borg/borg/helpers.py

from .support import argparse  # see support/__init__.py docstring
                               # DEPRECATED - remove after requiring py 3.4

import binascii
from collections import namedtuple
from functools import wraps
import grp
import os
import pwd
import re
import sys
import time
import unicodedata

from datetime import datetime, timezone, timedelta
from fnmatch import translate
from operator import attrgetter

def have_cython():
    """allow for a way to disable Cython includes

    this is used during usage docs build, in setup.py. It is to avoid
    loading the Cython libraries which are built, but sometimes not in
    the search path (namely, during Tox runs).

    we simply check an environment variable (``BORG_CYTHON_DISABLE``)
    which, when set (to anything) will disable includes of Cython
    libraries in key places to enable usage docs to be built.

    :returns: True if Cython is available, False otherwise.
    """
    return not os.environ.get('BORG_CYTHON_DISABLE')

if have_cython():
    from . import hashindex
    from . import chunker
    from . import crypto
    import msgpack


class Error(Exception):
    """Error base class"""

    exit_code = 1

    def get_message(self):
        return 'Error: ' + type(self).__doc__.format(*self.args)


class ExtensionModuleError(Error):
    """The Borg binary extension modules do not seem to be properly installed"""


def check_extension_modules():
    from . import platform
    if hashindex.API_VERSION != 2:
        raise ExtensionModuleError
    if chunker.API_VERSION != 2:
        raise ExtensionModuleError
    if crypto.API_VERSION != 2:
        raise ExtensionModuleError
    if platform.API_VERSION != 2:
        raise ExtensionModuleError


class Manifest:

    MANIFEST_ID = b'\0' * 32

    def __init__(self, key, repository):
        self.archives = {}
        self.config = {}
        self.key = key
        self.repository = repository

    @classmethod
    def load(cls, repository, key=None):
        from .key import key_factory
        cdata = repository.get(cls.MANIFEST_ID)
        if not key:
            key = key_factory(repository, cdata)
        manifest = cls(key, repository)
        data = key.decrypt(None, cdata)
        manifest.id = key.id_hash(data)
        m = msgpack.unpackb(data)
        if not m.get(b'version') == 1:
            raise ValueError('Invalid manifest version')
        manifest.archives = dict((k.decode('utf-8'), v) for k, v in m[b'archives'].items())
        manifest.timestamp = m.get(b'timestamp')
        if manifest.timestamp:
            manifest.timestamp = manifest.timestamp.decode('ascii')
        manifest.config = m[b'config']
        return manifest, key

    def write(self):
        self.timestamp = datetime.utcnow().isoformat()
        data = msgpack.packb(StableDict({
            'version': 1,
            'archives': self.archives,
            'timestamp': self.timestamp,
            'config': self.config,
        }))
        self.id = self.key.id_hash(data)
        self.repository.put(self.MANIFEST_ID, self.key.encrypt(data))

    def list_archive_infos(self, sort_by=None, reverse=False):
        # inexpensive Archive.list_archives replacement if we just need .name, .id, .ts
        ArchiveInfo = namedtuple('ArchiveInfo', 'name id ts')
        archives = []
        for name, values in self.archives.items():
            ts = parse_timestamp(values[b'time'].decode('utf-8'))
            id = values[b'id']
            archives.append(ArchiveInfo(name=name, id=id, ts=ts))
        if sort_by is not None:
            archives = sorted(archives, key=attrgetter(sort_by), reverse=reverse)
        return archives


def prune_within(archives, within):
    multiplier = {'H': 1, 'd': 24, 'w': 24*7, 'm': 24*31, 'y': 24*365}
    try:
        hours = int(within[:-1]) * multiplier[within[-1]]
    except (KeyError, ValueError):
        # I don't like how this displays the original exception too:
        raise argparse.ArgumentTypeError('Unable to parse --within option: "%s"' % within)
    if hours <= 0:
        raise argparse.ArgumentTypeError('Number specified using --within option must be positive')
    target = datetime.now(timezone.utc) - timedelta(seconds=hours*60*60)
    return [a for a in archives if a.ts > target]


def prune_split(archives, pattern, n, skip=[]):
    last = None
    keep = []
    if n == 0:
        return keep
    for a in sorted(archives, key=attrgetter('ts'), reverse=True):
        period = to_localtime(a.ts).strftime(pattern)
        if period != last:
            last = period
            if a not in skip:
                keep.append(a)
                if len(keep) == n:
                    break
    return keep


class Statistics:

