+def IsNormAbsPath(path):
+ """Check whether a path is absolute and also normalized
+
+ This avoids things like /dir/../../other/path to be valid.
+
+ """
+ return os.path.normpath(path) == path and os.path.isabs(path)
+
+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
+
+
+def CommaJoin(names):
+ """Nicely join a set of identifiers.
+
+ @param names: set, list or tuple
+ @return: a string with the formatted results
+
+ """
+ return ", ".join(["'%s'" % val for val in names])
+