summaryrefslogtreecommitdiffstats
path: root/Lib/posixpath.py
blob: 6110f8e32471025e068cdedee2768612a14ca839 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
# Module 'posixpath' -- common operations on POSIX pathnames

import posix
import stat


# Normalize the case of a pathname.  Trivial in Posix, string.lower on Mac.
# On MS-DOS this may also turn slashes into backslashes; however, other
# normalizations (such as optimizing '../' away) are not allowed
# (another function should be defined to do that).

def normcase(s):
	return s


# Return wheter a path is absolute.
# Trivial in Posix, harder on the Mac or MS-DOS.

def isabs(s):
	return s[:1] == '/'


# Join two pathnames.
# Ignore the first part if the second part is absolute.
# Insert a '/' unless the first part is empty or already ends in '/'.

def join(a, b):
	if b[:1] == '/': return b
	if a == '' or a[-1:] == '/': return a + b
	# Note: join('x', '') returns 'x/'; is this what we want?
	return a + '/' + b


# Split a path in head (everything up to the last '/') and tail (the
# rest).  If the original path ends in '/' but is not the root, this
# '/' is stripped.  After the trailing '/' is stripped, the invariant
# join(head, tail) == p holds.
# The resulting head won't end in '/' unless it is the root.

def split(p):
	if p[-1:] == '/' and p <> '/'*len(p):
		while p[-1] == '/':
			p = p[:-1]
	head, tail = '', ''
	for c in p:
		tail = tail + c
		if c == '/':
			head, tail = head + tail, ''
	if head[-1:] == '/' and head <> '/'*len(head):
		while head[-1] == '/':
			head = head[:-1]
	return head, tail


# Split a path in root and extension.
# The extension is everything starting at the first dot in the last
# pathname component; the root is everything before that.
# It is always true that root + ext == p.

def splitext(p):
	root, ext = '', ''
	for c in p:
		if c == '/':
			root, ext = root + ext + c, ''
		elif c == '.' or ext:
			ext = ext + c
		else:
			root = root + c
	return root, ext


# Return the tail (basename) part of a path.

def basename(p):
	return split(p)[1]


# Return the head (dirname) part of a path.

def dirname(p):
	return split(p)[0]


# Return the longest prefix of all list elements.

def commonprefix(m):
	if not m: return ''
	prefix = m[0]
	for item in m:
		for i in range(len(prefix)):
			if prefix[:i+1] <> item[:i+1]:
				prefix = prefix[:i]
				if i == 0: return ''
				break
	return prefix


# Is a path a symbolic link?
# This will always return false on systems where posix.lstat doesn't exist.

def islink(path):
	try:
		st = posix.lstat(path)
	except (posix.error, AttributeError):
		return 0
	return stat.S_ISLNK(st[stat.ST_MODE])


# Does a path exist?
# This is false for dangling symbolic links.

def exists(path):
	try:
		st = posix.stat(path)
	except posix.error:
		return 0
	return 1


# Is a path a posix directory?
# This follows symbolic links, so both islink() and isdir() can be true
# for the same path.

def isdir(path):
	try:
		st = posix.stat(path)
	except posix.error:
		return 0
	return stat.S_ISDIR(st[stat.ST_MODE])


# Is a path a regular file?
# This follows symbolic links, so both islink() and isfile() can be true
# for the same path.

def isfile(path):
	try:
		st = posix.stat(path)
	except posix.error:
		return 0
	return stat.S_ISREG(st[stat.ST_MODE])


# Are two filenames really pointing to the same file?

def samefile(f1, f2):
	s1 = posix.stat(f1)
	s2 = posix.stat(f2)
	return samestat(s1, s2)


# Are two open files really referencing the same file?
# (Not necessarily the same file descriptor!)
# XXX Oops, posix.fstat() doesn't exist yet!

def sameopenfile(fp1, fp2):
	s1 = posix.fstat(fp1)
	s2 = posix.fstat(fp2)
	return samestat(s1, s2)


