os2emxpath.py revision ae882f798435266b41a9c8966562102345a3eda5 
1# Module 'os2emxpath' -- common operations on OS/2 pathnames
2"""Common pathname manipulations, OS/2 EMX version.
3
4Instead of importing this module directly, import os and refer to this
5module as os.path.
6"""
7
8import os
9import 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           "devnull","realpath","supports_unicode_filenames"]
17
18# strings representing various path-related bits and pieces
19curdir = '.'
20pardir = '..'
21extsep = '.'
22sep = '/'
23altsep = '\\'
24pathsep = ';'
25defpath = '.;C:\\bin'
26devnull = 'nul'
27
28# Normalize the case of a pathname and map slashes to backslashes.
29# Other normalizations (such as optimizing '../' away) are not done
30# (this is done by normpath).
31
32def normcase(s):
33    """Normalize case of pathname.
34
35    Makes all characters lowercase and all altseps into seps."""
36    return s.replace('\\', '/').lower()
37
38
39# Return whether a path is absolute.
40# Trivial in Posix, harder on the Mac or MS-DOS.
41# For DOS it is absolute if it starts with a slash or backslash (current
42# volume), or if a pathname after the volume letter and colon / UNC resource
43# starts with a slash or backslash.
44
45def isabs(s):
46    """Test whether a path is absolute"""
47    s = splitdrive(s)[1]
48    return s != '' and s[:1] in '/\\'
49
50
51# Join two (or more) paths.
52
53def join(a, *p):
54    """Join two or more pathname components, inserting sep as needed"""
55    path = a
56    for b in p:
57        if isabs(b):
58            path = b
59        elif path == '' or path[-1:] in '/\\:':
60            path = path + b
61        else:
62            path = path + '/' + b
63    return path
64
65
66# Split a path in a drive specification (a drive letter followed by a
67# colon) and the path specification.
68# It is always true that drivespec + pathspec == p
69def splitdrive(p):
70    """Split a pathname into drive and path specifiers. Returns a 2-tuple
71"(drive,path)";  either part may be empty"""
72    if p[1:2] == ':':
73        return p[0:2], p[2:]
74    return '', p
75
76
77# Parse UNC paths
78def splitunc(p):
79    """Split a pathname into UNC mount point and relative path specifiers.
80
81    Return a 2-tuple (unc, rest); either part may be empty.
82    If unc is not empty, it has the form '//host/mount' (or similar
83    using backslashes).  unc+rest is always the input path.
84    Paths containing drive letters never have an UNC part.
85    """
86    if p[1:2] == ':':
87        return '', p # Drive letter present
88    firstTwo = p[0:2]
89    if firstTwo == '/' * 2 or firstTwo == '\\' * 2:
90        # is a UNC path:
91        # vvvvvvvvvvvvvvvvvvvv equivalent to drive letter
92        # \\machine\mountpoint\directories...
93        #           directory ^^^^^^^^^^^^^^^
94        normp = normcase(p)
95        index = normp.find('/', 2)
96        if index == -1:
97            ##raise RuntimeError, 'illegal UNC path: "' + p + '"'
98            return ("", p)
99        index = normp.find('/', index + 1)
100        if index == -1:
101            index = len(p)
102        return p[:index], p[index:]
103    return '', p
104
105
106# Split a path in head (everything up to the last '/') and tail (the
107# rest).  After the trailing '/' is stripped, the invariant
108# join(head, tail) == p holds.
109# The resulting head won't end in '/' unless it is the root.
110
111def split(p):
112    """Split a pathname.
113
114    Return tuple (head, tail) where tail is everything after the final slash.
115    Either part may be empty."""
116
117    d, p = splitdrive(p)
118    # set i to index beyond p's last slash
119    i = len(p)
120    while i and p[i-1] not in '/\\':
121        i = i - 1
122    head, tail = p[:i], p[i:]  # now tail has no slashes
123    # remove trailing slashes from head, unless it's all slashes
124    head2 = head
125    while head2 and head2[-1] in '/\\':
126        head2 = head2[:-1]
127    head = head2 or head
128    return d + head, tail
129
130
131# Split a path in root and extension.
132# The extension is everything starting at the last dot in the last
133# pathname component; the root is everything before that.
