1075 lines
37 KiB
Python
1075 lines
37 KiB
Python
from __future__ import annotations
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import calendar
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import codecs
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import collections
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import mmap
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import os
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import re
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import time
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import zlib
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from typing import IO, Any, NamedTuple, Union
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# see 7.9.2.2 Text String Type on page 86 and D.3 PDFDocEncoding Character Set
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# on page 656
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def encode_text(s: str) -> bytes:
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return codecs.BOM_UTF16_BE + s.encode("utf_16_be")
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PDFDocEncoding = {
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0x16: "\u0017",
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0x18: "\u02d8",
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0x19: "\u02c7",
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0x1A: "\u02c6",
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0x1B: "\u02d9",
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0x1C: "\u02dd",
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0x1D: "\u02db",
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0x1E: "\u02da",
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0x1F: "\u02dc",
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0x80: "\u2022",
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0x81: "\u2020",
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0x82: "\u2021",
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0x83: "\u2026",
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0x84: "\u2014",
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0x85: "\u2013",
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0x86: "\u0192",
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0x87: "\u2044",
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0x88: "\u2039",
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0x89: "\u203a",
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0x8A: "\u2212",
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0x8B: "\u2030",
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0x8C: "\u201e",
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0x8D: "\u201c",
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0x8E: "\u201d",
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0x8F: "\u2018",
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0x90: "\u2019",
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0x91: "\u201a",
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0x92: "\u2122",
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0x93: "\ufb01",
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0x94: "\ufb02",
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0x95: "\u0141",
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0x96: "\u0152",
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0x97: "\u0160",
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0x98: "\u0178",
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0x99: "\u017d",
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0x9A: "\u0131",
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0x9B: "\u0142",
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0x9C: "\u0153",
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0x9D: "\u0161",
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0x9E: "\u017e",
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0xA0: "\u20ac",
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}
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def decode_text(b: bytes) -> str:
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if b[: len(codecs.BOM_UTF16_BE)] == codecs.BOM_UTF16_BE:
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return b[len(codecs.BOM_UTF16_BE) :].decode("utf_16_be")
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else:
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return "".join(PDFDocEncoding.get(byte, chr(byte)) for byte in b)
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class PdfFormatError(RuntimeError):
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"""An error that probably indicates a syntactic or semantic error in the
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PDF file structure"""
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pass
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def check_format_condition(condition: bool, error_message: str) -> None:
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if not condition:
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raise PdfFormatError(error_message)
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class IndirectReferenceTuple(NamedTuple):
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object_id: int
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generation: int
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class IndirectReference(IndirectReferenceTuple):
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def __str__(self) -> str:
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return f"{self.object_id} {self.generation} R"
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def __bytes__(self) -> bytes:
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return self.__str__().encode("us-ascii")
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def __eq__(self, other: object) -> bool:
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if self.__class__ is not other.__class__:
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return False
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assert isinstance(other, IndirectReference)
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return other.object_id == self.object_id and other.generation == self.generation
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def __ne__(self, other: object) -> bool:
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return not (self == other)
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def __hash__(self) -> int:
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return hash((self.object_id, self.generation))
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class IndirectObjectDef(IndirectReference):
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def __str__(self) -> str:
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return f"{self.object_id} {self.generation} obj"
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class XrefTable:
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def __init__(self) -> None:
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self.existing_entries: dict[int, tuple[int, int]] = (
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{}
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) # object ID => (offset, generation)
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self.new_entries: dict[int, tuple[int, int]] = (
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{}
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) # object ID => (offset, generation)
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self.deleted_entries = {0: 65536} # object ID => generation
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self.reading_finished = False
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def __setitem__(self, key: int, value: tuple[int, int]) -> None:
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if self.reading_finished:
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self.new_entries[key] = value
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else:
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self.existing_entries[key] = value
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if key in self.deleted_entries:
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del self.deleted_entries[key]
