878 lines
23 KiB
Python
878 lines
23 KiB
Python
"""Miscellaneous Routines."""
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import io
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import pathlib
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import string
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from collections.abc import Callable, Iterable, Iterator
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from html import escape
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from typing import (
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TYPE_CHECKING,
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Any,
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BinaryIO,
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Generic,
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TextIO,
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TypeVar,
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Union,
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cast,
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)
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from pdfminer.pdfexceptions import PDFTypeError, PDFValueError
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if TYPE_CHECKING:
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from pdfminer.layout import LTComponent
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import contextlib
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import charset_normalizer # For str encoding detection
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# from sys import maxint as INF doesn't work anymore under Python3, but PDF
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# still uses 32 bits ints
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INF = (1 << 31) - 1
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FileOrName = Union[pathlib.PurePath, str, io.IOBase]
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AnyIO = Union[TextIO, BinaryIO]
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class open_filename:
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"""Context manager that allows opening a filename
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(str or pathlib.PurePath type is supported) and closes it on exit,
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(just like `open`), but does nothing for file-like objects.
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"""
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def __init__(self, filename: FileOrName, *args: Any, **kwargs: Any) -> None:
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if isinstance(filename, pathlib.PurePath):
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filename = str(filename)
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if isinstance(filename, str):
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self.file_handler: AnyIO = open(filename, *args, **kwargs) # noqa: SIM115
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self.closing = True
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elif isinstance(filename, io.IOBase):
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self.file_handler = cast(AnyIO, filename)
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self.closing = False
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else:
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raise PDFTypeError(f"Unsupported input type: {type(filename)}")
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def __enter__(self) -> AnyIO:
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return self.file_handler
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def __exit__(self, exc_type: object, exc_val: object, exc_tb: object) -> None:
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if self.closing:
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self.file_handler.close()
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def make_compat_bytes(in_str: str) -> bytes:
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"""Converts to bytes, encoding to unicode."""
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assert isinstance(in_str, str), str(type(in_str))
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return in_str.encode()
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def make_compat_str(o: object) -> str:
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"""Converts everything to string, if bytes guessing the encoding."""
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if isinstance(o, bytes):
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enc = charset_normalizer.detect(o)
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if enc["encoding"] is None:
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return str(o)
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try:
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return o.decode(enc["encoding"])
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except UnicodeDecodeError:
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return str(o)
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else:
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return str(o)
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def shorten_str(s: str, size: int) -> str:
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if size < 7:
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return s[:size]
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if len(s) > size:
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length = (size - 5) // 2
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return f"{s[:length]} ... {s[-length:]}"
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else:
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return s
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def compatible_encode_method(
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bytesorstring: bytes | str,
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encoding: str = "utf-8",
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erraction: str = "ignore",
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) -> str:
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"""When Py2 str.encode is called, it often means bytes.encode in Py3.
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This does either.
