#!/usr/bin/env python
#coding=utf-8
 
import os
 
def scan_files(directory,prefix=None,postfix=None):
  files_list=[]
   
  for root, sub_dirs, files in os.walk(directory):
    for special_file in files:
      if postfix:
        if special_file.endswith(postfix):
          files_list.append(os.path.join(root,special_file))
      elif prefix:
        if special_file.startswith(prefix):
          files_list.append(os.path.join(root,special_file))
      else:
        files_list.append(os.path.join(root,special_file))
              
  return files_list