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def __getitem__(self, key: int) -> tuple[int, int]:
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try:
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return self.new_entries[key]
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except KeyError:
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return self.existing_entries[key]
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def __delitem__(self, key: int) -> None:
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if key in self.new_entries:
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generation = self.new_entries[key][1] + 1
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del self.new_entries[key]
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self.deleted_entries[key] = generation
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elif key in self.existing_entries:
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generation = self.existing_entries[key][1] + 1
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self.deleted_entries[key] = generation
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elif key in self.deleted_entries:
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generation = self.deleted_entries[key]
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else:
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msg = f"object ID {key} cannot be deleted because it doesn't exist"
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raise IndexError(msg)
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def __contains__(self, key: int) -> bool:
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return key in self.existing_entries or key in self.new_entries
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def __len__(self) -> int:
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return len(
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set(self.existing_entries.keys())
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| set(self.new_entries.keys())
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| set(self.deleted_entries.keys())
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)
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def keys(self) -> set[int]:
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return (
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set(self.existing_entries.keys()) - set(self.deleted_entries.keys())
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) | set(self.new_entries.keys())
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def write(self, f: IO[bytes]) -> int:
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keys = sorted(set(self.new_entries.keys()) | set(self.deleted_entries.keys()))
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deleted_keys = sorted(set(self.deleted_entries.keys()))
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startxref = f.tell()
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f.write(b"xref\n")
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while keys:
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# find a contiguous sequence of object IDs
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prev: int | None = None
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for index, key in enumerate(keys):
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if prev is None or prev + 1 == key:
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prev = key
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else:
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contiguous_keys = keys[:index]
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keys = keys[index:]
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break
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else:
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contiguous_keys = keys
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keys = []
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f.write(b"%d %d\n" % (contiguous_keys[0], len(contiguous_keys)))
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for object_id in contiguous_keys:
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if object_id in self.new_entries:
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f.write(b"%010d %05d n \n" % self.new_entries[object_id])
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else:
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this_deleted_object_id = deleted_keys.pop(0)
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check_format_condition(
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object_id == this_deleted_object_id,
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f"expected the next deleted object ID to be {object_id}, "
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f"instead found {this_deleted_object_id}",
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)
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try:
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next_in_linked_list = deleted_keys[0]
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except IndexError:
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next_in_linked_list = 0
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f.write(
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b"%010d %05d f \n"
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% (next_in_linked_list, self.deleted_entries[object_id])
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)
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return startxref
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class PdfName:
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name: bytes
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def __init__(self, name: PdfName | bytes | str) -> None:
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if isinstance(name, PdfName):
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self.name = name.name
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elif isinstance(name, bytes):
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self.name = name
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else:
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self.name = name.encode("us-ascii")
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def name_as_str(self) -> str:
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return self.name.decode("us-ascii")
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def __eq__(self, other: object) -> bool:
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return (
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isinstance(other, PdfName) and other.name == self.name
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) or other == self.name
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def __hash__(self) -> int:
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return hash(self.name)
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def __repr__(self) -> str:
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return f"{self.__class__.__name__}({repr(self.name)})"
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@classmethod
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def from_pdf_stream(cls, data: bytes) -> PdfName:
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return cls(PdfParser.interpret_name(data))
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allowed_chars = set(range(33, 127)) - {ord(c) for c in "#%/()<>[]{}"}
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def __bytes__(self) -> bytes:
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result = bytearray(b"/")
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for b in self.name:
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if b in self.allowed_chars:
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result.append(b)
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else:
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result.extend(b"#%02X" % b)
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return bytes(result)
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class PdfArray(list[Any]):
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def __bytes__(self) -> bytes:
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return b"[ " + b" ".join(pdf_repr(x) for x in self) + b" ]"