    def __init__(self):
        self.osize = self.csize = self.usize = self.nfiles = 0

    def update(self, size, csize, unique):
        self.osize += size
        self.csize += csize
        if unique:
            self.usize += csize

    def print_(self, label, cache):
        buf = str(self) % label
        buf += "\n"
        buf += str(cache)
        return buf

    def __str__(self):
        return format(self, """\
                       Original size      Compressed size    Deduplicated size
%-15s {0.osize:>20s} {0.csize:>20s} {0.usize:>20s}""")

    def __format__(self, format_spec):
        fields = ['osize', 'csize', 'usize']
        FormattedStats = namedtuple('FormattedStats', fields)
        return format_spec.format(FormattedStats(*map(format_file_size, [ getattr(self, x) for x in fields ])))

    def show_progress(self, item=None, final=False):
        if not final:
            path = remove_surrogates(item[b'path']) if item else ''
            if len(path) > 43:
                path = '%s...%s' % (path[:20], path[-20:])
            msg = '%9s O %9s C %9s D %-43s' % (
                format_file_size(self.osize), format_file_size(self.csize), format_file_size(self.usize), path)
        else:
            msg = ' ' * 79
        print(msg, file=sys.stderr, end='\r')
        sys.stderr.flush()


def get_keys_dir():
    """Determine where to repository keys and cache"""
    return os.environ.get('BORG_KEYS_DIR',
                          os.path.join(os.path.expanduser('~'), '.borg', 'keys'))


def get_cache_dir():
    """Determine where to repository keys and cache"""
    xdg_cache = os.environ.get('XDG_CACHE_HOME', os.path.join(os.path.expanduser('~'), '.cache'))
    return os.environ.get('BORG_CACHE_DIR', os.path.join(xdg_cache, 'borg'))


def to_localtime(ts):
    """Convert datetime object from UTC to local time zone"""
    return datetime(*time.localtime((ts - datetime(1970, 1, 1, tzinfo=timezone.utc)).total_seconds())[:6])


def parse_timestamp(timestamp):
    """Parse a ISO 8601 timestamp string"""
    if '.' in timestamp:  # microseconds might not be pressent
        return datetime.strptime(timestamp, '%Y-%m-%dT%H:%M:%S.%f').replace(tzinfo=timezone.utc)
    else:
        return datetime.strptime(timestamp, '%Y-%m-%dT%H:%M:%S').replace(tzinfo=timezone.utc)


def update_excludes(args):
    """Merge exclude patterns from files with those on command line.
    Empty lines and lines starting with '#' are ignored, but whitespace
    is not stripped."""
    if hasattr(args, 'exclude_files') and args.exclude_files:
        if not hasattr(args, 'excludes') or args.excludes is None:
            args.excludes = []
        for file in args.exclude_files:
            patterns = [line.rstrip('\r\n') for line in file if not line.startswith('#')]
            args.excludes += [ExcludePattern(pattern) for pattern in patterns if pattern]
            file.close()


def adjust_patterns(paths, excludes):
    if paths:
        return (excludes or []) + [IncludePattern(path) for path in paths] + [ExcludePattern('*')]
    else:
        return excludes


def exclude_path(path, patterns):
    """Used by create and extract sub-commands to determine
    whether or not an item should be processed.
    """
    for pattern in (patterns or []):
        if pattern.match(path):
            return isinstance(pattern, ExcludePattern)
    return False


# For both IncludePattern and ExcludePattern, we require that
# the pattern either match the whole path or an initial segment
# of the path up to but not including a path separator.  To
# unify the two cases, we add a path separator to the end of
# the path before matching.

def normalized(func):
    """ Decorator for the Pattern match methods, returning a wrapper that
    normalizes OSX paths to match the normalized pattern on OSX, and 
    returning the original method on other platforms"""
    @wraps(func)
    def normalize_wrapper(self, path):
        return func(self, unicodedata.normalize("NFD", path))

    if sys.platform in ('darwin',):
        # HFS+ converts paths to a canonical form, so users shouldn't be
        # required to enter an exact match
        return normalize_wrapper
    else:
        # Windows and Unix filesystems allow different forms, so users
        # always have to enter an exact match
        return func


class IncludePattern:
    """Literal files or directories listed on the command line
    for some operations (e.g. extract, but not create).
    If a directory is specified, all paths that start with that
    path match as well.  A trailing slash makes no difference.
    """
    def __init__(self, pattern):
        self.pattern_orig = pattern
        self.match_count = 0

