import errno
import os
import sys
from shutil import rmtree
from time import sleep
[docs]
def ensure_created(dname):
dname.mkdir(exist_ok=True)
[docs]
def rmdir(dname):
for i in range(5):
if dname.exists():
try:
rmtree(dname)
return
except OSError:
sleep(0.1)
else:
return
raise OSError(f"unable to remove directory: '{dname}'")
[docs]
def ensure_path(pth):
pth.parent.mkdir(parents=True, exist_ok=True)
# code taken from
# https://stackoverflow.com/questions/9532499/check-whether-a-path-is-valid-in-python-without-creating-a-file-at-the-paths-ta
# Sadly, Python fails to provide the following magic number for us.
ERROR_INVALID_NAME = 123
'''
Windows-specific error code indicating an invalid pathname.
See Also
----------
https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382%28v=vs.85%29.aspx
Official listing of all such codes.
'''
[docs]
def is_pathname_valid(pathname):
"""Check pathname validity
`True` if the passed pathname is a valid pathname for the current OS;
`False` otherwise.
Args:
pathname (str): does not need to exists
Returns:
(bool)
"""
# If this pathname is either not a string or is but is empty, this pathname
# is invalid.
try:
if not isinstance(pathname, str) or not pathname:
return False
# Strip this pathname's Windows-specific drive specifier (e.g., `C:\`)
# if any. Since Windows prohibits path components from containing `:`
# characters, failing to strip this `:`-suffixed prefix would
# erroneously invalidate all valid absolute Windows pathnames.
_, pathname = os.path.splitdrive(pathname)
# Directory guaranteed to exist. If the current OS is Windows, this is
# the drive to which Windows was installed (e.g., the "%HOMEDRIVE%"
# environment variable); else, the typical root directory.
root_dirname = os.environ.get('HOMEDRIVE', 'C:') if sys.platform == 'win32' else os.path.sep
assert os.path.isdir(root_dirname) # ...Murphy and her ironclad Law
# Append a path separator to this directory if needed.
root_dirname = root_dirname.rstrip(os.path.sep) + os.path.sep
# Test whether each path component split from this pathname is valid or
# not, ignoring non-existent and non-readable path components.
for pathname_part in pathname.split(os.path.sep):
try:
os.lstat(root_dirname + pathname_part)
# If an OS-specific exception is raised, its error code
# indicates whether this pathname is valid or not. Unless this
# is the case, this exception implies an ignorable kernel or
# filesystem complaint (e.g., path not found or inaccessible).
#
# Only the following exceptions indicate invalid pathnames:
#
# * Instances of the Windows-specific "WindowsError" class
# defining the "winerror" attribute whose value is
# "ERROR_INVALID_NAME". Under Windows, "winerror" is more
# fine-grained and hence useful than the generic "errno"
# attribute. When a too-long pathname is passed, for example,
# "errno" is "ENOENT" (i.e., no such file or directory) rather
# than "ENAMETOOLONG" (i.e., file name too long).
# * Instances of the cross-platform "OSError" class defining the
# generic "errno" attribute whose value is either:
# * Under most POSIX-compatible OSes, "ENAMETOOLONG".
# * Under some edge-case OSes (e.g., SunOS, *BSD), "ERANGE".
except OSError as exc:
if hasattr(exc, 'winerror'):
if exc.winerror == ERROR_INVALID_NAME:
return False
elif exc.errno in {errno.ENAMETOOLONG, errno.ERANGE}:
return False
# If a "TypeError" exception was raised, it almost certainly has the
# error message "embedded NUL character" indicating an invalid pathname.
except TypeError as exc:
return False
# If no exception was raised, all path components and hence this
# pathname itself are valid. (Praise be to the curmudgeonly python.)
else:
return True
# If any other exception was raised, this is an unrelated fatal issue
# (e.g., a bug). Permit this exception to unwind the call stack.
#
# Did we mention this should be shipped with Python already?