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TYPE_CHECKING = False
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if TYPE_CHECKING:
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_DictBase = collections.UserDict[Union[str, bytes], Any]
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else:
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_DictBase = collections.UserDict
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class PdfDict(_DictBase):
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def __setattr__(self, key: str, value: Any) -> None:
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if key == "data":
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collections.UserDict.__setattr__(self, key, value)
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else:
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self[key.encode("us-ascii")] = value
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def __getattr__(self, key: str) -> str | time.struct_time:
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try:
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value = self[key.encode("us-ascii")]
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except KeyError as e:
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raise AttributeError(key) from e
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if isinstance(value, bytes):
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value = decode_text(value)
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if key.endswith("Date"):
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if value.startswith("D:"):
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value = value[2:]
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relationship = "Z"
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if len(value) > 17:
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relationship = value[14]
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offset = int(value[15:17]) * 60
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if len(value) > 20:
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offset += int(value[18:20])
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format = "%Y%m%d%H%M%S"[: len(value) - 2]
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value = time.strptime(value[: len(format) + 2], format)
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if relationship in ["+", "-"]:
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offset *= 60
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if relationship == "+":
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offset *= -1
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value = time.gmtime(calendar.timegm(value) + offset)
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return value
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def __bytes__(self) -> bytes:
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out = bytearray(b"<<")
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for key, value in self.items():
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if value is None:
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continue
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value = pdf_repr(value)
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out.extend(b"\n")
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out.extend(bytes(PdfName(key)))
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out.extend(b" ")
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out.extend(value)
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out.extend(b"\n>>")
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return bytes(out)
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class PdfBinary:
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def __init__(self, data: list[int] | bytes) -> None:
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self.data = data
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def __bytes__(self) -> bytes:
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return b"<%s>" % b"".join(b"%02X" % b for b in self.data)
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class PdfStream:
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def __init__(self, dictionary: PdfDict, buf: bytes) -> None:
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self.dictionary = dictionary
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self.buf = buf
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def decode(self) -> bytes:
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try:
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filter = self.dictionary[b"Filter"]
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except KeyError:
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return self.buf
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if filter == b"FlateDecode":
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try:
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expected_length = self.dictionary[b"DL"]
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except KeyError:
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expected_length = self.dictionary[b"Length"]
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return zlib.decompress(self.buf, bufsize=int(expected_length))
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else:
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msg = f"stream filter {repr(filter)} unknown/unsupported"
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raise NotImplementedError(msg)
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def pdf_repr(x: Any) -> bytes:
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if x is True:
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return b"true"
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elif x is False:
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return b"false"
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elif x is None:
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return b"null"
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elif isinstance(x, (PdfName, PdfDict, PdfArray, PdfBinary)):
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return bytes(x)
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elif isinstance(x, (int, float)):
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return str(x).encode("us-ascii")
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elif isinstance(x, time.struct_time):
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return b"(D:" + time.strftime("%Y%m%d%H%M%SZ", x).encode("us-ascii") + b")"
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elif isinstance(x, dict):
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return bytes(PdfDict(x))
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elif isinstance(x, list):
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return bytes(PdfArray(x))
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elif isinstance(x, str):
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return pdf_repr(encode_text(x))
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elif isinstance(x, bytes):
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# XXX escape more chars? handle binary garbage
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x = x.replace(b"\\", b"\\\\")
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x = x.replace(b"(", b"\\(")
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x = x.replace(b")", b"\\)")
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return b"(" + x + b")"
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else:
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return bytes(x)
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class PdfParser:
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"""Based on
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https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/PDF32000_2008.pdf
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Supports PDF up to 1.4
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"""
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def __init__(
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self,
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filename: str | None = None,