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"""
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if isinstance(bytesorstring, str):
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return bytesorstring
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assert isinstance(bytesorstring, bytes), str(type(bytesorstring))
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return bytesorstring.decode(encoding, erraction)
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def paeth_predictor(left: int, above: int, upper_left: int) -> int:
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# From http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
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# Initial estimate
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p = left + above - upper_left
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# Distances to a,b,c
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pa = abs(p - left)
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pb = abs(p - above)
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pc = abs(p - upper_left)
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# Return nearest of a,b,c breaking ties in order a,b,c
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if pa <= pb and pa <= pc:
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return left
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elif pb <= pc:
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return above
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else:
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return upper_left
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def apply_tiff_predictor(
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colors: int, columns: int, bitspercomponent: int, data: bytes
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) -> bytes:
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"""Reverse the effect of the TIFF predictor 2
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Documentation:
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https://www.itu.int/itudoc/itu-t/com16/tiff-fx/docs/tiff6.pdf
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(Section 14, page 64)
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"""
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if bitspercomponent != 8:
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error_msg = f"Unsupported `bitspercomponent': {bitspercomponent}"
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raise PDFValueError(error_msg)
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bpp = colors * (bitspercomponent // 8)
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nbytes = columns * bpp
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buf: list[int] = []
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for scanline_i in range(0, len(data), nbytes):
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raw: list[int] = []
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for i in range(nbytes):
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new_value = data[scanline_i + i]
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if i >= bpp:
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new_value += raw[i - bpp]
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new_value %= 256
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raw.append(new_value)
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buf.extend(raw)
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return bytes(buf)
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def apply_png_predictor(
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pred: int,
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colors: int,
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columns: int,
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bitspercomponent: int,
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data: bytes,
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) -> bytes:
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"""Reverse the effect of the PNG predictor
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Documentation: http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
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"""
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if bitspercomponent not in [8, 1]:
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msg = f"Unsupported `bitspercomponent': {bitspercomponent}"
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raise PDFValueError(msg)
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nbytes = colors * columns * bitspercomponent // 8
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bpp = colors * bitspercomponent // 8 # number of bytes per complete pixel
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buf = []
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line_above = list(b"\x00" * columns)
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for scanline_i in range(0, len(data), nbytes + 1):
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filter_type = data[scanline_i]
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line_encoded = data[scanline_i + 1 : scanline_i + 1 + nbytes]
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raw = []
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if filter_type == 0:
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# Filter type 0: None
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raw = list(line_encoded)
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elif filter_type == 1:
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# Filter type 1: Sub
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# To reverse the effect of the Sub() filter after decompression,
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# output the following value:
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# Raw(x) = Sub(x) + Raw(x - bpp)
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# (computed mod 256), where Raw() refers to the bytes already
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# decoded.
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for j, sub_x in enumerate(line_encoded):
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raw_x_bpp = 0 if j - bpp < 0 else int(raw[j - bpp])
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raw_x = (sub_x + raw_x_bpp) & 255
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raw.append(raw_x)
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elif filter_type == 2:
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# Filter type 2: Up
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# To reverse the effect of the Up() filter after decompression,
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# output the following value:
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# Raw(x) = Up(x) + Prior(x)
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# (computed mod 256), where Prior() refers to the decoded bytes of
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# the prior scanline.
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for up_x, prior_x in zip(line_encoded, line_above, strict=False):
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raw_x = (up_x + prior_x) & 255
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raw.append(raw_x)
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elif filter_type == 3:
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# Filter type 3: Average
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# To reverse the effect of the Average() filter after
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# decompression, output the following value:
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# Raw(x) = Average(x) + floor((Raw(x-bpp)+Prior(x))/2)
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# where the result is computed mod 256, but the prediction is
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# calculated in the same way as for encoding. Raw() refers to the
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# bytes already decoded, and Prior() refers to the decoded bytes of
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# the prior scanline.
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for j, average_x in enumerate(line_encoded):
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raw_x_bpp = 0 if j - bpp < 0 else int(raw[j - bpp])
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prior_x = int(line_above[j])
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raw_x = (average_x + (raw_x_bpp + prior_x) // 2) & 255
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raw.append(raw_x)
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elif filter_type == 4:
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# Filter type 4: Paeth
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# To reverse the effect of the Paeth() filter after decompression,
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# output the following value:
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# Raw(x) = Paeth(x)
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# + PaethPredictor(Raw(x-bpp), Prior(x), Prior(x-bpp))
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# (computed mod 256), where Raw() and Prior() refer to bytes
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# already decoded. Exactly the same PaethPredictor() function is
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# used by both encoder and decoder.
