/pypy/interpreter/error.py

import os, sys
from pypy.rlib import jit
from pypy.rlib.objectmodel import we_are_translated
from errno import EINTR

AUTO_DEBUG = os.getenv('PYPY_DEBUG')
RECORD_INTERPLEVEL_TRACEBACK = True


class OperationError(Exception):
    """Interpreter-level exception that signals an exception that should be
    sent to the application level.

    OperationError instances have three attributes (and no .args),
    w_type, _w_value and _application_traceback, which contain the wrapped
    type and value describing the exception, and a chained list of
    PyTraceback objects making the application-level traceback.
    """

    _w_value = None
    _application_traceback = None

    def __init__(self, w_type, w_value, tb=None):
        assert w_type is not None
        self.setup(w_type)
        self._w_value = w_value
        self._application_traceback = tb

    def setup(self, w_type):
        self.w_type = w_type
        if not we_are_translated():
            self.debug_excs = []

    def clear(self, space):
        # for sys.exc_clear()
        self.w_type = space.w_None
        self._w_value = space.w_None
        self._application_traceback = None
        if not we_are_translated():
            del self.debug_excs[:]

    def match(self, space, w_check_class):
        "Check if this application-level exception matches 'w_check_class'."
        return space.exception_match(self.w_type, w_check_class)

    def async(self, space):
        "Check if this is an exception that should better not be caught."
        return (self.match(space, space.w_SystemExit) or
                self.match(space, space.w_KeyboardInterrupt))

    def __str__(self):
        "NOT_RPYTHON: Convenience for tracebacks."
        s = self._w_value
        if self.__class__ is not OperationError and s is None:
            s = self._compute_value()
        return '[%s: %s]' % (self.w_type, s)

    def errorstr(self, space, use_repr=False):
        "The exception class and value, as a string."
        w_value = self.get_w_value(space)
        if space is None:
            # this part NOT_RPYTHON
            exc_typename = str(self.w_type)
            exc_value    = str(w_value)
        else:
            w = space.wrap
            if space.is_w(space.type(self.w_type), space.w_str):
                exc_typename = space.str_w(self.w_type)
            else:
                exc_typename = space.str_w(
                    space.getattr(self.w_type, w('__name__')))
            if space.is_w(w_value, space.w_None):
                exc_value = ""
            else:
                try:
                    if use_repr:
                        exc_value = space.str_w(space.repr(w_value))
                    else:
                        exc_value = space.str_w(space.str(w_value))
                except OperationError:
                    # oups, cannot __str__ the exception object
                    exc_value = "<oups, exception object itself cannot be str'd>"
        if not exc_value:
            return exc_typename
        else:
            return '%s: %s' % (exc_typename, exc_value)

    def record_interpreter_traceback(self):
        """Records the current traceback inside the interpreter.
        This traceback is only useful to debug the interpreter, not the
        application."""
        if not we_are_translated():
            if RECORD_INTERPLEVEL_TRACEBACK:
                self.debug_excs.append(sys.exc_info())

    def print_application_traceback(self, space, file=None):
        "NOT_RPYTHON: Dump a standard application-level traceback."
        if file is None: file = sys.stderr
        self.print_app_tb_only(file)
        print >> file, self.errorstr(space)

    def print_app_tb_only(self, file):
        "NOT_RPYTHON"
        tb = self._application_traceback
        if tb:
            import linecache
            print >> file, "Traceback (application-level):"
            while tb is not None:
                co = tb.frame.pycode
                lineno = tb.get_lineno()
                fname = co.co_filename
                if fname.startswith('<inline>\n'):
                    lines = fname.split('\n')
                    fname = lines[0].strip()
                    try:
                        l = lines[lineno]
                    except IndexError:
                        l = ''
                else:
                    l = linecache.getline(fname, lineno)
                print >> file, "  File \"%s\"," % fname,
                print >> file, "line", lineno, "in", co.co_name
                if l:
                    if l.endswith('\n'):
                        l = l[:-1]
                    l = "    " + l.lstrip()
                    print >> file, l
                tb = tb.next

