source: python/trunk/Lib/os2knixpath.py@ 384

Last change on this file since 384 was 381, checked in by dmik, 11 years ago

Add OS/2 version of os.path.relpath.

Based on the NT version (with a bug fix related to
trailing slashes).

  • Property svn:eol-style set to native
File size: 8.3 KB
Line 
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
10from genericpath import *
11from ntpath import (expanduser, expandvars, isabs, islink, splitdrive,
12 splitext, split, walk)
13
14__all__ = ["normcase","isabs","join","splitdrive","split","splitext",
15 "basename","dirname","commonprefix","getsize","getmtime",
16 "getatime","getctime", "islink","exists","lexists","isdir","isfile",
17 "ismount","walk","expanduser","expandvars","normpath","abspath",
18 "samefile","sameopenfile","samestat",
19 "splitunc","curdir","pardir","sep","pathsep","defpath","altsep",
20 "extsep","devnull","realpath","supports_unicode_filenames"]
21
22# strings representing various path-related bits and pieces
23curdir = '.'
24pardir = '..'
25extsep = '.'
26sep = '/'
27altsep = '\\'
28pathsep = ';'
29defpath = '.;C:\\bin'
30devnull = 'nul'
31
32# Normalize the case of a pathname and map slashes to backslashes.
33# Other normalizations (such as optimizing '../' away) are not done
34# (this is done by normpath).
35
36def normcase(s):
37 """Normalize case of pathname.
38
39 Makes all characters lowercase and all altseps into seps."""
40 return s.replace('\\', '/').lower()
41
42
43# Join two (or more) paths.
44
45def join(a, *p):
46 """Join two or more pathname components, inserting sep as needed"""
47 path = a
48 for b in p:
49 if isabs(b):
50 path = b
51 elif path == '' or path[-1:] in '/\\:':
52 path = path + b
53 else:
54 path = path + '/' + b
55 return path
56
57
58# Parse UNC paths
59def splitunc(p):
60 """Split a pathname into UNC mount point and relative path specifiers.
61
62 Return a 2-tuple (unc, rest); either part may be empty.
63 If unc is not empty, it has the form '//host/mount' (or similar
64 using backslashes). unc+rest is always the input path.
65 Paths containing drive letters never have an UNC part.
66 """
67 if p[1:2] == ':':
68 return '', p # Drive letter present
69 firstTwo = p[0:2]
70 if firstTwo == '/' * 2 or firstTwo == '\\' * 2:
71 # is a UNC path:
72 # vvvvvvvvvvvvvvvvvvvv equivalent to drive letter
73 # \\machine\mountpoint\directories...
74 # directory ^^^^^^^^^^^^^^^
75 normp = normcase(p)
76 index = normp.find('/', 2)
77 if index == -1:
78 ##raise RuntimeError, 'illegal UNC path: "' + p + '"'
79 return ("", p)
80 index = normp.find('/', index + 1)
81 if index == -1:
82 index = len(p)
83 return p[:index], p[index:]
84 return '', p
85
86
87# Return the tail (basename) part of a path.
88
89def basename(p):
90 """Returns the final component of a pathname"""
91 return split(p)[1]
92
93
94# Return the head (dirname) part of a path.
95
96def dirname(p):
97 """Returns the directory component of a pathname"""
98 return split(p)[0]
99
100
101# Is a path a directory?
102
103# Is a path a mount point? Either a root (with or without drive letter)
104# or an UNC path with at most a / or \ after the mount point.
105
106def ismount(path):
107 """Test whether a path is a mount point (defined as root of drive)"""
108 unc, rest = splitunc(path)
109 if unc:
110 return rest in ("", "/", "\\")
111 p = splitdrive(path)[1]
112 return len(p) == 1 and p[0] in '/\\'
113
114
115# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.
116
117def normpath(path):
118 """Normalize path, eliminating double slashes, etc."""
119 path = path.replace('\\', '/')
120 prefix, path = splitdrive(path)
121 while path[:1] == '/':
122 prefix = prefix + '/'
123 path = path[1:]
124 comps = path.split('/')
125 i = 0
126 while i < len(comps):
127 if comps[i] == '.':
128 del comps[i]
129 elif comps[i] == '..' and i > 0 and comps[i-1] not in ('', '..'):
130 del comps[i-1:i+1]
131 i = i - 1
132 elif comps[i] == '' and i > 0 and comps[i-1] != '':
133 del comps[i]
134 else:
135 i = i + 1
136 # If the path is now empty, substitute '.'
137 if not prefix and not comps:
138 comps.append('.')
139 return prefix + '/'.join(comps)
140
141
142# Return an absolute path.