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for j, paeth_x in enumerate(line_encoded):
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if j - bpp < 0:
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raw_x_bpp = 0
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prior_x_bpp = 0
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else:
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raw_x_bpp = int(raw[j - bpp])
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prior_x_bpp = int(line_above[j - bpp])
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prior_x = int(line_above[j])
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paeth = paeth_predictor(raw_x_bpp, prior_x, prior_x_bpp)
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raw_x = (paeth_x + paeth) & 255
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raw.append(raw_x)
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else:
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raise PDFValueError(f"Unsupported predictor value: {filter_type}")
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buf.extend(raw)
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line_above = raw
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return bytes(buf)
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Point = tuple[float, float]
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Rect = tuple[float, float, float, float]
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Matrix = tuple[float, float, float, float, float, float]
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PathSegment = Union[
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tuple[str], # Literal['h']
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tuple[str, float, float], # Literal['m', 'l']
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tuple[str, float, float, float, float], # Literal['v', 'y']
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tuple[str, float, float, float, float, float, float],
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] # Literal['c']
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# Matrix operations
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MATRIX_IDENTITY: Matrix = (1, 0, 0, 1, 0, 0)
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def parse_rect(o: Any) -> Rect:
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try:
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(x0, y0, x1, y1) = o
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return float(x0), float(y0), float(x1), float(y1)
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except ValueError as err:
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raise PDFValueError("Could not parse rectangle") from err
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def mult_matrix(m1: Matrix, m0: Matrix) -> Matrix:
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(a1, b1, c1, d1, e1, f1) = m1
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(a0, b0, c0, d0, e0, f0) = m0
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"""Returns the multiplication of two matrices."""
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return (
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a0 * a1 + c0 * b1,
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b0 * a1 + d0 * b1,
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a0 * c1 + c0 * d1,
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b0 * c1 + d0 * d1,
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a0 * e1 + c0 * f1 + e0,
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b0 * e1 + d0 * f1 + f0,
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)
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def translate_matrix(m: Matrix, v: Point) -> Matrix:
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"""Translates a matrix by (x, y) inside the projection.
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The matrix is changed so that its origin is at the specified point in its own
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coordinate system. Note that this is different from translating it within the
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original coordinate system."""
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(a, b, c, d, e, f) = m
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(x, y) = v
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return a, b, c, d, x * a + y * c + e, x * b + y * d + f
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def apply_matrix_pt(m: Matrix, v: Point) -> Point:
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"""Applies a matrix to a point."""
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(a, b, c, d, e, f) = m
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(x, y) = v
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return a * x + c * y + e, b * x + d * y + f
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def apply_matrix_rect(m: Matrix, rect: Rect) -> Rect:
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"""Applies a matrix to a rectangle.
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Note that the result is not a rotated rectangle, but a rectangle with the same
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orientation that tightly fits the outside of the rotated content.
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:param m: The rotation matrix.
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:param rect: The rectangle coordinates (x0, y0, x1, y1), where x0 < x1 and y0 < y1.
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:returns a rectangle with the same orientation, but that would fit the rotated
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content.
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"""
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(x0, y0, x1, y1) = rect
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left_bottom = (x0, y0)
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right_bottom = (x1, y0)
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right_top = (x1, y1)
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left_top = (x0, y1)
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(left1, bottom1) = apply_matrix_pt(m, left_bottom)
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(right1, bottom2) = apply_matrix_pt(m, right_bottom)
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(right2, top1) = apply_matrix_pt(m, right_top)
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(left2, top2) = apply_matrix_pt(m, left_top)
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return (
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min(left1, left2, right1, right2),
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min(bottom1, bottom2, top1, top2),
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max(left1, left2, right1, right2),
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max(bottom1, bottom2, top1, top2),
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)
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def apply_matrix_norm(m: Matrix, v: Point) -> Point:
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"""Equivalent to apply_matrix_pt(M, (p,q)) - apply_matrix_pt(M, (0,0))"""
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(a, b, c, d, _e, _f) = m
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(p, q) = v
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return a * p + c * q, b * p + d * q
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# Utility functions
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def isnumber(x: object) -> bool:
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return isinstance(x, (int, float))
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_T = TypeVar("_T")
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def uniq(objs: Iterable[_T]) -> Iterator[_T]:
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"""Eliminates duplicated elements."""
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done = set()
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for obj in objs:
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if obj in done:
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continue
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done.add(obj)
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yield obj
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def fsplit(pred: Callable[[_T], bool], objs: Iterable[_T]) -> tuple[list[_T], list[_T]]:
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"""Split a list into two classes according to the predicate."""
