#!/usr/bin/python
# -*- coding: utf-8 -*-
"""Process new requests to download per-package data"""
# Copyright (C) 2012 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 3 of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

import glob
import os
import sys
import subprocess
import re
import traceback
import urllib
import debian.deb822
import string
import apt
import debconf
from datetime import datetime

# avoid hanging forever (LP: #1243090)
import socket
socket.setdefaulttimeout(60)


DATADIR = "/usr/share/package-data-downloads/"
STAMPDIR = "/var/lib/update-notifier/package-data-downloads/"
NOTIFIER_SOURCE_FILE = "/usr/share/update-notifier/package-data-downloads-failed"
NOTIFIER_FILE = "/var/lib/update-notifier/user.d/data-downloads-failed"
NOTIFIER_PERMANENT_SOURCE_FILE = NOTIFIER_SOURCE_FILE + '-permanently'
NOTIFIER_PERMANENT_FILE = NOTIFIER_FILE + '-permanently'

failures = []
permanent_failures = []

def create_or_update_stampfile(file):
"""Create or update the indicated stampfile, and remove failure flags"""

try:
with open(file, 'w'):
pass
# Ignore errors
except Exception:
traceback.print_exc(file=sys.stderr)

os.utime(file, None)

for ext in ('.failed', '.permanent-failure'):
if os.path.exists(file + ext):
os.unlink(file + ext)


def mark_hook_failed(hook_name, permanent=False):
"""Create a stampfile recording that a hook failed

We create separate stampfiles for failed hooks so we can
keep track of how long the hook has been failing and if the failure
should be considered permanent."""

if permanent:
filename = hook_name + '.permanent-failure'
else:
filename = hook_name + '.failed'

failure_file = os.path.join(STAMPDIR, filename)
try:
with open(failure_file, 'w'):
pass

# Ignore errors
except Exception:
traceback.print_exc(file=sys.stderr)

for ext in ('', '.failed', '.permanent-failure'):
stampfile = hook_name + ext
if filename != stampfile \
and os.path.exists(os.path.join(STAMPDIR, stampfile)):
os.unlink(os.path.join(STAMPDIR, stampfile))


def hook_is_permanently_failed(hook_name):
"""Check if this hook has been marked as permanently failing.

If so, don't raise any more errors about it."""

failure_file = os.path.join(STAMPDIR, hook_name + '.permanent-failure')
return os.path.exists(failure_file)


def hook_aged_out(hook_name):
"""Check if this hook has been failing consistently for >= 3 days"""

failure_file = os.path.join(STAMPDIR, hook_name + '.failed')
try:
hook_date = datetime.fromtimestamp(os.stat(failure_file).st_ctime)
cur_time = datetime.now()
d = cur_time - hook_date
if d.days >= 3:
return True
except OSError:
pass
except Exception:
traceback.print_exc(file=sys.stderr)
return False


def record_failure(hook):
"""Record that the named hook has failed"""
if hook_aged_out(hook):
permanent_failures.append(hook)
else:
failures.append(hook)


def existing_permanent_failures():
"""Return the list of all previously recorded permanent failures"""

files = glob.glob(os.path.join(STAMPDIR, "*.permanent-failure"))
return [os.path.splitext(os.path.basename(path))[0] for path in files]


def trigger_update_notifier(failures, permanent=False):
"""Tell update-notifier that there were failed packages"""

try:
if permanent:
with open(NOTIFIER_PERMANENT_SOURCE_FILE, 'r') as f:
input = f.read()
output_file = open(NOTIFIER_PERMANENT_FILE, 'w')
else:
with open(NOTIFIER_SOURCE_FILE, 'r') as f:
input = f.read()
output_file = open(NOTIFIER_FILE, 'w')
except Exception:
# Things failed and we can't even notify about it. Break the
# trigger so that there's some error propagation, even if not
# the most pleasant sort.
traceback.print_exc(file=sys.stderr)
sys.exit(1)

packages = [os.path.basename(failure) for failure in failures]
output_file.write(
string.Template(input).substitute(
{'packages' : ", ".join(packages)}))
output_file.close()

def get_hook_file_names():
res = []
for relfile in os.listdir(DATADIR):
# ignore files ending in .dpkg-*
if (os.path.splitext(relfile)[1] and
os.path.splitext(relfile)[1].startswith(".dpkg")):
continue
res.append(relfile)
return res

def process_download_requests():
"""Process requests to download package data files

