Lib/os2emxpath.py

   1 # Module 'os2emxpath' -- common operations on OS/2 pathnames
   2 """Common pathname manipulations, OS/2 EMX version.
   3
   4 Instead of importing this module directly, import os and refer to this
   5 module as os.path.
   6 """
   7
   8 import os
   9 import stat
  10
  11 __all__ = ["normcase","isabs","join","splitdrive","split","splitext",
  12            "basename","dirname","commonprefix","getsize","getmtime",
  13            "getatime","getctime", "islink","exists","isdir","isfile","ismount",
  14            "walk","expanduser","expandvars","normpath","abspath","splitunc",
  15            "curdir","pardir","sep","pathsep","defpath","altsep","extsep",
  16            "realpath","supports_unicode_filenames"]
  17
  18 # strings representing various path-related bits and pieces
  19 curdir = '.'
  20 pardir = '..'
  21 extsep = '.'
  22 sep = '/'
  23 altsep = '\\'
  24 pathsep = ';'
  25 defpath = '.;C:\\bin'
  26
  27 # Normalize the case of a pathname and map slashes to backslashes.
  28 # Other normalizations (such as optimizing '../' away) are not done
  29 # (this is done by normpath).
  30
  31 def normcase(s):
  32     """Normalize case of pathname.
  33
  34     Makes all characters lowercase and all altseps into seps."""
  35     return s.replace('\\', '/').lower()
  36
  37
  38 # Return whether a path is absolute.
  39 # Trivial in Posix, harder on the Mac or MS-DOS.
  40 # For DOS it is absolute if it starts with a slash or backslash (current
  41 # volume), or if a pathname after the volume letter and colon / UNC resource
  42 # starts with a slash or backslash.
  43
  44 def isabs(s):
  45     """Test whether a path is absolute"""
  46     s = splitdrive(s)[1]
  47     return s != '' and s[:1] in '/\\'
  48
  49
  50 # Join two (or more) paths.
  51
  52 def join(a, *p):
  53     """Join two or more pathname components, inserting sep as needed"""
  54     path = a
  55     for b in p:
  56         if isabs(b):
  57             path = b
  58         elif path == '' or path[-1:] in '/\\:':
  59             path = path + b
  60         else:
  61             path = path + '/' + b
  62     return path
  63
  64
  65 # Split a path in a drive specification (a drive letter followed by a
  66 # colon) and the path specification.
  67 # It is always true that drivespec + pathspec == p
  68 def splitdrive(p):
  69     """Split a pathname into drive and path specifiers. Returns a 2-tuple
  70 "(drive,path)";  either part may be empty"""
  71     if p[1:2] == ':':
  72         return p[0:2], p[2:]
  73     return '', p
  74
  75
  76 # Parse UNC paths
  77 def splitunc(p):
  78     """Split a pathname into UNC mount point and relative path specifiers.
  79
  80     Return a 2-tuple (unc, rest); either part may be empty.
  81     If unc is not empty, it has the form '//host/mount' (or similar
  82     using backslashes).  unc+rest is always the input path.
  83     Paths containing drive letters never have an UNC part.
  84     """
  85     if p[1:2] == ':':
  86         return '', p # Drive letter present
  87     firstTwo = p[0:2]
  88     if firstTwo == '/' * 2 or firstTwo == '\\' * 2:
  89         # is a UNC path:
  90         # vvvvvvvvvvvvvvvvvvvv equivalent to drive letter
  91         # \\machine\mountpoint\directories...
  92         #           directory ^^^^^^^^^^^^^^^
  93         normp = normcase(p)
  94         index = normp.find('/', 2)
  95         if index == -1:
  96             ##raise RuntimeError, 'illegal UNC path: "' + p + '"'
  97             return ("", p)
  98         index = normp.find('/', index + 1)
  99         if index == -1:
 100             index = len(p)
 101         return p[:index], p[index:]
 102     return '', p
 103
 104
 105 # Split a path in head (everything up to the last '/') and tail (the
 106 # rest).  After the trailing '/' is stripped, the invariant
 107 # join(head, tail) == p holds.
 108 # The resulting head won't end in '/' unless it is the root.
 109
 110 def split(p):
 111     """Split a pathname.
 112
 113     Return tuple (head, tail) where tail is everything after the final slash.
 114     Either part may be empty."""
 115
 116     d, p = splitdrive(p)
 117     # set i to index beyond p's last slash
 118     i = len(p)
 119     while i and p[i-1] not in '/\\':
 120         i = i - 1
 121     head, tail = p[:i], p[i:]  # now tail has no slashes
 122     # remove trailing slashes from head, unless it's all slashes
 123     head2 = head
 124     while head2 and head2[-1] in '/\\':
 125         head2 = head2[:-1]
 126     head = head2 or head
 127     return d + head, tail
 128
 129
 130 # Split a path in root and extension.
