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Issue #8741: Fixed the TarFile.makelink() method that is responsible

Browse source 
for extracting symbolic and hard link entries as regular files as a
work-around on platforms that do not support filesystem links.

This stopped working reliably after a change in r74571. I also added
a few tests for this functionality.
This commit is contained in:
Lars Gustäbel 2010-06-03 12:34:14 +00:00
parent 2ee9c6fa50
commit 4da7d410b3
3 changed files with 90 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

71
Lib/tarfile.py
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@ -2127,8 +2127,7 @@ class TarFile(object):
raise StreamError("cannot extract (sym)link as file object")
else:
# A (sym)link's file object is its target's file object.
return self.extractfile(self._getmember(tarinfo.linkname,
tarinfo))
return self.extractfile(self._find_link_target(tarinfo))
else:
# If there's no data associated with the member (directory, chrdev,
# blkdev, etc.), return None instead of a file object.
@ -2237,27 +2236,21 @@ class TarFile(object):
(platform limitation), we try to make a copy of the referenced file
instead of a link.
"""
try:
if hasattr(os, "symlink") and hasattr(os, "link"):
# For systems that support symbolic and hard links.
if tarinfo.issym():
os.symlink(tarinfo.linkname, targetpath)
else:
# See extract().
os.link(tarinfo._link_target, targetpath)
except AttributeError:
if tarinfo.issym():
linkpath = os.path.dirname(tarinfo.name) + "/" + \
tarinfo.linkname
else:
linkpath = tarinfo.linkname
if os.path.exists(tarinfo._link_target):
os.link(tarinfo._link_target, targetpath)
else:
self._extract_member(self._find_link_target(tarinfo), targetpath)
else:
try:
self._extract_member(self.getmember(linkpath), targetpath)
except (EnvironmentError, KeyError), e:
linkpath = linkpath.replace("/", os.sep)
try:
shutil.copy2(linkpath, targetpath)
except EnvironmentError, e:
raise IOError("link could not be created")
self._extract_member(self._find_link_target(tarinfo), targetpath)
except KeyError:
raise ExtractError("unable to resolve link inside archive")
def chown(self, tarinfo, targetpath):
"""Set owner of targetpath according to tarinfo.
@ -2356,21 +2349,28 @@ class TarFile(object):
#--------------------------------------------------------------------------
# Little helper methods:
def _getmember(self, name, tarinfo=None):
def _getmember(self, name, tarinfo=None, normalize=False):
"""Find an archive member by name from bottom to top.
If tarinfo is given, it is used as the starting point.
"""
# Ensure that all members have been loaded.
members = self.getmembers()
if tarinfo is None:
end = len(members)
else:
end = members.index(tarinfo)
# Limit the member search list up to tarinfo.
if tarinfo is not None:
members = members[:members.index(tarinfo)]
for i in xrange(end - 1, -1, -1):
if name == members[i].name:
return members[i]
if normalize:
name = os.path.normpath(name)
for member in reversed(members):
if normalize:
member_name = os.path.normpath(member.name)
else:
member_name = member.name
if name == member_name:
return member
def _load(self):
"""Read through the entire archive file and look for readable
@ -2391,6 +2391,25 @@ class TarFile(object):
if mode is not None and self.mode not in mode:
raise IOError("bad operation for mode %r" % self.mode)
def _find_link_target(self, tarinfo):
"""Find the target member of a symlink or hardlink member in the
archive.
"""
if tarinfo.issym():
# Always search the entire archive.
linkname = os.path.dirname(tarinfo.name) + "/" + tarinfo.linkname
limit = None
else:
# Search the archive before the link, because a hard link is
# just a reference to an already archived file.
linkname = tarinfo.linkname
limit = tarinfo
member = self._getmember(linkname, tarinfo=limit, normalize=True)
if member is None:
raise KeyError("linkname %r not found" % linkname)
return member
def __iter__(self):
"""Provide an iterator object.
"""