support/munge-symlinks

   1 #!/usr/bin/env python3
   2 # This script will either prefix all symlink values with the string
   3 # "/rsyncd-munged/" or remove that prefix.
   4
   5 import os, sys, argparse
   6
   7 SYMLINK_PREFIX = '/rsyncd-munged/'
   8 PREFIX_LEN = len(SYMLINK_PREFIX)
   9
  10 def main():
  11     for arg in args.names:
  12         if os.path.islink(arg):
  13             process_one_arg(arg)
  14         elif os.path.isdir(arg):
  15             for fn in find_symlinks(arg):
  16                 process_one_arg(fn)
  17         else:
  18             print("Arg is not a symlink or a dir:", arg, file=sys.stderr)
  19
  20
  21 def find_symlinks(path):
  22     for entry in os.scandir(path):
  23         if entry.is_symlink():
  24             yield entry.path
  25         elif entry.is_dir(follow_symlinks=False):
  26             yield from find_symlinks(entry.path)
  27
  28
  29 def process_one_arg(fn):
  30     lnk = os.readlink(fn)
  31     if args.unmunge:
  32         if not lnk.startswith(SYMLINK_PREFIX):
  33             return
  34         lnk = lnk[PREFIX_LEN:]
  35         while args.all and lnk.startswith(SYMLINK_PREFIX):
  36             lnk = lnk[PREFIX_LEN:]
  37     else:
  38         if not args.all and lnk.startswith(SYMLINK_PREFIX):
  39             return
  40         lnk = SYMLINK_PREFIX + lnk
  41
  42     try:
  43         os.unlink(fn)
  44     except OSError as e:
  45         print("Unable to unlink symlink:", str(e), file=sys.stderr)
  46         return
  47     try:
  48         os.symlink(lnk, fn)
  49     except OSError as e:
  50         print("Unable to recreate symlink", fn, '->', lnk + ':', str(e), file=sys.stderr)
  51         return
  52     print(fn, '->', lnk)
  53
  54
  55 if __name__ == '__main__':
  56     our_desc = """\
  57 Adds or removes the %s prefix to/from the start of each symlink's value.
  58 When given the name of a directory, affects all the symlinks in that directory hierarchy.
  59 """ % SYMLINK_PREFIX
  60     epilog = 'See the "munge symlinks" option in the rsyncd.conf manpage for more details.'
  61     parser = argparse.ArgumentParser(description=our_desc, epilog=epilog, add_help=False)
  62     uniq_group = parser.add_mutually_exclusive_group()
  63     uniq_group.add_argument('--munge', action='store_true', help="Add the prefix to symlinks (the default).")
  64     uniq_group.add_argument('--unmunge', action='store_true', help="Remove the prefix from symlinks.")
  65     parser.add_argument('--all', action='store_true', help="Always adds the prefix when munging (even if already munged) or removes multiple instances of the prefix when unmunging.")
  66     parser.add_argument('--help', '-h', action='help', help="Output this help message and exit.")
  67     parser.add_argument('names', metavar='NAME', nargs='+', help="One or more directories and/or symlinks to process.")
  68     args = parser.parse_args()
  69     main()
  70
  71 # vim: sw=4 et