134# It is always true that root + ext == p.
135
136def splitext(p):
137    """Split the extension from a pathname.
138
139    Extension is everything from the last dot to the end.
140    Return (root, ext), either part may be empty."""
141    root, ext = '', ''
142    for c in p:
143        if c in ['/','\\']:
144            root, ext = root + ext + c, ''
145        elif c == '.':
146            if ext:
147                root, ext = root + ext, c
148            else:
149                ext = c
150        elif ext:
151            ext = ext + c
152        else:
153            root = root + c
154    return root, ext
155
156
157# Return the tail (basename) part of a path.
158
159def basename(p):
160    """Returns the final component of a pathname"""
161    return split(p)[1]
162
163
164# Return the head (dirname) part of a path.
165
166def dirname(p):
167    """Returns the directory component of a pathname"""
168    return split(p)[0]
169
170
171# Return the longest prefix of all list elements.
172
173def commonprefix(m):
174    "Given a list of pathnames, returns the longest common leading component"
175    if not m: return ''
176    prefix = m[0]
177    for item in m:
178        for i in range(len(prefix)):
179            if prefix[:i+1] != item[:i+1]:
180                prefix = prefix[:i]
181                if i == 0: return ''
182                break
183    return prefix
184
185
186# Get size, mtime, atime of files.
187
188def getsize(filename):
189    """Return the size of a file, reported by os.stat()"""
190    return os.stat(filename).st_size
191
192def getmtime(filename):
193    """Return the last modification time of a file, reported by os.stat()"""
194    return os.stat(filename).st_mtime
195
196def getatime(filename):
197    """Return the last access time of a file, reported by os.stat()"""
198    return os.stat(filename).st_atime
199
200def getctime(filename):
201    """Return the creation time of a file, reported by os.stat()."""
202    return os.stat(filename).st_ctime
203
204# Is a path a symbolic link?
205# This will always return false on systems where posix.lstat doesn't exist.
206
207def islink(path):
208    """Test for symbolic link.  On OS/2 always returns false"""
209    return False
210
211
212# Does a path exist?
213# This is false for dangling symbolic links.
214
215def exists(path):
216    """Test whether a path exists"""
217    try:
218        st = os.stat(path)
219    except os.error:
220        return False
221    return True
222
223lexists = exists
224
225
226# Is a path a directory?
227
228def isdir(path):
229    """Test whether a path is a directory"""
230    try:
231        st = os.stat(path)
232    except os.error:
233        return False
234    return stat.S_ISDIR(st.st_mode)
235
236
237# Is a path a regular file?
238# This follows symbolic links, so both islink() and isdir() can be true
239# for the same path.
240
241def isfile(path):
242    """Test whether a path is a regular file"""
243    try:
244        st = os.stat(path)
245    except os.error:
246        return False
247    return stat.S_ISREG(st.st_mode)
248
249
250# Is a path a mount point?  Either a root (with or without drive letter)
251# or an UNC path with at most a / or \ after the mount point.
252
253def ismount(path):
254    """Test whether a path is a mount point (defined as root of drive)"""
255    unc, rest = splitunc(path)
256    if unc:
257        return rest in ("", "/", "\\")
258    p = splitdrive(path)[1]
259    return len(p) == 1 and p[0] in '/\\'
260
261
262# Directory tree walk.
263# For each directory under top (including top itself, but excluding
264# '.' and '..'), func(arg, dirname, filenames) is called, where
265# dirname is the name of the directory and filenames is the list
266# of files (and subdirectories etc.) in the directory.
267# The func may modify the filenames list, to implement a filter,
268# or to impose a different order of visiting.
269
270def walk(top, func, arg):
271    """Directory tree walk whth callback function.
272
273    walk(top, func, arg) calls func(arg, d, files) for each directory d
274    in the tree rooted at top (including top itself); files is a list
275    of all the files and subdirs in directory d."""
276    try:
277        names = os.listdir(top)
278    except os.error:
279        return
280    func(arg, top, names)
281    exceptions = ('.', '..')
282    for name in names:
283        if name not in exceptions:
284            name = join(top, name)
285            if isdir(name):
286                walk(name, func, arg)
287
288
289# Expand paths beginning with '~' or '~user'.
