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# encoding: utf-8
"""
Utilities for path handling.
"""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
import os
import sys
import errno
import shutil
import random
from . import py3compat
fs_encoding = sys.getfilesystemencoding()
def filefind(filename, path_dirs=None):
"""Find a file by looking through a sequence of paths.
This iterates through a sequence of paths looking for a file and returns
the full, absolute path of the first occurence of the file. If no set of
path dirs is given, the filename is tested as is, after running through
:func:`expandvars` and :func:`expanduser`. Thus a simple call::
filefind('myfile.txt')
will find the file in the current working dir, but::
filefind('~/myfile.txt')
Will find the file in the users home directory. This function does not
automatically try any paths, such as the cwd or the user's home directory.
Parameters
----------
filename : str
The filename to look for.
path_dirs : str, None or sequence of str
The sequence of paths to look for the file in. If None, the filename
need to be absolute or be in the cwd. If a string, the string is
put into a sequence and the searched. If a sequence, walk through
each element and join with ``filename``, calling :func:`expandvars`
and :func:`expanduser` before testing for existence.
Returns
-------
Raises :exc:`IOError` or returns absolute path to file.
"""
# If paths are quoted, abspath gets confused, strip them...
filename = filename.strip('"').strip("'")
# If the input is an absolute path, just check it exists
if os.path.isabs(filename) and os.path.isfile(filename):
return filename
if path_dirs is None:
path_dirs = ("",)
elif isinstance(path_dirs, py3compat.string_types):
path_dirs = (path_dirs,)
for path in path_dirs:
if path == '.': path = py3compat.getcwd()
testname = expand_path(os.path.join(path, filename))
if os.path.isfile(testname):
return os.path.abspath(testname)
raise IOError("File %r does not exist in any of the search paths: %r" %
(filename, path_dirs) )
def expand_path(s):
"""Expand $VARS and ~names in a string, like a shell
:Examples:
In [2]: os.environ['FOO']='test'
In [3]: expand_path('variable FOO is $FOO')
Out[3]: 'variable FOO is test'
"""
# This is a pretty subtle hack. When expand user is given a UNC path
# on Windows (\\server\share$\%username%), os.path.expandvars, removes
# the $ to get (\\server\share\%username%). I think it considered $
# alone an empty var. But, we need the $ to remains there (it indicates
# a hidden share).
if os.name=='nt':
s = s.replace('$\\', 'IPYTHON_TEMP')
s = os.path.expandvars(os.path.expanduser(s))
if os.name=='nt':
s = s.replace('IPYTHON_TEMP', '$\\')
return s
try:
ENOLINK = errno.ENOLINK
except AttributeError:
ENOLINK = 1998
def link(src, dst):
"""Hard links ``src`` to ``dst``, returning 0 or errno.
Note that the special errno ``ENOLINK`` will be returned if ``os.link`` isn't
supported by the operating system.
"""
if not hasattr(os, "link"):
return ENOLINK
link_errno = 0
try:
os.link(src, dst)
except OSError as e:
link_errno = e.errno
return link_errno
def link_or_copy(src, dst):
"""Attempts to hardlink ``src`` to ``dst``, copying if the link fails.
Attempts to maintain the semantics of ``shutil.copy``.
Because ``os.link`` does not overwrite files, a unique temporary file
will be used if the target already exists, then that file will be moved
into place.
"""
if os.path.isdir(dst):
dst = os.path.join(dst, os.path.basename(src))
link_errno = link(src, dst)
if link_errno == errno.EEXIST:
if os.stat(src).st_ino == os.stat(dst).st_ino:
# dst is already a hard link to the correct file, so we don't need
# to do anything else. If we try to link and rename the file
# anyway, we get duplicate files - see http://bugs.python.org/issue21876
return
new_dst = dst + "-temp-%04X" %(random.randint(1, 16**4), )
try:
link_or_copy(src, new_dst)
except:
try:
os.remove(new_dst)
except OSError:
pass
raise
os.rename(new_dst, dst)
elif link_errno != 0:
# Either link isn't supported, or the filesystem doesn't support
# linking, or 'src' and 'dst' are on different filesystems.
shutil.copy(src, dst)
def ensure_dir_exists(path, mode=0o755):
"""ensure that a directory exists
If it doesn't exist, try to create it and protect against a race condition
if another process is doing the same.
The default permissions are 755, which differ from os.makedirs default of 777.
"""
if not os.path.exists(path):
try:
os.makedirs(path, mode=mode)
except OSError as e:
if e.errno != errno.EEXIST:
raise
elif not os.path.isdir(path):
raise IOError("%r exists but is not a directory" % path)
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