def Run(self, cmd_val):
        # type: (cmd_value__Argv) -> int
        """
    printf: printf [-v var] format [argument ...]
    """
        arg_r = args.Reader(cmd_val.argv, spids=cmd_val.arg_spids)
        arg_r.Next()  # skip argv[0]
        arg = PRINTF_SPEC.Parse(arg_r)

        fmt, fmt_spid = arg_r.ReadRequired2('requires a format string')
        varargs, spids = arg_r.Rest2()

        #log('fmt %s', fmt)
        #log('vals %s', vals)

        arena = self.parse_ctx.arena
        if fmt in self.parse_cache:
            parts = self.parse_cache[fmt]
        else:
            line_reader = reader.StringLineReader(fmt, arena)
            # TODO: Make public
            lexer = self.parse_ctx._MakeLexer(line_reader)
            p = _FormatStringParser(lexer)
            arena.PushSource(source.ArgvWord(fmt_spid))
            try:
                parts = p.Parse()
            except error.Parse as e:
                self.errfmt.PrettyPrintError(e)
                return 2  # parse error
            finally:
                arena.PopSource()

            self.parse_cache[fmt] = parts

        if 0:
            print()
            for part in parts:
                part.PrettyPrint()
                print()

        out = []
        arg_index = 0
        num_args = len(varargs)
        backslash_c = False

        while True:
            for part in parts:
                if isinstance(part, printf_part.Literal):
                    token = part.token
                    if token.id == Id.Format_EscapedPercent:
                        s = '%'
                    else:
                        s = word_compile.EvalCStringToken(token.id, token.val)
                    out.append(s)

                elif isinstance(part, printf_part.Percent):
                    flags = None
                    if len(part.flags) > 0:
                        flags = ''
                        for flag_token in part.flags:
                            flags += flag_token.val

                    width = None
                    if part.width:
                        if part.width.id in (Id.Format_Num, Id.Format_Zero):
                            width = part.width.val
                            width_spid = part.width.span_id
                        elif part.width.id == Id.Format_Star:
                            if arg_index < num_args:
                                width = varargs[arg_index]
                                width_spid = spids[arg_index]
                                arg_index += 1
                            else:
                                width = ''
                                width_spid = runtime.NO_SPID
                        else:
                            raise AssertionError()

                        try:
                            width = int(width)
                        except ValueError:
                            if width_spid == runtime.NO_SPID:
                                width_spid = part.width.span_id
                            self.errfmt.Print(
                                "printf got invalid number %r for the width",
                                s,
                                span_id=width_spid)
                            return 1

                    precision = None
                    if part.precision:
                        if part.precision.id == Id.Format_Dot:
                            precision = '0'
                            precision_spid = part.precision.span_id
                        elif part.precision.id in (Id.Format_Num,
                                                   Id.Format_Zero):
                            precision = part.precision.val
                            precision_spid = part.precision.span_id
                        elif part.precision.id == Id.Format_Star:
                            if arg_index < num_args:
                                precision = varargs[arg_index]
                                precision_spid = spids[arg_index]
                                arg_index += 1
                            else:
                                precision = ''
                                precision_spid = runtime.NO_SPID
                        else:
                            raise AssertionError()

                        try:
                            precision = int(precision)
                        except ValueError:
                            if precision_spid == runtime.NO_SPID:
                                precision_spid = part.precision.span_id
                            self.errfmt.Print(
                                "printf got invalid number %r for the precision",
                                s,
                                span_id=precision_spid)
                            return 1

                    if arg_index < num_args:
                        s = varargs[arg_index]
                        word_spid = spids[arg_index]
                        arg_index += 1
                    else:
                        s = ''
                        word_spid = runtime.NO_SPID

                    typ = part.type.val
                    if typ == 's':
                        if precision is not None:
                            s = s[:precision]  # truncate

                    elif typ == 'q':
                        s = qsn.maybe_shell_encode(s)

                    elif typ == 'b':
                        # Process just like echo -e, except \c handling is simpler.