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t = []
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f = []
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for obj in objs:
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if pred(obj):
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t.append(obj)
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else:
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f.append(obj)
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return t, f
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def drange(v0: float, v1: float, d: int) -> range:
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"""Returns a discrete range."""
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return range(int(v0) // d, int(v1 + d) // d)
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def get_bound(pts: Iterable[Point]) -> Rect:
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"""Compute a minimal rectangle that covers all the points."""
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limit: Rect = (INF, INF, -INF, -INF)
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(x0, y0, x1, y1) = limit
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for x, y in pts:
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x0 = min(x0, x)
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y0 = min(y0, y)
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x1 = max(x1, x)
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y1 = max(y1, y)
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return x0, y0, x1, y1
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def pick(
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seq: Iterable[_T],
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func: Callable[[_T], float],
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maxobj: _T | None = None,
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) -> _T | None:
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"""Picks the object obj where func(obj) has the highest value."""
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maxscore = None
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for obj in seq:
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score = func(obj)
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if maxscore is None or maxscore < score:
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(maxscore, maxobj) = (score, obj)
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return maxobj
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def choplist(n: int, seq: Iterable[_T]) -> Iterator[tuple[_T, ...]]:
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"""Groups every n elements of the list."""
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r = []
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for x in seq:
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r.append(x)
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if len(r) == n:
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yield tuple(r)
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r = []
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def nunpack(s: bytes, default: int = 0) -> int:
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"""Unpacks variable-length unsigned integers (big endian)."""
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length = len(s)
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if not length:
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return default
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else:
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return int.from_bytes(s, byteorder="big", signed=False)
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PDFDocEncoding = "".join(
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chr(x)
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for x in (
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0x0000,
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0x0001,
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0x0002,
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0x0003,
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0x0004,
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0x0005,
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0x0006,
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0x0007,
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0x0008,
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0x0009,
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0x000A,
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0x000B,
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0x000C,
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0x000D,
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0x000E,
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0x000F,
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0x0010,
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0x0011,
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0x0012,
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0x0013,
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0x0014,
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0x0015,
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0x0017,
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0x0017,
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0x02D8,
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0x02C7,
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0x02C6,
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0x02D9,
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0x02DD,
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0x02DB,
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0x02DA,
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0x02DC,
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0x0020,
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0x0021,
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0x0022,
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0x0023,
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0x0024,
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0x0025,