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f: IO[bytes] | None = None,
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buf: bytes | bytearray | None = None,
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start_offset: int = 0,
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mode: str = "rb",
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) -> None:
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if buf and f:
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msg = "specify buf or f or filename, but not both buf and f"
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raise RuntimeError(msg)
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self.filename = filename
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self.buf: bytes | bytearray | mmap.mmap | None = buf
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self.f = f
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self.start_offset = start_offset
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self.should_close_buf = False
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self.should_close_file = False
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if filename is not None and f is None:
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self.f = f = open(filename, mode)
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self.should_close_file = True
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if f is not None:
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self.buf = self.get_buf_from_file(f)
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self.should_close_buf = True
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if not filename and hasattr(f, "name"):
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self.filename = f.name
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self.cached_objects: dict[IndirectReference, Any] = {}
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self.root_ref: IndirectReference | None
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self.info_ref: IndirectReference | None
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self.pages_ref: IndirectReference | None
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self.last_xref_section_offset: int | None
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if self.buf:
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self.read_pdf_info()
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else:
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self.file_size_total = self.file_size_this = 0
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self.root = PdfDict()
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self.root_ref = None
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self.info = PdfDict()
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self.info_ref = None
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self.page_tree_root = PdfDict()
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self.pages: list[IndirectReference] = []
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self.orig_pages: list[IndirectReference] = []
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self.pages_ref = None
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self.last_xref_section_offset = None
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self.trailer_dict: dict[bytes, Any] = {}
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self.xref_table = XrefTable()
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self.xref_table.reading_finished = True
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if f:
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self.seek_end()
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|
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def __enter__(self) -> PdfParser:
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return self
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|
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def __exit__(self, *args: object) -> None:
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self.close()
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|
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def start_writing(self) -> None:
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self.close_buf()
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self.seek_end()
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|
|
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def close_buf(self) -> None:
|
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if isinstance(self.buf, mmap.mmap):
|
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self.buf.close()
|
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self.buf = None
|
|
|
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def close(self) -> None:
|
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if self.should_close_buf:
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self.close_buf()
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if self.f is not None and self.should_close_file:
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self.f.close()
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self.f = None
|
|
|
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def seek_end(self) -> None:
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assert self.f is not None
|
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self.f.seek(0, os.SEEK_END)
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|
|
def write_header(self) -> None:
|
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assert self.f is not None
|
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self.f.write(b"%PDF-1.4\n")
|
|
|
|
def write_comment(self, s: str) -> None:
|
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assert self.f is not None
|
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self.f.write(f"% {s}\n".encode())
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|
|
|
def write_catalog(self) -> IndirectReference:
|
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assert self.f is not None
|
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self.del_root()
|
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self.root_ref = self.next_object_id(self.f.tell())
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self.pages_ref = self.next_object_id(0)
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self.rewrite_pages()
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self.write_obj(self.root_ref, Type=PdfName(b"Catalog"), Pages=self.pages_ref)
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self.write_obj(
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self.pages_ref,
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Type=PdfName(b"Pages"),
|
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Count=len(self.pages),
|
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Kids=self.pages,
|
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)
|
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return self.root_ref
|
|
|
|
def rewrite_pages(self) -> None:
|
|
pages_tree_nodes_to_delete = []
|
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for i, page_ref in enumerate(self.orig_pages):
|
|
page_info = self.cached_objects[page_ref]
|
|
del self.xref_table[page_ref.object_id]
|
|
pages_tree_nodes_to_delete.append(page_info[PdfName(b"Parent")])
|
|
if page_ref not in self.pages:
|
|
# the page has been deleted
|
|
continue
|
|
# make dict keys into strings for passing to write_page
|
|
stringified_page_info = {}
|
|
for key, value in page_info.items():
|
|
# key should be a PdfName
|
|
stringified_page_info[key.name_as_str()] = value
|
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stringified_page_info["Parent"] = self.pages_ref
|
|
new_page_ref = self.write_page(None, **stringified_page_info)
|
|
for j, cur_page_ref in enumerate(self.pages):
|
|
if cur_page_ref == page_ref:
|
|
# replace the page reference with the new one
|
|
self.pages[j] = new_page_ref
|
|
# delete redundant Pages tree nodes from xref table
|
|
for pages_tree_node_ref in pages_tree_nodes_to_delete:
|
|
while pages_tree_node_ref:
|
|
pages_tree_node = self.cached_objects[pages_tree_node_ref]
|
|
if pages_tree_node_ref.object_id in self.xref_table:
|
|
