mirror of
git://github.com/kovidgoyal/calibre.git
synced 2026-01-02 20:26:02 +01:00
Use atomic writes for the config files
Avoids the need for file locking and also ensures no partial data is written in case of crash/powerloss. Fixes #1964123 [Settings reset in main calibre program when pc turns off due to power failure](https://bugs.launchpad.net/calibre/+bug/1964123)
This commit is contained in:
Kovid Goyal
parent
15ded1182f
commit
007099dd60
2 changed files with 74 additions and 60 deletions
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@ -15,12 +15,10 @@
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)
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from calibre.utils.config_base import (
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Config, ConfigInterface, ConfigProxy, Option, OptionSet, OptionValues,
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StringConfig, json_dumps, json_loads, make_config_dir, plugin_dir, prefs,
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tweaks, from_json, to_json
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StringConfig, commit_data, from_json, json_dumps, json_loads, make_config_dir,
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plugin_dir, prefs, read_data, to_json, tweaks
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)
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from calibre.utils.lock import ExclusiveFile
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from polyglot.builtins import string_or_bytes, native_string_type
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from polyglot.builtins import native_string_type, string_or_bytes
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# optparse uses gettext.gettext instead of _ from builtins, so we
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# monkey patch it.
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@ -29,7 +27,7 @@
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if False:
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# Make pyflakes happy
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Config, ConfigProxy, Option, OptionValues, StringConfig, OptionSet,
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ConfigInterface, tweaks, plugin_dir, prefs, from_json, to_json
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ConfigInterface, tweaks, plugin_dir, prefs, from_json, to_json, make_config_dir
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def check_config_write_access():
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@ -53,6 +51,7 @@ def format_heading(self, heading):
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def format_option(self, option):
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import textwrap
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from calibre.utils.terminal import colored
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result = []
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@ -91,6 +90,7 @@ def __init__(self,
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conflict_handler='resolve',
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**kwds):
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import textwrap
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from calibre.utils.terminal import colored
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usage = textwrap.dedent(usage)
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@ -219,8 +219,8 @@ def decouple(self, prefix):
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self.refresh()
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def read_old_serialized_representation(self):
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from calibre.utils.shared_file import share_open
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from calibre.utils.serialize import pickle_loads
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from calibre.utils.shared_file import share_open
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path = self.file_path.rpartition('.')[0]
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try:
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with share_open(path, 'rb') as f:
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@ -238,9 +238,12 @@ def refresh(self, clear_current=True):
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migrate = False
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if clear_current:
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self.clear()
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if os.path.exists(self.file_path):
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with ExclusiveFile(self.file_path) as f:
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raw = f.read()
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try:
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raw = read_data(self.file_path)
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except FileNotFoundError:
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d = self.read_old_serialized_representation()
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migrate = bool(d)
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else:
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if raw:
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try:
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d = json_loads(raw)
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@ -250,14 +253,9 @@ def refresh(self, clear_current=True):
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else:
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d = self.read_old_serialized_representation()
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migrate = bool(d)
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else:
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d = self.read_old_serialized_representation()
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migrate = bool(d)
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if migrate and d:
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raw = json_dumps(d, ignore_unserializable=True)
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with ExclusiveFile(self.file_path) as f:
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f.seek(0), f.truncate()
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f.write(raw)
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commit_data(self.file_path, raw)
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self.update(d)
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@ -283,13 +281,8 @@ def set(self, key, val):
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def commit(self):
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if not getattr(self, 'name', None):
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return
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if not os.path.exists(self.file_path):
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make_config_dir()
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raw = json_dumps(self)
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with ExclusiveFile(self.file_path) as f:
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f.seek(0)
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f.truncate()
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f.write(raw)
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commit_data(self.file_path, raw)
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dynamic = DynamicConfig()
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@ -345,17 +338,19 @@ def decouple(self, prefix):
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def refresh(self, clear_current=True):
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d = {}
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if os.path.exists(self.file_path):
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with ExclusiveFile(self.file_path) as f:
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raw = f.read()
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try:
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d = self.raw_to_object(raw) if raw.strip() else {}
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except SystemError:
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pass
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except:
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import traceback
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traceback.print_exc()
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d = {}
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try:
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raw = read_data(self.file_path)
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except FileNotFoundError:
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pass
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else:
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try:
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d = self.raw_to_object(raw) if raw.strip() else {}
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except SystemError:
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pass
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except:
