tools/python/google/path_utils.py

   1 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 """Some utility methods for getting and manipulating paths."""
   6
   7 # TODO(pamg): Have the buildbot use these, too.
   8
   9
  10 import errno
  11 import os
  12 import sys
  13
  14 class PathNotFound(Exception): pass
  15
  16 def ScriptDir():
  17   """Get the full path to the directory containing the current script."""
  18   script_filename = os.path.abspath(sys.argv[0])
  19   return os.path.dirname(script_filename)
  20
  21 def FindAncestor(start_dir, ancestor):
  22   """Finds an ancestor dir in a path.
  23
  24   For example, FindAncestor('c:\foo\bar\baz', 'bar') would return
  25   'c:\foo\bar'.  Unlike FindUpward*, this only looks at direct path ancestors.
  26   """
  27   start_dir = os.path.abspath(start_dir)
  28   path = start_dir
  29   while True:
  30     (parent, tail) = os.path.split(path)
  31     if tail == ancestor:
  32       return path
  33     if not tail:
  34       break
  35     path = parent
  36   raise PathNotFound("Unable to find ancestor %s in %s" % (ancestor, start_dir))
  37
  38 def FindUpwardParent(start_dir, *desired_list):
  39   """Finds the desired object's parent, searching upward from the start_dir.
  40
  41   Searches start_dir and all its parents looking for the desired directory
  42   or file, which may be given in one or more path components. Returns the
  43   first directory in which the top desired path component was found, or raises
  44   PathNotFound if it wasn't.
  45   """
  46   desired_path = os.path.join(*desired_list)
  47   last_dir = ''
  48   cur_dir = start_dir
  49   found_path = os.path.join(cur_dir, desired_path)
  50   while not os.path.exists(found_path):
  51     last_dir = cur_dir
  52     cur_dir = os.path.dirname(cur_dir)
  53     if last_dir == cur_dir:
  54       raise PathNotFound('Unable to find %s above %s' %
  55                          (desired_path, start_dir))
  56     found_path = os.path.join(cur_dir, desired_path)
  57   # Strip the entire original desired path from the end of the one found
  58   # and remove a trailing path separator, if present.
  59   found_path = found_path[:len(found_path) - len(desired_path)]
  60   if found_path.endswith(os.sep):
  61     found_path = found_path[:len(found_path) - 1]
  62   return found_path
  63
  64
  65 def FindUpward(start_dir, *desired_list):
  66   """Returns a path to the desired directory or file, searching upward.
  67
  68   Searches start_dir and all its parents looking for the desired directory
  69   or file, which may be given in one or more path components. Returns the full
  70   path to the desired object, or raises PathNotFound if it wasn't found.
  71   """
  72   parent = FindUpwardParent(start_dir, *desired_list)
  73   return os.path.join(parent, *desired_list)
  74
  75
  76 def MaybeMakeDirectory(*path):
  77   """Creates an entire path, if it doesn't already exist."""
  78   file_path = os.path.join(*path)
  79   try:
  80     os.makedirs(file_path)
  81   except OSError, e:
  82     # errno.EEXIST is "File exists".  If we see another error, re-raise.
  83     if e.errno != errno.EEXIST:
  84       raise