 131 # The extension is everything starting at the last dot in the last
 132 # pathname component; the root is everything before that.
 133 # It is always true that root + ext == p.
 134
 135 def splitext(p):
 136     """Split the extension from a pathname.
 137
 138     Extension is everything from the last dot to the end.
 139     Return (root, ext), either part may be empty."""
 140     root, ext = '', ''
 141     for c in p:
 142         if c in ['/','\\']:
 143             root, ext = root + ext + c, ''
 144         elif c == '.':
 145             if ext:
 146                 root, ext = root + ext, c
 147             else:
 148                 ext = c
 149         elif ext:
 150             ext = ext + c
 151         else:
 152             root = root + c
 153     return root, ext
 154
 155
 156 # Return the tail (basename) part of a path.
 157
 158 def basename(p):
 159     """Returns the final component of a pathname"""
 160     return split(p)[1]
 161
 162
 163 # Return the head (dirname) part of a path.
 164
 165 def dirname(p):
 166     """Returns the directory component of a pathname"""
 167     return split(p)[0]
 168
 169
 170 # Return the longest prefix of all list elements.
 171
 172 def commonprefix(m):
 173     "Given a list of pathnames, returns the longest common leading component"
 174     if not m: return ''
 175     prefix = m[0]
 176     for item in m:
 177         for i in range(len(prefix)):
 178             if prefix[:i+1] != item[:i+1]:
 179                 prefix = prefix[:i]
 180                 if i == 0: return ''
 181                 break
 182     return prefix
 183
 184
 185 # Get size, mtime, atime of files.
 186
 187 def getsize(filename):
 188     """Return the size of a file, reported by os.stat()"""
 189     return os.stat(filename).st_size
 190
 191 def getmtime(filename):
 192     """Return the last modification time of a file, reported by os.stat()"""
 193     return os.stat(filename).st_mtime
 194
 195 def getatime(filename):
 196     """Return the last access time of a file, reported by os.stat()"""
 197     return os.stat(filename).st_atime
 198
 199 def getctime(filename):
 200     """Return the creation time of a file, reported by os.stat()."""
 201     return os.stat(filename).st_ctime
 202
 203 # Is a path a symbolic link?
 204 # This will always return false on systems where posix.lstat doesn't exist.
 205
 206 def islink(path):
 207     """Test for symbolic link.  On OS/2 always returns false"""
 208     return False
 209
 210
 211 # Does a path exist?
 212 # This is false for dangling symbolic links.
 213
 214 def exists(path):
 215     """Test whether a path exists"""
 216     try:
 217         st = os.stat(path)
 218     except os.error:
 219         return False
 220     return True
 221
 222
 223 # Is a path a directory?
 224
 225 def isdir(path):
 226     """Test whether a path is a directory"""
 227     try:
 228         st = os.stat(path)
 229     except os.error:
 230         return False
 231     return stat.S_ISDIR(st.st_mode)
 232
 233
 234 # Is a path a regular file?
 235 # This follows symbolic links, so both islink() and isdir() can be true
 236 # for the same path.
 237
 238 def isfile(path):
 239     """Test whether a path is a regular file"""
 240     try:
 241         st = os.stat(path)
 242     except os.error:
 243         return False
 244     return stat.S_ISREG(st.st_mode)
 245
 246
 247 # Is a path a mount point?  Either a root (with or without drive letter)
 248 # or an UNC path with at most a / or \ after the mount point.
 249
 250 def ismount(path):
 251     """Test whether a path is a mount point (defined as root of drive)"""
 252     unc, rest = splitunc(path)
 253     if unc:
 254         return rest in ("", "/", "\\")
 255     p = splitdrive(path)[1]
 256     return len(p) == 1 and p[0] in '/\\'
 257
 258
 259 # Directory tree walk.
 260 # For each directory under top (including top itself, but excluding
 261 # '.' and '..'), func(arg, dirname, filenames) is called, where
 262 # dirname is the name of the directory and filenames is the list
 263 # files files (and subdirectories etc.) in the directory.
 264 # The func may modify the filenames list, to implement a filter,
 265 # or to impose a different order of visiting.
 266
 267 def walk(top, func, arg):
 268     """Directory tree walk whth callback function.
 269
 270     walk(top, func, arg) calls func(arg, d, files) for each directory d
 271     in the tree rooted at top (including top itself); files is a list
 272     of all the files and subdirs in directory d."""
 273     try:
 274         names = os.listdir(top)
 275     except os.error:
 276         return
 277     func(arg, top, names)
 278     exceptions = ('.', '..')
