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# SPDX-FileCopyrightText: Florian Bruhin (The-Compiler) <mail@qutebrowser.org>
#
# SPDX-License-Identifier: GPL-3.0-or-later
"""Utilities for parsing binary files.
Used by elf.py as well as pakjoy.py.
"""
import struct
from typing import Any, IO, Tuple
class ParseError(Exception):
"""Raised when the file can't be parsed."""
def unpack(fmt: str, fobj: IO[bytes]) -> Tuple[Any, ...]:
"""Unpack the given struct format from the given file."""
size = struct.calcsize(fmt)
data = safe_read(fobj, size)
try:
return struct.unpack(fmt, data)
except struct.error as e:
raise ParseError(e)
def safe_read(fobj: IO[bytes], size: int) -> bytes:
"""Read from a file, handling possible exceptions."""
try:
return fobj.read(size)
except (OSError, OverflowError) as e:
raise ParseError(e)
def safe_seek(fobj: IO[bytes], pos: int) -> None:
"""Seek in a file, handling possible exceptions."""
try:
fobj.seek(pos)
except (OSError, OverflowError) as e:
raise ParseError(e)
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