del self.xref_table[pages_tree_node_ref.object_id]
|
|
pages_tree_node_ref = pages_tree_node.get(b"Parent", None)
|
|
self.orig_pages = []
|
|
|
|
def write_xref_and_trailer(
|
|
self, new_root_ref: IndirectReference | None = None
|
|
) -> None:
|
|
assert self.f is not None
|
|
if new_root_ref:
|
|
self.del_root()
|
|
self.root_ref = new_root_ref
|
|
if self.info:
|
|
self.info_ref = self.write_obj(None, self.info)
|
|
start_xref = self.xref_table.write(self.f)
|
|
num_entries = len(self.xref_table)
|
|
trailer_dict: dict[str | bytes, Any] = {
|
|
b"Root": self.root_ref,
|
|
b"Size": num_entries,
|
|
}
|
|
if self.last_xref_section_offset is not None:
|
|
trailer_dict[b"Prev"] = self.last_xref_section_offset
|
|
if self.info:
|
|
trailer_dict[b"Info"] = self.info_ref
|
|
self.last_xref_section_offset = start_xref
|
|
self.f.write(
|
|
b"trailer\n"
|
|
+ bytes(PdfDict(trailer_dict))
|
|
+ b"\nstartxref\n%d\n%%%%EOF" % start_xref
|
|
)
|
|
|
|
def write_page(
|
|
self, ref: int | IndirectReference | None, *objs: Any, **dict_obj: Any
|
|
) -> IndirectReference:
|
|
obj_ref = self.pages[ref] if isinstance(ref, int) else ref
|
|
if "Type" not in dict_obj:
|
|
dict_obj["Type"] = PdfName(b"Page")
|
|
if "Parent" not in dict_obj:
|
|
dict_obj["Parent"] = self.pages_ref
|
|
return self.write_obj(obj_ref, *objs, **dict_obj)
|
|
|
|
def write_obj(
|
|
self, ref: IndirectReference | None, *objs: Any, **dict_obj: Any
|
|
) -> IndirectReference:
|
|
assert self.f is not None
|
|
f = self.f
|
|
if ref is None:
|
|
ref = self.next_object_id(f.tell())
|
|
else:
|
|
self.xref_table[ref.object_id] = (f.tell(), ref.generation)
|
|
f.write(bytes(IndirectObjectDef(*ref)))
|
|
stream = dict_obj.pop("stream", None)
|
|
if stream is not None:
|
|
dict_obj["Length"] = len(stream)
|
|
if dict_obj:
|
|
f.write(pdf_repr(dict_obj))
|
|
for obj in objs:
|
|
f.write(pdf_repr(obj))
|
|
if stream is not None:
|
|
f.write(b"stream\n")
|
|
f.write(stream)
|
|
f.write(b"\nendstream\n")
|
|
f.write(b"endobj\n")
|
|
return ref
|
|
|
|
def del_root(self) -> None:
|
|
if self.root_ref is None:
|
|
return
|
|
del self.xref_table[self.root_ref.object_id]
|
|
del self.xref_table[self.root[b"Pages"].object_id]
|
|
|
|
@staticmethod
|
|
def get_buf_from_file(f: IO[bytes]) -> bytes | mmap.mmap:
|
|
if hasattr(f, "getbuffer"):
|
|
return f.getbuffer()
|
|
elif hasattr(f, "getvalue"):
|
|
return f.getvalue()
|
|
else:
|
|
try:
|
|
return mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)
|
|
except ValueError: # cannot mmap an empty file
|
|
return b""
|
|
|
|
def read_pdf_info(self) -> None:
|
|
assert self.buf is not None
|
|
self.file_size_total = len(self.buf)
|
|
self.file_size_this = self.file_size_total - self.start_offset
|
|
self.read_trailer()
|
|
check_format_condition(
|
|
self.trailer_dict.get(b"Root") is not None, "Root is missing"
|
|
)
|
|
self.root_ref = self.trailer_dict[b"Root"]
|
|
assert self.root_ref is not None
|
|
self.info_ref = self.trailer_dict.get(b"Info", None)
|
|
self.root = PdfDict(self.read_indirect(self.root_ref))
|
|
if self.info_ref is None:
|
|
self.info = PdfDict()
|
|
else:
|
|
self.info = PdfDict(self.read_indirect(self.info_ref))
|
|
check_format_condition(b"Type" in self.root, "/Type missing in Root")
|
|
check_format_condition(
|
|
self.root[b"Type"] == b"Catalog", "/Type in Root is not /Catalog"
|
|
)
|
|
check_format_condition(
|
|
self.root.get(b"Pages") is not None, "/Pages missing in Root"
|
|
)
|
|
check_format_condition(
|
|
isinstance(self.root[b"Pages"], IndirectReference),
|
|
"/Pages in Root is not an indirect reference",
|
|
)
|
|
self.pages_ref = self.root[b"Pages"]
|
|
assert self.pages_ref is not None
|
|
self.page_tree_root = self.read_indirect(self.pages_ref)
|
|
self.pages = self.linearize_page_tree(self.page_tree_root)
|
|
# save the original list of page references
|
|
# in case the user modifies, adds or deletes some pages
|
|
# and we need to rewrite the pages and their list
|
|
self.orig_pages = self.pages[:]
|
|
|
|
def next_object_id(self, offset: int | None = None) -> IndirectReference:
|
|
try:
|
|
# TODO: support reuse of deleted objects
|
|
reference = IndirectReference(max(self.xref_table.keys()) + 1, 0)
|
|
except ValueError:
|
|
reference = IndirectReference(1, 0)
|
|
if offset is not None:
|
|
self.xref_table[reference.object_id] = (offset, 0)
|
|
return reference
|
|
|
|
delimiter = rb"[][()<>{}/%]"
|
|
delimiter_or_ws = rb"[][()<>{}/%\000\011\012\014\015\040]"
|
|
whitespace = rb"[\000\011\012\014\015\040]"
|
|
whitespace_or_hex = rb"[\000\011\012\014\015\0400-9a-fA-F]"
|
|
whitespace_optional = whitespace + b"*"
|
|
whitespace_mandatory = whitespace + b"+"
|
|
# No "\012" aka "\n" or "\015" aka "\r":
|
|
whitespace_optional_no_nl = rb"[\000\011\014\040]*"
|
|
newline_only = rb"[\r\n]+"
|
|
newline = whitespace_optional_no_nl + newline_only + whitespace_optional_no_nl
|
|
re_trailer_end = re.compile(
|
|
whitespace_mandatory
|
|
+ rb"trailer"
|
|
+ whitespace_optional
|
|
+ rb"<<(.*>>)"
|
|
+ newline
|
|
+ rb"startxref"
|
|
+ newline
|
|
+ rb"([0-9]+)"
|
|
+ newline
|
|
+ rb"%%EOF"
|
|
+ whitespace_optional
|
|
+ rb"$",
|
|
re.DOTALL,
|
|
)
|
|
re_trailer_prev = re.compile(
|
|
whitespace_optional
|
|
+ rb"trailer"
|
|
+ whitespace_optional
|
|
+ rb"<<(.*?>>)"
|
|
+ newline
|
|
+ rb"startxref"
|
|
+ newline
|
|
+ rb"([0-9]+)"
|
|
+ newline
|
|
+ rb"%%EOF"
|
|
+ whitespace_optional,
|
|
re.DOTALL,
|
|
)
|
|
|
|
def read_trailer(self) -> None:
|
|
assert self.buf is not None
|
|
search_start_offset = len(self.buf) - 16384
|
|
if search_start_offset < self.start_offset:
|
|
search_start_offset = self.start_offset
|
|
m = self.re_trailer_end.search(self.buf, search_start_offset)
|
|
check_format_condition(m is not None, "trailer end not found")
|
|
# make sure we found the LAST trailer
|
|
last_match = m
|
|
while m:
|
|
last_match = m
|
|
m = self.re_trailer_end.search(self.buf, m.start() + 16)
|
|
if not m:
|
|
m = last_match
|
|
assert m is not None
|
|
trailer_data = m.group(1)
|
|
self.last_xref_section_offset = int(m.group(2))
|
|
self.trailer_dict = self.interpret_trailer(trailer_data)
|
|
self.xref_table = XrefTable()
|
|
self.read_xref_table(xref_section_offset=self.last_xref_section_offset)
|
|
if b"Prev" in self.trailer_dict:
|
|
self.read_prev_trailer(self.trailer_dict[b"Prev"])
|
|
|
|
def read_prev_trailer(self, xref_section_offset: int) -> None:
|
|
assert self.buf is not None
|
|
trailer_offset = self.read_xref_table(xref_section_offset=xref_section_offset)
|
|
m = self.re_trailer_prev.search(
|
|
self.buf[trailer_offset : trailer_offset + 16384]
|
|
)
|
|
check_format_condition(m is not None, "previous trailer not found")
|
|
assert m is not None
|
|
trailer_data = m.group(1)
|
|
check_format_condition(
|
|
int(m.group(2)) == xref_section_offset,
|
|
"xref section offset in previous trailer doesn't match what was expected",
|
|
)
|
|
trailer_dict = self.interpret_trailer(trailer_data)
|
|
if b"Prev" in trailer_dict:
|
|
self.read_prev_trailer(trailer_dict[b"Prev"])
|
|
|
|
re_whitespace_optional = re.compile(whitespace_optional)
|
|
re_name = re.compile(
|
|
whitespace_optional
|
|
+ rb"/([!-$&'*-.0-;=?-Z\\^-z|~]+)(?="
|
|
+ delimiter_or_ws
|
|
+ rb")"
|
|
)
|
|
re_dict_start = re.compile(whitespace_optional + rb"<<")
|
|
re_dict_end = re.compile(whitespace_optional + rb">>" + whitespace_optional)
|
|
|
|
@classmethod
|
|
def interpret_trailer(cls, trailer_data: bytes) -> dict[bytes, Any]:
|
|
trailer = {}
|
|
offset = 0
|
|
while True:
|
|
m = cls.re_name.match(trailer_data, offset)
|
|
if not m:
|
|
m = cls.re_dict_end.match(trailer_data, offset)
|
|
check_format_condition(
|
|
m is not None and m.end() == len(trailer_data),
|
|
"name not found in trailer, remaining data: "
|
|
+ repr(trailer_data[offset:]),
|
|
)
|
|
break
|
|
key = cls.interpret_name(m.group(1))
|
|
assert isinstance(key, bytes)
|
|
value, value_offset = cls.get_value(trailer_data, m.end())
|
|
trailer[key] = value
|
|
if value_offset is None:
|
|
break
|
|
offset = value_offset
|
|
check_format_condition(
|
|
b"Size" in trailer and isinstance(trailer[b"Size"], int),
|
|
"/Size not in trailer or not an integer",
|
|
)
|
|
check_format_condition(
|
|
b"Root" in trailer and isinstance(trailer[b"Root"], IndirectReference),
|
|
"/Root not in trailer or not an indirect reference",
|
|
)
|
|
return trailer
|
|
|
|
re_hashes_in_name = re.compile(rb"([^#]*)(#([0-9a-fA-F]{2}))?")