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0x0026,
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0x0027,
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0x0028,
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0x0029,
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0x002A,
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0x002B,
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0x002C,
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0x002D,
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0x002E,
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0x002F,
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0x0030,
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0x0031,
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0x0032,
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0x0033,
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0x0034,
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0x0035,
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0x0036,
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0x0037,
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0x0038,
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0x0039,
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0x003A,
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0x003B,
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0x003C,
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0x003D,
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0x003E,
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0x003F,
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0x0040,
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0x0041,
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0x0042,
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0x0043,
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0x0044,
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0x0045,
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0x0046,
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0x0047,
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0x0048,
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0x0049,
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0x004A,
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0x004B,
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0x004C,
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0x004D,
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0x004E,
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0x004F,
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0x0050,
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0x0051,
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0x0052,
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0x0053,
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0x0054,
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0x0055,
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0x0056,
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0x0057,
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0x0058,
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0x0059,
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0x005A,
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0x005B,
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0x005C,
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0x005D,
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0x005E,
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0x005F,
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0x0060,
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0x0061,
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0x0062,
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0x0063,
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0x0064,
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0x0065,
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0x0066,
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0x0067,
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0x0068,
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0x0069,
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0x006A,
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0x006B,
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0x006C,
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0x006D,
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0x006E,
|
|
0x006F,
|
|
0x0070,
|
|
0x0071,
|
|
0x0072,
|
|
0x0073,
|
|
0x0074,
|
|
0x0075,
|
|
0x0076,
|
|
0x0077,
|
|
0x0078,
|
|
0x0079,
|
|
0x007A,
|
|
0x007B,
|
|
0x007C,
|
|
0x007D,
|
|
0x007E,
|
|
0x0000,
|
|
0x2022,
|
|
0x2020,
|
|
0x2021,
|
|
0x2026,
|
|
0x2014,
|
|
0x2013,
|
|
0x0192,
|
|
0x2044,
|
|
0x2039,
|
|
0x203A,
|
|
0x2212,
|
|
0x2030,
|
|
0x201E,
|
|
0x201C,
|
|
0x201D,
|
|
0x2018,
|
|
0x2019,
|
|
0x201A,
|
|
0x2122,
|
|
0xFB01,
|
|
0xFB02,
|
|
0x0141,
|
|
0x0152,
|
|
0x0160,
|
|
0x0178,
|
|
0x017D,
|
|
0x0131,
|
|
0x0142,
|
|
0x0153,
|
|
0x0161,
|
|
0x017E,
|
|
0x0000,
|
|
0x20AC,
|
|
0x00A1,
|
|
0x00A2,
|
|
0x00A3,
|
|
0x00A4,
|
|
0x00A5,
|
|
0x00A6,
|
|
0x00A7,
|
|
0x00A8,
|
|
0x00A9,
|
|
0x00AA,
|
|
0x00AB,
|
|
0x00AC,
|
|
0x0000,
|
|
0x00AE,
|
|
0x00AF,
|
|
0x00B0,
|
|
0x00B1,
|
|
0x00B2,
|
|
0x00B3,
|
|
0x00B4,
|
|
0x00B5,
|
|
0x00B6,
|
|
0x00B7,
|
|
0x00B8,
|
|
0x00B9,
|
|
0x00BA,
|
|
0x00BB,
|
|
0x00BC,
|
|
0x00BD,
|
|
0x00BE,
|
|
0x00BF,
|
|
0x00C0,
|
|
0x00C1,
|
|
0x00C2,
|
|
0x00C3,
|
|
0x00C4,
|
|
0x00C5,
|
|
0x00C6,
|
|
0x00C7,
|
|
0x00C8,
|
|
0x00C9,
|
|
0x00CA,
|
|
0x00CB,
|
|
0x00CC,
|
|
0x00CD,
|
|
0x00CE,
|
|
0x00CF,
|
|
0x00D0,
|
|
0x00D1,
|
|
0x00D2,
|
|
0x00D3,
|
|
0x00D4,
|
|
0x00D5,
|
|
0x00D6,
|
|
0x00D7,
|
|
0x00D8,
|
|
0x00D9,
|
|
0x00DA,
|
|
0x00DB,
|
|
0x00DC,
|
|
0x00DD,
|
|
0x00DE,
|
|
0x00DF,
|
|
0x00E0,
|
|
0x00E1,
|
|
0x00E2,
|
|
0x00E3,
|
|
0x00E4,
|
|
0x00E5,
|
|
0x00E6,
|
|
0x00E7,
|
|
0x00E8,
|
|
0x00E9,
|
|
0x00EA,
|
|
0x00EB,
|
|
0x00EC,
|
|
0x00ED,
|
|
0x00EE,
|
|
0x00EF,
|
|
0x00F0,
|
|
0x00F1,
|
|
0x00F2,
|
|
0x00F3,
|
|
0x00F4,
|
|
0x00F5,
|
|
0x00F6,
|
|
0x00F7,
|
|
0x00F8,
|
|
0x00F9,
|
|
0x00FA,
|
|
0x00FB,
|
|
0x00FC,
|
|
0x00FD,
|
|
0x00FE,
|
|
0x00FF,
|
|
)
|
|
)
|
|
|
|
|
|
def decode_text(s: bytes) -> str:
|
|
"""Decodes a PDFDocEncoding string to Unicode."""