143def abspath(path):
144 """Return the absolute version of a path"""
145 if not isabs(path):
146 path = join(os.getcwd(), path)
147 return normpath(path)
148
149
150# Return a canonical path (i.e. the absolute location of a file on the
151# filesystem).
152
153def realpath(filename):
154 """Return the canonical path of the specified filename, eliminating any
155symbolic links encountered in the path."""
156 if isabs(filename):
157 bits = ['/'] + filename.split('/')[1:]
158 else:
159 bits = [''] + filename.split('/')
160
161 for i in range(2, len(bits)+1):
162 component = join(*bits[0:i])
163 # Resolve symbolic links.
164 if islink(component):
165 resolved = _resolve_link(component)
166 if resolved is None:
167 # Infinite loop -- return original component + rest of the path
168 return abspath(join(*([component] + bits[i:])))
169 else:
170 newpath = join(*([resolved] + bits[i:]))
171 return realpath(newpath)
172
173 return abspath(filename)
174
175
176def _resolve_link(path):
177 """Internal helper function. Takes a path and follows symlinks
178 until we either arrive at something that isn't a symlink, or
179 encounter a path we've seen before (meaning that there's a loop).
180 """
181 paths_seen = []
182 while islink(path):
183 if path in paths_seen:
184 # Already seen this path, so we must have a symlink loop
185 return None
186 paths_seen.append(path)
187 # Resolve where the link points to
188 resolved = os.readlink(path)
189 if not isabs(resolved):
190 dir = dirname(path)
191 path = normpath(join(dir, resolved))
192 else:
193 path = normpath(resolved)
194 return path
195
196
197# Is a path a symbolic link?
198# This will always return false on systems where os.lstat doesn't exist.
199
200def islink(path):
201 """Test whether a path is a symbolic link"""
202 try:
203 st = os.lstat(path)
204 except (os.error, AttributeError):
205 return False
206 return stat.S_ISLNK(st.st_mode)
207
208# Being true for dangling symbolic links is also useful.
209
210def lexists(path):
211 """Test whether a path exists. Returns True for broken symbolic links"""
212 try:
213 st = os.lstat(path)
214 except os.error:
215 return False
216 return True
217
218
219# Are two filenames really pointing to the same file?
220
221def samefile(f1, f2):
222 """Test whether two pathnames reference the same actual file"""
223 s1 = os.stat(f1)
224 s2 = os.stat(f2)
225 return samestat(s1, s2)
226
227
228# Are two open files really referencing the same file?
229# (Not necessarily the same file descriptor!)
230
231def sameopenfile(fp1, fp2):
232 """Test whether two open file objects reference the same file"""
233 s1 = os.fstat(fp1)
234 s2 = os.fstat(fp2)
235 return samestat(s1, s2)
236
237
238# Are two stat buffers (obtained from stat, fstat or lstat)
239# describing the same file?
240
241def samestat(s1, s2):
242 """Test whether two stat buffers reference the same file"""
243 return s1.st_ino == s2.st_ino and \
244 s1.st_dev == s2.st_dev
245
246
247supports_unicode_filenames = False
248
249
250def relpath(path, start=curdir):
251 """Return a relative version of a path"""
252
253 if not path:
254 raise ValueError("no path specified")
255 start_list = abspath(start).split(sep)
256 path_list = abspath(path).split(sep)
257 # Remove empty components after trailing slashes
258 if (start_list[-1] == ''):
259 start_list.pop()
260 if (path_list[-1] == ''):
261 path_list.pop()
262 if start_list[0].lower() != path_list[0].lower():
263 unc_path, rest = splitunc(path)
264 unc_start, rest = splitunc(start)
265 if bool(unc_path) ^ bool(unc_start):
266 raise ValueError("Cannot mix UNC and non-UNC paths (%s and %s)"
267 % (path, start))
268 else:
269 raise ValueError("path is on drive %s, start on drive %s"
270 % (path_list[0], start_list[0]))
271 # Work out how much of the filepath is shared by start and path.
272 for i in range(min(len(start_list), len(path_list))):
273 if start_list[i].lower() != path_list[i].lower():
274 break
275 else:
276 i += 1
277
278 rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
279 if not rel_list:
280 return curdir
281 return join(*rel_list)
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