                        parts = []  # type: List[str]
                        lex = match.EchoLexer(s)
                        while True:
                            id_, value = lex.Next()
                            if id_ == Id.Eol_Tok:  # Note: This is really a NUL terminator
                                break

                            p = word_compile.EvalCStringToken(id_, value)

                            # Unusual behavior: '\c' aborts processing!
                            if p is None:
                                backslash_c = True
                                break

                            parts.append(p)
                        s = ''.join(parts)

                    elif typ in 'diouxX' or part.type.id == Id.Format_Time:
                        try:
                            d = int(s)
                        except ValueError:
                            if len(s) >= 1 and s[0] in '\'"':
                                # TODO: utf-8 decode s[1:] to be more correct.  Probably
                                # depends on issue #366, a utf-8 library.
                                # Note: len(s) == 1 means there is a NUL (0) after the quote..
                                d = ord(s[1]) if len(s) >= 2 else 0
                            elif part.type.id == Id.Format_Time and len(
                                    s) == 0 and word_spid == runtime.NO_SPID:
                                # Note: No argument means -1 for %(...)T as in Bash Reference
                                #   Manual 4.2 "If no argument is specified, conversion behaves
                                #   as if -1 had been given."
                                d = -1
                            else:
                                # This works around the fact that in the arg recycling case, you have no spid.
                                if word_spid == runtime.NO_SPID:
                                    self.errfmt.Print(
                                        "printf got invalid number %r for this substitution",
                                        s,
                                        span_id=part.type.span_id)
                                else:
                                    self.errfmt.Print(
                                        "printf got invalid number %r",
                                        s,
                                        span_id=word_spid)

                                return 1

                        if typ in 'di':
                            s = str(d)
                        elif typ in 'ouxX':
                            if d < 0:
                                e_die(
                                    "Can't format negative number %d with %%%s",
                                    d,
                                    typ,
                                    span_id=part.type.span_id)
                            if typ == 'u':
                                s = str(d)
                            elif typ == 'o':
                                s = '%o' % d
                            elif typ == 'x':
                                s = '%x' % d
                            elif typ == 'X':
                                s = '%X' % d
                        elif part.type.id == Id.Format_Time:
                            # %(...)T

                            # Initialize timezone:
                            #   `localtime' uses the current timezone information initialized
                            #   by `tzset'.  The function `tzset' refers to the environment
                            #   variable `TZ'.  When the exported variable `TZ' is present,
                            #   its value should be reflected in the real environment
                            #   variable `TZ' before call of `tzset'.
                            #
                            # Note: unlike LANG, TZ doesn't seem to change behavior if it's
                            # not exported.
                            #
                            # TODO: In Oil, provide an API that doesn't rely on libc's
                            # global state.

                            tzcell = self.mem.GetCell('TZ')
                            if tzcell and tzcell.exported and tzcell.val.tag_(
                            ) == value_e.Str:
                                tzval = cast(value__Str, tzcell.val)
                                posix.putenv('TZ', tzval.s)

                            time.tzset()

                            # Handle special values:
                            #   User can specify two special values -1 and -2 as in Bash
                            #   Reference Manual 4.2: "Two special argument values may be
                            #   used: -1 represents the current time, and -2 represents the
                            #   time the shell was invoked." from
                            #   https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html#index-printf
                            if d == -1:  # the current time
                                d = time.time()
                            elif d == -2:  # the shell start time
                                d = shell_start_time

                            s = time.strftime(typ[1:-2], time.localtime(d))
                            if precision is not None:
                                s = s[:precision]  # truncate

                        else:
                            raise AssertionError()

                    else:
                        raise AssertionError()

                    if width is not None:
                        if flags:
                            if '-' in flags:
                                s = s.ljust(width, ' ')
                            elif '0' in flags:
                                s = s.rjust(width, '0')
                            else:
                                pass
                        else:
                            s = s.rjust(width, ' ')

                    out.append(s)

                else:
                    raise AssertionError()

                if backslash_c:  # 'printf %b a\cb xx' - \c terminates processing!
                    break

            if arg_index >= num_args:
                break
            # Otherwise there are more args.  So cycle through the loop once more to
            # implement the 'arg recycling' behavior.

        result = ''.join(out)
        if arg.v:
            var_name = arg.v

            # Notes:
            # - bash allows a[i] here (as in unset and ${!x}), but we haven't
            # implemented it.
            # - TODO: get the span_id for arg.v!
            if not match.IsValidVarName(var_name):
                raise error.Usage('got invalid variable name %r' % var_name)
            state.SetStringDynamic(self.mem, var_name, result)
        else:
            sys.stdout.write(result)
        return 0
Beispiel #2
0
    def Run(self, cmd_val):
        # type: (cmd_value__Argv) -> int
        """
    printf: printf [-v var] format [argument ...]
    """
        attrs, arg_r = flag_spec.ParseCmdVal('printf', cmd_val)
        arg = arg_types.printf(attrs.attrs)

        fmt, fmt_spid = arg_r.ReadRequired2('requires a format string')
        varargs, spids = arg_r.Rest2()

