testbed/aws-cloudformation__cfn-lint/src/cfnlint/decode/cfn_json.py

"""
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
SPDX-License-Identifier: MIT-0
"""

import fileinput
import json
import logging
import sys
from json.decoder import WHITESPACE  # type: ignore
from json.decoder import BACKSLASH, STRINGCHUNK, WHITESPACE_STR  # type: ignore
from json.scanner import NUMBER_RE

from cfnlint.decode.mark import Mark
from cfnlint.decode.node import dict_node, list_node, str_node
from cfnlint.match import Match
from cfnlint.rules.errors import ParseError

LOGGER = logging.getLogger(__name__)


class DuplicateError(Exception):
    """
    Error thrown when the template contains duplicates
    """

    def __init__(self, message, key):
        super().__init__(message)
        self.duplicates = []
        self.append(key)

    def append(self, key):
        self.duplicates.append(key)


def check_duplicates(ordered_pairs, beg_mark, end_mark):
    """
    Check for duplicate keys on the current level, this is not desirable
    because a dict does not support this. It overwrites it with the last
    occurrence, which can give unexpected results
    """
    err = None
    mapping = dict_node({}, beg_mark, end_mark)
    for key, value in ordered_pairs:
        for m_key in mapping:
            if m_key == key:
                if err is None:
                    err = DuplicateError(f'"{key}"', key)
                    err.append(m_key)
                else:
                    err.append(key)
        if key not in mapping:
            mapping[key] = value

    if err is not None:
        raise err

    return mapping


class JSONDecodeError(ValueError):
    """Subclass of ValueError with the following additional properties:
    msg: The unformatted error message
    doc: The JSON document being parsed
    pos: The start index of doc where parsing failed
    lineno: The line corresponding to pos
    colno: The column corresponding to pos
    """

    # Note that this exception is used from _json

    def __init__(self, doc, pos, errors):
        if isinstance(errors, Match):
            errors = [errors]

        errmsg = (
            f"{errors[0].message}: line {errors[0].linenumber} column"
            f" {errors[0].linenumber} (char {pos})"
        )
        ValueError.__init__(self, errmsg)
        self.msg = errors[0].message
        self.doc = doc
        self.pos = pos
        self.lineno = errors[0].linenumber
        self.colno = errors[0].linenumber
        self.matches = errors

    def __reduce__(self):
        return self.__class__, (self.msg, self.doc, self.pos)


def build_match(message, doc, pos, key=" "):
    lineno = doc.count("\n", 0, pos) + 1
    colno = pos - doc.rfind("\n", 0, pos)

    return Match.create(
        message=message,
        filename="",
        rule=ParseError(),
        linenumber=lineno,
        columnnumber=colno + 1,
        linenumberend=lineno,
        columnnumberend=colno + 1 + len(key),
    )


def build_match_from_key(message, key):
    return Match.create(
        message=message,
        filename="",
        rule=ParseError(),
        linenumber=key.start_mark.line,
        columnnumber=key.start_mark.column + 1,
        linenumberend=key.end_mark.line,
        columnnumberend=key.end_mark.column + 1 + len(key),
    )