|
|
|
|
@classmethod
|
|
def interpret_name(cls, raw: bytes, as_text: bool = False) -> str | bytes:
|
|
name = b""
|
|
for m in cls.re_hashes_in_name.finditer(raw):
|
|
if m.group(3):
|
|
name += m.group(1) + bytearray.fromhex(m.group(3).decode("us-ascii"))
|
|
else:
|
|
name += m.group(1)
|
|
if as_text:
|
|
return name.decode("utf-8")
|
|
else:
|
|
return bytes(name)
|
|
|
|
re_null = re.compile(whitespace_optional + rb"null(?=" + delimiter_or_ws + rb")")
|
|
re_true = re.compile(whitespace_optional + rb"true(?=" + delimiter_or_ws + rb")")
|
|
re_false = re.compile(whitespace_optional + rb"false(?=" + delimiter_or_ws + rb")")
|
|
re_int = re.compile(
|
|
whitespace_optional + rb"([-+]?[0-9]+)(?=" + delimiter_or_ws + rb")"
|
|
)
|
|
re_real = re.compile(
|
|
whitespace_optional
|
|
+ rb"([-+]?([0-9]+\.[0-9]*|[0-9]*\.[0-9]+))(?="
|
|
+ delimiter_or_ws
|
|
+ rb")"
|
|
)
|
|
re_array_start = re.compile(whitespace_optional + rb"\[")
|
|
re_array_end = re.compile(whitespace_optional + rb"]")
|
|
re_string_hex = re.compile(
|
|
whitespace_optional + rb"<(" + whitespace_or_hex + rb"*)>"
|
|
)
|
|
re_string_lit = re.compile(whitespace_optional + rb"\(")
|
|
re_indirect_reference = re.compile(
|
|
whitespace_optional
|
|
+ rb"([-+]?[0-9]+)"
|
|
+ whitespace_mandatory
|
|
+ rb"([-+]?[0-9]+)"
|
|
+ whitespace_mandatory
|
|
+ rb"R(?="
|
|
+ delimiter_or_ws
|
|
+ rb")"
|
|
)
|
|
re_indirect_def_start = re.compile(
|
|
whitespace_optional
|
|
+ rb"([-+]?[0-9]+)"
|
|
+ whitespace_mandatory
|
|
+ rb"([-+]?[0-9]+)"
|
|
+ whitespace_mandatory
|
|
+ rb"obj(?="
|
|
+ delimiter_or_ws
|
|
+ rb")"
|
|
)
|
|
re_indirect_def_end = re.compile(
|
|
whitespace_optional + rb"endobj(?=" + delimiter_or_ws + rb")"
|
|
)
|
|
re_comment = re.compile(
|
|
rb"(" + whitespace_optional + rb"%[^\r\n]*" + newline + rb")*"
|
|
)
|
|
re_stream_start = re.compile(whitespace_optional + rb"stream\r?\n")
|
|
re_stream_end = re.compile(
|
|
whitespace_optional + rb"endstream(?=" + delimiter_or_ws + rb")"
|
|
)
|
|
|
|
@classmethod
|
|
def get_value(
|
|
cls,
|
|
data: bytes | bytearray | mmap.mmap,
|
|
offset: int,
|
|
expect_indirect: IndirectReference | None = None,
|
|
max_nesting: int = -1,
|
|
) -> tuple[Any, int | None]:
|
|
if max_nesting == 0:
|
|
return None, None
|
|
m = cls.re_comment.match(data, offset)
|
|
if m:
|
|
offset = m.end()
|
|
m = cls.re_indirect_def_start.match(data, offset)
|
|
if m:
|
|
check_format_condition(
|
|
int(m.group(1)) > 0,
|
|
"indirect object definition: object ID must be greater than 0",
|
|
)
|
|
check_format_condition(
|
|
int(m.group(2)) >= 0,
|
|
"indirect object definition: generation must be non-negative",
|
|
)
|
|
check_format_condition(
|
|
expect_indirect is None
|
|
or expect_indirect
|
|
== IndirectReference(int(m.group(1)), int(m.group(2))),
|
|
"indirect object definition different than expected",
|
|
)
|
|
object, object_offset = cls.get_value(
|
|
data, m.end(), max_nesting=max_nesting - 1
|
|
)
|
|
