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bpo-28564: Use os.scandir() in shutil.rmtree(). (#4085) 

This speeds up it to 20-40%.
This commit is contained in:
Serhiy Storchaka 2017-11-04 14:16:35 +02:00 committed by GitHub
parent 82cd3cede8
commit d4d79bc1ff
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4 changed files with 55 additions and 31 deletions
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9
Doc/whatsnew/3.7.rst
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@ -440,6 +440,10 @@ Optimizations
using the :func:`os.scandir` function.
(Contributed by Serhiy Storchaka in :issue:`25996`.)
* The :func:`shutil.rmtree` function has been sped up to 20--40%.
This was done using the :func:`os.scandir` function.
(Contributed by Serhiy Storchaka in :issue:`28564`.)
* Optimized case-insensitive matching and searching of :mod:`regular
expressions <re>`. Searching some patterns can now be up to 20 times faster.
(Contributed by Serhiy Storchaka in :issue:`30285`.)
@ -656,6 +660,11 @@ Changes in the Python API
* ``repr`` for :class:`datetime.timedelta` has changed to include keyword arguments
in the output. (Contributed by Utkarsh Upadhyay in :issue:`30302`.)
* Because :func:`shutil.rmtree` is now implemented using the :func:`os.scandir`
function, the user specified handler *onerror* is now called with the first
argument ``os.scandir`` instead of ``os.listdir`` when listing the direcory
is failed.
Changes in the C API
--------------------

73
Lib/shutil.py
View File

@ -362,25 +362,27 @@ def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,
# version vulnerable to race conditions
def _rmtree_unsafe(path, onerror):
try:
if os.path.islink(path):
# symlinks to directories are forbidden, see bug #1669
raise OSError("Cannot call rmtree on a symbolic link")
with os.scandir(path) as scandir_it:
entries = list(scandir_it)
except OSError:
onerror(os.path.islink, path, sys.exc_info())
# can't continue even if onerror hook returns
return
names = []
try:
names = os.listdir(path)
except OSError:
onerror(os.listdir, path, sys.exc_info())
for name in names:
fullname = os.path.join(path, name)
onerror(os.scandir, path, sys.exc_info())
entries = []
for entry in entries:
fullname = entry.path
try:
mode = os.lstat(fullname).st_mode
is_dir = entry.is_dir(follow_symlinks=False)
except OSError:
mode = 0
if stat.S_ISDIR(mode):
is_dir = False
if is_dir:
try:
if entry.is_symlink():
# This can only happen if someone replaces
# a directory with a symlink after the call to
# os.scandir or entry.is_dir above.
raise OSError("Cannot call rmtree on a symbolic link")
except OSError:
onerror(os.path.islink, fullname, sys.exc_info())
continue
_rmtree_unsafe(fullname, onerror)
else:
try:
@ -394,22 +396,25 @@ def _rmtree_unsafe(path, onerror):
# Version using fd-based APIs to protect against races
def _rmtree_safe_fd(topfd, path, onerror):
names = []
try:
names = os.listdir(topfd)
with os.scandir(topfd) as scandir_it:
entries = list(scandir_it)
except OSError as err:
err.filename = path
onerror(os.listdir, path, sys.exc_info())
for name in names:
fullname = os.path.join(path, name)
onerror(os.scandir, path, sys.exc_info())
return
for entry in entries:
fullname = os.path.join(path, entry.name)
try:
orig_st = os.stat(name, dir_fd=topfd, follow_symlinks=False)
mode = orig_st.st_mode
is_dir = entry.is_dir(follow_symlinks=False)
if is_dir:
orig_st = entry.stat(follow_symlinks=False)
is_dir = stat.S_ISDIR(orig_st.st_mode)
except OSError:
mode = 0
if stat.S_ISDIR(mode):
is_dir = False
if is_dir:
try:
dirfd = os.open(name, os.O_RDONLY, dir_fd=topfd)
dirfd = os.open(entry.name, os.O_RDONLY, dir_fd=topfd)
except OSError:
onerror(os.open, fullname, sys.exc_info())
else:
@ -417,14 +422,14 @@ def _rmtree_safe_fd(topfd, path, onerror):
if os.path.samestat(orig_st, os.fstat(dirfd)):
_rmtree_safe_fd(dirfd, fullname, onerror)
try:
os.rmdir(name, dir_fd=topfd)
os.rmdir(entry.name, dir_fd=topfd)
except OSError:
onerror(os.rmdir, fullname, sys.exc_info())
else:
try:
# This can only happen if someone replaces
# a directory with a symlink after the call to
# stat.S_ISDIR above.
# os.scandir or stat.S_ISDIR above.
raise OSError("Cannot call rmtree on a symbolic "
"link")
except OSError:
@ -433,13 +438,13 @@ def _rmtree_safe_fd(topfd, path, onerror):
os.close(dirfd)
else:
try:
os.unlink(name, dir_fd=topfd)
os.unlink(entry.name, dir_fd=topfd)
except OSError:
onerror(os.unlink, fullname, sys.exc_info())
_use_fd_functions = ({os.open, os.stat, os.unlink, os.rmdir} <=
os.supports_dir_fd and
os.listdir in os.supports_fd and
os.scandir in os.supports_fd and
os.stat in os.supports_follow_symlinks)
def rmtree(path, ignore_errors=False, onerror=None):
@ -491,6 +496,14 @@ def rmtree(path, ignore_errors=False, onerror=None):
finally:
os.close(fd)
else:
try:
if os.path.islink(path):
# symlinks to directories are forbidden, see bug #1669
raise OSError("Cannot call rmtree on a symbolic link")
except OSError:
onerror(os.path.islink, path, sys.exc_info())
# can't continue even if onerror hook returns
return
return _rmtree_unsafe(path, onerror)
# Allow introspection of whether or not the hardening against symlink

2
Lib/test/test_shutil.py
View File

@ -183,7 +183,7 @@ class TestShutil(unittest.TestCase):
errors.append(args)
shutil.rmtree(filename, onerror=onerror)
self.assertEqual(len(errors), 2)
self.assertIs(errors[0][0], os.listdir)
self.assertIs(errors[0][0], os.scandir)
self.assertEqual(errors[0][1], filename)
self.assertIsInstance(errors[0][2][1], NotADirectoryError)
self.assertIn(errors[0][2][1].filename, possible_args)

2
Misc/NEWS.d/next/Library/2017-10-23-16-22-54.bpo-28564.Tx-l-I.rst Normal file
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@ -0,0 +1,2 @@
The shutil.rmtree() function has been sped up to 20--40%. This was done
using the os.scandir() function.