Issue #6975: os.path.realpath() now correctly resolves multiple nested symlinks on POSIX platforms.
This commit is contained in:
Serhiy Storchaka
commit
d83c82440b
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@ -391,52 +391,60 @@ def abspath(path):
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def realpath(filename):
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"""Return the canonical path of the specified filename, eliminating any
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symbolic links encountered in the path."""
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if isinstance(filename, bytes):
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path, ok = _joinrealpath(filename[:0], filename, {})
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return abspath(path)
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# Join two paths, normalizing ang eliminating any symbolic links
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# encountered in the second path.
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def _joinrealpath(path, rest, seen):
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if isinstance(path, bytes):
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sep = b'/'
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empty = b''
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curdir = b'.'
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pardir = b'..'
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else:
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sep = '/'
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empty = ''
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if isabs(filename):
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bits = [sep] + filename.split(sep)[1:]
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else:
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bits = [empty] + filename.split(sep)
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curdir = '.'
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pardir = '..'
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for i in range(2, len(bits)+1):
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component = join(*bits[0:i])
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# Resolve symbolic links.
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if islink(component):
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resolved = _resolve_link(component)
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if resolved is None:
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# Infinite loop -- return original component + rest of the path
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return abspath(join(*([component] + bits[i:])))
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if isabs(rest):
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rest = rest[1:]
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path = sep
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while rest:
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name, _, rest = rest.partition(sep)
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if not name or name == curdir:
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# current dir
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continue
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if name == pardir:
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# parent dir
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if path:
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path = dirname(path)
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else:
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newpath = join(*([resolved] + bits[i:]))
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return realpath(newpath)
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path = name
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continue
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newpath = join(path, name)
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if not islink(newpath):
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path = newpath
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continue
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# Resolve the symbolic link
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if newpath in seen:
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# Already seen this path
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path = seen[newpath]
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if path is not None:
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# use cached value
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continue
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# The symlink is not resolved, so we must have a symlink loop.
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# Return already resolved part + rest of the path unchanged.
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return join(newpath, rest), False
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seen[newpath] = None # not resolved symlink
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path, ok = _joinrealpath(path, os.readlink(newpath), seen)
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if not ok:
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return join(path, rest), False
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seen[newpath] = path # resolved symlink
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return abspath(filename)
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return path, True
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def _resolve_link(path):
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"""Internal helper function. Takes a path and follows symlinks
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until we either arrive at something that isn't a symlink, or
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encounter a path we've seen before (meaning that there's a loop).
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"""
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paths_seen = set()
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while islink(path):
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if path in paths_seen:
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# Already seen this path, so we must have a symlink loop
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return None
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paths_seen.add(path)
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# Resolve where the link points to
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resolved = os.readlink(path)
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if not isabs(resolved):
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dir = dirname(path)
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path = normpath(join(dir, resolved))
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else:
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path = normpath(resolved)
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return path
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supports_unicode_filenames = (sys.platform == 'darwin')
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def relpath(path, start=None):
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@ -377,6 +377,22 @@ class PosixPathTest(unittest.TestCase):
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self.assertEqual(realpath(ABSTFN+"1"), ABSTFN+"1")
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self.assertEqual(realpath(ABSTFN+"2"), ABSTFN+"2")
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self.assertEqual(realpath(ABSTFN+"1/x"), ABSTFN+"1/x")
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self.assertEqual(realpath(ABSTFN+"1/.."), dirname(ABSTFN))
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self.assertEqual(realpath(ABSTFN+"1/../x"), dirname(ABSTFN) + "/x")
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os.symlink(ABSTFN+"x", ABSTFN+"y")
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self.assertEqual(realpath(ABSTFN+"1/../" + basename(ABSTFN) + "y"),
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ABSTFN + "y")
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self.assertEqual(realpath(ABSTFN+"1/../" + basename(ABSTFN) + "1"),
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ABSTFN + "1")
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os.symlink(basename(ABSTFN) + "a/b", ABSTFN+"a")
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self.assertEqual(realpath(ABSTFN+"a"), ABSTFN+"a/b")
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os.symlink("../" + basename(dirname(ABSTFN)) + "/" +
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basename(ABSTFN) + "c", ABSTFN+"c")
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self.assertEqual(realpath(ABSTFN+"c"), ABSTFN+"c")
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# Test using relative path as well.
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os.chdir(dirname(ABSTFN))
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self.assertEqual(realpath(basename(ABSTFN)), ABSTFN)
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@ -385,6 +401,45 @@ class PosixPathTest(unittest.TestCase):
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support.unlink(ABSTFN)
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support.unlink(ABSTFN+"1")
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support.unlink(ABSTFN+"2")
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support.unlink(ABSTFN+"y")
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support.unlink(ABSTFN+"c")
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@unittest.skipUnless(hasattr(os, "symlink"),
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"Missing symlink implementation")
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@skip_if_ABSTFN_contains_backslash
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def test_realpath_repeated_indirect_symlinks(self):
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# Issue #6975.
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try:
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os.mkdir(ABSTFN)
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os.symlink('../' + basename(ABSTFN), ABSTFN + '/self')
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os.symlink('self/self/self', ABSTFN + '/link')
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self.assertEqual(realpath(ABSTFN + '/link'), ABSTFN)
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finally:
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support.unlink(ABSTFN + '/self')
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support.unlink(ABSTFN + '/link')
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safe_rmdir(ABSTFN)
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@unittest.skipUnless(hasattr(os, "symlink"),
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"Missing symlink implementation")
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@skip_if_ABSTFN_contains_backslash
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def test_realpath_deep_recursion(self):
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depth = 10
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old_path = abspath('.')
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try:
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os.mkdir(ABSTFN)
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for i in range(depth):
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os.symlink('/'.join(['%d' % i] * 10), ABSTFN + '/%d' % (i + 1))
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os.symlink('.', ABSTFN + '/0')
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self.assertEqual(realpath(ABSTFN + '/%d' % depth), ABSTFN)
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# Test using relative path as well.
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os.chdir(ABSTFN)
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self.assertEqual(realpath('%d' % depth), ABSTFN)
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finally:
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os.chdir(old_path)
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for i in range(depth + 1):
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support.unlink(ABSTFN + '/%d' % i)
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safe_rmdir(ABSTFN)
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@unittest.skipUnless(hasattr(os, "symlink"),
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"Missing symlink implementation")
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