Numeric argument to operation (if any), otherwise None"_Instruction.argval.__doc__ = "Resolved arg value (if known), otherwise same as arg"_Instruction.argrepr.__doc__ = "Human readable description of operation argument"_Instruction.offset.__doc__ = "Start index of operation within bytecode sequence"_Instruction.starts_line.__doc__ = "Line started by this opcode (if any), otherwise None"_Instruction.is_jump_target.__doc__ = "True if other code jumps to here, otherwise False" _OPNAME_WIDTH = 20_OPARG_WIDTH = 5 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, offset_width=4):        """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        *offset_width* sets the width of the instruction offset field        """        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(offset_width))        # Column: Opcode name        fields.append(self.opname.ljust(_OPNAME_WIDTH))        # Column: Opcode argument        if self.arg is not None:            fields.append(repr(self.arg).rjust(_OPARG_WIDTH))            # Column: Opcode argument details            if self.argrepr:                fields.append('(' + self.argrepr + ')')        return ' '.join(fields).rstrip()  def get_instructions(x, *, first_line=None):    """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.     If *first_line* is not None, it indicates the line number that should    be reported for the first source line in the disassembled code.    Otherwise, the source line information (if any) is taken directly from    the disassembled code object.    """    co = _get_code_object(x)    cell_names = co.co_cellvars + co.co_freevars    linestarts = dict(findlinestarts(co))    if first_line is not None:        line_offset = first_line - co.co_firstlineno    else:        line_offset = 0    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)    starts_line = None    for offset, op, arg in _unpack_opargs(code):        if linestarts is not None:            starts_line = linestarts.get(offset, None)            if starts_line is not None:                starts_line += line_offset        is_jump_target = offset in labels        argval = None        argrepr = ''        if arg is not None:            #  Set argval to the dereferenced value of the argument when            #  available, 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 = offset + 2 + 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 == FORMAT_VALUE:                argval, argrepr = FORMAT_VALUE_CONVERTERS[arg & 0x3]                argval = (argval, bool(arg & 0x4))                if argval[1]:                    if argrepr:                        argrepr += ', '                    argrepr += 'with format'            elif op == MAKE_FUNCTION:                argrepr = ', '.join(s for i, s in enumerate(MAKE_FUNCTION_FLAGS)                                    if arg & (1<<i))        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_recursive(co, *, file=None, depth=None):    disassemble(co, file=file)    if depth is None or depth > 0:        if depth is not None:            depth = depth - 1        for x in co.co_consts:            if hasattr(x, 'co_code'):                print(file=file)                print("Disassembly of %r:" % (x,), file=file)                _disassemble_recursive(x, file=file, depth=depth) def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,                       constants=None, cells=None, linestarts=None,                       *, file=None, line_offset=0):    # Omit the line number column entirely if we have no line number info    show_lineno = linestarts is not None    if show_lineno:        maxlineno = max(linestarts.values()) + line_offset        if maxlineno >= 1000:            lineno_width = len(str(maxlineno))        else:            lineno_width = 3    else:        lineno_width = 0    maxoffset = len(code) - 2    if maxoffset >= 10000:        offset_width = len(str(maxoffset))    else:        offset_width = 4    for instr in _get_instructions_bytes(code, varnames, names,                                         constants, cells, linestarts,                                         line_offset=line_offset):        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, offset_width),              file=file) def _disassemble_str(source, **kwargs):    """Compile the source string, then disassemble the code object."""    _disassemble_recursive(_try_compile(source, '<dis>'), **kwargs) disco = disassemble                     # XXX For backwards compatibility def _unpack_opargs(code):    extended_arg = 0    for i in range(0, len(code), 2):        op = code[i]        if op >= HAVE_ARGUMENT:            arg = code[i+1] | extended_arg            extended_arg = (arg << 8) if op == EXTENDED_ARG else 0        else:            arg = None        yield (i, op, arg) def findlabels(code):    """Detect all offsets in a byte code which are jump targets.     Return the list of offsets.     """    labels = []    for offset, op, arg in _unpack_opargs(code):        if arg is not None:            if op in hasjrel:                label = offset + 2 + arg            elif op in hasjabs:                label = arg            else:                continue            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 = code.co_lnotab[0::2]    line_increments = code.co_lnotab[1::2]    bytecode_len = len(code.co_code)     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            if addr >= bytecode_len:                # The rest of the lnotab byte offsets are past the end of                # the bytecode, so the lines were optimized away.                return        if line_incr >= 0x80:            # line_increments is an array of 8-bit signed integers            line_incr -= 0x100        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, other compiled object, 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, *, first_line=None, current_offset=None):        self.codeobj = co = _get_code_object(x)        if first_line is None:            self.first_line = co.co_firstlineno            self._line_offset = 0        else:            self.first_line = first_line            self._line_offset = first_line - co.co_firstlineno        self._cell_names = co.co_cellvars + co.co_freevars        self._linestarts = dict(findlinestarts(co))        self._original_object = x        self.current_offset = current_offset     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,                                       line_offset=self._line_offset)     def __repr__(self):        return "{}({!r})".format(self.__class__.__name__,                                 self._original_object)     @classmethod    def from_traceback(cls, tb):        """ Construct a Bytecode from the given traceback """        while tb.tb_next:            tb = tb.tb_next        return cls(tb.tb_frame.f_code, current_offset=tb.tb_lasti)     def info(self):        """Return formatted information about the code object."""        return _format_code_info(self.codeobj)     def dis(self):        """Return a formatted view of the bytecode operations."""        co = self.codeobj        if self.current_offset is not None:            offset = self.current_offset        else:            offset = -1        with io.StringIO() as output:            _disassemble_bytes(co.co_code, varnames=co.co_varnames,                               names=co.co_names, constants=co.co_consts,                               cells=self._cell_names,                               linestarts=self._linestarts,                               line_offset=self._line_offset,                               file=output,                               lasti=offset)            return output.getvalue()  def _test():    """Simple test program to disassemble a file."""    import argparse     parser = argparse.ArgumentParser()    parser.add_argument('infile', type=argparse.FileType('rb'), 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()