Source code for qubes.backup

#
# The Qubes OS Project, http://www.qubes-os.org
#
# Copyright (C) 2013-2017  Marek Marczykowski-Górecki
#                                   <[email protected]>
# Copyright (C) 2013  Olivier Médoc <[email protected]>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, see <https://www.gnu.org/licenses/>.
#
#
from __future__ import unicode_literals

import asyncio
import datetime
import fcntl
import functools
import grp
import itertools
import logging
import os
import pwd
import re
import shutil
import stat
import string
import subprocess
import tempfile
import termios
import time

from .utils import size_to_human
import qubes
import qubes.storage
import qubes.storage.file
import qubes.vm.templatevm

QUEUE_ERROR = "ERROR"

QUEUE_FINISHED = "FINISHED"

HEADER_FILENAME = 'backup-header'
DEFAULT_CRYPTO_ALGORITHM = 'aes-256-cbc'
# 'scrypt' is not exactly HMAC algorithm, but a tool we use to
# integrity-protect the data
DEFAULT_HMAC_ALGORITHM = 'scrypt'
DEFAULT_COMPRESSION_FILTER = 'gzip'
CURRENT_BACKUP_FORMAT_VERSION = '4'
# Maximum size of error message get from process stderr (including VM process)
MAX_STDERR_BYTES = 1024
# header + qubes.xml max size
HEADER_QUBES_XML_MAX_SIZE = 1024 * 1024
# hmac file max size - regardless of backup format version!
HMAC_MAX_SIZE = 4096

BLKSIZE = 512

_re_alphanum = re.compile(r'^[A-Za-z0-9-]*$')


[docs]class BackupCanceledError(qubes.exc.QubesException): def __init__(self, msg, tmpdir=None): super(BackupCanceledError, self).__init__(msg) self.tmpdir = tmpdir
[docs]class BackupHeader: '''Structure describing backup-header file included as the first file in backup archive ''' # pylint: disable=too-few-public-methods header_keys = { 'version': 'version', 'encrypted': 'encrypted', 'compressed': 'compressed', 'compression-filter': 'compression_filter', 'crypto-algorithm': 'crypto_algorithm', 'hmac-algorithm': 'hmac_algorithm', 'backup-id': 'backup_id' } bool_options = ['encrypted', 'compressed'] int_options = ['version'] def __init__(self, version=None, encrypted=None, compressed=None, compression_filter=None, hmac_algorithm=None, crypto_algorithm=None, backup_id=None): # repeat the list to help code completion... self.version = version self.encrypted = encrypted self.compressed = compressed # Options introduced in backup format 3+, which always have a header, # so no need for fallback in function parameter self.compression_filter = compression_filter self.hmac_algorithm = hmac_algorithm self.crypto_algorithm = crypto_algorithm self.backup_id = backup_id def save(self, filename): with open(filename, "w") as f_header: # make sure 'version' is the first key f_header.write('version={}\n'.format(self.version)) for key, attr in self.header_keys.items(): if key == 'version': continue if getattr(self, attr) is None: continue f_header.write("{!s}={!s}\n".format(key, getattr(self, attr)))
class SendWorker: # pylint: disable=too-few-public-methods def __init__(self, queue, base_dir, backup_stdout): super(SendWorker, self).__init__() self.queue = queue self.base_dir = base_dir self.backup_stdout = backup_stdout self.log = logging.getLogger('qubes.backup') @asyncio.coroutine def run(self): self.log.debug("Started sending thread") while True: filename = yield from self.queue.get() if filename in (QUEUE_FINISHED, QUEUE_ERROR): break self.log.debug("Sending file {}".format(filename)) # This tar used for sending data out need to be as simple, as # simple, as featureless as possible. It will not be # verified before untaring. tar_final_cmd = ["tar", "-cO", "--posix", "-C", self.base_dir, filename] # pylint: disable=not-an-iterable final_proc = yield from asyncio.create_subprocess_exec( *tar_final_cmd, stdout=self.backup_stdout) retcode = yield from final_proc.wait() if retcode >= 2: # handle only exit code 2 (tar fatal error) or # greater (call failed?) raise qubes.exc.QubesException( "ERROR: Failed to write the backup, out of disk space? " "Check console output or ~/.xsession-errors for details.") # Delete the file as we don't need it anymore self.log.debug("Removing file {}".format(filename)) os.remove(os.path.join(self.base_dir, filename)) self.log.debug("Finished sending thread")
