[file_utils] Add unln.py

file_utils/README

@@ -1,3 +1,5 @@
+# mvparent.sh #
+
 mvparent.sh was originally written to be integrated in the ROX-Filer
 directory "Send to" menu (and was named mv_here.sh). It moves the
 contents of a directory into its parent directory, then deletes the
@@ -11,3 +13,30 @@ If you want to integrate it in ROX-Filer:
   mkdir -p ~/.config/rox.sourceforge.net/SendTo/.inode_directory
   cd ~/.config/rox.sourceforge.net/SendTo/.inode_directory
   ln -s `which mvparent.sh` "Move here"
+
+
+# unln.py #
+
+I wrote this script after accidentally merging all my "duplicate" files
+with the cleaning tool fslint (thanks guys for a totally confusing clear
+UI!). It does the opposite than the ln command, that is separate file
+names given as arguments from their respective inodes by doing the
+equivalent of (cp -p file tmp && mv tmp file). Checks are done in order
+to work only on regular files which have more than one hard link, so the
+minimal amount of copies are done.
+
+/!\ Warning: the copy function used is shutil.copy2(), which tries to
+    preserve all the metadata it can, but as of Python 3.3 it is not
+    guaranteed that extended attributes will be preserved. See the
+    documentation for details:
+      http://docs.python.org/3/library/shutil.html
+
+/!\ FILE OWNER AND GROUP CANNOT BE PRESERVED, as a file is always
+    created with the current user's UID and GID.
+
+Tip: if you have a file listing all the file names you want to work on,
+with one name per line, you can use xargs with the --delimiter='\n'
+option:
+  xargs --delimiter='\n' <list.txt unln.py
+Without this option, you would have troubles with file names containing
+spaces.

file_utils/unln.py

@@ -0,0 +1,135 @@
+#!/usr/bin/python3
+#
+# unln.py, Copyright © 2013 Matteo Cypriani <mcy@lm7.fr>
+#
+########################################################################
+# This program is licensed under the terms of the Expat license.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+########################################################################
+#
+# This script separates file names given as arguments from their respective
+# inodes by doing the equivalent of (cp -p file tmp && mv tmp file).
+#
+# TODO:
+# - Handle exceptions (permission denied on copy, etc.)
+# - Option verbose
+# - Option to follow symlinks
+# - Summarise skipped regular files with more than one link
+
+
+import sys
+import os
+import tempfile
+import shutil
+
+
+def verbose(*message, **args):
+    """Prints the message on the standard output if verbose mode is on.
+
+    This function is a simple wrapper around print(), and you can use any
+    keyword argument you would use with print().
+    """
+    if options["verbose"]:
+        print(*message, **args)
+
+def warn(*message, prefix="Warning:", **args):
+    """Prints the message on the error output, prepended by 'prefix'.
+
+    This function is a simple wrapper around print(), and you can use any
+    keyword argument you would use with print().
+    """
+    print(prefix, *message, file=sys.stderr, **args)
+
+def error(error_code, *message, **args):
+    """Prints the message on the error output and exits.
+
+    This function is a simple wrapper around print(), and you can use any
+    keyword argument you would use with print().
+    """
+    print(*message, file=sys.stderr, **args)
+    sys.exit(error_code)
+
+def quote(string):
+    """ Quotes a string. """
+    return "``{}´´".format(string)
+
+
+# Default options
+options = {
+    "verbose": True
+    }
+
+# Name of this program
+progname = os.path.basename(sys.argv[0])
+
+# Short usage string
+usage_string = "Usage:\n\t{} <file1> [file2 ...]\n".format(progname)
+
+# Error codes
+ERR_BAD_USAGE = 1
+
+
+# Check command-line arguments
+if len(sys.argv) < 2:
+    error(ERR_BAD_USAGE, usage_string)
+
+
+# Main loop
+for filename in sys.argv[1:]:
+    # Exists?
+    if not os.path.exists(filename):
+        warn(quote(filename), "does not exist, ignoring.")
+        continue
+
+    # Is a symbolic link?
+    if os.path.islink(filename):
+        warn(quote(filename), "is a symbolic link, ignoring.")
+        continue
+
+    # Is a regular file?
+    if not os.path.isfile(filename):
+        warn(quote(filename), "is not a regular file, ignoring.")
+        continue
+
+    # Number of links?
+    nlinks = os.stat(filename).st_nlink
+    if nlinks == 1:
+        verbose(quote(filename), "has only one link, ignoring.")
+        continue
+
+    verbose(quote(filename), "has", nlinks, "hard links, proceeding", end="... ")
+
+    # Reserve a temporary file name
+    dirname = os.path.dirname(filename)
+    handle, tmpfilename = tempfile.mkstemp(
+        prefix="{}-".format(filename),
+        suffix="-{}.tmp".format(progname),
+        dir=dirname)
+    os.close(handle) # we just need a temporary file name
+
+    # Copy the original file to the temporary file
+    verbose("Copying to temporary file", quote(tmpfilename), end="... ")
+    shutil.copy2(filename, tmpfilename) # cp -p
+
+    # Rename the temporary file with the original file name
+    verbose("Moving back {} to {}...".format(
+            quote(tmpfilename), quote(filename)))
+    os.rename(tmpfilename, filename)