 279     for name in names:
 280         if name not in exceptions:
 281             name = join(top, name)
 282             if isdir(name):
 283                 walk(name, func, arg)
 284
 285
 286 # Expand paths beginning with '~' or '~user'.
 287 # '~' means $HOME; '~user' means that user's home directory.
 288 # If the path doesn't begin with '~', or if the user or $HOME is unknown,
 289 # the path is returned unchanged (leaving error reporting to whatever
 290 # function is called with the expanded path as argument).
 291 # See also module 'glob' for expansion of *, ? and [...] in pathnames.
 292 # (A function should also be defined to do full *sh-style environment
 293 # variable expansion.)
 294
 295 def expanduser(path):
 296     """Expand ~ and ~user constructs.
 297
 298     If user or $HOME is unknown, do nothing."""
 299     if path[:1] != '~':
 300         return path
 301     i, n = 1, len(path)
 302     while i < n and path[i] not in '/\\':
 303         i = i + 1
 304     if i == 1:
 305         if 'HOME' in os.environ:
 306             userhome = os.environ['HOME']
 307         elif not 'HOMEPATH' in os.environ:
 308             return path
 309         else:
 310             try:
 311                 drive = os.environ['HOMEDRIVE']
 312             except KeyError:
 313                 drive = ''
 314             userhome = join(drive, os.environ['HOMEPATH'])
 315     else:
 316         return path
 317     return userhome + path[i:]
 318
 319
 320 # Expand paths containing shell variable substitutions.
 321 # The following rules apply:
 322 #       - no expansion within single quotes
 323 #       - no escape character, except for '$$' which is translated into '$'
 324 #       - ${varname} is accepted.
 325 #       - varnames can be made out of letters, digits and the character '_'
 326 # XXX With COMMAND.COM you can use any characters in a variable name,
 327 # XXX except '^|<>='.
 328
 329 def expandvars(path):
 330     """Expand shell variables of form $var and ${var}.
 331
 332     Unknown variables are left unchanged."""
 333     if '$' not in path:
 334         return path
 335     import string
 336     varchars = string.letters + string.digits + '_-'
 337     res = ''
 338     index = 0
 339     pathlen = len(path)
 340     while index < pathlen:
 341         c = path[index]
 342         if c == '\'':   # no expansion within single quotes
 343             path = path[index + 1:]
 344             pathlen = len(path)
 345             try:
 346                 index = path.index('\'')
 347                 res = res + '\'' + path[:index + 1]
 348             except ValueError:
 349                 res = res + path
 350                 index = pathlen - 1
 351         elif c == '$':  # variable or '$$'
 352             if path[index + 1:index + 2] == '$':
 353                 res = res + c
 354                 index = index + 1
 355             elif path[index + 1:index + 2] == '{':
 356                 path = path[index+2:]
 357                 pathlen = len(path)
 358                 try:
 359                     index = path.index('}')
 360                     var = path[:index]
 361                     if var in os.environ:
 362                         res = res + os.environ[var]
 363                 except ValueError:
 364                     res = res + path
 365                     index = pathlen - 1
 366             else:
 367                 var = ''
 368                 index = index + 1
 369                 c = path[index:index + 1]
 370                 while c != '' and c in varchars:
 371                     var = var + c
 372                     index = index + 1
 373                     c = path[index:index + 1]
 374                 if var in os.environ:
 375                     res = res + os.environ[var]
 376                 if c != '':
 377                     res = res + c
 378         else:
 379             res = res + c
 380         index = index + 1
 381     return res
 382
 383
 384 # Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.
 385
 386 def normpath(path):
 387     """Normalize path, eliminating double slashes, etc."""
 388     path = path.replace('\\', '/')
 389     prefix, path = splitdrive(path)
 390     while path[:1] == '/':
 391         prefix = prefix + '/'
 392         path = path[1:]
 393     comps = path.split('/')
 394     i = 0
 395     while i < len(comps):
 396         if comps[i] == '.':
 397             del comps[i]
 398         elif comps[i] == '..' and i > 0 and comps[i-1] not in ('', '..'):
 399             del comps[i-1:i+1]
 400             i = i - 1
 401         elif comps[i] == '' and i > 0 and comps[i-1] != '':
 402             del comps[i]
 403         else:
 404             i = i + 1
 405     # If the path is now empty, substitute '.'
 406     if not prefix and not comps:
 407         comps.append('.')
 408     return prefix + '/'.join(comps)
 409
 410
 411 # Return an absolute path.
 412 def abspath(path):
 413     """Return the absolute version of a path"""
 414     if not isabs(path):
 415         path = join(os.getcwd(), path)
 416     return normpath(path)
 417
 418 # realpath is a no-op on systems without islink support
 419 realpath = abspath
 420
 421 supports_unicode_filenames = False