        #log('fmt %s', fmt)
        #log('vals %s', vals)

        arena = self.parse_ctx.arena
        if fmt in self.parse_cache:
            parts = self.parse_cache[fmt]
        else:
            line_reader = reader.StringLineReader(fmt, arena)
            # TODO: Make public
            lexer = self.parse_ctx._MakeLexer(line_reader)
            parser = _FormatStringParser(lexer)

            with alloc.ctx_Location(arena, source.ArgvWord(fmt_spid)):
                try:
                    parts = parser.Parse()
                except error.Parse as e:
                    self.errfmt.PrettyPrintError(e)
                    return 2  # parse error

            self.parse_cache[fmt] = parts

        if 0:
            print()
            for part in parts:
                part.PrettyPrint()
                print()

        out = []  # type: List[str]
        arg_index = 0
        num_args = len(varargs)
        backslash_c = False

        while True:
            for part in parts:
                UP_part = part
                if part.tag_() == printf_part_e.Literal:
                    part = cast(printf_part__Literal, UP_part)
                    token = part.token
                    if token.id == Id.Format_EscapedPercent:
                        s = '%'
                    else:
                        s = word_compile.EvalCStringToken(token)
                    out.append(s)

                elif part.tag_() == printf_part_e.Percent:
                    part = cast(printf_part__Percent, UP_part)
                    flags = []  # type: List[str]
                    if len(part.flags) > 0:
                        for flag_token in part.flags:
                            flags.append(flag_token.val)

                    width = -1  # nonexistent
                    if part.width:
                        if part.width.id in (Id.Format_Num, Id.Format_Zero):
                            width_str = part.width.val
                            width_spid = part.width.span_id
                        elif part.width.id == Id.Format_Star:
                            if arg_index < num_args:
                                width_str = varargs[arg_index]
                                width_spid = spids[arg_index]
                                arg_index += 1
                            else:
                                width_str = ''  # invalid
                                width_spid = runtime.NO_SPID
                        else:
                            raise AssertionError()

                        try:
                            width = int(width_str)
                        except ValueError:
                            if width_spid == runtime.NO_SPID:
                                width_spid = part.width.span_id
                            self.errfmt.Print_("printf got invalid width %r" %
                                               width_str,
                                               span_id=width_spid)
                            return 1

                    precision = -1  # nonexistent
                    if part.precision:
                        if part.precision.id == Id.Format_Dot:
                            precision_str = '0'
                            precision_spid = part.precision.span_id
                        elif part.precision.id in (Id.Format_Num,
                                                   Id.Format_Zero):
                            precision_str = part.precision.val
                            precision_spid = part.precision.span_id
                        elif part.precision.id == Id.Format_Star:
                            if arg_index < num_args:
                                precision_str = varargs[arg_index]
                                precision_spid = spids[arg_index]
                                arg_index += 1
                            else:
                                precision_str = ''
                                precision_spid = runtime.NO_SPID
                        else:
                            raise AssertionError()

                        try:
                            precision = int(precision_str)
                        except ValueError:
                            if precision_spid == runtime.NO_SPID:
                                precision_spid = part.precision.span_id
                            self.errfmt.Print_(
                                'printf got invalid precision %r' %
                                precision_str,
                                span_id=precision_spid)
                            return 1

                    #log('index=%d n=%d', arg_index, num_args)
                    if arg_index < num_args:
                        s = varargs[arg_index]
                        word_spid = spids[arg_index]
                        arg_index += 1
                    else:
                        s = ''
                        word_spid = runtime.NO_SPID

                    typ = part.type.val
                    if typ == 's':
                        if precision >= 0:
                            s = s[:precision]  # truncate

                    elif typ == 'q':
                        s = qsn.maybe_shell_encode(s)

                    elif typ == 'b':
                        # Process just like echo -e, except \c handling is simpler.