[docs]@asyncio.coroutine def launch_proc_with_pty(args, stdin=None, stdout=None, stderr=None, echo=True): """Similar to pty.fork, but handle stdin/stdout according to parameters instead of connecting to the pty :return tuple (subprocess.Popen, pty_master) """ def set_ctty(ctty_fd, master_fd): os.setsid() os.close(master_fd) fcntl.ioctl(ctty_fd, termios.TIOCSCTTY, 0) if not echo: termios_p = termios.tcgetattr(ctty_fd) # termios_p.c_lflags termios_p[3] &= ~termios.ECHO termios.tcsetattr(ctty_fd, termios.TCSANOW, termios_p) (pty_master, pty_slave) = os.openpty() # pylint: disable=not-an-iterable p = yield from asyncio.create_subprocess_exec(*args, stdin=stdin, stdout=stdout, stderr=stderr, preexec_fn=lambda: set_ctty(pty_slave, pty_master)) os.close(pty_slave) return p, open(pty_master, 'wb+', buffering=0)
[docs]@asyncio.coroutine def launch_scrypt(action, input_name, output_name, passphrase): ''' Launch 'scrypt' process, pass passphrase to it and return subprocess.Popen object. :param action: 'enc' or 'dec' :param input_name: input path or '-' for stdin :param output_name: output path or '-' for stdout :param passphrase: passphrase :type passphrase: bytes :return: subprocess.Popen object ''' command_line = ['scrypt', action, input_name, output_name] (p, pty) = yield from launch_proc_with_pty(command_line, stdin=subprocess.PIPE if input_name == '-' else None, stdout=subprocess.PIPE if output_name == '-' else None, stderr=subprocess.PIPE, echo=False) if action == 'enc': prompts = (b'Please enter passphrase: ', b'Please confirm passphrase: ') else: prompts = (b'Please enter passphrase: ',) for prompt in prompts: actual_prompt = yield from p.stderr.read(len(prompt)) if actual_prompt != prompt: raise qubes.exc.QubesException( 'Unexpected prompt from scrypt: {}'.format(actual_prompt)) pty.write(passphrase + b'\n') pty.flush() # save it here, so garbage collector would not close it (which would kill # the child) p.pty = pty return p
[docs]class Backup: '''Backup operation manager. Usage: >>> app = qubes.Qubes() >>> # optional - you can use 'None' to use default list (based on >>> # vm.include_in_backups property) >>> vms = [app.domains[name] for name in ['my-vm1', 'my-vm2', 'my-vm3']] >>> exclude_vms = [] >>> options = { >>> 'encrypted': True, >>> 'compressed': True, >>> 'passphrase': 'This is very weak backup passphrase', >>> 'target_vm': app.domains['sys-usb'], >>> 'target_dir': '/media/disk', >>> } >>> backup_op = Backup(app, vms, exclude_vms, **options) >>> print(backup_op.get_backup_summary()) >>> asyncio.get_event_loop().run_until_complete(backup_op.backup_do()) See attributes of this object for all available options. ''' # pylint: disable=too-many-instance-attributes class FileToBackup: # pylint: disable=too-few-public-methods def __init__(self, file_path, subdir=None, name=None, size=None): if size is None: size = qubes.storage.file.get_disk_usage(file_path) if subdir is None: abs_file_path = os.path.abspath(file_path) abs_base_dir = os.path.abspath( qubes.config.system_path["qubes_base_dir"]) + '/' abs_file_dir = os.path.dirname(abs_file_path) + '/' (nothing, directory, subdir) = \ abs_file_dir.partition(abs_base_dir) assert nothing == "" assert directory == abs_base_dir else: if subdir and not subdir.endswith('/'): subdir += '/' #: real path to the file self.path = file_path #: size of the file self.size = size #: directory in backup archive where file should be placed self.subdir = subdir #: use this name in the archive (aka rename) self.name = os.path.basename(file_path) if name is not None: self.name = name class VMToBackup: # pylint: disable=too-few-public-methods def __init__(self, vm, files, subdir): self.vm = vm self.files = files self.subdir = subdir @property def size(self): return functools.reduce(lambda x, y: x + y.size, self.files, 0) def __init__(self, app, vms_list=None, exclude_list=None, **kwargs): """ If vms = None, include all (sensible) VMs; exclude_list is always applied """ super(Backup, self).