Synnefo » snf-ganeti » ganeti-local

#: Shell param checker regexp

_SHELLPARAM_REGEX = re.compile(r"^[-a-zA-Z0-9._+/:%@]+$")

def IsValidShellParam(word):

  """Verifies is the given word is safe from the shell's p.o.v.

  This means that we can pass this to a command via the shell and be

  sure that it doesn't alter the command line and is passed as such to

  the actual command.

  Note that we are overly restrictive here, in order to be on the safe

  side.

  @type word: str

  @param word: the word to check

  @rtype: boolean

  @return: True if the word is 'safe'

  """

  return bool(_SHELLPARAM_REGEX.match(word))

def BuildShellCmd(template, *args):

  """Build a safe shell command line from the given arguments.

  This function will check all arguments in the args list so that they

  are valid shell parameters (i.e. they don't contain shell

  metacharacters). If everything is ok, it will return the result of

  template % args.

  @type template: str

  @param template: the string holding the template for the

      string formatting

  @rtype: str

  @return: the expanded command line

  """

  for word in args:

    if not IsValidShellParam(word):

      raise errors.ProgrammerError("Shell argument '%s' contains"

                                   " invalid characters" % word)

  return template % args