                        c_parts = []  # type: List[str]
                        lex = match.EchoLexer(s)
                        while True:
                            id_, tok_val = lex.Next()
                            if id_ == Id.Eol_Tok:  # Note: This is really a NUL terminator
                                break

                            # TODO: add span_id from argv
                            tok = Token(id_, runtime.NO_SPID, tok_val)
                            p = word_compile.EvalCStringToken(tok)

                            # Unusual behavior: '\c' aborts processing!
                            if p is None:
                                backslash_c = True
                                break

                            c_parts.append(p)
                        s = ''.join(c_parts)

                    elif typ in 'diouxX' or part.type.id == Id.Format_Time:
                        try:
                            d = int(s)
                        except ValueError:
                            if len(s) >= 1 and s[0] in '\'"':
                                # TODO: utf-8 decode s[1:] to be more correct.  Probably
                                # depends on issue #366, a utf-8 library.
                                # Note: len(s) == 1 means there is a NUL (0) after the quote..
                                d = ord(s[1]) if len(s) >= 2 else 0
                            elif part.type.id == Id.Format_Time and len(
                                    s) == 0 and word_spid == runtime.NO_SPID:
                                # Note: No argument means -1 for %(...)T as in Bash Reference
                                #   Manual 4.2 "If no argument is specified, conversion behaves
                                #   as if -1 had been given."
                                d = -1
                            else:
                                if word_spid == runtime.NO_SPID:
                                    # Blame the format string
                                    blame_spid = part.type.span_id
                                else:
                                    blame_spid = word_spid
                                self.errfmt.Print_(
                                    'printf expected an integer, got %r' % s,
                                    span_id=blame_spid)
                                return 1

                        if typ in 'di':
                            s = str(d)
                        elif typ in 'ouxX':
                            if d < 0:
                                e_die(
                                    "Can't format negative number %d with %%%s",
                                    d,
                                    typ,
                                    span_id=part.type.span_id)
                            if typ == 'u':
                                s = str(d)
                            elif typ == 'o':
                                s = mylib.octal(d)
                            elif typ == 'x':
                                s = mylib.hex_lower(d)
                            elif typ == 'X':
                                s = mylib.hex_upper(d)

                        elif part.type.id == Id.Format_Time:
                            # %(...)T

                            # Initialize timezone:
                            #   `localtime' uses the current timezone information initialized
                            #   by `tzset'.  The function `tzset' refers to the environment
                            #   variable `TZ'.  When the exported variable `TZ' is present,
                            #   its value should be reflected in the real environment
                            #   variable `TZ' before call of `tzset'.
                            #
                            # Note: unlike LANG, TZ doesn't seem to change behavior if it's
                            # not exported.
                            #
                            # TODO: In Oil, provide an API that doesn't rely on libc's
                            # global state.

                            tzcell = self.mem.GetCell('TZ')
                            if tzcell and tzcell.exported and tzcell.val.tag_(
                            ) == value_e.Str:
                                tzval = cast(value__Str, tzcell.val)
                                posix.putenv('TZ', tzval.s)

                            time_.tzset()

                            # Handle special values:
                            #   User can specify two special values -1 and -2 as in Bash
                            #   Reference Manual 4.2: "Two special argument values may be
                            #   used: -1 represents the current time, and -2 represents the
                            #   time the shell was invoked." from
                            #   https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html#index-printf
                            if d == -1:  # the current time
                                ts = time_.time()
                            elif d == -2:  # the shell start time
                                ts = self.shell_start_time
                            else:
                                ts = d

                            s = time_.strftime(typ[1:-2], time_.localtime(ts))
                            if precision >= 0:
                                s = s[:precision]  # truncate

                        else:
                            raise AssertionError()

                    else:
                        raise AssertionError()

                    if width >= 0:
                        if len(flags):
                            if '-' in flags:
                                s = s.ljust(width, ' ')
                            elif '0' in flags:
                                s = s.rjust(width, '0')
                            else:
                                pass
                        else:
                            s = s.rjust(width, ' ')

                    out.append(s)

                else:
                    raise AssertionError()

                if backslash_c:  # 'printf %b a\cb xx' - \c terminates processing!
                    break

            if arg_index >= num_args:
                break
            # Otherwise there are more args.  So cycle through the loop once more to
            # implement the 'arg recycling' behavior.

        result = ''.join(out)
        if arg.v is not None:
            # TODO: get the span_id for arg.v!
            v_spid = runtime.NO_SPID

            arena = self.parse_ctx.arena
            a_parser = self.parse_ctx.MakeArithParser(arg.v)

            with alloc.ctx_Location(arena, source.ArgvWord(v_spid)):
                try:
                    anode = a_parser.Parse()
                except error.Parse as e:
                    ui.PrettyPrintError(e, arena)  # show parse error
                    e_usage('Invalid -v expression', span_id=v_spid)

            lval = self.arith_ev.EvalArithLhs(anode, v_spid)

            if not self.exec_opts.eval_unsafe_arith(
            ) and lval.tag_() != lvalue_e.Named:
                e_usage(
                    '-v expected a variable name.  shopt -s eval_unsafe_arith allows expressions',
                    span_id=v_spid)

            state.SetRef(self.mem, lval, value.Str(result))
        else:
            mylib.Stdout().write(result)
        return 0
Beispiel #3
0
    def _Format(self, parts, varargs, spids, out):
        # type: (List[printf_part_t], List[str], List[int], List[str]) -> int
        """Hairy printf formatting logic."""