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import traceback
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traceback.print_exc()
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d = {}
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if clear_current:
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self.clear()
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self.update(d)
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@ -393,15 +388,11 @@ def __delitem__(self, key):
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def commit(self):
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if self.no_commit:
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return
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if hasattr(self, 'file_path') and self.file_path:
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if getattr(self, 'file_path', None):
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dpath = os.path.dirname(self.file_path)
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if not os.path.exists(dpath):
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os.makedirs(dpath, mode=CONFIG_DIR_MODE)
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with ExclusiveFile(self.file_path) as f:
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raw = self.to_raw()
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f.seek(0)
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f.truncate()
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f.write(raw)
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commit_data(self.file_path, self.to_raw())
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def __enter__(self):
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self.no_commit = True
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@ -5,11 +5,11 @@
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__docformat__ = 'restructuredtext en'
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import os, re, traceback, numbers
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from contextlib import suppress
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from functools import partial
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from collections import defaultdict
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from copy import deepcopy
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from calibre.utils.lock import ExclusiveFile
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from calibre.constants import config_dir, CONFIG_DIR_MODE, preferred_encoding, filesystem_encoding, iswindows
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from polyglot.builtins import iteritems
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@ -344,6 +344,34 @@ def smart_update(self, opts1, opts2):
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self.option_set.smart_update(opts1, opts2)
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def read_data(file_path, count=10, sleep_time=0.2):
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import time
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count = 10
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for i in range(count):
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try:
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with open(file_path, 'rb') as f:
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return f.read()
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except FileNotFoundError:
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raise
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except OSError:
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if i > count - 2:
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raise
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# Try the operation repeatedly in case something like a virus
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# scanner has opened one of the files (I love windows)
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time.sleep(sleep_time)
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def commit_data(file_path, data):
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import tempfile
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from calibre.utils.filenames import atomic_rename
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bdir = os.path.dirname(file_path)
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os.makedirs(bdir, exist_ok=True, mode=CONFIG_DIR_MODE)
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with tempfile.NamedTemporaryFile(dir=bdir, delete=False) as f:
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f.write(data)
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atomic_rename(f.name, file_path)
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class Config(ConfigInterface):
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'''
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A file based configuration.
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@ -361,13 +389,13 @@ def parse(self):
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src = ''
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migrate = False
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path = self.config_file_path
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if os.path.exists(path):
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with ExclusiveFile(path) as f:
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try:
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src = f.read().decode('utf-8')
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except ValueError:
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print("Failed to parse", path)
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traceback.print_exc()
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with suppress(FileNotFoundError):
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src_bytes = read_data(path)
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try:
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src = src_bytes.decode('utf-8')
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except ValueError:
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print("Failed to parse", path)
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traceback.print_exc()
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if not src:
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path = path.rpartition('.')[0]
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from calibre.utils.shared_file import share_open
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@ -381,9 +409,7 @@ def parse(self):
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ans = self.option_set.parse_string(src)
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if migrate:
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new_src = self.option_set.serialize(ans, ignore_unserializable=True)
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with ExclusiveFile(self.config_file_path) as f:
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f.seek(0), f.truncate()
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f.write(new_src)
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commit_data(self.config_file_path, new_src)
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return ans
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def set(self, name, val):
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@ -391,16 +417,13 @@ def set(self, name, val):
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raise ValueError('The option %s is not defined.'%name)
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if not os.path.exists(config_dir):
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make_config_dir()
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with ExclusiveFile(self.config_file_path) as f:
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src = f.read()
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opts = self.option_set.parse_string(src)
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setattr(opts, name, val)
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src = self.option_set.serialize(opts)
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f.seek(0)
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f.truncate()
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if isinstance(src, str):
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src = src.encode('utf-8')
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f.write(src)
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src = read_data(self.config_file_path)
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opts = self.option_set.parse_string(src)
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setattr(opts, name, val)
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src = self.option_set.serialize(opts)
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if isinstance(src, str):
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src = src.encode('utf-8')
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commit_data(self.config_file_path, src)
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class StringConfig(ConfigInterface):
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