text: #! /usr/bin/env python3
  
  """Script to synchronize two source trees.
  
  Invoke with two arguments:
  
  python treesync.py slave master
  
  The assumption is that "master" contains CVS administration while
  slave doesn't.  All files in the slave tree that have a CVS/Entries
  entry in the master tree are synchronized.  This means:
  
      If the files differ:
          if the slave file is newer:
              normalize the slave file
              if the files still differ:
                  copy the slave to the master
          else (the master is newer):
              copy the master to the slave
  
      normalizing the slave means replacing CRLF with LF when the master
      doesn't use CRLF
  
  """
  
  import os, sys, stat, getopt
  
  # Interactivity options
  default_answer = "ask"
  create_files = "yes"
  create_directories = "no"
  write_slave = "ask"
  write_master = "ask"
  
  def main():
      global always_no, always_yes
      global create_directories, write_master, write_slave
      opts, args = getopt.getopt(sys.argv[1:], "nym:s:d:f:a:")
      for o, a in opts:
          if o == '-y':
              default_answer = "yes"
          if o == '-n':
              default_answer = "no"
          if o == '-s':
              write_slave = a
          if o == '-m':
              write_master = a
          if o == '-d':
              create_directories = a
          if o == '-f':
              create_files = a
          if o == '-a':
              create_files = create_directories = write_slave = write_master = a
      try:
          [slave, master] = args
      except ValueError:
          print("usage: python", sys.argv[0] or "treesync.py", end=' ')
          print("[-n] [-y] [-m y|n|a] [-s y|n|a] [-d y|n|a] [-f n|y|a]", end=' ')
          print("slavedir masterdir")
          return
      process(slave, master)
  
  def process(slave, master):
      cvsdir = os.path.join(master, "CVS")
      if not os.path.isdir(cvsdir):
          print("skipping master subdirectory", master)
          print("-- not under CVS")
          return
      print("-"*40)
      print("slave ", slave)
      print("master", master)
      if not os.path.isdir(slave):
          if not okay("create slave directory %s?" % slave,
                      answer=create_directories):
              print("skipping master subdirectory", master)
              print("-- no corresponding slave", slave)
              return
          print("creating slave directory", slave)
          try:
              os.mkdir(slave)
          except OSError as msg:
              print("can't make slave directory", slave, ":", msg)
              return
          else:
              print("made slave directory", slave)
      cvsdir = None
      subdirs = []
      names = os.listdir(master)
      for name in names:
          mastername = os.path.join(master, name)
          slavename = os.path.join(slave, name)
          if name == "CVS":
              cvsdir = mastername
          else:
              if os.path.isdir(mastername) and not os.path.islink(mastername):
                  subdirs.append((slavename, mastername))
      if cvsdir:
          entries = os.path.join(cvsdir, "Entries")
          for e in open(entries).readlines():
              words = e.split('/')
              if words[0] == '' and words[1:]:
                  name = words[1]
                  s = os.path.join(slave, name)
                  m = os.path.join(master, name)
                  compare(s, m)
      for (s, m) in subdirs:
          process(s, m)
  
  def compare(slave, master):
      try:
          sf = open(slave, 'r')
      except IOError:
          sf = None
      try:
          mf = open(master, 'rb')
      except IOError:
          mf = None
      if not sf:
          if not mf:
              print("Neither master nor slave exists", master)
              return
          print("Creating missing slave", slave)
          copy(master, slave, answer=create_files)
          return
      if not mf:
          print("Not updating missing master", master)
          return
      if sf and mf:
          if identical(sf, mf):
              return
      sft = mtime(sf)
      mft = mtime(mf)
      if mft > sft:
          # Master is newer -- copy master to slave
          sf.close()
          mf.close()
          print("Master             ", master)
          print("is newer than slave", slave)
          copy(master, slave, answer=write_slave)
          return
      # Slave is newer -- copy slave to master
      print("Slave is", sft-mft, "seconds newer than master")
      # But first check what to do about CRLF
      mf.seek(0)
      fun = funnychars(mf)
      mf.close()
      sf.close()
      if fun:
          print("***UPDATING MASTER (BINARY COPY)***")
          copy(slave, master, "rb", answer=write_master)
      else:
          print("***UPDATING MASTER***")
          copy(slave, master, "r", answer=write_master)
  
  BUFSIZE = 16*1024
  
  def identical(sf, mf):
      while 1:
          sd = sf.read(BUFSIZE)
          md = mf.read(BUFSIZE)
          if sd != md: return 0
          if not sd: break
      return 1
  
  def mtime(f):
      st = os.fstat(f.fileno())
      return st[stat.ST_MTIME]
  
  def funnychars(f):
      while 1:
          buf = f.read(BUFSIZE)
          if not buf: break
          if '\r' in buf or '\0' in buf: return 1
      return 0
  
  def copy(src, dst, rmode="rb", wmode="wb", answer='ask'):
      print("copying", src)
      print("     to", dst)
      if not okay("okay to copy? ", answer):
          return
      f = open(src, rmode)
      g = open(dst, wmode)
      while 1:
          buf = f.read(BUFSIZE)
          if not buf: break
          g.write(buf)
      f.close()
      g.close()
  
  def raw_input(prompt):
      sys.stdout.write(prompt)
      sys.stdout.flush()
      return sys.stdin.readline()
  
  def okay(prompt, answer='ask'):
      answer = answer.strip().lower()
      if not answer or answer[0] not in 'ny':
          answer = input(prompt)
          answer = answer.strip().lower()
          if not answer:
              answer = default_answer
      if answer[:1] == 'y':
          return 1
      if answer[:1] == 'n':
          return 0
      print("Yes or No please -- try again:")
      return okay(prompt)
  
  if __name__ == '__main__':
      main()
  