if object_offset is None:
|
|
return object, None
|
|
m = cls.re_indirect_def_end.match(data, object_offset)
|
|
check_format_condition(
|
|
m is not None, "indirect object definition end not found"
|
|
)
|
|
assert m is not None
|
|
return object, m.end()
|
|
check_format_condition(
|
|
not expect_indirect, "indirect object definition not found"
|
|
)
|
|
m = cls.re_indirect_reference.match(data, offset)
|
|
if m:
|
|
check_format_condition(
|
|
int(m.group(1)) > 0,
|
|
"indirect object reference: object ID must be greater than 0",
|
|
)
|
|
check_format_condition(
|
|
int(m.group(2)) >= 0,
|
|
"indirect object reference: generation must be non-negative",
|
|
)
|
|
return IndirectReference(int(m.group(1)), int(m.group(2))), m.end()
|
|
m = cls.re_dict_start.match(data, offset)
|
|
if m:
|
|
offset = m.end()
|
|
result: dict[Any, Any] = {}
|
|
m = cls.re_dict_end.match(data, offset)
|
|
current_offset: int | None = offset
|
|
while not m:
|
|
assert current_offset is not None
|
|
key, current_offset = cls.get_value(
|
|
data, current_offset, max_nesting=max_nesting - 1
|
|
)
|
|
if current_offset is None:
|
|
return result, None
|
|
value, current_offset = cls.get_value(
|
|
data, current_offset, max_nesting=max_nesting - 1
|
|
)
|
|
result[key] = value
|
|
if current_offset is None:
|
|
return result, None
|
|
m = cls.re_dict_end.match(data, current_offset)
|
|
current_offset = m.end()
|
|
m = cls.re_stream_start.match(data, current_offset)
|
|
if m:
|
|
stream_len = result.get(b"Length")
|
|
if stream_len is None or not isinstance(stream_len, int):
|
|
msg = f"bad or missing Length in stream dict ({stream_len})"
|
|
raise PdfFormatError(msg)
|
|
stream_data = data[m.end() : m.end() + stream_len]
|
|
m = cls.re_stream_end.match(data, m.end() + stream_len)
|
|
check_format_condition(m is not None, "stream end not found")
|
|
assert m is not None
|
|
current_offset = m.end()
|
|
return PdfStream(PdfDict(result), stream_data), current_offset
|
|
return PdfDict(result), current_offset
|
|
m = cls.re_array_start.match(data, offset)
|
|
if m:
|
|
offset = m.end()
|
|
results = []
|
|
m = cls.re_array_end.match(data, offset)
|
|
current_offset = offset
|
|
while not m:
|
|
assert current_offset is not None
|
|
value, current_offset = cls.get_value(
|
|
data, current_offset, max_nesting=max_nesting - 1
|
|
)
|
|
results.append(value)
|
|
if current_offset is None:
|
|
return results, None
|
|
m = cls.re_array_end.match(data, current_offset)
|
|
return results, m.end()
|
|
m = cls.re_null.match(data, offset)
|
|
if m:
|
|
return None, m.end()
|
|
m = cls.re_true.match(data, offset)
|
|
if m:
|
|
return True, m.end()
|
|
m = cls.re_false.match(data, offset)
|
|
if m:
|
|
return False, m.end()
|
|
m = cls.re_name.match(data, offset)
|
|
if m:
|
|
return PdfName(cls.interpret_name(m.group(1))), m.end()
|
|
m = cls.re_int.match(data, offset)
|
|
if m:
|
|
return int(m.group(1)), m.end()
|
|
m = cls.re_real.match(data, offset)
|
|
if m:
