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Issue #6975: os.path.realpath() now correctly resolves multiple nested symlinks on POSIX platforms.

This commit is contained in:
Serhiy Storchaka 2013-02-10 12:24:06 +02:00
parent e35042d13a d83c82440b
commit f2619236eb
3 changed files with 104 additions and 38 deletions
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84
Lib/posixpath.py
View File

@ -363,52 +363,60 @@ def abspath(path):
def realpath(filename):
"""Return the canonical path of the specified filename, eliminating any
symbolic links encountered in the path."""
if isinstance(filename, bytes):
path, ok = _joinrealpath(filename[:0], filename, {})
return abspath(path)
# Join two paths, normalizing ang eliminating any symbolic links
# encountered in the second path.
def _joinrealpath(path, rest, seen):
if isinstance(path, bytes):
sep = b'/'
empty = b''
curdir = b'.'
pardir = b'..'
else:
sep = '/'
empty = ''
if isabs(filename):
bits = [sep] + filename.split(sep)[1:]
else:
bits = [empty] + filename.split(sep)
curdir = '.'
pardir = '..'
for i in range(2, len(bits)+1):
component = join(*bits[0:i])
# Resolve symbolic links.
if islink(component):
resolved = _resolve_link(component)
if resolved is None:
# Infinite loop -- return original component + rest of the path
return abspath(join(*([component] + bits[i:])))
if isabs(rest):
rest = rest[1:]
path = sep
while rest:
name, _, rest = rest.partition(sep)
if not name or name == curdir:
# current dir
continue
if name == pardir:
# parent dir
if path:
path = dirname(path)
else:
newpath = join(*([resolved] + bits[i:]))
return realpath(newpath)
path = name
continue
newpath = join(path, name)
if not islink(newpath):
path = newpath
continue
# Resolve the symbolic link
if newpath in seen:
# Already seen this path
path = seen[newpath]
if path is not None:
# use cached value
continue
# The symlink is not resolved, so we must have a symlink loop.
# Return already resolved part + rest of the path unchanged.
return join(newpath, rest), False
seen[newpath] = None # not resolved symlink
path, ok = _joinrealpath(path, os.readlink(newpath), seen)
if not ok:
return join(path, rest), False
seen[newpath] = path # resolved symlink
return abspath(filename)
return path, True
def _resolve_link(path):
"""Internal helper function. Takes a path and follows symlinks
until we either arrive at something that isn't a symlink, or
encounter a path we've seen before (meaning that there's a loop).
"""
paths_seen = set()
while islink(path):
if path in paths_seen:
# Already seen this path, so we must have a symlink loop
return None
paths_seen.add(path)
# Resolve where the link points to
resolved = os.readlink(path)
if not isabs(resolved):
dir = dirname(path)
path = normpath(join(dir, resolved))
else:
path = normpath(resolved)
return path
supports_unicode_filenames = (sys.platform == 'darwin')
def relpath(path, start=None):

55
Lib/test/test_posixpath.py
View File

@ -320,6 +320,22 @@ class PosixPathTest(unittest.TestCase):
self.assertEqual(realpath(ABSTFN+"1"), ABSTFN+"1")
self.assertEqual(realpath(ABSTFN+"2"), ABSTFN+"2")
self.assertEqual(realpath(ABSTFN+"1/x"), ABSTFN+"1/x")
self.assertEqual(realpath(ABSTFN+"1/.."), dirname(ABSTFN))
self.assertEqual(realpath(ABSTFN+"1/../x"), dirname(ABSTFN) + "/x")
os.symlink(ABSTFN+"x", ABSTFN+"y")
self.assertEqual(realpath(ABSTFN+"1/../" + basename(ABSTFN) + "y"),
ABSTFN + "y")
self.assertEqual(realpath(ABSTFN+"1/../" + basename(ABSTFN) + "1"),
ABSTFN + "1")
os.symlink(basename(ABSTFN) + "a/b", ABSTFN+"a")
self.assertEqual(realpath(ABSTFN+"a"), ABSTFN+"a/b")
os.symlink("../" + basename(dirname(ABSTFN)) + "/" +
basename(ABSTFN) + "c", ABSTFN+"c")
self.assertEqual(realpath(ABSTFN+"c"), ABSTFN+"c")
# Test using relative path as well.
os.chdir(dirname(ABSTFN))
self.assertEqual(realpath(basename(ABSTFN)), ABSTFN)
@ -328,6 +344,45 @@ class PosixPathTest(unittest.TestCase):
support.unlink(ABSTFN)
support.unlink(ABSTFN+"1")
support.unlink(ABSTFN+"2")
support.unlink(ABSTFN+"y")
support.unlink(ABSTFN+"c")
@unittest.skipUnless(hasattr(os, "symlink"),
"Missing symlink implementation")
@skip_if_ABSTFN_contains_backslash
def test_realpath_repeated_indirect_symlinks(self):
# Issue #6975.
try:
os.mkdir(ABSTFN)
os.symlink('../' + basename(ABSTFN), ABSTFN + '/self')
os.symlink('self/self/self', ABSTFN + '/link')
self.assertEqual(realpath(ABSTFN + '/link'), ABSTFN)
finally:
support.unlink(ABSTFN + '/self')
support.unlink(ABSTFN + '/link')
safe_rmdir(ABSTFN)
@unittest.skipUnless(hasattr(os, "symlink"),
"Missing symlink implementation")
@skip_if_ABSTFN_contains_backslash
def test_realpath_deep_recursion(self):
depth = 10
old_path = abspath('.')
try:
os.mkdir(ABSTFN)
for i in range(depth):
os.symlink('/'.join(['%d' % i] * 10), ABSTFN + '/%d' % (i + 1))
os.symlink('.', ABSTFN + '/0')
self.assertEqual(realpath(ABSTFN + '/%d' % depth), ABSTFN)
# Test using relative path as well.
os.chdir(ABSTFN)
self.assertEqual(realpath('%d' % depth), ABSTFN)
finally:
os.chdir(old_path)
for i in range(depth + 1):
support.unlink(ABSTFN + '/%d' % i)
safe_rmdir(ABSTFN)
@unittest.skipUnless(hasattr(os, "symlink"),
"Missing symlink implementation")

3
Misc/NEWS
View File

@ -244,6 +244,9 @@ Core and Builtins
Library
-------
- Issue #6975: os.path.realpath() now correctly resolves multiple nested
symlinks on POSIX platforms.
- Issue #13773: sqlite3.connect() gets a new `uri` parameter to pass the
filename as a URI, allowing to pass custom options.