Files
OCRmyPDF/src/ocrmypdf/helpers.py
T
James R. Barlow b93cf51c0f Disable pikepdf mmap
Infrequently we can reproduce this error:

terminating with uncaught exception of type std::runtime_error: pybind11_object_dealloc(): Tried to deallocate unregistered instance!

The error is probably related to pybind11 issue #2252 and a bunch of
other related issues. Until that is resolved in pybind11 and pikepdf
we will disable the pikepdf mmap interface.
2020-09-16 23:48:55 -07:00

242 lines
6.8 KiB
Python

# © 2016 James R. Barlow: github.com/jbarlow83
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
import logging
import multiprocessing
import os
import shutil
import warnings
from collections import namedtuple
from collections.abc import Iterable
from contextlib import suppress
from functools import wraps
from io import StringIO
from math import isclose
from pathlib import Path
from typing import Any, Sequence, TypeVar
import pikepdf
log = logging.getLogger(__name__)
class Resolution(namedtuple('Resolution', ('x', 'y'))):
"""The number of pixels per inch in each 2D direction."""
__slots__ = ()
def round(self, ndigits: int):
return Resolution(round(self.x, ndigits), round(self.y, ndigits))
def to_int(self):
return Resolution(int(round(self.x)), int(round(self.y)))
@property
def is_square(self) -> bool:
return isclose(self.x, self.y, rel_tol=1e-3)
def take_max(self, vals, yvals=None):
if yvals is not None:
return Resolution(max(self.x, *vals), max(self.y, *yvals))
max_x, max_y = self.x, self.y
for x, y in vals:
max_x = max(x, max_x)
max_y = max(y, max_y)
return Resolution(max_x, max_y)
def flip_axis(self):
return Resolution(self.y, self.x)
def __str__(self):
return f"{self.x:f}x{self.y:f}"
def __repr__(self):
return f"Resolution({self.x}x{self.y} dpi)"
def safe_symlink(input_file: os.PathLike, soft_link_name: os.PathLike):
"""
Helper function: relinks soft symbolic link if necessary
"""
input_file = os.fspath(input_file)
soft_link_name = os.fspath(soft_link_name)
# Guard against soft linking to oneself
if input_file == soft_link_name:
log.warning(
"No symbolic link made. You are using "
"the original data directory as the working directory."
)
return
# Soft link already exists: delete for relink?
if os.path.lexists(soft_link_name):
# do not delete or overwrite real (non-soft link) file
if not os.path.islink(soft_link_name):
raise FileExistsError(f"{soft_link_name} exists and is not a link")
try:
os.unlink(soft_link_name)
except OSError:
log.debug("Can't unlink %s", soft_link_name)
if not os.path.exists(input_file):
raise FileNotFoundError(f"trying to create a broken symlink to {input_file}")
if os.name == 'nt':
# Don't actually use symlinks on Windows due to permission issues
shutil.copyfile(input_file, soft_link_name)
return
log.debug("os.symlink(%s, %s)", input_file, soft_link_name)
# Create symbolic link using absolute path
os.symlink(os.path.abspath(input_file), soft_link_name)
def samefile(f1: os.PathLike, f2: os.PathLike):
if os.name == 'nt':
return f1 == f2
else:
return os.path.samefile(f1, f2)
def is_iterable_notstr(thing: Any) -> bool:
"""Is this is an iterable type, other than a string?"""
return isinstance(thing, Iterable) and not isinstance(thing, str)
def monotonic(L: Sequence) -> bool:
"""Does list increase monotonically?"""
return all(b > a for a, b in zip(L, L[1:]))
def page_number(input_file: os.PathLike) -> int:
"""Get one-based page number implied by filename (000002.pdf -> 2)"""
return int(os.path.basename(os.fspath(input_file))[0:6])
def available_cpu_count() -> int:
"""Returns number of CPUs in the system."""
try:
return multiprocessing.cpu_count()
except NotImplementedError:
pass
warnings.warn(
"Could not get CPU count. Assuming one (1) CPU." "Use -j N to set manually."
)
return 1
def is_file_writable(test_file: os.PathLike) -> bool:
"""Intentionally racy test if target is writable.
We intend to write to the output file if and only if we succeed and
can replace it atomically. Before doing the OCR work, make sure
the location is writable.
"""
try:
p = Path(test_file)
if p.is_symlink():
p = p.resolve(strict=False)
# p.is_file() throws an exception in some cases
if p.exists() and p.is_file():
return os.access(
os.fspath(p),
os.W_OK,
effective_ids=(os.access in os.supports_effective_ids),
)
else:
try:
fp = p.open('wb')
except OSError:
return False
else:
fp.close()
with suppress(OSError):
p.unlink()
return True
except (EnvironmentError, RuntimeError) as e:
log.debug(e)
log.error(str(e))
return False
def check_pdf(input_file: Path) -> bool:
"""Check if a PDF complies with the PDF specification.
Checks for proper formatting and proper linearization.
"""
pdf = None
try:
pdf = pikepdf.open(input_file)
except pikepdf.PdfError as e:
log.error(e)
return False
else:
messages = pdf.check()
for msg in messages:
if 'error' in msg.lower():
log.error(msg)
else:
log.warning(msg)
sio = StringIO()
linearize = None
try:
pdf.check_linearization(sio)
except RuntimeError:
pass
else:
linearize = sio.getvalue()
if linearize:
log.warning(linearize)
if not messages and not linearize:
return True
return False
finally:
if pdf:
pdf.close()
T = TypeVar('T')
def clamp(n: T, smallest: T, largest: T) -> T:
"""Clamps the value of n to between smallest and largest."""
return max(smallest, min(n, largest))
def pikepdf_enable_mmap():
# try:
# if pikepdf._qpdf.set_access_default_mmap(True):
# log.debug("pikepdf mmap enabled")
# except AttributeError:
# log.debug("pikepdf mmap not available")
# We found a race condition probably related to pybind issue #2252 that can
# cause a crash. For now, disable pikepdf mmap to be on the safe side.
log.debug("pikepdf mmap disabled")
return
def deprecated(func):
"""Warn that function is deprecated"""
@wraps(func)
def new_func(*args, **kwargs):
warnings.simplefilter('always', DeprecationWarning) # turn off filter
warnings.warn(
"Call to deprecated function {}.".format(func.__name__),
category=DeprecationWarning,
stacklevel=2,
)
warnings.simplefilter('default', DeprecationWarning) # reset filter
return func(*args, **kwargs)
return new_func