        if sys.platform in ('darwin',):
            pattern = unicodedata.normalize("NFD", pattern)

        self.pattern = os.path.normpath(pattern).rstrip(os.path.sep)+os.path.sep

    @normalized
    def match(self, path):
        matches = (path+os.path.sep).startswith(self.pattern)
        if matches:
            self.match_count += 1
        return matches

    def __repr__(self):
        return '%s(%s)' % (type(self), self.pattern)

    def __str__(self):
        return self.pattern_orig


class ExcludePattern(IncludePattern):
    """Shell glob patterns to exclude.  A trailing slash means to
    exclude the contents of a directory, but not the directory itself.
    """
    def __init__(self, pattern):
        self.pattern_orig = pattern
        self.match_count = 0

        if pattern.endswith(os.path.sep):
            self.pattern = os.path.normpath(pattern).rstrip(os.path.sep)+os.path.sep+'*'+os.path.sep
        else:
            self.pattern = os.path.normpath(pattern)+os.path.sep+'*'

        if sys.platform in ('darwin',):
            self.pattern = unicodedata.normalize("NFD", self.pattern)

        # fnmatch and re.match both cache compiled regular expressions.
        # Nevertheless, this is about 10 times faster.
        self.regex = re.compile(translate(self.pattern))

    @normalized
    def match(self, path):
        matches = self.regex.match(path+os.path.sep) is not None
        if matches:
            self.match_count += 1
        return matches

    def __repr__(self):
        return '%s(%s)' % (type(self), self.pattern)

    def __str__(self):
        return self.pattern_orig


def timestamp(s):
    """Convert a --timestamp=s argument to a datetime object"""
    try:
        # is it pointing to a file / directory?
        ts = os.stat(s).st_mtime
        return datetime.utcfromtimestamp(ts)
    except OSError:
        # didn't work, try parsing as timestamp. UTC, no TZ, no microsecs support.
        for format in ('%Y-%m-%dT%H:%M:%SZ', '%Y-%m-%dT%H:%M:%S+00:00',
                       '%Y-%m-%dT%H:%M:%S', '%Y-%m-%d %H:%M:%S',
                       '%Y-%m-%dT%H:%M', '%Y-%m-%d %H:%M',
                       '%Y-%m-%d', '%Y-%j',
                       ):
            try:
                return datetime.strptime(s, format)
            except ValueError:
                continue
        raise ValueError


def ChunkerParams(s):
    chunk_min, chunk_max, chunk_mask, window_size = s.split(',')
    if int(chunk_max) > 23:
        # do not go beyond 2**23 (8MB) chunk size now,
        # COMPR_BUFFER can only cope with up to this size
        raise ValueError('max. chunk size exponent must not be more than 23 (2^23 = 8MiB max. chunk size)')
    return int(chunk_min), int(chunk_max), int(chunk_mask), int(window_size)


def CompressionSpec(s):
    values = s.split(',')
    count = len(values)
    if count < 1:
        raise ValueError
    compression = values[0]
    try:
        compression = int(compression)
        if count > 1:
            raise ValueError
        # DEPRECATED: it is just --compression N
        if 0 <= compression <= 9:
            return dict(name='zlib', level=compression)
        raise ValueError
    except ValueError:
        # --compression algo[,...]
        name = compression
        if name in ('none', 'lz4', ):
            return dict(name=name)
        if name in ('zlib', 'lzma', ):
            if count < 2:
                level = 6  # default compression level in py stdlib
            elif count == 2:
                level = int(values[1])
                if not 0 <= level <= 9:
                    raise ValueError
            else:
                raise ValueError
            return dict(name=name, level=level)
        raise ValueError


def is_cachedir(path):
    """Determines whether the specified path is a cache directory (and
    therefore should potentially be excluded from the backup) according to
    the CACHEDIR.TAG protocol
    (http://www.brynosaurus.com/cachedir/spec.html).
    """

    tag_contents = b'Signature: 8a477f597d28d172789f06886806bc55'
    tag_path = os.path.join(path, 'CACHEDIR.TAG')
    try:
        if os.path.exists(tag_path):
            with open(tag_path, 'rb') as tag_file:
                tag_data = tag_file.read(len(tag_contents))
                if tag_data == tag_contents:
                    return True
    except OSError:
        pass
    return False


def format_time(t):
    """Format datetime suitable for fixed length list output
    """
    if abs((datetime.now() - t).days) < 365:
        return t.strftime('%b %d %H:%M')
    else:
        return t.strftime('%b %d  %Y')