    def print_detailed_traceback(self, space=None, file=None):
        """NOT_RPYTHON: Dump a nice detailed interpreter- and
        application-level traceback, useful to debug the interpreter."""
        import traceback, cStringIO
        if file is None: file = sys.stderr
        f = cStringIO.StringIO()
        for i in range(len(self.debug_excs)-1, -1, -1):
            print >> f, "Traceback (interpreter-level):"
            traceback.print_tb(self.debug_excs[i][2], file=f)
        f.seek(0)
        debug_print(''.join(['|| ' + line for line in f.readlines()]), file)
        if self.debug_excs:
            from pypy.tool import tb_server
            tb_server.publish_exc(self.debug_excs[-1])
        self.print_app_tb_only(file)
        print >> file, '(application-level)', self.errorstr(space)
        if AUTO_DEBUG:
            import debug
            debug.fire(self)

    @jit.unroll_safe
    def normalize_exception(self, space):
        """Normalize the OperationError.  In other words, fix w_type and/or
        w_value to make sure that the __class__ of w_value is exactly w_type.
        """
        #
        # This method covers all ways in which the Python statement
        # "raise X, Y" can produce a valid exception type and instance.
        #
        # In the following table, 'Class' means a subclass of BaseException
        # and 'inst' is an instance of either 'Class' or a subclass of it.
        # Or 'Class' can also be an old-style class and 'inst' an old-style
        # instance of it.
        #
        # The flow object space only deals with non-advanced case. Old-style
        # classes and instances *are* advanced.
        #
        #  input (w_type, w_value)... becomes...                advanced case?
        # ---------------------------------------------------------------------
        #  (tuple, w_value)           (tuple[0], w_value)             yes
        #  (Class, None)              (Class, Class())                no
        #  (Class, inst)              (inst.__class__, inst)          no
        #  (Class, tuple)             (Class, Class(*tuple))          yes
        #  (Class, x)                 (Class, Class(x))               no
        #  ("string", ...)            ("string", ...)              deprecated
        #  (inst, None)               (inst.__class__, inst)          no
        #
        w_type  = self.w_type
        w_value = self.get_w_value(space)
        while space.is_true(space.isinstance(w_type, space.w_tuple)):
            w_type = space.getitem(w_type, space.wrap(0))

        if space.exception_is_valid_obj_as_class_w(w_type):
            # this is for all cases of the form (Class, something)
            if space.is_w(w_value, space.w_None):
                # raise Type: we assume we have to instantiate Type
                w_value = space.call_function(w_type)
                w_type = self._exception_getclass(space, w_value)
            else:
                w_valuetype = space.exception_getclass(w_value)
                if space.exception_issubclass_w(w_valuetype, w_type):
                    # raise Type, Instance: let etype be the exact type of value
                    w_type = w_valuetype
                else:
                    if space.is_true(space.isinstance(w_value, space.w_tuple)):
                        # raise Type, tuple: assume the tuple contains the
                        #                    constructor args
                        w_value = space.call(w_type, w_value)
                    else:
                        # raise Type, X: assume X is the constructor argument
                        w_value = space.call_function(w_type, w_value)
                    w_type = self._exception_getclass(space, w_value)

        else:
            # the only case left here is (inst, None), from a 'raise inst'.
            w_inst = w_type
            w_instclass = self._exception_getclass(space, w_inst)
            if not space.is_w(w_value, space.w_None):
                raise OperationError(space.w_TypeError,
                                     space.wrap("instance exception may not "
                                                "have a separate value"))
            w_value = w_inst
            w_type = w_instclass

        self.w_type   = w_type
        self._w_value = w_value

    def _exception_getclass(self, space, w_inst):
        w_type = space.exception_getclass(w_inst)
        if not space.exception_is_valid_class_w(w_type):
            typename = w_type.getname(space)
            msg = ("exceptions must be old-style classes or derived "
                   "from BaseException, not %s")
            raise operationerrfmt(space.w_TypeError, msg, typename)
        return w_type