# pylint: disable=W0102
# Exception based on builtin Python Function
def py_scanstring(s, end, strict=True, _b=BACKSLASH, _m=STRINGCHUNK.match):
    """Scan the string s for a JSON string. End is the index of the
    character in s after the quote that started the JSON string.
    Unescapes all valid JSON string escape sequences and raises ValueError
    on attempt to decode an invalid string. If strict is False then literal
    control characters are allowed in the string.
    Returns a tuple of the decoded string and the index of the character in s
    after the end quote."""
    chunks = []
    _append = chunks.append
    begin = end - 1
    while 1:
        chunk = _m(s, end)
        if chunk is None:
            raise JSONDecodeError(
                doc=s,
                pos=begin,
                errors=[
                    build_match(
                        message="Unterminated string starting at",
                        doc=s,
                        pos=begin,
                    ),
                ],
            )
        end = chunk.end()
        content, terminator = chunk.groups()
        # Content is contains zero or more unescaped string characters
        if content:
            _append(content)
        # Terminator is the end of string, a literal control character,
        # or a backslash denoting that an escape sequence follows
        if terminator == '"':
            break
        if terminator != "\\":
            if strict:
                msg = f"Invalid control character {terminator!r} at"
                raise JSONDecodeError(
                    doc=s,
                    pos=end,
                    errors=[
                        build_match(
                            message=msg,
                            doc=s,
                            pos=end,
                        ),
                    ],
                )
            _append(terminator)
            continue
        try:
            esc = s[end]
        except IndexError as exc:
            raise JSONDecodeError(
                doc=s,
                pos=begin,
                errors=[
                    build_match(
                        message="Unterminated string starting at",
                        doc=s,
                        pos=begin,
                    ),
                ],
            ) from exc
        # If not a unicode escape sequence, must be in the lookup table
        if esc != "u":
            try:
                char = _b[esc]
            except KeyError as exc:
                msg = f"Invalid \\escape: {esc!r}"
                raise JSONDecodeError(
                    doc=s,
                    pos=end,
                    errors=[
                        build_match(
                            message=msg,
                            doc=s,
                            pos=end,
                        ),
                    ],
                ) from exc
            end += 1
        else:
            uni = _decode_uXXXX(s, end)
            end += 5
            if 0xD800 <= uni <= 0xDBFF and s[end : end + 2] == "\\u":
                uni2 = _decode_uXXXX(s, end + 1)
                if 0xDC00 <= uni2 <= 0xDFFF:
                    uni = 0x10000 + (((uni - 0xD800) << 10) | (uni2 - 0xDC00))
                    end += 6
            char = chr(uni)
        _append(char)
    return "".join(chunks), end


def _decode_uXXXX(s, pos):
    esc = s[pos + 1 : pos + 5]
    if len(esc) == 4 and esc[1] not in "xX":
        try:
            return int(esc, 16)
        except ValueError:
            pass
    msg = "Invalid \\uXXXX escape"
    raise JSONDecodeError(
        doc=s,
        pos=pos,
        errors=[
            build_match(
                message=msg,
                doc=s,
                pos=pos,
            ),
        ],
    )


def py_make_scanner(context):
    """
    Make python based scanner
    For this use case we will not use the C based scanner
    """
    parse_object = context.parse_object
    parse_array = context.parse_array
    parse_string = context.parse_string
    match_number = NUMBER_RE.match
    strict = context.strict
    parse_float = context.parse_float
    parse_int = context.parse_int
    parse_constant = context.parse_constant
    object_hook = context.object_hook
    object_pairs_hook = context.object_pairs_hook
    memo = context.memo

    # pylint: disable=R0911
    # Based on Python standard function
    def _scan_once(string, idx):
        """Scan once internal function"""
        try:
            nextchar = string[idx]
        except IndexError as exc:
            raise StopIteration(idx) from exc

        if nextchar == '"':
            return parse_string(string, idx + 1, strict)
        if nextchar == "{":
            return parse_object(
                (string, idx + 1),
                strict,
                scan_once,
                object_hook,
                object_pairs_hook,
                memo,
            )
        if nextchar == "[":
            return parse_array((string, idx + 1), _scan_once)
        if nextchar == "n" and string[idx : idx + 4] == "null":
            return None, idx + 4
        if nextchar == "t" and string[idx : idx + 4] == "true":
            return True, idx + 4
        if nextchar == "f" and string[idx : idx + 5] == "false":
            return False, idx + 5

        m = match_number(string, idx)
        if m is not None:
            integer, frac, exp = m.groups()
            if frac or exp:
                res = parse_float(integer + (frac or "") + (exp or ""))
            else:
                res = parse_int(integer)
            return res, m.end()
        if nextchar == "N" and string[idx : idx + 3] == "NaN":
            return parse_constant("NaN"), idx + 3
        if nextchar == "I" and string[idx : idx + 8] == "Infinity":
            return parse_constant("Infinity"), idx + 8
        if nextchar == "-" and string[idx : idx + 9] == "-Infinity":
            return parse_constant("-Infinity"), idx + 9

        raise StopIteration(idx)

