#! /usr/bin/env python3

# findlinksto
#
# find symbolic links to a path matching a regular expression

import os
import sys
import re
import getopt

def main():
 try:
 opts, args = getopt.getopt(sys.argv[1:], '')
 if len(args) < 2:
 raise getopt.GetoptError('not enough arguments', None)
 except getopt.GetoptError as msg:
 sys.stdout = sys.stderr
 print(msg)
 print('usage: findlinksto pattern directory ...')
 sys.exit(2)
 pat, dirs = args[0], args[1:]
 prog = re.compile(pat)
 for dirname in dirs:
 os.walk(dirname, visit, prog)

def visit(prog, dirname, names):
 if os.path.islink(dirname):
 names[:] = []
 return
 if os.path.ismount(dirname):
 print('descend into', dirname)
 for name in names:
 name = os.path.join(dirname, name)
 try:
 linkto = os.readlink(name)
 if prog.search(linkto) is not None:
 print(name, '->', linkto)
 except OSError:
 pass

if __name__ == '__main__':
 main()