    def write_unraisable(self, space, where, w_object=None):
        if w_object is None:
            objrepr = ''
        else:
            try:
                objrepr = space.str_w(space.repr(w_object))
            except OperationError:
                objrepr = '?'
        msg = 'Exception %s in %s%s ignored\n' % (
            self.errorstr(space, use_repr=True), where, objrepr)
        try:
            space.call_method(space.sys.get('stderr'), 'write', space.wrap(msg))
        except OperationError:
            pass   # ignored

    def get_w_value(self, space):
        w_value = self._w_value
        if w_value is None:
            value = self._compute_value()
            self._w_value = w_value = space.wrap(value)
        return w_value

    def _compute_value(self):
        raise NotImplementedError

    def get_traceback(self):
        """Calling this marks the PyTraceback as escaped, i.e. it becomes
        accessible and inspectable by app-level Python code.  For the JIT.
        Note that this has no effect if there are already several traceback
        frames recorded, because in this case they are already marked as
        escaping by executioncontext.leave() being called with
        got_exception=True.
        """
        from pypy.interpreter.pytraceback import PyTraceback
        tb = self._application_traceback
        if tb is not None and isinstance(tb, PyTraceback):
            tb.frame.mark_as_escaped()
        return tb

    def set_traceback(self, traceback):
        """Set the current traceback.  It should either be a traceback
        pointing to some already-escaped frame, or a traceback for the
        current frame.  To support the latter case we do not mark the
        frame as escaped.  The idea is that it will be marked as escaping
        only if the exception really propagates out of this frame, by
        executioncontext.leave() being called with got_exception=True.
        """
        self._application_traceback = traceback

# ____________________________________________________________
# optimization only: avoid the slowest operation -- the string
# formatting with '%' -- in the common case were we don't
# actually need the message.  Only supports %s and %d.

_fmtcache = {}
_fmtcache2 = {}

def decompose_valuefmt(valuefmt):
    """Returns a tuple of string parts extracted from valuefmt,
    and a tuple of format characters."""
    formats = []
    parts = valuefmt.split('%')
    i = 1
    while i < len(parts):
        if parts[i].startswith('s') or parts[i].startswith('d'):
            formats.append(parts[i][0])
            parts[i] = parts[i][1:]
            i += 1
        elif parts[i] == '':    # support for '%%'
            parts[i-1] += '%' + parts[i+1]
            del parts[i:i+2]
        else:
            raise ValueError("invalid format string (only %s or %d supported)")
    assert len(formats) > 0, "unsupported: no % command found"
    return tuple(parts), tuple(formats)

def get_operrcls2(valuefmt):
    strings, formats = decompose_valuefmt(valuefmt)
    assert len(strings) == len(formats) + 1
    try:
        OpErrFmt = _fmtcache2[formats]
    except KeyError:
        from pypy.rlib.unroll import unrolling_iterable
        attrs = ['x%d' % i for i in range(len(formats))]
        entries = unrolling_iterable(enumerate(attrs))
        #
        class OpErrFmt(OperationError):
            def __init__(self, w_type, strings, *args):
                self.setup(w_type)
                assert len(args) == len(strings) - 1
                self.xstrings = strings
                for i, attr in entries:
                    setattr(self, attr, args[i])
                assert w_type is not None
            def _compute_value(self):
                lst = [None] * (len(formats) + len(formats) + 1)
                for i, attr in entries:
                    string = self.xstrings[i]
                    value = getattr(self, attr)
                    lst[i+i] = string
                    lst[i+i+1] = str(value)
                lst[-1] = self.xstrings[-1]
                return ''.join(lst)
        #
        _fmtcache2[formats] = OpErrFmt
    return OpErrFmt, strings

def get_operationerr_class(valuefmt):
    try:
        result = _fmtcache[valuefmt]
    except KeyError:
        result = _fmtcache[valuefmt] = get_operrcls2(valuefmt)
    return result
get_operationerr_class._annspecialcase_ = 'specialize:memo'

def operationerrfmt(w_type, valuefmt, *args):
    """Equivalent to OperationError(w_type, space.wrap(valuefmt % args)).
    More efficient in the (common) case where the value is not actually
    needed."""
    OpErrFmt, strings = get_operationerr_class(valuefmt)
    return OpErrFmt(w_type, strings, *args)
operationerrfmt._annspecialcase_ = 'specialize:arg(1)'