        arg_index = 0
        num_args = len(varargs)
        backslash_c = False

        while True:  # loop over arguments
            for part in parts:  # loop over parsed format string
                UP_part = part
                if part.tag_() == printf_part_e.Literal:
                    part = cast(printf_part__Literal, UP_part)
                    token = part.token
                    if token.id == Id.Format_EscapedPercent:
                        s = '%'
                    else:
                        s = word_compile.EvalCStringToken(token)
                    out.append(s)

                elif part.tag_() == printf_part_e.Percent:
                    # Note: This case is very long, but hard to refactor because of the
                    # error cases and "recycling" of args!  (arg_index, return 1, etc.)
                    part = cast(printf_part__Percent, UP_part)

                    # TODO: These calculations are independent of the data, so could be
                    # cached
                    flags = []  # type: List[str]
                    if len(part.flags) > 0:
                        for flag_token in part.flags:
                            flags.append(flag_token.val)

                    width = -1  # nonexistent
                    if part.width:
                        if part.width.id in (Id.Format_Num, Id.Format_Zero):
                            width_str = part.width.val
                            width_spid = part.width.span_id
                        elif part.width.id == Id.Format_Star:
                            if arg_index < num_args:
                                width_str = varargs[arg_index]
                                width_spid = spids[arg_index]
                                arg_index += 1
                            else:
                                width_str = ''  # invalid
                                width_spid = runtime.NO_SPID
                        else:
                            raise AssertionError()

                        try:
                            width = int(width_str)
                        except ValueError:
                            if width_spid == runtime.NO_SPID:
                                width_spid = part.width.span_id
                            self.errfmt.Print_("printf got invalid width %r" %
                                               width_str,
                                               span_id=width_spid)
                            return 1

                    precision = -1  # nonexistent
                    if part.precision:
                        if part.precision.id == Id.Format_Dot:
                            precision_str = '0'
                            precision_spid = part.precision.span_id
                        elif part.precision.id in (Id.Format_Num,
                                                   Id.Format_Zero):
                            precision_str = part.precision.val
                            precision_spid = part.precision.span_id
                        elif part.precision.id == Id.Format_Star:
                            if arg_index < num_args:
                                precision_str = varargs[arg_index]
                                precision_spid = spids[arg_index]
                                arg_index += 1
                            else:
                                precision_str = ''
                                precision_spid = runtime.NO_SPID
                        else:
                            raise AssertionError()

                        try:
                            precision = int(precision_str)
                        except ValueError:
                            if precision_spid == runtime.NO_SPID:
                                precision_spid = part.precision.span_id
                            self.errfmt.Print_(
                                'printf got invalid precision %r' %
                                precision_str,
                                span_id=precision_spid)
                            return 1

                    if arg_index < num_args:
                        s = varargs[arg_index]
                        word_spid = spids[arg_index]
                        arg_index += 1
                        has_arg = True
                    else:
                        s = ''
                        word_spid = runtime.NO_SPID
                        has_arg = False

                    typ = part.type.val
                    if typ == 's':
                        if precision >= 0:
                            s = s[:precision]  # truncate

                    elif typ == 'q':
                        # TODO: most shells give \' for single quote, while OSH gives $'\''
                        # this could matter when SSH'ing
                        s = qsn.maybe_shell_encode(s)

                    elif typ == 'b':
                        # Process just like echo -e, except \c handling is simpler.