__init__() #: progress of the backup - bytes handled of the current VM self.chunk_size = 100 * 1024 * 1024 self._current_vm_bytes = 0 #: progress of the backup - bytes handled of finished VMs self._done_vms_bytes = 0 #: total backup size (set by :py:meth:`get_files_to_backup`) self.total_backup_bytes = 0 #: application object self.app = app #: directory for temporary files - set after creating the directory self.tmpdir = None # Backup settings - defaults #: should the backup be compressed? self.compressed = True #: what passphrase should be used to intergrity protect (and encrypt) #: the backup; required self.passphrase = None #: custom compression filter; a program which process stdin to stdout self.compression_filter = DEFAULT_COMPRESSION_FILTER #: VM to which backup should be sent (if any) self.target_vm = None #: directory to save backup in (either in dom0 or target VM, #: depending on :py:attr:`target_vm` self.target_dir = None #: callback for progress reporting. Will be called with one argument #: - progress in percents self.progress_callback = None self.last_progress_time = time.time() #: backup ID, needs to be unique (for a given user), #: not necessary unpredictable; automatically generated self.backup_id = datetime.datetime.now().strftime( '%Y%m%dT%H%M%S-' + str(os.getpid())) for key, value in kwargs.items(): if hasattr(self, key): setattr(self, key, value) else: raise AttributeError(key) self.log = logging.getLogger('qubes.backup') if exclude_list is None: exclude_list = [] if vms_list is None: vms_list = [vm for vm in app.domains if vm.include_in_backups] # Apply exclude list self.vms_for_backup = [vm for vm in vms_list if vm.name not in exclude_list] self._files_to_backup = self.get_files_to_backup() def __del__(self): if self.tmpdir and os.path.exists(self.tmpdir): shutil.rmtree(self.tmpdir) def get_files_to_backup(self): files_to_backup = {} for vm in self.vms_for_backup: if vm.qid == 0: # handle dom0 later continue subdir = 'vm%d/' % vm.qid vm_files = [] for name, volume in vm.volumes.items(): if not volume.save_on_stop: continue vm_files.append(self.FileToBackup( volume.export(), subdir, name + '.img', volume.usage)) vm_files.extend(self.FileToBackup(i, subdir) for i in vm.fire_event('backup-get-files')) firewall_conf = os.path.join(vm.dir_path, vm.firewall_conf) if os.path.exists(firewall_conf): vm_files.append(self.FileToBackup(firewall_conf, subdir)) if not vm_files: # subdir/ is needed in the tar file, otherwise restore # of a (Disp)VM without any backed up files is going # to fail. Adding a zero-sized file here happens to be # more straightforward than adding an empty directory. empty = self.FileToBackup("/var/run/qubes/empty", subdir) assert empty.size == 0 vm_files.append(empty) files_to_backup[vm.qid] = self.VMToBackup(vm, vm_files, subdir) # Dom0 user home if 0 in [vm.qid for vm in self.vms_for_backup]: local_user = grp.getgrnam('qubes').gr_mem[0] home_dir = pwd.getpwnam(local_user).pw_dir # Home dir should have only user-owned files, so fix it now # to prevent permissions problems - some root-owned files can # left after 'sudo bash' and similar commands subprocess.check_call(['sudo', 'chown', '-R', local_user, home_dir]) home_to_backup = [ self.FileToBackup(home_dir, 'dom0-home/')] vm_files = home_to_backup files_to_backup[0] = self.VMToBackup(self.app.domains[0], vm_files, os.path.join('dom0-home', os.path.basename(home_dir))) self.total_backup_bytes = functools.reduce( lambda x, y: x + y.size, files_to_backup.values(), 0) return files_to_backup def get_backup_summary(self): summary = "" fields_to_display = [ {"name": "VM", "width": 16}, {"name": "type", "width": 12}, {"name": "size", "width": 12} ] # Display the header for field in fields_to_display: fmt = "{{0:-^{0}}}-+".format(field["width"] + 1) summary += fmt.format('-') summary += "\n" for field in fields_to_display: fmt = "{{0:>{0}}} |".format(field["width"] + 1) summary += fmt.format(field["name"]) summary += "\n" for field in fields_to_display: fmt = "{{0:-^{0}}}-+".format(field["width"] + 1) summary += fmt.format('-') summary += "\n" files_to_backup = self._files_to_backup for qid, vm_info in files_to_backup.items(): summary_line = "" fmt = "{{0:>{0}}} |".format(fields_to_display[0]["width"] + 1) summary_line += fmt.format(vm_info.vm.name) fmt = "{{0:>{0}}} |".format(fields_to_display[1]["width"] + 1) if qid == 0: summary_line += fmt.format("User home") elif isinstance(vm_info.vm, qubes.vm.templatevm.TemplateVM): summary_line += fmt.format("Template VM") else: summary_line += fmt.format("VM" + (" + Sys" if vm_info.vm.updateable else "")) vm_size = vm_info.size fmt = "{{0:>{0}}} |".format(fields_to_display[2]["width"] + 1) summary_line += fmt.format(size_to_human(vm_size)) if qid != 0 and vm_info.vm.is_running(): summary_line += " <-- The VM is running, backup will contain " \ "its state from before its start!" summary += summary_line + "\n" for field in fields_to_display: fmt = "{{0:-^{0}}}-+".format(field["width"] + 1) summary += fmt.format('-') summary += "\n" fmt = "{{0:>{0}}} |".format(fields_to_display[0]["width"] + 1) summary += fmt.format("Total size:") fmt = "{{0:>{0}}} |".format( fields_to_display[1]["width"] + 1 + 2 + fields_to_display[2][ "width"] + 1) summary += fmt.format(size_to_human(self.total_backup_bytes)) summary += "\n" for field in fields_to_display: fmt = "{{0:-^{0}}}-+".format(field["width"] + 1) summary += fmt.format('-') summary += "\n" vms_not_for_backup = [vm.name for vm in self.app.domains if vm not in self.vms_for_backup] summary += "VMs not selected for backup:\n - " + "\n - ".join( sorted(vms_not_for_backup)) + "\n" return summary @asyncio.coroutine def _prepare_backup_header(self): header_file_path = os.path.join(self.tmpdir, HEADER_FILENAME) backup_header = BackupHeader( version=CURRENT_BACKUP_FORMAT_VERSION, hmac_algorithm=DEFAULT_HMAC_ALGORITHM, encrypted=True, compressed=self.compressed, compression_filter=self.compression_filter, backup_id=self.backup_id, ) backup_header.save(header_file_path) # Start encrypt, scrypt will also handle integrity # protection scrypt_passphrase = '{filename}!'.format( filename=HEADER_FILENAME).encode() + self.passphrase scrypt = yield from launch_scrypt( 'enc', header_file_path, header_file_path + '.hmac', scrypt_passphrase) retcode = yield from scrypt.wait() if retcode: raise qubes.exc.QubesException( "Failed to compute hmac of header file: " + scrypt.stderr.read()) return HEADER_FILENAME, HEADER_FILENAME + ".hmac" def _send_progress_update(self): if not self.total_backup_bytes: return if callable(self.progress_callback): if time.time() - self.last_progress_time >= 1: # avoid flooding progress = ( 100 * (self._done_vms_bytes + self._current_vm_bytes) / self.total_backup_bytes) self.last_progress_time = time.time() # pylint: disable=not-callable self.progress_callback(progress) def _add_vm_progress(self, bytes_done): self._current_vm_bytes += bytes_done self._send_progress_update() @asyncio.coroutine def _split_and_send(self, input_stream, file_basename, output_queue): '''Split *input_stream* into parts of max *chunk_size* bytes and send to *output_queue*. :param input_stream: stream (asyncio reader stream) of data to split :param file_basename: basename (i.e. without part number and '.enc') of output files :param output_queue: asyncio.Queue instance to put produced files to - queue will get only filenames of written chunks ''' # Wait for compressor (tar) process to finish or for any # error of other subprocesses i = 0 run_error = "size_limit" scrypt = None while run_error == "size_limit": # Prepare a first chunk chunkfile = file_basename + ".%03d.enc" % i i += 1 # Start encrypt, scrypt will also handle integrity # protection scrypt_passphrase = \ '{backup_id}!{filename}!'