|
|
# XXX Decimal instead of float???
|
|
return float(m.group(1)), m.end()
|
|
m = cls.re_string_hex.match(data, offset)
|
|
if m:
|
|
# filter out whitespace
|
|
hex_string = bytearray(
|
|
b for b in m.group(1) if b in b"0123456789abcdefABCDEF"
|
|
)
|
|
if len(hex_string) % 2 == 1:
|
|
# append a 0 if the length is not even - yes, at the end
|
|
hex_string.append(ord(b"0"))
|
|
return bytearray.fromhex(hex_string.decode("us-ascii")), m.end()
|
|
m = cls.re_string_lit.match(data, offset)
|
|
if m:
|
|
return cls.get_literal_string(data, m.end())
|
|
# return None, offset # fallback (only for debugging)
|
|
msg = f"unrecognized object: {repr(data[offset : offset + 32])}"
|
|
raise PdfFormatError(msg)
|
|
|
|
re_lit_str_token = re.compile(
|
|
rb"(\\[nrtbf()\\])|(\\[0-9]{1,3})|(\\(\r\n|\r|\n))|(\r\n|\r|\n)|(\()|(\))"
|
|
)
|
|
escaped_chars = {
|
|
b"n": b"\n",
|
|
b"r": b"\r",
|
|
b"t": b"\t",
|
|
b"b": b"\b",
|
|
b"f": b"\f",
|
|
b"(": b"(",
|
|
b")": b")",
|
|
b"\\": b"\\",
|
|
ord(b"n"): b"\n",
|
|
ord(b"r"): b"\r",
|
|
ord(b"t"): b"\t",
|
|
ord(b"b"): b"\b",
|
|
ord(b"f"): b"\f",
|
|
ord(b"("): b"(",
|
|
ord(b")"): b")",
|
|
ord(b"\\"): b"\\",
|
|
}
|
|
|
|
@classmethod
|
|
def get_literal_string(
|
|
cls, data: bytes | bytearray | mmap.mmap, offset: int
|
|
) -> tuple[bytes, int]:
|
|
nesting_depth = 0
|
|
result = bytearray()
|
|
for m in cls.re_lit_str_token.finditer(data, offset):
|
|
result.extend(data[offset : m.start()])
|
|
if m.group(1):
|
|
result.extend(cls.escaped_chars[m.group(1)[1]])
|
|
elif m.group(2):
|
|
result.append(int(m.group(2)[1:], 8))
|
|
elif m.group(3):
|
|
pass
|
|
elif m.group(5):
|
|
result.extend(b"\n")
|
|
elif m.group(6):
|
|
result.extend(b"(")
|
|
nesting_depth += 1
|
|
elif m.group(7):
|
|
if nesting_depth == 0:
|
|
return bytes(result), m.end()
|
|
result.extend(b")")
|
|
nesting_depth -= 1
|
|
offset = m.end()
|
|
msg = "unfinished literal string"
|
|
raise PdfFormatError(msg)
|
|
|
|
re_xref_section_start = re.compile(whitespace_optional + rb"xref" + newline)
|
|
re_xref_subsection_start = re.compile(
|
|
whitespace_optional
|
|
+ rb"([0-9]+)"
|
|
+ whitespace_mandatory
|
|
+ rb"([0-9]+)"
|
|
+ whitespace_optional
|
|
+ newline_only
|
|
)
|
|
re_xref_entry = re.compile(rb"([0-9]{10}) ([0-9]{5}) ([fn])( \r| \n|\r\n)")
|
|
|
|
def read_xref_table(self, xref_section_offset: int) -> int:
|
|
assert self.buf is not None
|
|
subsection_found = False
|
|
m = self.re_xref_section_start.match(
|
|
self.buf, xref_section_offset + self.start_offset
|
|
)
|
|
check_format_condition(m is not None, "xref section start not found")
|
|
assert m is not None
|
|
offset = m.end()
|
|
while True:
|
|
m = self.re_xref_subsection_start.match(self.buf, offset)
|
|
if not m:
|
|
check_format_condition(
|
|
subsection_found, "xref subsection start not found"
|
|
)
|
|
break
|
|
subsection_found = True
|
|
offset = m.end()
|
|
first_object = int(m.group(1))
|
|
num_objects = int(m.group(2))
|
|
for i in range(first_object, first_object + num_objects):
|
|
m = self.re_xref_entry.match(self.buf, offset)
|
|
check_format_condition(m is not None, "xref entry not found")
|
|
assert m is not None
|
|
offset = m.end()
|
|
is_free = m.group(3) == b"f"
|
|
if not is_free:
|
|
generation = int(m.group(2))
|
|
new_entry = (int(m.group(1)), generation)
|
|
if i not in self.xref_table:
|
|
self.xref_table[i] = new_entry
|
|
return offset
|
|
|
|
def read_indirect(self, ref: IndirectReference, max_nesting: int = -1) -> Any:
|
|
offset, generation = self.xref_table[ref[0]]
|
|
check_format_condition(
|
|
generation == ref[1],
|
|
f"expected to find generation {ref[1]} for object ID {ref[0]} in xref "
|
|
f"table, instead found generation {generation} at offset {offset}",
|
|
)
|
|
assert self.buf is not None
|
|
value = self.get_value(
|
|
self.buf,
|
|
offset + self.start_offset,
|
|
expect_indirect=IndirectReference(*ref),
|
|
max_nesting=max_nesting,
|
|
)[0]
|
|
self.cached_objects[ref] = value
|
|
return value
|
|
|
|
def linearize_page_tree(
|
|
self, node: PdfDict | None = None
|
|
) -> list[IndirectReference]:
|
|
page_node = node if node is not None else self.page_tree_root
|
|
check_format_condition(
|
|
page_node[b"Type"] == b"Pages", "/Type of page tree node is not /Pages"
|
|
)
|
|
pages = []
|
|
for kid in page_node[b"Kids"]:
|
|
kid_object = self.read_indirect(kid)
|
|
if kid_object[b"Type"] == b"Page":
|
|
pages.append(kid)
|
|
else:
|
|
pages.extend(self.linearize_page_tree(node=kid_object))
|
|
return pages
|