290# '~' means $HOME; '~user' means that user's home directory.
291# If the path doesn't begin with '~', or if the user or $HOME is unknown,
292# the path is returned unchanged (leaving error reporting to whatever
293# function is called with the expanded path as argument).
294# See also module 'glob' for expansion of *, ? and [...] in pathnames.
295# (A function should also be defined to do full *sh-style environment
296# variable expansion.)
297
298def expanduser(path):
299    """Expand ~ and ~user constructs.
300
301    If user or $HOME is unknown, do nothing."""
302    if path[:1] != '~':
303        return path
304    i, n = 1, len(path)
305    while i < n and path[i] not in '/\\':
306        i = i + 1
307    if i == 1:
308        if 'HOME' in os.environ:
309            userhome = os.environ['HOME']
310        elif not 'HOMEPATH' in os.environ:
311            return path
312        else:
313            try:
314                drive = os.environ['HOMEDRIVE']
315            except KeyError:
316                drive = ''
317            userhome = join(drive, os.environ['HOMEPATH'])
318    else:
319        return path
320    return userhome + path[i:]
321
322
323# Expand paths containing shell variable substitutions.
324# The following rules apply:
325#       - no expansion within single quotes
326#       - no escape character, except for '$$' which is translated into '$'
327#       - ${varname} is accepted.
328#       - varnames can be made out of letters, digits and the character '_'
329# XXX With COMMAND.COM you can use any characters in a variable name,
330# XXX except '^|<>='.
331
332def expandvars(path):
333    """Expand shell variables of form $var and ${var}.
334
335    Unknown variables are left unchanged."""
336    if '$' not in path:
337        return path
338    import string
339    varchars = string.letters + string.digits + '_-'
340    res = ''
341    index = 0
342    pathlen = len(path)
343    while index < pathlen:
344        c = path[index]
345        if c == '\'':   # no expansion within single quotes
346            path = path[index + 1:]
347            pathlen = len(path)
348            try:
349                index = path.index('\'')
350                res = res + '\'' + path[:index + 1]
351            except ValueError:
352                res = res + path
353                index = pathlen - 1
354        elif c == '$':  # variable or '$$'
355            if path[index + 1:index + 2] == '$':
356                res = res + c
357                index = index + 1
358            elif path[index + 1:index + 2] == '{':
359                path = path[index+2:]
360                pathlen = len(path)
361                try:
362                    index = path.index('}')
363                    var = path[:index]
364                    if var in os.environ:
365                        res = res + os.environ[var]
366                except ValueError:
367                    res = res + path
368                    index = pathlen - 1
369            else:
370                var = ''
371                index = index + 1
372                c = path[index:index + 1]
373                while c != '' and c in varchars:
374                    var = var + c
375                    index = index + 1
376                    c = path[index:index + 1]
377                if var in os.environ:
378                    res = res + os.environ[var]
379                if c != '':
380                    res = res + c
381        else:
382            res = res + c
383        index = index + 1
384    return res
385
386
387# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.
388
389def normpath(path):
390    """Normalize path, eliminating double slashes, etc."""
391    path = path.replace('\\', '/')
392    prefix, path = splitdrive(path)
393    while path[:1] == '/':
394        prefix = prefix + '/'
395        path = path[1:]
396    comps = path.split('/')
397    i = 0
398    while i < len(comps):
399        if comps[i] == '.':
400            del comps[i]
401        elif comps[i] == '..' and i > 0 and comps[i-1] not in ('', '..'):
402            del comps[i-1:i+1]
403            i = i - 1
404        elif comps[i] == '' and i > 0 and comps[i-1] != '':
405            del comps[i]
406        else:
407            i = i + 1
408    # If the path is now empty, substitute '.'
409    if not prefix and not comps:
410        comps.append('.')
411    return prefix + '/'.join(comps)
412
413
414# Return an absolute path.
415def abspath(path):
416    """Return the absolute version of a path"""
417    if not isabs(path):
418        path = join(os.getcwd(), path)
419    return normpath(path)
420
421# realpath is a no-op on systems without islink support
422realpath = abspath
423
424supports_unicode_filenames = False
425