|
|
if s.startswith(b"\xfe\xff"):
|
|
return str(s[2:], "utf-16be", "ignore")
|
|
else:
|
|
return "".join(PDFDocEncoding[c] for c in s)
|
|
|
|
|
|
def enc(x: str) -> str:
|
|
"""Encodes a string for SGML/XML/HTML"""
|
|
if isinstance(x, bytes):
|
|
return ""
|
|
return escape(x)
|
|
|
|
|
|
def bbox2str(bbox: Rect) -> str:
|
|
(x0, y0, x1, y1) = bbox
|
|
return f"{x0:.3f},{y0:.3f},{x1:.3f},{y1:.3f}"
|
|
|
|
|
|
def matrix2str(m: Matrix) -> str:
|
|
(a, b, c, d, e, f) = m
|
|
return f"[{a:.2f},{b:.2f},{c:.2f},{d:.2f}, ({e:.2f},{f:.2f})]"
|
|
|
|
|
|
def vecBetweenBoxes(obj1: "LTComponent", obj2: "LTComponent") -> Point:
|
|
"""A distance function between two TextBoxes.
|
|
|
|
Consider the bounding rectangle for obj1 and obj2.
|
|
Return vector between 2 boxes boundaries if they don't overlap, otherwise
|
|
returns vector between boxes centers
|
|
|
|
+------+..........+ (x1, y1)
|
|
| obj1 | :
|
|
+------+www+------+
|
|
: | obj2 |
|
|
(x0, y0) +..........+------+
|
|
"""
|
|
(x0, y0) = (min(obj1.x0, obj2.x0), min(obj1.y0, obj2.y0))
|
|
(x1, y1) = (max(obj1.x1, obj2.x1), max(obj1.y1, obj2.y1))
|
|
(ow, oh) = (x1 - x0, y1 - y0)
|
|
(iw, ih) = (ow - obj1.width - obj2.width, oh - obj1.height - obj2.height)
|
|
if iw < 0 and ih < 0:
|
|
# if one is inside another we compute euclidean distance
|
|
(xc1, yc1) = ((obj1.x0 + obj1.x1) / 2, (obj1.y0 + obj1.y1) / 2)
|
|
(xc2, yc2) = ((obj2.x0 + obj2.x1) / 2, (obj2.y0 + obj2.y1) / 2)
|
|
return xc1 - xc2, yc1 - yc2
|
|
else:
|
|
return max(0, iw), max(0, ih)
|
|
|
|
|
|
LTComponentT = TypeVar("LTComponentT", bound="LTComponent")
|
|
|
|
|
|
class Plane(Generic[LTComponentT]):
|
|
"""A set-like data structure for objects placed on a plane.
|
|
|
|
Can efficiently find objects in a certain rectangular area.
|
|
It maintains two parallel lists of objects, each of
|
|
which is sorted by its x or y coordinate.
|
|
"""
|
|
|
|
def __init__(self, bbox: Rect, gridsize: int = 50) -> None:
|
|
self._seq: list[LTComponentT] = [] # preserve the object order.
|
|
self._objs: set[LTComponentT] = set()
|
|
self._grid: dict[Point, list[LTComponentT]] = {}
|
|
self.gridsize = gridsize
|
|
(self.x0, self.y0, self.x1, self.y1) = bbox
|
|
|
|
def __repr__(self) -> str:
|
|
return f"<Plane objs={list(self)!r}>"
|
|
|
|
def __iter__(self) -> Iterator[LTComponentT]:
|
|
return (obj for obj in self._seq if obj in self._objs)
|
|
|
|
def __len__(self) -> int:
|
|
return len(self._objs)
|
|
|
|
def __contains__(self, obj: object) -> bool:
|
|
return obj in self._objs
|
|
|
|
def _getrange(self, bbox: Rect) -> Iterator[Point]:
|
|
(x0, y0, x1, y1) = bbox
|
|
if x1 <= self.x0 or self.x1 <= x0 or y1 <= self.y0 or self.y1 <= y0:
|
|
return
|
|
x0 = max(self.x0, x0)
|
|
y0 = max(self.y0, y0)
|
|
x1 = min(self.x1, x1)
|
|
y1 = min(self.y1, y1)
|
|
for grid_y in drange(y0, y1, self.gridsize):
|
|
for grid_x in drange(x0, x1, self.gridsize):
|
|
yield (grid_x, grid_y)
|
|
|
|
def extend(self, objs: Iterable[LTComponentT]) -> None:
|
|
for obj in objs:
|
|
self.add(obj)
|
|
|
|
def add(self, obj: LTComponentT) -> None:
|
|
"""Place an object."""