Iterate over /usr/share/package-data-downloads and download any
package data specified in the contained file, then hand off to
the indicated handler for further processing.

Successful downloads are recorded in
/var/lib/update-notifier/package-data-downloads to avoid unnecessary
repeat handling.

Failed downloads are reported to the user via the
update-notifier interface."""

# Get our proxy settings from the environment
proxies = {}
try:
for proto in ('http','https','ftp'):
try:
proxies[proto] = os.environ[proto+"_proxy"]
except KeyError:
pass

if proxies:
urllib._urlopener = urllib.FancyURLopener(proxies)
except Exception:
pass

# Iterate through all the available hooks. If we get a failure
# processing any of them (download failure, checksum failure, or
# failure to run the hook script), record it but continue processing
# the rest of the hooks since some of them may succeed.
for relfile in get_hook_file_names():

stampfile = os.path.join(STAMPDIR, relfile)
file = os.path.join(DATADIR, relfile)
try:
hook_date = os.stat(file).st_mtime
stamp_date = os.stat(stampfile).st_mtime
if hook_date < stamp_date:
continue
except Exception as e:
if not isinstance(e, OSError):
traceback.print_exc(file=sys.stderr)

hook = debian.deb822.Deb822()
files = []
sums = []
for para in hook.iter_paragraphs(open(file)):
if 'script' in para:
if not files:
record_failure(relfile)
break
command = [para['script']]

if 'should-download' in para:
db = debconf.DebconfCommunicator('update-notifier')
try:
should = db.get(para['should-download'])
if should == "false":
# Do nothing with this file.
break
except:
pass
finally:
db.shutdown()

# Download each file and verify the sum
try:
for i in range(len(files)):
print("%s: downloading %s" % (relfile, files[i]))
dest_file = urllib.urlretrieve(files[i])[0]
output = subprocess.check_output(["sha256sum", dest_file])
output = output.split(' ')[0]
if output == sums[i]:
command.append(dest_file)
else:
record_failure(relfile)
break
if relfile in failures + permanent_failures:
break

sys.stdout.flush()
result = subprocess.call(command)
if result:
# There's no sense redownloading if the script fails
permanent_failures.append(relfile)
else:
create_or_update_stampfile(stampfile)
break
except Exception:
traceback.print_exc(file=sys.stderr)

record_failure(relfile)
# The 'script' is always the last stanza
break

# Not in a 'script' stanza, so we should have some urls
try:
files.append(para['url'])
sums.append(para['sha256'])
except Exception as e:
if not isinstance(e, KeyError):
traceback.print_exc(file=sys.stderr)
record_failure(relfile)
break

previous_failures = existing_permanent_failures()

# We only report about "permanent" failures when there are new ones,
# but we want the whole list of permanently-failing hooks so when
# we clobber the update-notifier file we don't lose information the
# user may not have seen yet
if permanent_failures:
new_failures = False
for failure in permanent_failures:
if failure not in previous_failures:
mark_hook_failed(failure, permanent=True)
previous_failures.append(failure)
new_failures = True
if new_failures:
trigger_update_notifier(previous_failures, permanent=True)

# Filter out new failure reports for permanently-failed packages
our_failures = [x for x in failures if x not in previous_failures]

if our_failures:
for failure in our_failures:
mark_hook_failed(failure)
trigger_update_notifier(our_failures)


if __name__ == "__main__":
process_download_requests()