    def scan_once(string, idx):
        """Scan Once"""
        try:
            return _scan_once(string, idx)
        finally:
            memo.clear()

    return _scan_once


def find_indexes(s, ch="\n"):
    """Finds all instances of given char and returns list of indexes"""
    return [i for i, ltr in enumerate(s) if ltr == ch]


def count_occurrences(arr, key):
    """Binary search indexes to replace str.count"""
    n = len(arr)
    left = 0
    right = n - 1
    count = 0

    while left <= right:
        mid = int((right + left) / 2)

        if arr[mid] <= key:
            count = mid + 1
            left = mid + 1
        else:
            right = mid - 1
    return count


def largest_less_than(indexes, line_num, pos):
    """Replacement func for python str.rfind using indexes"""
    return indexes[line_num - 1] if indexes and count_occurrences(indexes, pos) else -1


def get_beg_end_mark(start, end, indexes):
    """Get the Start and End Mark"""
    beg_lineno = count_occurrences(indexes, start)
    beg_colno = start - largest_less_than(indexes, beg_lineno, start)
    beg_mark = Mark(beg_lineno, beg_colno)

    offset = 1 if len(indexes) > 1 else 0
    end_lineno = count_occurrences(indexes, end) - offset
    end_colno = end - largest_less_than(indexes, end_lineno, end)
    end_mark = Mark(end_lineno, end_colno)

    return beg_mark, end_mark


def load(filename):
    """
    Load the given JSON file
    """

    content = ""

    if (filename is None) and (not sys.stdin.isatty()):
        filename = "-"  # no filename provided, it's stdin
        fileinput_args = {"files": filename}
        if sys.version_info.major <= 3 and sys.version_info.minor >= 10:
            fileinput_args["encoding"] = "utf-8"
        with fileinput.input(**fileinput_args) as f:
            for line in f:
                content = content + line
    else:
        with open(filename, encoding="utf-8") as fp:
            content = fp.read()

    return json.loads(content, cls=CfnJSONDecoder)


def loads(json_string):
    """
    Load the given JSON string
    """
    return json.loads(json_string, cls=CfnJSONDecoder)


class CfnJSONDecoder(json.JSONDecoder):
    """
    Converts a json string, where datetime and timedelta objects were converted
    into strings using the DateTimeAwareJSONEncoder, into a python object.
    """

    def __init__(self, *args, **kwargs):
        json.JSONDecoder.__init__(self, *args, **kwargs)
        self.parse_object = self.cfn_json_object
        self.parse_array = self.JSONArray
        self.parse_string = py_scanstring
        self.memo = {}
        self.object_pairs_hook = check_duplicates
        self.scan_once = py_make_scanner(self)
        self.newline_indexes = []

    def decode(self, s, _w=WHITESPACE.match):
        """Overridden to retrieve indexes"""
        self.newline_indexes = find_indexes(s)
        obj = super().decode(s, _w)
        return obj

    def JSONArray(self, s_and_end, scan_once, **kwargs):
        """Convert JSON array to be a list_node object"""
        values, end = json.decoder.JSONArray(s_and_end, scan_once, **kwargs)
        start = s_and_end[1]
        beg_mark, end_mark = get_beg_end_mark(start, end, self.newline_indexes)
        return list_node(values, beg_mark, end_mark), end

