Source code for scrapy.utils.iterators

import csv
import logging
import re
from io import StringIO
from typing import (
    TYPE_CHECKING,
    Any,
    Callable,
    Dict,
    Generator,
    Iterable,
    List,
    Literal,
    Optional,
    Union,
    cast,
    overload,
)
from warnings import warn

from lxml import etree  # nosec

from scrapy.exceptions import ScrapyDeprecationWarning
from scrapy.http import Response, TextResponse
from scrapy.selector import Selector
from scrapy.utils.python import re_rsearch, to_unicode

if TYPE_CHECKING:
    from lxml._types import SupportsReadClose  # nosec

logger = logging.getLogger(__name__)


def xmliter(
    obj: Union[Response, str, bytes], nodename: str
) -> Generator[Selector, Any, None]:
    """Return a iterator of Selector's over all nodes of a XML document,
       given the name of the node to iterate. Useful for parsing XML feeds.

    obj can be:
    - a Response object
    - a unicode string
    - a string encoded as utf-8
    """
    warn(
        (
            "xmliter is deprecated and its use strongly discouraged because "
            "it is vulnerable to ReDoS attacks. Use xmliter_lxml instead. See "
            "https://github.com/scrapy/scrapy/security/advisories/GHSA-cc65-xxvf-f7r9"
        ),
        ScrapyDeprecationWarning,
        stacklevel=2,
    )

    nodename_patt = re.escape(nodename)

    DOCUMENT_HEADER_RE = re.compile(r"<\?xml[^>]+>\s*", re.S)
    HEADER_END_RE = re.compile(rf"<\s*/{nodename_patt}\s*>", re.S)
    END_TAG_RE = re.compile(r"<\s*/([^\s>]+)\s*>", re.S)
    NAMESPACE_RE = re.compile(r"((xmlns[:A-Za-z]*)=[^>\s]+)", re.S)
    text = _body_or_str(obj)

    document_header_match = re.search(DOCUMENT_HEADER_RE, text)
    document_header = (
        document_header_match.group().strip() if document_header_match else ""
    )
    header_end_idx = re_rsearch(HEADER_END_RE, text)
    header_end = text[header_end_idx[1] :].strip() if header_end_idx else ""
    namespaces: Dict[str, str] = {}
    if header_end:
        for tagname in reversed(re.findall(END_TAG_RE, header_end)):
            assert header_end_idx
            tag = re.search(
                rf"<\s*{tagname}.*?xmlns[:=][^>]*>", text[: header_end_idx[1]], re.S
            )
            if tag:
                for x in re.findall(NAMESPACE_RE, tag.group()):
                    namespaces[x[1]] = x[0]

    r = re.compile(rf"<{nodename_patt}[\s>].*?</{nodename_patt}>", re.DOTALL)
    for match in r.finditer(text):
        nodetext = (
            document_header
            + match.group().replace(
                nodename, f'{nodename} {" ".join(namespaces.values())}', 1
            )
            + header_end
        )
        yield Selector(text=nodetext, type="xml")