# ____________________________________________________________

# Utilities
from pypy.tool.ansi_print import ansi_print

def debug_print(text, file=None, newline=True):
    # 31: ANSI color code "red"
    ansi_print(text, esc="31", file=file, newline=newline)

try:
    WindowsError
except NameError:
    _WINDOWS = False
else:
    _WINDOWS = True

    def wrap_windowserror(space, e, w_filename=None):
        from pypy.rlib import rwin32

        winerror = e.winerror
        try:
            msg = rwin32.FormatError(winerror)
        except ValueError:
            msg = 'Windows Error %d' % winerror
        exc = space.w_WindowsError
        if w_filename is not None:
            w_error = space.call_function(exc, space.wrap(winerror),
                                          space.wrap(msg), w_filename)
        else:
            w_error = space.call_function(exc, space.wrap(winerror),
                                          space.wrap(msg))
        return OperationError(exc, w_error)

def wrap_oserror2(space, e, w_filename=None, exception_name='w_OSError',
                  w_exception_class=None):
    assert isinstance(e, OSError)

    if _WINDOWS and isinstance(e, WindowsError):
        return wrap_windowserror(space, e, w_filename)

    errno = e.errno

    if errno == EINTR:
        space.getexecutioncontext().checksignals()

    try:
        msg = os.strerror(errno)
    except ValueError:
        msg = 'error %d' % errno
    if w_exception_class is None:
        exc = getattr(space, exception_name)
    else:
        exc = w_exception_class
    if w_filename is not None:
        w_error = space.call_function(exc, space.wrap(errno),
                                      space.wrap(msg), w_filename)
    else:
        w_error = space.call_function(exc, space.wrap(errno),
                                      space.wrap(msg))
    return OperationError(exc, w_error)
wrap_oserror2._annspecialcase_ = 'specialize:arg(3)'

def wrap_oserror(space, e, filename=None, exception_name='w_OSError',
                 w_exception_class=None):
    if filename is not None:
        return wrap_oserror2(space, e, space.wrap(filename),
                             exception_name=exception_name,
                             w_exception_class=w_exception_class)
    else:
        return wrap_oserror2(space, e, None,
                             exception_name=exception_name,
                             w_exception_class=w_exception_class)
wrap_oserror._annspecialcase_ = 'specialize:arg(3)'

def exception_from_errno(space, w_type):
    from pypy.rlib.rposix import get_errno

    errno = get_errno()
    msg = os.strerror(errno)
    w_error = space.call_function(w_type, space.wrap(errno), space.wrap(msg))
    return OperationError(w_type, w_error)

def new_exception_class(space, name, w_bases=None, w_dict=None):
    """Create a new exception type.
    @param name: the name of the type.
    @param w_bases: Either an exception type, or a wrapped tuple of
                    exception types.  default is space.w_Exception.
    @param w_dict: an optional dictionary to populate the class __dict__.
    """
    if '.' in name:
        module, name = name.rsplit('.', 1)
    else:
        module = None
    if w_bases is None:
        w_bases = space.newtuple([space.w_Exception])
    elif not space.isinstance_w(w_bases, space.w_tuple):
        w_bases = space.newtuple([w_bases])
    if w_dict is None:
        w_dict = space.newdict()
    w_exc = space.call_function(
        space.w_type, space.wrap(name), w_bases, w_dict)
    if module:
        space.setattr(w_exc, space.wrap("__module__"), space.wrap(module))
    return w_exc

def typed_unwrap_error_msg(space, expected, w_obj):
    type_name = space.type(w_obj).getname(space)
    return space.wrap("expected %s, got %s object" % (expected, type_name))