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