[docs]def xmliter_lxml( obj: Union[Response, str, bytes], nodename: str, namespace: Optional[str] = None, prefix: str = "x", ) -> Generator[Selector, Any, None]: reader = _StreamReader(obj) tag = f"{{{namespace}}}{nodename}" if namespace else nodename iterable = etree.iterparse( cast("SupportsReadClose[bytes]", reader), encoding=reader.encoding, events=("end", "start-ns"), resolve_entities=False, huge_tree=True, ) selxpath = "//" + (f"{prefix}:{nodename}" if namespace else nodename) needs_namespace_resolution = not namespace and ":" in nodename if needs_namespace_resolution: prefix, nodename = nodename.split(":", maxsplit=1) for event, data in iterable: if event == "start-ns": assert isinstance(data, tuple) if needs_namespace_resolution: _prefix, _namespace = data if _prefix != prefix: continue namespace = _namespace needs_namespace_resolution = False selxpath = f"//{prefix}:{nodename}" tag = f"{{{namespace}}}{nodename}" continue assert isinstance(data, etree._Element) node = data if node.tag != tag: continue nodetext = etree.tostring(node, encoding="unicode") node.clear() xs = Selector(text=nodetext, type="xml") if namespace: xs.register_namespace(prefix, namespace) yield xs.xpath(selxpath)[0]
class _StreamReader: def __init__(self, obj: Union[Response, str, bytes]): self._ptr: int = 0 self._text: Union[str, bytes] if isinstance(obj, TextResponse): self._text, self.encoding = obj.body, obj.encoding elif isinstance(obj, Response): self._text, self.encoding = obj.body, "utf-8" else: self._text, self.encoding = obj, "utf-8" self._is_unicode: bool = isinstance(self._text, str) self._is_first_read: bool = True def read(self, n: int = 65535) -> bytes: method: Callable[[int], bytes] = ( self._read_unicode if self._is_unicode else self._read_string ) result = method(n) if self._is_first_read: self._is_first_read = False result = result.lstrip() return result def _read_string(self, n: int = 65535) -> bytes: s, e = self._ptr, self._ptr + n self._ptr = e return cast(bytes, self._text)[s:e] def _read_unicode(self, n: int = 65535) -> bytes: s, e = self._ptr, self._ptr + n self._ptr = e return cast(str, self._text)[s:e].encode("utf-8")
[docs]def csviter( obj: Union[Response, str, bytes], delimiter: Optional[str] = None, headers: Optional[List[str]] = None, encoding: Optional[str] = None, quotechar: Optional[str] = None, ) -> Generator[Dict[str, str], Any, None]: """Returns an iterator of dictionaries from the given csv object obj can be: - a Response object - a unicode string - a string encoded as utf-8 delimiter is the character used to separate fields on the given obj. headers is an iterable that when provided offers the keys for the returned dictionaries, if not the first row is used. quotechar is the character used to enclosure fields on the given obj. """ encoding = obj.encoding if isinstance(obj, TextResponse) else encoding or "utf-8" def row_to_unicode(row_: Iterable) -> List[str]: return [to_unicode(field, encoding) for field in row_] lines = StringIO(_body_or_str(obj, unicode=True)) kwargs: Dict[str, Any] = {} if delimiter: kwargs["delimiter"] = delimiter if quotechar: kwargs["quotechar"] = quotechar csv_r = csv.reader(lines, **kwargs) if not headers: try: row = next(csv_r) except StopIteration: return headers = row_to_unicode(row) for row in csv_r: row = row_to_unicode(row) if len(row) != len(headers): logger.warning( "ignoring row %(csvlnum)d (length: %(csvrow)d, " "should be: %(csvheader)d)", { "csvlnum": csv_r.line_num, "csvrow": len(row), "csvheader": len(headers), }, ) continue yield dict(zip(headers, row))
@overload def _body_or_str(obj: Union[Response, str, bytes]) -> str: ... @overload def _body_or_str(obj: Union[Response, str, bytes], unicode: Literal[True]) -> str: ... @overload def _body_or_str( obj: Union[Response, str, bytes], unicode: Literal[False] ) -> bytes: ... def _body_or_str( obj: Union[Response, str, bytes], unicode: bool = True ) -> Union[str, bytes]: expected_types = (Response, str, bytes) if not isinstance(obj, expected_types): expected_types_str = " or ".join(t.__name__ for t in expected_types) raise TypeError( f"Object {obj!r} must be {expected_types_str}, not {type(obj).__name__}" ) if isinstance(obj, Response): if not unicode: return obj.body if isinstance(obj, TextResponse): return obj.text return obj.body.decode("utf-8") if isinstance(obj, str): return obj if unicode else obj.encode("utf-8") return obj.decode("utf-8") if unicode else obj