+ fmt = "%(asctime)s: " + program + " pid=%(process)d"
+ if multithreaded:
+ fmt += "/%(threadName)s"
+ if debug:
+ fmt += " %(module)s:%(lineno)s"
+ fmt += " %(levelname)s %(message)s"
+ formatter = logging.Formatter(fmt)
+
+ root_logger = logging.getLogger("")
+ root_logger.setLevel(logging.NOTSET)
+
+ # Remove all previously setup handlers
+ for handler in root_logger.handlers:
+ handler.close()
+ root_logger.removeHandler(handler)
+
+ if stderr_logging:
+ stderr_handler = logging.StreamHandler()
+ stderr_handler.setFormatter(formatter)
+ if debug:
+ stderr_handler.setLevel(logging.NOTSET)
+ else:
+ stderr_handler.setLevel(logging.CRITICAL)
+ root_logger.addHandler(stderr_handler)
+
+ # this can fail, if the logging directories are not setup or we have
+ # a permisssion problem; in this case, it's best to log but ignore
+ # the error if stderr_logging is True, and if false we re-raise the
+ # exception since otherwise we could run but without any logs at all
+ try:
+ logfile_handler = logging.FileHandler(logfile)
+ logfile_handler.setFormatter(formatter)
+ if debug:
+ logfile_handler.setLevel(logging.DEBUG)
+ else:
+ logfile_handler.setLevel(logging.INFO)
+ root_logger.addHandler(logfile_handler)
+ except EnvironmentError:
+ if stderr_logging:
+ logging.exception("Failed to enable logging to file '%s'", logfile)
+ else:
+ # we need to re-raise the exception
+ raise
+
+
+def TailFile(fname, lines=20):
+ """Return the last lines from a file.
+
+ @note: this function will only read and parse the last 4KB of
+ the file; if the lines are very long, it could be that less
+ than the requested number of lines are returned
+
+ @param fname: the file name
+ @type lines: int
+ @param lines: the (maximum) number of lines to return
+
+ """
+ fd = open(fname, "r")
+ try:
+ fd.seek(0, 2)
+ pos = fd.tell()
+ pos = max(0, pos-4096)
+ fd.seek(pos, 0)
+ raw_data = fd.read()
+ finally:
+ fd.close()
+
+ rows = raw_data.splitlines()
+ return rows[-lines:]
+
+
+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 disply/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 again encode it
+ via 'string_escape' which converts '\n' into '\\n' so that log
+ messages remain one-line.
+
+ @type text: str or unicode
+ @param text: input data
+ @rtype: str
+ @return: a safe version of text
+
+ """
+ text = text.encode('ascii', 'backslashreplace')
+ text = text.encode('string_escape')
+ return text