Eryk Sun <[email protected]> added the comment:
Itai, you can add a test to Win32NtTests in Lib/test/test_os.py. Maybe spawn a
child process that creates and unlinks a file in a loop. In the parent process
execute a loop that tries to stat the file and ignores errors when the file or
path isn't found. For example:
@support.requires_subprocess()
def test_stat_unlink_race(self):
# bpo-46785: the implementation of os.stat() falls back on reading
# the parent directory if CreateFileW() fails with a permission
# error. If reading the parent directory fails because the file or
# directory is subsequently unlinked or because the volume or
# share is no longer available, then the original permission error
# should not be restored.
fname = os.path.join(os.environ['TEMP'], os_helper.TESTFN + '_46785')
self.addCleanup(os_helper.unlink, fname)
command = '''if 1:
import os
import sys
fname = sys.argv[1]
while True:
try:
with open(fname, "w") as f:
pass
except OSError:
pass
try:
os.remove(fname)
except OSError:
pass
'''
ignored_errors = (
2, # ERROR_FILE_NOT_FOUND
3, # ERROR_PATH_NOT_FOUND
21, # ERROR_NOT_READY
67, # ERROR_BAD_NET_NAME
)
deadline = time.time() + 5
p = subprocess.Popen([sys.executable, '-c', command, fname])
try:
while time.time() < deadline:
try:
os.stat(fname)
except OSError as e:
if e.winerror not in ignored_errors:
raise
finally:
p.terminate()
As the above test shows, I think the error should also be kept if
attributes_from_dir() fails with ERROR_NOT_READY or ERROR_BAD_NET_NAME. For
example:
switch (error) {
case ERROR_ACCESS_DENIED: /* Cannot sync or read attributes. */
case ERROR_SHARING_VIOLATION: /* It's a paging file. */
/* Try reading the parent directory. */
if (!attributes_from_dir(path, &fileInfo, &tagInfo.ReparseTag)) {
/* Cannot read the parent directory. */
switch (GetLastError()) {
// keep these error codes
case ERROR_FILE_NOT_FOUND:
case ERROR_PATH_NOT_FOUND:
case ERROR_NOT_READY:
case ERROR_BAD_NET_NAME:
break;
// restore the error from CreateFileW()
default:
SetLastError(error);
}
return -1;
}
----------
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Python tracker <[email protected]>
<https://bugs.python.org/issue46785>
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