diff --git a/Lib/plat-riscos/riscospath.py b/Lib/plat-riscos/riscospath.py
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+# Module 'riscospath' -- common operations on RISC OS pathnames.
+
+# contributed by Andrew Clover  ( andrew@oaktree.co.uk )
+
+# The "os.path" name is an alias for this module on RISC OS systems;
+# on other systems (e.g. Mac, Windows), os.path provides the same
+# operations in a manner specific to that platform, and is an alias
+# to another module (e.g. macpath, ntpath).
+
+"""
+Instead of importing this module directly, import os and refer to this module
+as os.path.
+"""
+
+
+# Imports - make an error-generating swi object if the swi module is not
+# available (ie. we are not running on RISC OS Python)
+
+import os, stat, string
+
+try:
+  import swi
+except ImportError:
+  class _swi:
+    def swi(*a):
+      raise AttributeError, 'This function only available under RISC OS'
+    block= swi
+  swi= _swi()
+
+[_false, _true]= range(2)
+
+_roots= ['$', '&', '%', '@', '\\']
+
+
+# _allowMOSFSNames
+# After importing riscospath, set _allowMOSFSNames true if you want the module
+# to understand the "-SomeFS-" notation left over from the old BBC Master MOS,
+# as well as the standard "SomeFS:" notation. Set this to be fully backwards
+# compatible but remember that "-SomeFS-" can also be a perfectly valid file
+# name so care must be taken when splitting and joining paths.
+
+_allowMOSFSNames= _false
+
+
+## Path manipulation, RISC OS stylee.
+
+def _split(p):
+  """
+split filing system name (including special field) and drive specifier from rest
+of path. This is needed by many riscospath functions.
+"""
+  dash= _allowMOSFSNames and p[:1]=='-'
+  if dash:
+    q= string.find(p, '-', 1)+1
+  else:
+    if p[:1]==':':
+      q= 0
+    else:
+      q= string.find(p, ':')+1 # q= index of start of non-FS portion of path
+  s= string.find(p, '#')
+  if s==-1 or s>q:
+    s= q # find end of main FS name, not including special field
+  else:
+    for c in p[dash:s]:
+      if c not in string.letters:
+        q= 0
+        break # disallow invalid non-special-field characters in FS name
+  r= q
+  if p[q:q+1]==':':
+    r= string.find(p, '.', q+1)+1
+    if r==0:
+      r= len(p) # find end of drive name (if any) following FS name (if any)
+  return (p[:q], p[q:r], p[r:])
+
+
+def normcase(p):
+  """
+Normalize the case of a pathname. This converts to lowercase as the native RISC
+OS filesystems are case-insensitive. However, not all filesystems have to be,
+and there's no simple way to find out what type an FS is argh.
+"""
+  return string.lower(p)
+
+
+def isabs(p):
+  """
+Return whether a path is absolute. Under RISC OS, a file system specifier does
+not make a path absolute, but a drive name or number does, and so does using the
+symbol for root, URD, library, CSD or PSD. This means it is perfectly possible
+to have an "absolute" URL dependent on the current working directory, and
+equally you can have a "relative" URL that's on a completely different device to
+the current one argh.
+"""
+  (fs, drive, path)= _split(p)
+  return drive!='' or path[:1] in _roots
+
+
+def join(a, *p):
+  """
+Join path elements with the directory separator, replacing the entire path when
+an absolute or FS-changing path part is found.
+"""
+  j= a
+  for b in p:
+    (fs, drive, path)= _split(b)
+    if fs!='' or drive!='' or path[:1] in _roots:
+      j= b
+    else:
+      j= j+'.'+b
+  return j
+
+
+def split(p):
+  """
+Split a path in head (everything up to the last '.') and tail (the rest). FS
+name must still be dealt with separately since special field may contain '.'.
+"""
+  (fs, drive, path)= _split(p)
+  q= string.rfind(path, '.')
+  if q!=-1:
+    return (fs+drive+path[:q], path[q+1:])
+  return ('', p)
+
+
+def splitext(p):
+  """
+Split a path in root and extension. This assumes the 'using slash for dot and
+dot for slash with foreign files' convention common in RISC OS is in force.
+"""
+  (tail, head)= split(p)
+  if '/' in head:
+    q= len(head)-string.rfind(head, '/')
+    return (p[:-q], p[-q:])
+  return (p, '')
+
+
+def splitdrive(p):
+  """
+Split a pathname into a drive specification (including FS name) and the rest of
+the path. The terminating dot of the drive name is included in the drive
+specification.
+"""
+  (fs, drive, path)= _split(p)
+  return (fs+drive, p)
+
+
+def basename(p):
+  """
+Return the tail (basename) part of a path.
+"""
+  return split(p)[1]
+
+
+def dirname(p):
+  """
+Return the head (dirname) part of a path.
+"""
+  return split(p)[0]
+
+
+def commonprefix(ps):
+  """
+Return the longest prefix of all list elements. Purely string-based; does not
+separate any path parts. Why am I in os.path?