    def cfn_json_object(
        self,
        s_and_end,
        strict,
        scan_once,
        object_hook,
        object_pairs_hook,
        memo=None,
        _w=WHITESPACE.match,
        _ws=WHITESPACE_STR,
    ):
        """Custom Cfn JSON Object to store keys with start and end times"""
        s, end = s_and_end
        orginal_end = end
        pairs = []
        pairs_append = pairs.append
        # Backwards compatibility
        if memo is None:
            memo = {}
        memo_get = memo.setdefault
        # Use a slice to prevent IndexError from being raised, the following
        # check will raise a more specific ValueError if the string is empty
        nextchar = s[end : end + 1]
        # Normally we expect nextchar == '"'
        if nextchar != '"':
            if nextchar in _ws:
                end = _w(s, end).end()
                nextchar = s[end : end + 1]
            # Trivial empty object
            if nextchar == "}":
                if object_pairs_hook is not None:
                    try:
                        beg_mark, end_mark = get_beg_end_mark(
                            orginal_end, end + 1, self.newline_indexes
                        )
                        result = object_pairs_hook(pairs, beg_mark, end_mark)
                        return result, end + 1
                    except DuplicateError as err:
                        errs = []
                        for m in err.duplicates:
                            errs.append(
                                build_match_from_key(
                                    message=f"Duplicate found {err}",
                                    key=m,
                                )
                            )
                        raise JSONDecodeError(
                            doc=s,
                            pos=end,
                            errors=errs,
                        ) from err
                pairs = {}
                if object_hook is not None:
                    beg_mark, end_mark = get_beg_end_mark(
                        orginal_end, end + 1, self.newline_indexes
                    )
                    pairs = object_hook(pairs, beg_mark, end_mark)
                return pairs, end + 1

            if nextchar != '"':
                raise JSONDecodeError(
                    doc=s,
                    pos=end,
                    errors=[
                        build_match(
                            message="Expecting property name enclosed in double quotes",
                            doc=s,
                            pos=end,
                        ),
                    ],
                )
        end += 1
        while True:
            begin = end - 1
            key, end = py_scanstring(s, end, strict)
            key = memo_get(key, key)
            # To skip some function call overhead we optimize the fast paths where
            # the JSON key separator is ": " or just ":".
            if s[end : end + 1] != ":":
                end = _w(s, end).end()
                if s[end : end + 1] != ":":
                    raise JSONDecodeError(
                        doc=s,
                        pos=end,
                        errors=[
                            build_match(
                                message="Expecting ':' delimiter",
                                doc=s,
                                pos=end,
                            ),
                        ],
                    )
            end += 1

            try:
                if s[end] in _ws:
                    end += 1
                    if s[end] in _ws:
                        end = _w(s, end + 1).end()
            except IndexError:
                pass

            beg_mark, end_mark = get_beg_end_mark(
                begin, begin + len(key), self.newline_indexes
            )
            try:
                value, end = scan_once(s, end)
            except StopIteration as err:
                raise JSONDecodeError(
                    doc=s,
                    pos=str(err),
                    errors=[
                        build_match(
                            message="Expecting value",
                            doc=s,
                            pos=str(err),
                        ),
                    ],
                ) from err
            key_str = str_node(key, beg_mark, end_mark)
            pairs_append((key_str, value))
            try:
                nextchar = s[end]
                if nextchar in _ws:
                    end = _w(s, end + 1).end()
                    nextchar = s[end]
            except IndexError:
                nextchar = ""
            end += 1

            if nextchar == "}":
                break
            if nextchar != ",":
                raise JSONDecodeError(
                    doc=s,
                    pos=end - 1,
                    errors=[
                        build_match(
                            message="Expecting ',' delimiter",
                            doc=s,
                            pos=end - 1,
                        ),
                    ],
                )
            end = _w(s, end).end()
            nextchar = s[end : end + 1]
            end += 1
            if nextchar != '"':
                raise JSONDecodeError(
                    doc=s,
                    pos=end - 1,
                    errors=[
                        build_match(
                            message="Expecting property name enclosed in double quotes",
                            doc=s,
                            pos=end - 1,
                        ),
                    ],
                )
        if object_pairs_hook is not None:
            try:
                beg_mark, end_mark = get_beg_end_mark(
                    orginal_end, end, self.newline_indexes
                )
                result = object_pairs_hook(pairs, beg_mark, end_mark)
            except DuplicateError as err:
                errs = []
                for m in err.duplicates:
                    errs.append(
                        build_match_from_key(
                            message=f"Duplicate found {err}",
                            key=m,
                        )
                    )
                raise JSONDecodeError(
                    doc=s,
                    pos=end,
                    errors=errs,
                ) from err
            return result, end

        pairs = dict(pairs)
        if object_hook is not None:
            beg_mark, end_mark = get_beg_end_mark(
                orginal_end, end, self.newline_indexes
            )
            pairs = object_hook(pairs, beg_mark, end_mark)
        return pairs, end