|
|
for k in self._getrange((obj.x0, obj.y0, obj.x1, obj.y1)):
|
|
if k not in self._grid:
|
|
r: list[LTComponentT] = []
|
|
self._grid[k] = r
|
|
else:
|
|
r = self._grid[k]
|
|
r.append(obj)
|
|
self._seq.append(obj)
|
|
self._objs.add(obj)
|
|
|
|
def remove(self, obj: LTComponentT) -> None:
|
|
"""Displace an object."""
|
|
for k in self._getrange((obj.x0, obj.y0, obj.x1, obj.y1)):
|
|
with contextlib.suppress(KeyError, ValueError):
|
|
self._grid[k].remove(obj)
|
|
self._objs.remove(obj)
|
|
|
|
def find(self, bbox: Rect) -> Iterator[LTComponentT]:
|
|
"""Finds objects that are in a certain area."""
|
|
(x0, y0, x1, y1) = bbox
|
|
done = set()
|
|
for k in self._getrange(bbox):
|
|
if k not in self._grid:
|
|
continue
|
|
for obj in self._grid[k]:
|
|
if obj in done:
|
|
continue
|
|
done.add(obj)
|
|
if obj.x1 <= x0 or x1 <= obj.x0 or obj.y1 <= y0 or y1 <= obj.y0:
|
|
continue
|
|
yield obj
|
|
|
|
|
|
ROMAN_ONES = ["i", "x", "c", "m"]
|
|
ROMAN_FIVES = ["v", "l", "d"]
|
|
|
|
|
|
def format_int_roman(value: int) -> str:
|
|
"""Format a number as lowercase Roman numerals."""
|
|
assert 0 < value < 4000
|
|
result: list[str] = []
|
|
index = 0
|
|
|
|
while value != 0:
|
|
value, remainder = divmod(value, 10)
|
|
if remainder == 9:
|
|
result.insert(0, ROMAN_ONES[index])
|
|
result.insert(1, ROMAN_ONES[index + 1])
|
|
elif remainder == 4:
|
|
result.insert(0, ROMAN_ONES[index])
|
|
result.insert(1, ROMAN_FIVES[index])
|
|
else:
|
|
over_five = remainder >= 5
|
|
if over_five:
|
|
result.insert(0, ROMAN_FIVES[index])
|
|
remainder -= 5
|
|
result.insert(1 if over_five else 0, ROMAN_ONES[index] * remainder)
|
|
index += 1
|
|
|
|
return "".join(result)
|
|
|
|
|
|
def format_int_alpha(value: int) -> str:
|
|
"""Format a number as lowercase letters a-z, aa-zz, etc."""
|
|
assert value > 0
|
|
result: list[str] = []
|
|
|
|
while value != 0:
|
|
value, remainder = divmod(value - 1, len(string.ascii_lowercase))
|
|
result.append(string.ascii_lowercase[remainder])
|
|
|
|
result.reverse()
|
|
return "".join(result)
|
|
|
|
|
|
def unpad_aes(padded: bytes) -> bytes:
|
|
"""Remove block padding as described in PDF 1.7 section 7.6.2:
|
|
|
|
> For an original message length of M, the pad shall consist of 16 -
|
|
(M mod 16) bytes whose value shall also be 16 - (M mod 16).
|
|
> Note that the pad is present when M is evenly divisible by 16;
|
|
it contains 16 bytes of 0x10.
|
|
"""
|
|
if len(padded) == 0:
|
|
return padded
|
|
# Check for a potential padding byte (bytes are unsigned)
|
|
padding = padded[-1]
|
|
if padding > 16:
|
|
return padded
|
|
# A valid padding byte is the length of the padding
|
|
if padding > len(padded): # Obviously invalid
|
|
return padded
|
|
# Every byte of padding is equal to the length of padding
|
|
if all(x == padding for x in padded[-padding:]):
|
|
return padded[:-padding]
|
|
return padded
|