+"""
+  if len(ps)==0:
+    return ''
+  prefix= ps[0]
+  for p in ps[1:]:
+    prefix= prefix[:len(p)]
+    for i in range(len(prefix)):
+      if prefix[i] <> p[i]:
+        prefix= prefix[:i]
+        if i==0:
+          return ''
+        break
+  return prefix
+
+
+## File access functions. Why are we in os.path?
+
+def getsize(p):
+  """
+Return the size of a file, reported by os.stat().
+"""
+  st= os.stat(p)
+  return st[stat.ST_SIZE]
+
+
+def getmtime(p):
+  """
+Return the last modification time of a file, reported by os.stat().
+"""
+  st = os.stat(p)
+  return st[stat.ST_MTIME]
+
+getatime= getmtime
+
+
+# RISC OS-specific file access functions
+
+def exists(p):
+  """
+Test whether a path exists.
+"""
+  return swi.swi('OS_File', '5s;i', p)!=0
+
+
+def isdir(p):
+  """
+Is a path a directory? Includes image files.
+"""
+  return swi.swi('OS_File', '5s;i', p) in [2, 3]
+
+
+def isfile(p):
+  """
+Test whether a path is a file, including image files.
+"""
+  return swi.swi('OS_File', '5s;i', p) in [1, 3]
+
+
+def islink(p):
+  """
+RISC OS has no links or mounts.
+"""
+  return _false
+
+ismount= islink
+
+
+# Same-file testing.
+
+# samefile works on filename comparison since there is no ST_DEV and ST_INO is
+# not reliably unique (esp. directories). First it has to normalise the
+# pathnames, which it can do 'properly' using OS_FSControl since samefile can
+# assume it's running on RISC OS (unlike normpath).
+
+def samefile(fa, fb):
+  """
+Test whether two pathnames reference the same actual file.
+"""
+  l= 512
+  b= swi.block(l)
+  swi.swi('OS_FSControl', 'isb..i', 37, fa, b, l)
+  fa= b.ctrlstring()
+  swi.swi('OS_FSControl', 'isb..i', 37, fb, b, l)
+  fb= b.ctrlstring()
+  return fa==fb
+
+
+def sameopenfile(a, b):
+  """
+Test whether two open file objects reference the same file.
+"""
+  return os.fstat(a)[stat.ST_INO]==os.fstat(b)[stat.ST_INO]
+
+
+## Path canonicalisation
+
+# 'user directory' is taken as meaning the User Root Directory, which is in
+# practice never used, for anything.
+
+def expanduser(p):
+  (fs, drive, path)= _split(p)
+  l= 512
+  b= swi.block(l)
+
+  if path[:1]!='@':
+    return p
+  if fs=='':
+    fsno= swi.swi('OS_Args', '00;i')
+    swi.swi('OS_FSControl', 'iibi', 33, fsno, b, l)
+    fsname= b.ctrlstring()
+  else:
+    if fs[:1]=='-':
+      fsname= fs[1:-1]
+    else:
+      fsname= fs[:-1]
+    fsname= string.split(fsname, '#', 1)[0] # remove special field from fs
+  x= swi.swi('OS_FSControl', 'ib2s.i;.....i', 54, b, fsname, l)
+  if x<l:
+    urd= b.tostring(0, l-x-1)
+  else: # no URD! try CSD
+    x= swi.swi('OS_FSControl', 'ib0s.i;.....i', 54, b, fsname, l)
+    if x<l:
+      urd= b.tostring(0, l-x-1)
+    else: # no CSD! use root
+      urd= '$'
+  return fsname+':'+urd+path[1:]
+
+# Environment variables are in angle brackets.
+
+def expandvars(p):
+  """
+Expand environment variables using OS_GSTrans.
+"""
+  l= 512
+  b= swi.block(l)
+  return b.tostring(0, swi.swi('OS_GSTrans', 'sbi;..i', p, b, l))
+
+
+# Return an absolute path.
+
+def abspath(p):
+  return normpath(join(os.getcwd(), p))
+
+
+# Normalize a path. Only special path element under RISC OS is "^" for "..".
+
+def normpath(p):
+  """
+Normalize path, eliminating up-directory ^s.
+"""
+  (fs, drive, path)= _split(p)
+  rhs= ''
+  ups= 0
+  while path!='':
+    (path, el)= split(path)
+    if el=='^':
+      ups= ups+1
+    else:
+      if ups>0:
+        ups= ups-1
+      else:
+        if rhs=='':
+          rhs= el
+        else:
+          rhs= el+'.'+rhs
+  while ups>0:
+    ups= ups-1
+    rhs= '^.'+rhs
+  return fs+drive+rhs
+
+
+# Directory tree walk.
+# Independent of host system. Why am I in os.path?
+
+def walk(top, func, arg):
+  """
+walk(top,func,args) calls func(arg, d, files) for each directory "d" in the tree
+rooted at "top" (including "top" itself). "files" is a list of all the files and
+subdirs in directory "d".
+"""
+  try:
+    names= os.listdir(top)
+  except os.error:
+    return
+  func(arg, top, names)
+  for name in names:
+    name= join(top, name)
+    if isdir(name) and not islink(name):
+       walk(name, func, arg)
+