183 lines
6.6 KiB
Python
Executable File
183 lines
6.6 KiB
Python
Executable File
#!/usr/bin/env python3
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#
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# unln.py, Copyright © 2013 Matteo Cypriani <mcy@lm7.fr>
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#
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########################################################################
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# This program is licensed under the terms of the Expat license.
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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########################################################################
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#
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# This script separates file names given as arguments from their respective
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# inodes by doing the equivalent of (cp -p file tmp && mv tmp file).
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import argparse
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import sys
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import os
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import tempfile
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import shutil
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def verbose(*message, **args):
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"""Prints the message on the standard output if verbose mode is on.
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This function is a simple wrapper around print(), and you can use any
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keyword argument you would use with print().
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"""
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if options.verbose:
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print(*message, **args)
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def warn(*message, prefix="Warning!", **args):
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"""Prints the message on the error output, prepended by 'prefix'.
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The standard output is flushed prior to printing the error message, to
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enable the messages to be displayed in the right order.
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This function is a simple wrapper around print(), and you can use any
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keyword argument you would use with print().
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"""
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sys.stdout.flush()
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print(prefix, *message, file=sys.stderr, **args)
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def quote(string):
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""" Quotes a string. """
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return "``{}´´".format(string)
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def dereference(path):
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"""Follows a symbolic link recursively.
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Returns the final target's path, that may or may not exist in the file
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system. If 'path' is not a symbolic link, it is returned as is.
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"""
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if not os.path.islink(path):
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return path
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dereferenced = os.readlink(path)
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# If it's a relative link we must convert it to an absolute path
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if not os.path.isabs(dereferenced):
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dereferenced = os.path.join(os.path.dirname(path), dereferenced)
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return dereference(dereferenced)
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# Parse command-line arguments
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arg_parser = argparse.ArgumentParser(
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description="Separates a file name from its other hard links",
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epilog="For more information about this program, see the README file \
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provided with the distribution.")
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arg_parser.add_argument("-L", "--dereference", action="store_true",
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help="follow symbolic links")
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arg_parser.add_argument("-s", "--sync", action="store_true",
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help="sync files after a copy to be more fail safe \
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(requires Python 3.3 or above, will be ignored with lower versions)")
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arg_parser.add_argument("-v", "--verbose", action="store_true",
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help="increase output verbosity")
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arg_parser.add_argument("filenames", metavar="file", nargs="+",
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help="file names to work on")
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options = arg_parser.parse_args()
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# List of filenames that were supposed to be worked on but could not because of
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# an error
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error_filenames = []
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# Main loop
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for filename in options.filenames:
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# Is a symbolic link?
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if os.path.islink(filename):
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if not options.dereference:
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warn(quote(filename), "is a symbolic link, ignoring.")
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continue
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# Dereference the link
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dereferenced = dereference(filename)
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verbose("Dereferenced {} -> {}.".format(
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quote(filename), quote(dereferenced)))
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filename = dereferenced
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# Exists?
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if not os.path.exists(filename):
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warn(quote(filename), "does not exist, ignoring.")
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continue
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# Is a regular file?
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if not os.path.isfile(filename):
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warn(quote(filename), "is not a regular file, ignoring.")
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continue
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# Number of links?
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nlinks = os.stat(filename).st_nlink
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if nlinks == 1:
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verbose(quote(filename), "has only one link, ignoring.")
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continue
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verbose(quote(filename), "has", nlinks, "hard links, proceeding", end="... ")
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# Reserve a temporary file name
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dirname = os.path.dirname(filename) # filename's directory
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progname = os.path.basename(__file__) # name of this program
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try:
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handle, tmpfilename = tempfile.mkstemp(
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prefix="{}-".format(filename),
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suffix="-{}.tmp".format(progname),
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dir=dirname)
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except:
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warn("Cannot create temporary file to copy {}:".format(quote(filename)),
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sys.exc_info()[1])
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error_filenames.append(filename)
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continue
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os.close(handle) # we just need a temporary file name
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# Copy the original file to the temporary file
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verbose("Copying to temporary file", quote(tmpfilename), end="... ")
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try:
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shutil.copy2(filename, tmpfilename) # cp -p
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except:
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warn("Cannot copy {} to {}:".format(quote(filename), quote(tmpfilename)),
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sys.exc_info()[1])
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error_filenames.append(filename)
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# Delete temporary file
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os.remove(tmpfilename)
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continue
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# Sync (if we are running Python >= 3.3)
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if options.sync and sys.version_info.minor >= 3:
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verbose("Syncing", end="... ")
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os.sync()
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# Rename the temporary file with the original file name
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verbose("Moving back {} to {}...".format(
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quote(tmpfilename), quote(filename)))
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try:
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os.rename(tmpfilename, filename)
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except:
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warn("Cannot move {} to {}:".format(
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quote(tmpfilename), quote(filename)),
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sys.exc_info()[1], "Deleting temporary file", quote(tmpfilename))
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error_filenames.append(filename)
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# Delete temporary file
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os.remove(tmpfilename)
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# Display the list of files in error
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if error_filenames:
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warn("The following regular files still have more than one hard link:")
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print(*error_filenames, sep="\n", file=sys.stderr)
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