                        c_parts = []  # type: List[str]
                        lex = match.EchoLexer(s)
                        while True:
                            id_, tok_val = lex.Next()
                            if id_ == Id.Eol_Tok:  # Note: This is really a NUL terminator
                                break

                            # TODO: add span_id from argv
                            tok = Token(id_, runtime.NO_SPID, tok_val)
                            p = word_compile.EvalCStringToken(tok)

                            # Unusual behavior: '\c' aborts processing!
                            if p is None:
                                backslash_c = True
                                break

                            c_parts.append(p)
                        s = ''.join(c_parts)

                    elif part.type.id == Id.Format_Time or typ in 'diouxX':
                        # %(...)T and %d share this complex integer conversion logic

                        try:
                            d = int(
                                s
                            )  # note: spaces like ' -42 ' accepted and normalized

                        except ValueError:
                            # 'a is interpreted as the ASCII value of 'a'
                            if len(s) >= 1 and s[0] in '\'"':
                                # TODO: utf-8 decode s[1:] to be more correct.  Probably
                                # depends on issue #366, a utf-8 library.
                                # Note: len(s) == 1 means there is a NUL (0) after the quote..
                                d = ord(s[1]) if len(s) >= 2 else 0

                            # No argument means -1 for %(...)T as in Bash Reference Manual
                            # 4.2 "If no argument is specified, conversion behaves as if -1
                            # had been given."
                            elif not has_arg and part.type.id == Id.Format_Time:
                                d = -1

                            else:
                                blame_spid = word_spid if has_arg else part.type.span_id
                                self.errfmt.Print_(
                                    'printf expected an integer, got %r' % s,
                                    span_id=blame_spid)
                                return 1

                        if part.type.id == Id.Format_Time:
                            # Initialize timezone:
                            #   `localtime' uses the current timezone information initialized
                            #   by `tzset'.  The function `tzset' refers to the environment
                            #   variable `TZ'.  When the exported variable `TZ' is present,
                            #   its value should be reflected in the real environment
                            #   variable `TZ' before call of `tzset'.
                            #
                            # Note: unlike LANG, TZ doesn't seem to change behavior if it's
                            # not exported.
                            #
                            # TODO: In Oil, provide an API that doesn't rely on libc's
                            # global state.

                            tzcell = self.mem.GetCell('TZ')
                            if tzcell and tzcell.exported and tzcell.val.tag_(
                            ) == value_e.Str:
                                tzval = cast(value__Str, tzcell.val)
                                posix.putenv('TZ', tzval.s)

                            time_.tzset()

                            # Handle special values:
                            #   User can specify two special values -1 and -2 as in Bash
                            #   Reference Manual 4.2: "Two special argument values may be
                            #   used: -1 represents the current time, and -2 represents the
                            #   time the shell was invoked." from
                            #   https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html#index-printf
                            if d == -1:  # the current time
                                ts = time_.time()
                            elif d == -2:  # the shell start time
                                ts = self.shell_start_time
                            else:
                                ts = d

                            s = time_.strftime(typ[1:-2], time_.localtime(ts))
                            if precision >= 0:
                                s = s[:precision]  # truncate

                        else:  # typ in 'diouxX'
                            # Disallowed because it depends on 32- or 64- bit
                            if d < 0 and typ in 'ouxX':
                                e_die(
                                    "Can't format negative number %d with %%%s",
                                    d,
                                    typ,
                                    span_id=part.type.span_id)

                            if typ == 'o':
                                s = mylib.octal(d)
                            elif typ == 'x':
                                s = mylib.hex_lower(d)
                            elif typ == 'X':
                                s = mylib.hex_upper(d)
                            else:  # diu
                                s = str(d)  # without spaces like ' -42 '

                            # There are TWO different ways to ZERO PAD, and they differ on
                            # the negative sign!  See spec/builtin-printf

                            zero_pad = 0  # no zero padding
                            if width >= 0 and '0' in flags:
                                zero_pad = 1  # style 1
                            elif precision > 0 and len(s) < precision:
                                zero_pad = 2  # style 2

                            if zero_pad:
                                negative = (s[0] == '-')
                                if negative:
                                    digits = s[1:]
                                    sign = '-'
                                    if zero_pad == 1:
                                        # [%06d] -42 becomes [-00042] (6 TOTAL)
                                        n = width - 1
                                    else:
                                        # [%6.6d] -42 becomes [-000042] (1 for '-' + 6)
                                        n = precision
                                else:
                                    digits = s
                                    sign = ''
                                    if zero_pad == 1:
                                        n = width
                                    else:
                                        n = precision
                                s = sign + digits.rjust(n, '0')

                    else:
                        raise AssertionError()

                    if width >= 0:
                        if '-' in flags:
                            s = s.ljust(width, ' ')
                        else:
                            s = s.rjust(width, ' ')

                    out.append(s)

                else:
                    raise AssertionError()

                if backslash_c:  # 'printf %b a\cb xx' - \c terminates processing!
                    break

            if arg_index >= num_args:
                break
            # Otherwise there are more args.  So cycle through the loop once more to
            # implement the 'arg recycling' behavior.

        return 0