Add support for getting last system update dates

plugins/functions/fmod_package_updates.py

 import os
+import errno
 import re
+from datetime import datetime
 from settingsd import const
 from settingsd import config
 from settingsd import service
@@ -10,8 +12,18 @@ from settingsd.tools.process import execProcess
 INTERFACE_NAME = "packageUpdates"
 SERVICE_NAME = "package_updates"
 APT_EXECUTABLE = "/usr/bin/apt"
+APT_COMMANDS = (
+	'install', 'upgrade', 'update', 'remove', 'purge', 'dist-upgrade', 'search',
+	'autoremove', 'dselect-upgrade', 'check', 'clean', 'autoclean', 'source',
+	'download', 'changelog', 'build-dep', 'full-upgrade', 'show', 'list',
+	'edit-sources'
+)
 PACKAGE_REGEX = re.compile(r'^(\S+)/\S+')
 
+MULTIPLE_SPACES_REGEX = re.compile(r'\s{2,}')
+
+HISTORY_BLOCK_SIZE = 2 ** 16 # bytes
+
 
 class PackageUpdates(service.FunctionObject) :
 	@service.functionMethod(INTERFACE_NAME, in_signature="", out_signature="as")
@@ -19,6 +31,24 @@ class PackageUpdates(service.FunctionObject) :
 		execProcess([APT_EXECUTABLE, 'update'])
 		raw_output, = execProcess([APT_EXECUTABLE, 'list', '--upgradable'])[:1]
 		return self._extract_upgradable_packages(raw_output.decode('utf-8'))
+
+	@service.functionMethod(INTERFACE_NAME, in_signature="", out_signature="i")
+	def get_last_update_date(self):
+		with open('/var/log/apt/history.log', 'r') as apt_history_file:
+			apt_history_file.seek(0, os.SEEK_END)
+			file_size = apt_history_file.tell()
+			full_block_count = file_size // HISTORY_BLOCK_SIZE
+			block = 0
+			while True:
+				offset = 0 if block >= full_block_count else file_size - HISTORY_BLOCK_SIZE * (block + 1)
+				result = self._try_extract_upgrade_date(apt_history_file, offset, file_size)
+				if result:
+					return result.timestamp()
+
+				if block < full_block_count:
+					block += 1
+				else:
+					return 0
 	
 	@service.functionMethod(INTERFACE_NAME, in_signature="", out_signature="")
 	def install_updates(self):
@@ -29,6 +59,53 @@ class PackageUpdates(service.FunctionObject) :
 		matches = [PACKAGE_REGEX.match(line) for line in lines]
 		return [m[1] for m in matches if m]
 
+	def _parse_apt_block(self, block):
+		fields = {}
+		for line in block.split('\n'):
+			parts = line.split(':', 1)
+			if len(parts) != 2:
+				continue
+			fields[parts[0].strip()] = parts[1].strip()
+		return fields
+
+	def _parse_apt_operations(self, blocks):
+		operations = []
+		for block in blocks:
+			fields = self._parse_apt_block(block)
+			if all(key in fields for key in ('Start-Date', 'Commandline', 'End-Date')):
+				operations.append({
+					'startDate': self._parse_date(fields['Start-Date']),
+					'command': self._parse_command(fields['Commandline'])
+				})
+		return operations
+
+	def _parse_command(self, commandline):
+		words = [w for w in commandline.split(' ') if len(w) and not w.startswith('-')]
+		for word in words:
+			if word in APT_COMMANDS:
+				return word
+
+	def _parse_date(self, date_str):
+		date_str = MULTIPLE_SPACES_REGEX.sub(' ', date_str)
+		return datetime.strptime(date_str, '%Y-%m-%d %H:%M:%S')
+
+	def _read_apt_blocks(self, apt_history_file, offset, block_size):
+		apt_history_file.seek(offset, os.SEEK_SET)
+		data = apt_history_file.read(block_size)
+		return data.split('\n\n')
+
+	def _try_extract_upgrade_date(self, apt_history_file, offset, file_size):
+		limit = max(file_size - offset, HISTORY_BLOCK_SIZE * 2) + 1
+		for block_size in range(HISTORY_BLOCK_SIZE * 2, limit, HISTORY_BLOCK_SIZE):
+			apt_operation_blocks = self._read_apt_blocks(apt_history_file, offset, block_size)
+			apt_operations = self._parse_apt_operations(apt_operation_blocks)
+			if len(apt_operations):
+				break
+
+		for operation in apt_operations[::-1]:
+			if operation['command'] == 'upgrade':
+				return operation['startDate']
+
 
 class Service(service.Service) :
 	def initService(self):