[file_utils] unln: option --dereference

file_utils/unln.py

@@ -27,9 +27,6 @@
 #
 # 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:
-# - Option to follow symlinks
 
 
 import argparse
@@ -64,12 +61,28 @@ def quote(string):
     """ Quotes a string. """
     return "``{}´´".format(string)
 
+def dereference(path):
+    """Follows a symbolic link recursively.
+
+    Returns the final target's path, that may or may not exist in the file
+    system. If 'path' is not a symbolic link, it is returned as is.
+    """
+    if not os.path.islink(path):
+        return path
+    dereferenced = os.readlink(path)
+    # If it's a relative link we must convert it to an absolute path
+    if not os.path.isabs(dereferenced):
+        dereferenced = os.path.join(os.path.dirname(path), dereferenced)
+    return dereference(dereferenced)
+
 
 # Parse command-line arguments
 arg_parser = argparse.ArgumentParser(
     description="Separate a file name from its other hard links",
     epilog="For more information about this program, see the README file \
 provided with the distribution.")
+arg_parser.add_argument("-L", "--dereference", action="store_true",
+                        help="follow symbolic links")
 arg_parser.add_argument("-s", "--sync", action="store_true",
                         help="sync files after a copy to be more fail safe \
 (requires Python 3.3 or above, will be ignored with lower versions)")
@@ -87,16 +100,23 @@ error_filenames = []
 
 # Main loop
 for filename in options.filenames:
+    # Is a symbolic link?
+    if os.path.islink(filename):
+        if not options.dereference:
+            warn(quote(filename), "is a symbolic link, ignoring.")
+            continue
+
+        # Dereference the link
+        dereferenced = dereference(filename)
+        verbose("Dereferenced {} -> {}.".format(
+                quote(filename), quote(dereferenced)))
+        filename = dereferenced
+
     # 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.")