235 def opener(base):

   236     """

   237     return a function that opens files relative to base

   238 

   239     this function is used to hide the details of COW semantics and

   240     remote file access from higher level code.

   241 

   242     todo: separate remote file access into a separate function

   243     """

   244     p = base

   245     def o(path, mode="r"):

   246         if p.startswith("http://"):

   247             f = os.path.join(p, urllib.quote(path))

   248             return httprangereader.httprangereader(f)

   249 

   250         f = os.path.join(p, path)

   251 

   252         mode += "b" # for that other OS

   253 

   254         if mode[0] != "r":

   255             try:

   256                 s = os.stat(f)

   257             except OSError:

   258                 d = os.path.dirname(f)

   259                 if not os.path.isdir(d):

   260                     os.makedirs(d)

   261             else:

   262                 if s.st_nlink > 1:

   263                     file(f + ".tmp", "wb").write(file(f, "rb").read())

   264                     rename(f+".tmp", f)

   265 

   266         return file(f, mode)

   267 

   268     return o

   269