.format( backup_id=self.backup_id, filename=os.path.relpath(chunkfile[:-4], self.tmpdir)).encode() + self.passphrase try: scrypt = yield from launch_scrypt( "enc", "-", chunkfile, scrypt_passphrase) run_error = yield from handle_streams( input_stream, scrypt.stdin, self.chunk_size, self._add_vm_progress ) self.log.debug( "handle_streams returned: {}".format(run_error)) except: scrypt.terminate() raise scrypt.stdin.close() yield from scrypt.wait() self.log.debug("scrypt return code: {}".format( scrypt.returncode)) # Send the chunk to the backup target yield from output_queue.put( os.path.relpath(chunkfile, self.tmpdir)) @asyncio.coroutine def _wrap_and_send_files(self, files_to_backup, output_queue): for vm_info in files_to_backup: for file_info in vm_info.files: self.log.debug("Backing up {}".format(file_info)) backup_tempfile = os.path.join( self.tmpdir, file_info.subdir, file_info.name) self.log.debug("Using temporary location: {}".format( backup_tempfile)) # Ensure the temporary directory exists if not os.path.isdir(os.path.dirname(backup_tempfile)): os.makedirs(os.path.dirname(backup_tempfile)) # The first tar cmd can use any complex feature as we want. # Files will be verified before untaring this. # Prefix the path in archive with filename["subdir"] to have it # verified during untar tar_cmdline = (["tar", "-Pc", '--sparse', '-C', os.path.dirname(file_info.path)] + (['--dereference'] if file_info.subdir != "dom0-home/" else []) + ['--xform=s:^%s:%s\\0:' % ( os.path.basename(file_info.path), file_info.subdir), os.path.basename(file_info.path) ]) file_stat = os.stat(file_info.path) if stat.S_ISBLK(file_stat.st_mode) or \ file_info.name != os.path.basename(file_info.path): # tar doesn't handle content of block device, use our # writer # also use our tar writer when renaming file assert not stat.S_ISDIR(file_stat.st_mode), \ "Renaming directories not supported" tar_cmdline = ['python3', '-m', 'qubes.tarwriter', '--override-name=%s' % ( os.path.join(file_info.subdir, os.path.basename( file_info.name))), file_info.path] if self.compressed: tar_cmdline.insert(-2, "--use-compress-program=%s" % self.compression_filter) self.log.debug(" ".join(tar_cmdline)) # Pipe: tar-sparse | scrypt | tar | backup_target # TODO: log handle stderr # pylint: disable=not-an-iterable tar_sparse = yield from asyncio.create_subprocess_exec( *tar_cmdline, stdout=subprocess.PIPE) try: yield from self._split_and_send( tar_sparse.stdout, backup_tempfile, output_queue) except: try: tar_sparse.terminate() except ProcessLookupError: pass raise yield from tar_sparse.wait() if tar_sparse.returncode: raise qubes.exc.QubesException( 'Failed to archive {} file'.format(file_info.path)) # This VM done, update progress self._done_vms_bytes += vm_info.size self._current_vm_bytes = 0 self._send_progress_update() yield from output_queue.put(QUEUE_FINISHED) @staticmethod @asyncio.coroutine def _monitor_process(proc, error_message): try: yield from proc.wait() except: proc.terminate() raise if proc.returncode: if proc.stderr is not None: proc_stderr = (yield from proc.stderr.read()) proc_stderr = proc_stderr.decode('ascii', errors='ignore') proc_stderr = ''.join( c for c in proc_stderr if c in string.printable and c not in '\r\n%{}') error_message += ': ' + proc_stderr raise qubes.exc.QubesException(error_message) @staticmethod @asyncio.coroutine def _cancel_on_error(future, previous_task): '''If further element of chain fail, cancel previous one to avoid deadlock. When earlier element of chain fail, it will be handled by :py:meth:`backup_do`. The chain is: :py:meth:`_wrap_and_send_files` -> :py:class:`SendWorker` -> vmproc ''' try: yield from future except: # pylint: disable=bare-except previous_task.cancel() @asyncio.coroutine def backup_do(self): # pylint: disable=too-many-statements if self.passphrase is None: raise qubes.exc.QubesException("No passphrase set") if not isinstance(self.passphrase, bytes): self.passphrase = self.passphrase.encode('utf-8') qubes_xml = self.app.store self.tmpdir = tempfile.mkdtemp() shutil.copy(qubes_xml, os.path.join(self.tmpdir, 'qubes.xml')) qubes_xml = os.path.join(self.tmpdir, 'qubes.xml') backup_app = qubes.Qubes(qubes_xml, offline_mode=True) backup_app.events_enabled = False files_to_backup = self._files_to_backup # make sure backup_content isn't set initially for vm in backup_app.domains: vm.events_enabled = False vm.features['backup-content'] = False for qid, vm_info in files_to_backup.items(): # VM is included in