def format_timedelta(td):
    """Format timedelta in a human friendly format
    """
    # Since td.total_seconds() requires python 2.7
    ts = (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10 ** 6) / float(10 ** 6)
    s = ts % 60
    m = int(ts / 60) % 60
    h = int(ts / 3600) % 24
    txt = '%.2f seconds' % s
    if m:
        txt = '%d minutes %s' % (m, txt)
    if h:
        txt = '%d hours %s' % (h, txt)
    if td.days:
        txt = '%d days %s' % (td.days, txt)
    return txt


def format_file_mode(mod):
    """Format file mode bits for list output
    """
    def x(v):
        return ''.join(v & m and s or '-'
                       for m, s in ((4, 'r'), (2, 'w'), (1, 'x')))
    return '%s%s%s' % (x(mod // 64), x(mod // 8), x(mod))


def format_file_size(v):
    """Format file size into a human friendly format
    """
    if abs(v) > 10**12:
        return '%.2f TB' % (v / 10**12)
    elif abs(v) > 10**9:
        return '%.2f GB' % (v / 10**9)
    elif abs(v) > 10**6:
        return '%.2f MB' % (v / 10**6)
    elif abs(v) > 10**3:
        return '%.2f kB' % (v / 10**3)
    else:
        return '%d B' % v


def format_archive(archive):
    return '%-36s %s' % (archive.name, to_localtime(archive.ts).strftime('%c'))


class IntegrityError(Error):
    """Data integrity error"""


def memoize(function):
    cache = {}

    def decorated_function(*args):
        try:
            return cache[args]
        except KeyError:
            val = function(*args)
            cache[args] = val
            return val
    return decorated_function


@memoize
def uid2user(uid, default=None):
    try:
        return pwd.getpwuid(uid).pw_name
    except KeyError:
        return default


@memoize
def user2uid(user, default=None):
    try:
        return user and pwd.getpwnam(user).pw_uid
    except KeyError:
        return default


@memoize
def gid2group(gid, default=None):
    try:
        return grp.getgrgid(gid).gr_name
    except KeyError:
        return default


@memoize
def group2gid(group, default=None):
    try:
        return group and grp.getgrnam(group).gr_gid
    except KeyError:
        return default


def posix_acl_use_stored_uid_gid(acl):
    """Replace the user/group field with the stored uid/gid
    """
    entries = []
    for entry in acl.decode('utf-8', 'surrogateescape').split('\n'):
        if entry:
            fields = entry.split(':')
            if len(fields) == 4:
                entries.append(':'.join([fields[0], fields[3], fields[2]]))
            else:
                entries.append(entry)
    return '\n'.join(entries).encode('utf-8', 'surrogateescape')


class Location:
    """Object representing a repository / archive location
    """
    proto = user = host = port = path = archive = None
    # borg mount's FUSE filesystem creates one level of directories from
    # the archive names. Thus, we must not accept "/" in archive names.
    ssh_re = re.compile(r'(?P<proto>ssh)://(?:(?P<user>[^@]+)@)?'
                        r'(?P<host>[^:/#]+)(?::(?P<port>\d+))?'
                        r'(?P<path>[^:]+)(?:::(?P<archive>[^/]+))?$')
    file_re = re.compile(r'(?P<proto>file)://'
                         r'(?P<path>[^:]+)(?:::(?P<archive>[^/]+))?$')
    scp_re = re.compile(r'((?:(?P<user>[^@]+)@)?(?P<host>[^:/]+):)?'
                        r'(?P<path>[^:]+)(?:::(?P<archive>[^/]+))?$')
    # get the repo from BORG_RE env and the optional archive from param.
    # if the syntax requires giving REPOSITORY (see "borg mount"),
    # use "::" to let it use the env var.
    # if REPOSITORY argument is optional, it'll automatically use the env.
    env_re = re.compile(r'(?:::(?P<archive>[^/]+)?)?$')

    def __init__(self, text=''):
        self.orig = text
        if not self.parse(self.orig):
            raise ValueError

    def parse(self, text):
        valid = self._parse(text)
        if valid:
            return True
        m = self.env_re.match(text)
        if not m:
            return False
        repo = os.environ.get('BORG_REPO')
        if repo is None:
            return False
        valid = self._parse(repo)
        if not valid:
            return False
        self.archive = m.group('archive')
        return True

    def _parse(self, text):
        m = self.ssh_re.match(text)
        if m:
            self.proto = m.group('proto')
            self.user = m.group('user')
            self.host = m.group('host')
            self.port = m.group('port') and int(m.group('port')) or None
            self.path = m.group('path')
            self.archive = m.group('archive')
            return True
        m = self.file_re.match(text)
        if m:
            self.proto = m.group('proto')
            self.path = m.group('path')
            self.archive = m.group('archive')
            return True
        m = self.scp_re.match(text)
        if m:
            self.user = m.group('user')
            self.host = m.group('host')
            self.path = m.group('path')
            self.archive = m.group('archive')
            self.proto = self.host and 'ssh' or 'file'
            return True
        return False

    def __str__(self):
        items = []
        items.append('proto=%r' % self.proto)
        items.append('user=%r' % self.user)
        items.append('host=%r' % self.host)
        items.append('port=%r' % self.port)
        items.append('path=%r' % self.path)
        items.append('archive=%r' % self.archive)
        return ', '.join(items)

    def to_key_filename(self):
        name = re.sub('[^\w]', '_', self.path).strip('_')
        if self.proto != 'file':
            name = self.host + '__' + name
        return os.path.join(get_keys_dir(), name)

    def __repr__(self):
        return "Location(%s)" % self

    def canonical_path(self):
        if self.proto == 'file':
            return self.path
        else:
            if self.path and self.path.startswith('~'):
                path = '/' + self.path
            elif self.path and not self.path.startswith('/'):
                path = '/~/' + self.path
            else:
                path = self.path
            return 'ssh://{}{}{}{}'.format('{}@'.format(self.user) if self.user else '',
                                           self.host,
                                           ':{}'.format(self.port) if self.port else '',
                                           path)


def location_validator(archive=None):
    def validator(text):
        try:
            loc = Location(text)
        except ValueError:
            raise argparse.ArgumentTypeError('Invalid location format: "%s"' % text)
        if archive is True and not loc.archive:
            raise argparse.ArgumentTypeError('"%s": No archive specified' % text)
        elif archive is False and loc.archive:
            raise argparse.ArgumentTypeError('"%s" No archive can be specified' % text)
        return loc
    return validator


def read_msgpack(filename):
    with open(filename, 'rb') as fd:
        return msgpack.unpack(fd)


def write_msgpack(filename, d):
    with open(filename + '.tmp', 'wb') as fd:
        msgpack.pack(d, fd)
        fd.flush()
        os.fsync(fd.fileno())
    os.rename(filename + '.tmp', filename)


def decode_dict(d, keys, encoding='utf-8', errors='surrogateescape'):
    for key in keys:
        if isinstance(d.get(key), bytes):
            d[key] = d[key].decode(encoding, errors)
    return d


def remove_surrogates(s, errors='replace'):
    """Replace surrogates generated by fsdecode with '?'
    """
    return s.encode('utf-8', errors).decode('utf-8')


_safe_re = re.compile(r'^((\.\.)?/+)+')


def make_path_safe(path):
    """Make path safe by making it relative and local
    """
    return _safe_re.sub('', path) or '.'


def daemonize():
    """Detach process from controlling terminal and run in background
    """
    pid = os.fork()
    if pid:
        os._exit(0)
    os.setsid()
    pid = os.fork()
    if pid:
        os._exit(0)
    os.chdir('/')
    os.close(0)
    os.close(1)
    os.close(2)
    fd = os.open('/dev/null', os.O_RDWR)
    os.dup2(fd, 0)
    os.dup2(fd, 1)
    os.dup2(fd, 2)


class StableDict(dict):
    """A dict subclass with stable items() ordering"""
    def items(self):
        return sorted(super().items())


if sys.version < '3.3':
    # st_mtime_ns attribute only available in 3.3+
    def st_mtime_ns(st):
        return int(st.st_mtime * 1e9)

    # unhexlify in < 3.3 incorrectly only accepts bytes input
    def unhexlify(data):
        if isinstance(data, str):
            data = data.encode('ascii')
        return binascii.unhexlify(data)
else:
    def st_mtime_ns(st):
        return st.st_mtime_ns

    unhexlify = binascii.unhexlify


def bigint_to_int(mtime):
    """Convert bytearray to int
    """
    if isinstance(mtime, bytes):
        return int.from_bytes(mtime, 'little', signed=True)
    return mtime


def int_to_bigint(value):
    """Convert integers larger than 64 bits to bytearray

    Smaller integers are left alone
    """
    if value.bit_length() > 63:
        return value.to_bytes((value.bit_length() + 9) // 8, 'little', signed=True)
    return value