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#4489: Fix usage of fd-based functions to new api introduced earlier today

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Also add an explicit test for safe implementation usage on supported platforms.

As a side effect, this commit adds a module-level attribute 'rmtree_is_safe'
which offers introspection whether the current rmtree implementation is safe
against symlink attacks.
This commit is contained in:
Hynek Schlawack 2012-06-23 20:28:32 +02:00
parent 1641cea02b
commit 2100b42317
3 changed files with 44 additions and 17 deletions
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23
Lib/shutil.py
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@ -362,9 +362,9 @@ def _rmtree_unsafe(path, onerror):
_rmtree_unsafe(fullname, onerror)
else:
try:
os.remove(fullname)
os.unlink(fullname)
except os.error:
onerror(os.remove, fullname, sys.exc_info())
onerror(os.unlink, fullname, sys.exc_info())
try:
os.rmdir(path)
except os.error:
@ -374,21 +374,21 @@ def _rmtree_unsafe(path, onerror):
def _rmtree_safe_fd(topfd, path, onerror):
names = []
try:
names = os.flistdir(topfd)
names = os.listdir(topfd)
except os.error:
onerror(os.flistdir, path, sys.exc_info())
onerror(os.listdir, path, sys.exc_info())
for name in names:
fullname = os.path.join(path, name)
try:
orig_st = os.fstatat(topfd, name)
orig_st = os.stat(name, dir_fd=topfd)
mode = orig_st.st_mode
except os.error:
mode = 0
if stat.S_ISDIR(mode):
try:
dirfd = os.openat(topfd, name, os.O_RDONLY)
dirfd = os.open(name, os.O_RDONLY, dir_fd=topfd)
except os.error:
onerror(os.openat, fullname, sys.exc_info())
onerror(os.open, fullname, sys.exc_info())
else:
try:
if os.path.samestat(orig_st, os.fstat(dirfd)):
@ -397,21 +397,22 @@ def _rmtree_safe_fd(topfd, path, onerror):
os.close(dirfd)
else:
try:
os.unlinkat(topfd, name)
os.unlink(name, dir_fd=topfd)
except os.error:
onerror(os.unlinkat, fullname, sys.exc_info())
onerror(os.unlink, fullname, sys.exc_info())
try:
os.rmdir(path)
except os.error:
onerror(os.rmdir, path, sys.exc_info())
_use_fd_functions = hasattr(os, 'openat') and hasattr(os, 'unlinkat')
rmtree_is_safe = _use_fd_functions = (os.unlink in os.supports_dir_fd and
os.open in os.supports_dir_fd)
def rmtree(path, ignore_errors=False, onerror=None):
"""Recursively delete a directory tree.
If ignore_errors is set, errors are ignored; otherwise, if onerror
is set, it is called to handle the error with arguments (func,
path, exc_info) where func is os.listdir, os.remove, or os.rmdir;
path, exc_info) where func is platform and implementation dependent;
path is the argument to that function that caused it to fail; and
exc_info is a tuple returned by sys.exc_info(). If ignore_errors
is false and onerror is None, an exception is raised.