# Are two stat buffers (obtained from stat, fstat or lstat)
# describing the same file?

def samestat(s1, s2):
	return s1[stat.ST_INO] == s2[stat.ST_INO] and \
		s1[stat.ST_DEV] == s2[stat.ST_DEV]


# Is a path a mount point?
# (Does this work for all UNIXes?  Is it even guaranteed to work by POSIX?)

def ismount(path):
	try:
		s1 = posix.stat(path)
		s2 = posix.stat(join(path, '..'))
	except posix.error:
		return 0 # It doesn't exist -- so not a mount point :-)
	dev1 = s1[stat.ST_DEV]
	dev2 = s2[stat.ST_DEV]
	if dev1 != dev2:
		return 1		# path/.. on a different device as path
	ino1 = s1[stat.ST_INO]
	ino2 = s2[stat.ST_INO]
	if ino1 == ino2:
		return 1		# path/.. is the same i-node as path
	return 0


# Directory tree walk.
# For each directory under top (including top itself, but excluding
# '.' and '..'), func(arg, dirname, filenames) is called, where
# dirname is the name of the directory and filenames is the list
# files files (and subdirectories etc.) in the directory.
# The func may modify the filenames list, to implement a filter,
# or to impose a different order of visiting.

def walk(top, func, arg):
	try:
		names = posix.listdir(top)
	except posix.error:
		return
	func(arg, top, names)
	exceptions = ('.', '..')
	for name in names:
		if name not in exceptions:
			name = join(top, name)
			if isdir(name) and not islink(name):
				walk(name, func, arg)


# Expand paths beginning with '~' or '~user'.
# '~' means $HOME; '~user' means that user's home directory.
# If the path doesn't begin with '~', or if the user or $HOME is unknown,
# the path is returned unchanged (leaving error reporting to whatever
# function is called with the expanded path as argument).
# See also module 'glob' for expansion of *, ? and [...] in pathnames.
# (A function should also be defined to do full *sh-style environment
# variable expansion.)

def expanduser(path):
	if path[:1] <> '~':
		return path
	i, n = 1, len(path)
	while i < n and path[i] <> '/':
		i = i+1
	if i == 1:
		if not posix.environ.has_key('HOME'):
			return path
		userhome = posix.environ['HOME']
	else:
		import pwd
		try:
			pwent = pwd.getpwnam(path[1:i])
		except KeyError:
			return path
		userhome = pwent[5]
	return userhome + path[i:]


# Expand paths containing shell variable substitutions.
# This expands the forms $variable and ${variable} only.
# Non-existant variables are left unchanged.

_varprog = None

def expandvars(path):
	global _varprog
	if '$' not in path:
		return path
	if not _varprog:
		import regex
		_varprog = regex.compile('$\([a-zA-Z0-9_]+\|{[^}]*}\)')
	i = 0
	while 1:
		i = _varprog.search(path, i)
		if i < 0:
			break
		name = _varprog.group(1)
		j = i + len(_varprog.group(0))
		if name[:1] == '{' and name[-1:] == '}':
			name = name[1:-1]
		if posix.environ.has_key(name):
			tail = path[j:]
			path = path[:i] + posix.environ[name]
			i = len(path)
			path = path + tail
		else:
			i = j
	return path


# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.
# It should be understood that this may change the meaning of the path
# if it contains symbolic links!

def normpath(path):
	import string
	# Treat initial slashes specially
	slashes = ''
	while path[:1] == '/':
		slashes = slashes + '/'
		path = path[1:]
	comps = string.splitfields(path, '/')
	i = 0
	while i < len(comps):
		if comps[i] == '.':
			del comps[i]
		elif comps[i] == '..' and i > 0 and \
					  comps[i-1] not in ('', '..'):
			del comps[i-1:i+1]
			i = i-1
		elif comps[i] == '' and i > 0 and comps[i-1] <> '':
			del comps[i]
		else:
			i = i+1
	# If the path is now empty, substitute '.'
	if not comps and not slashes:
		comps.append('.')
	return slashes + string.joinfields(comps, '/')