the backup backup_app.domains[qid].features['backup-content'] = True backup_app.domains[qid].features['backup-path'] = vm_info.subdir backup_app.domains[qid].features['backup-size'] = vm_info.size backup_app.save() del backup_app vmproc = None if self.target_vm is not None: # Prepare the backup target (Qubes service call) # If APPVM, STDOUT is a PIPE read_fd, write_fd = os.pipe() vmproc = yield from self.target_vm.run_service('qubes.Backup', stdin=read_fd, stderr=subprocess.PIPE, stdout=subprocess.DEVNULL) os.close(read_fd) os.write(write_fd, (self.target_dir. replace("\r", "").replace("\n", "") + "\n").encode()) backup_stdout = write_fd else: # Prepare the backup target (local file) if os.path.isdir(self.target_dir): backup_target = self.target_dir + "/qubes-{0}". \ format(time.strftime("%Y-%m-%dT%H%M%S")) else: backup_target = self.target_dir # Create the target directory if not os.path.exists(os.path.dirname(self.target_dir)): raise qubes.exc.QubesException( "ERROR: the backup directory for {0} does not exists". format(self.target_dir)) # If not APPVM, STDOUT is a local file backup_stdout = open(backup_target, 'wb') # Tar with tape length does not deals well with stdout # (close stdout between two tapes) # For this reason, we will use named pipes instead self.log.debug("Working in {}".format(self.tmpdir)) self.log.debug("Will backup: {}".format(files_to_backup)) header_files = yield from self._prepare_backup_header() # Setup worker to send encrypted data chunks to the backup_target to_send = asyncio.Queue(10) send_proc = SendWorker(to_send, self.tmpdir, backup_stdout) send_task = asyncio.ensure_future(send_proc.run()) vmproc_task = None if vmproc is not None: vmproc_task = asyncio.ensure_future( self._monitor_process(vmproc, 'Writing backup to VM {} failed'.format( self.target_vm.name))) asyncio.ensure_future(self._cancel_on_error( vmproc_task, send_task)) for file_name in header_files: yield from to_send.put(file_name) qubes_xml_info = self.VMToBackup( None, [self.FileToBackup(qubes_xml, '')], '' ) inner_archive_task = asyncio.ensure_future( self._wrap_and_send_files( itertools.chain([qubes_xml_info], files_to_backup.values()), to_send )) asyncio.ensure_future( self._cancel_on_error(send_task, inner_archive_task)) try: try: yield from inner_archive_task except: yield from to_send.put(QUEUE_ERROR) # in fact we may be handling CancelledError, induced by # exception in send_task or vmproc_task (and propagated by # self._cancel_on_error call above); in such a case this # yield from will raise exception, covering CancelledError - # this is intended behaviour if vmproc_task: yield from vmproc_task yield from send_task raise yield from send_task finally: if isinstance(backup_stdout, int): os.close(backup_stdout) else: backup_stdout.close() try: if vmproc_task: yield from vmproc_task finally: shutil.rmtree(self.tmpdir) # Save date of last backup, only when backup succeeded for qid, vm_info in files_to_backup.items(): if vm_info.vm: vm_info.vm.backup_timestamp = \ int(datetime.datetime.now().strftime('%s')) self.app.save()
[docs]@asyncio.coroutine def handle_streams(stream_in, stream_out, size_limit=None, progress_callback=None): ''' Copy stream_in to all streams_out and monitor all mentioned processes. If any of them terminate with non-zero code, interrupt the process. Copy at most `size_limit` data (if given). :param stream_in: StreamReader object to read data from :param stream_out: StreamWriter object to write data to :param size_limit: int maximum data amount to process :param progress_callback: callable function to report progress, will be given copied data size (it should accumulate internally) :return: "size_limit" or None (no error) ''' buffer_size = 409600 bytes_copied = 0 while True: if size_limit: to_copy = min(buffer_size, size_limit - bytes_copied) if to_copy <= 0: return "size_limit" else: to_copy = buffer_size buf = yield from stream_in.read(to_copy) if not buf: # done break if callable(progress_callback): progress_callback(len(buf)) stream_out.write(buf) bytes_copied += len(buf) return None
# vim:sw=4:et: