Synnefo » snf-ganeti » ganeti-local

import collections

_re_shell_unquoted = re.compile('^[-.,=:/_+@A-Za-z0-9]+$')

#: MAC checker regexp

_MAC_CHECK = re.compile("^([0-9a-f]{2}:){5}[0-9a-f]{2}$", re.I)

#: Unit checker regexp

_PARSEUNIT_REGEX = re.compile(r"^([.\d]+)\s*([a-zA-Z]+)?$")

def MatchNameComponent(key, name_list, case_sensitive=True):

  """Try to match a name against a list.

  This function will try to match a name like test1 against a list

  like C{['test1.example.com', 'test2.example.com', ...]}. Against

  this list, I{'test1'} as well as I{'test1.example'} will match, but

  not I{'test1.ex'}. A multiple match will be considered as no match

  at all (e.g. I{'test1'} against C{['test1.example.com',

  'test1.example.org']}), except when the key fully matches an entry

  (e.g. I{'test1'} against C{['test1', 'test1.example.com']}).

  @type key: str

  @param key: the name to be searched

  @type name_list: list

  @param name_list: the list of strings against which to search the key

  @type case_sensitive: boolean

  @param case_sensitive: whether to provide a case-sensitive match

  @rtype: None or str

  @return: None if there is no match I{or} if there are multiple matches,

      otherwise the element from the list which matches

  """

  if key in name_list:

    return key

  re_flags = 0

  if not case_sensitive:

    re_flags |= re.IGNORECASE

    key = key.upper()

  mo = re.compile("^%s(\..*)?$" % re.escape(key), re_flags)

  names_filtered = []

  string_matches = []

  for name in name_list:

    if mo.match(name) is not None:

      names_filtered.append(name)

      if not case_sensitive and key == name.upper():

        string_matches.append(name)

  if len(string_matches) == 1:

    return string_matches[0]

  if len(names_filtered) == 1:

    return names_filtered[0]

  return None

def FormatUnit(value, units):

  """Formats an incoming number of MiB with the appropriate unit.

  @type value: int

  @param value: integer representing the value in MiB (1048576)

  @type units: char

  @param units: the type of formatting we should do:

      - 'h' for automatic scaling

      - 'm' for MiBs

      - 'g' for GiBs

      - 't' for TiBs

  @rtype: str

  @return: the formatted value (with suffix)

  """

  if units not in ('m', 'g', 't', 'h'):

    raise errors.ProgrammerError("Invalid unit specified '%s'" % str(units))

  suffix = ''

  if units == 'm' or (units == 'h' and value < 1024):

    if units == 'h':

      suffix = 'M'

    return "%d%s" % (round(value, 0), suffix)

  elif units == 'g' or (units == 'h' and value < (1024 * 1024)):

    if units == 'h':

      suffix = 'G'

    return "%0.1f%s" % (round(float(value) / 1024, 1), suffix)

  else:

    if units == 'h':

      suffix = 'T'

    return "%0.1f%s" % (round(float(value) / 1024 / 1024, 1), suffix)

def ParseUnit(input_string):

  """Tries to extract number and scale from the given string.

  Input must be in the format C{NUMBER+ [DOT NUMBER+] SPACE*

  [UNIT]}. If no unit is specified, it defaults to MiB. Return value

  is always an int in MiB.

  """

  m = _PARSEUNIT_REGEX.match(str(input_string))

  if not m:

    raise errors.UnitParseError("Invalid format")

  value = float(m.groups()[0])

  unit = m.groups()[1]

  if unit:

    lcunit = unit.lower()

  else:

    lcunit = 'm'

  if lcunit in ('m', 'mb', 'mib'):

    # Value already in MiB

    pass

  elif lcunit in ('g', 'gb', 'gib'):

    value *= 1024

  elif lcunit in ('t', 'tb', 'tib'):

    value *= 1024 * 1024

  else:

    raise errors.UnitParseError("Unknown unit: %s" % unit)

  # Make sure we round up

  if int(value) < value:

    value += 1

  # Round up to the next multiple of 4

  value = int(value)

  if value % 4:

    value += 4 - value % 4

  return value

def ShellQuote(value):

  """Quotes shell argument according to POSIX.

  @type value: str

  @param value: the argument to be quoted

  @rtype: str

  @return: the quoted value

  """

  if _re_shell_unquoted.match(value):

    return value

  else:

    return "'%s'" % value.replace("'", "'\\''")

def ShellQuoteArgs(args):

  """Quotes a list of shell arguments.

  @type args: list

  @param args: list of arguments to be quoted

  @rtype: str

  @return: the quoted arguments concatenated with spaces

  """

  return ' '.join([ShellQuote(i) for i in args])

class ShellWriter:

  """Helper class to write scripts with indentation.

  """

  INDENT_STR = "  "

  def __init__(self, fh):

    """Initializes this class.

    """

    self._fh = fh

    self._indent = 0

  def IncIndent(self):

    """Increase indentation level by 1.

    """

    self._indent += 1

  def DecIndent(self):

    """Decrease indentation level by 1.

    """

    assert self._indent > 0

    self._indent -= 1

  def Write(self, txt, *args):

    """Write line to output file.

    """

    assert self._indent >= 0

    self._fh.write(self._indent * self.INDENT_STR)

    if args:

      self._fh.write(txt % args)

    else:

      self._fh.write(txt)

    self._fh.write("\n")

def GenerateSecret(numbytes=20):

  """Generates a random secret.

  This will generate a pseudo-random secret returning an hex string

  (so that it can be used where an ASCII string is needed).

  @param numbytes: the number of bytes which will be represented by the returned

      string (defaulting to 20, the length of a SHA1 hash)

  @rtype: str

  @return: an hex representation of the pseudo-random sequence

  """

  return os.urandom(numbytes).encode('hex')

def NormalizeAndValidateMac(mac):

  """Normalizes and check if a MAC address is valid.

  Checks whether the supplied MAC address is formally correct, only

  accepts colon separated format. Normalize it to all lower.

  @type mac: str

  @param mac: the MAC to be validated

  @rtype: str

  @return: returns the normalized and validated MAC.

  @raise errors.OpPrereqError: If the MAC isn't valid

  """

  if not _MAC_CHECK.match(mac):

    raise errors.OpPrereqError("Invalid MAC address specified: %s" %

                               mac, errors.ECODE_INVAL)

  return mac.lower()

def SafeEncode(text):

  """Return a 'safe' version of a source string.

  This function mangles the input string and returns a version that

  should be safe to display/encode as ASCII. To this end, we first

  convert it to ASCII using the 'backslashreplace' encoding which

  should get rid of any non-ASCII chars, and then we process it

  through a loop copied from the string repr sources in the python; we

  don't use string_escape anymore since that escape single quotes and

  backslashes too, and that is too much; and that escaping is not

  stable, i.e. string_escape(string_escape(x)) != string_escape(x).

  @type text: str or unicode

  @param text: input data

  @rtype: str

  @return: a safe version of text

  """

  if isinstance(text, unicode):

    # only if unicode; if str already, we handle it below

    text = text.encode('ascii', 'backslashreplace')

  resu = ""

  for char in text:

    c = ord(char)

    if char  == '\t':

      resu += r'\t'

    elif char == '\n':

      resu += r'\n'

    elif char == '\r':

      resu += r'\'r'

    elif c < 32 or c >= 127: # non-printable

      resu += "\\x%02x" % (c & 0xff)

    else:

      resu += char

  return resu

def UnescapeAndSplit(text, sep=","):

  """Split and unescape a string based on a given separator.

  This function splits a string based on a separator where the

  separator itself can be escape in order to be an element of the

  elements. The escaping rules are (assuming coma being the

  separator):

    - a plain , separates the elements

    - a sequence \\\\, (double backslash plus comma) is handled as a

      backslash plus a separator comma

    - a sequence \, (backslash plus comma) is handled as a

      non-separator comma

  @type text: string

  @param text: the string to split

  @type sep: string

  @param text: the separator

  @rtype: string

  @return: a list of strings

  """

  # we split the list by sep (with no escaping at this stage)

  slist = text.split(sep)

  # next, we revisit the elements and if any of them ended with an odd

  # number of backslashes, then we join it with the next

  rlist = []

  while slist:

    e1 = slist.pop(0)

    if e1.endswith("\\"):

      num_b = len(e1) - len(e1.rstrip("\\"))

      if num_b % 2 == 1:

        e2 = slist.pop(0)

        # here the backslashes remain (all), and will be reduced in

        # the next step

        rlist.append(e1 + sep + e2)

        continue

    rlist.append(e1)

  # finally, replace backslash-something with something

  rlist = [re.sub(r"\\(.)", r"\1", v) for v in rlist]

  return rlist

def CommaJoin(names):

  """Nicely join a set of identifiers.

  @param names: set, list or tuple

  @return: a string with the formatted results

  """

  return ", ".join([str(val) for val in names])

def FormatTime(val):

  """Formats a time value.

  @type val: float or None

  @param val: Timestamp as returned by time.time() (seconds since Epoch,

    1970-01-01 00:00:00 UTC)

  @return: a string value or N/A if we don't have a valid timestamp

  """

  if val is None or not isinstance(val, (int, float)):

    return "N/A"

  # these two codes works on Linux, but they are not guaranteed on all

  # platforms

  return time.strftime("%F %T", time.localtime(val))

def FormatSeconds(secs):

  """Formats seconds for easier reading.

  @type secs: number

  @param secs: Number of seconds

  @rtype: string

  @return: Formatted seconds (e.g. "2d 9h 19m 49s")

  """

  parts = []

  secs = round(secs, 0)

  if secs > 0:

    # Negative values would be a bit tricky

    for unit, one in [("d", 24 * 60 * 60), ("h", 60 * 60), ("m", 60)]:

      (complete, secs) = divmod(secs, one)

      if complete or parts:

        parts.append("%d%s" % (complete, unit))

  parts.append("%ds" % secs)

  return " ".join(parts)

class LineSplitter:

  """Splits data chunks into lines separated by newline.

  Instances provide a file-like interface.

  """

  def __init__(self, line_fn, *args):

    """Initializes this class.

    @type line_fn: callable

    @param line_fn: Function called for each line, first parameter is line

    @param args: Extra arguments for L{line_fn}

    """

    assert callable(line_fn)

    if args:

      # Python 2.4 doesn't have functools.partial yet

      self._line_fn = \

        lambda line: line_fn(line, *args) # pylint: disable-msg=W0142

    else:

      self._line_fn = line_fn

    self._lines = collections.deque()

    self._buffer = ""

  def write(self, data):

    parts = (self._buffer + data).split("\n")

    self._buffer = parts.pop()

    self._lines.extend(parts)

  def flush(self):

    while self._lines:

      self._line_fn(self._lines.popleft().rstrip("\r\n"))

  def close(self):

    self.flush()

    if self._buffer:

      self._line_fn(self._buffer)