#!/usr/bin/python
"""user filesystem implements files for the -f option to ncftpget

   (and possibly other ncftp-related programs)
   according to the manpage, the file should have this format:

           host sphygmomanometer.ncftp.com
           user gleason
           pass mypasswd

   and since we don't want to have to duplicate our existing $HOME/.netrc
   file, we implement this user filesytem to reformat .netrc to the above
   
   it is necessary to create a directory /mnt/fuse/ncftpgetrc writeable by
   you, or specify another directory when invoking this script, e.g.

   ./ncftpgetrc.py $HOME/mnt/fuse/ncftpgetrc

   on invoking this script, it will exit leaving a file for each host specified
   in $HOME/.netrc under /mnt/fuse/ncftpgetrc/.

   you can remove this by:

   fusermount -u /mnt/fuse/ncftpgetrc
"""
import os, sys, stat, errno, syslog
import fuse
from fuse import Fuse
fuse.fuse_python_api = (0, 2)
NCFTPGETRC = {
 'source': os.getenv('HOME') + os.path.sep + '.netrc',
 'contents': {},
 'mountpoint': '/mnt/fuse/ncftpgetrc',
 'stat': None,
}
INPUT_HEADERS = ['machine', 'login', 'password']
OUTPUT_HEADERS = ['host', 'user', 'pass']

class FuseStat(fuse.Stat):
 def __init__(self):
  attributes = ['st_mode', 'st_ino', 'st_dev',
   'st_nlink', 'st_uid', 'st_gid',
   'st_size', 'st_atime', 'st_mtime', 'st_ctime']
  from_source = ['st_uid', 'st_gid', 'st_atime', 'st_ctime', 'st_mtime']
  initial = dict([[attr, 0] for attr in attributes])
  try:
   if NCFTPGETRC['source']:
    syslog.syslog(syslog.LOG_INFO, 'stat %s' % NCFTPGETRC['source'])
    source_stat = os.stat(NCFTPGETRC['source'])
    for attribute in from_source:
     initial[attribute] = getattr(source_stat, attribute, 0)
  except:
   pass
  syslog.syslog(syslog.LOG_INFO, 'initial stat: %s' % repr(initial))
  for attribute in attributes:
   setattr(self, attribute, initial[attribute])

class NcftpgetrcFS(Fuse):
 def getattr(self, path):
  load_netrc()
  st = NCFTPGETRC['stat'] = FuseStat()
  if path == '/':
   st.st_mode = stat.S_IFDIR | 0755
   st.st_nlink = 2
  elif path[1:] in NCFTPGETRC['contents'].keys():
   st.st_mode = stat.S_IFREG | 0444
   st.st_nlink = 1
   st.st_size = len(NCFTPGETRC['contents'][path[1:]])
  else:
   return -errno.ENOENT
  return st
    
 def readdir(self, path, offset):
  load_netrc()
  syslog.syslog(syslog.LOG_DEBUG, 'readdir %s' % path)
  ret = ['.', '..'] + sorted(NCFTPGETRC['contents'].keys())
  syslog.syslog(syslog.LOG_DEBUG, repr(ret))
  for r in ret:
   yield fuse.Direntry(r)
    
 def open(self, path, flags):
  load_netrc()
  if not path[1:] in NCFTPGETRC['contents'].keys():
   return -errno.ENOENT
  if (flags & 3) != os.O_RDONLY:
   return -errno.EACCES
  return 0
    
 def read(self, path, size, offset):
  load_netrc()
  syslog.syslog(syslog.LOG_DEBUG, 'read %d bytes, offset %d, of %s' % (
   size, offset, path))
  if not path[1:] in NCFTPGETRC['contents'].keys():
   return -errno.ENOENT
  slen = len(NCFTPGETRC['contents'][path[1:]])
  if offset < slen:
   if offset + size > slen:
    size = slen - offset
   buf = NCFTPGETRC['contents'][path[1:]][offset:offset + size]
  else:
   buf = ''
  return buf

def main():
 if len(sys.argv) < 2:
  sys.argv.append(NCFTPGETRC['mountpoint'])
  if not os.path.exists(sys.argv[1]):
   os.mkdir(sys.argv[1], 0700)
 fusage = 'Userspace ncftpget login database\n\n' + Fuse.fusage
 syslog.openlog('ncftpgetrc', syslog.LOG_PID, syslog.LOG_KERN)
 syslog.syslog(syslog.LOG_INFO, 'starting FUSE "ncftpgetrc"')
 server = NcftpgetrcFS(version = "%prog " + fuse.__version__,
  usage = fusage, dash_s_do='setsingle')
 server.parse(values = server, errex = 1)
 server.main()

def readall(filename):
 input = open(filename)
 data = input.readlines()
 input.close()
 return data

def load_netrc():
 data = readall(NCFTPGETRC['source'])
 for line in data:
  row = line.split()
  if len(row) == 6 and [row[0], row[2], row[4]] == INPUT_HEADERS:
   NCFTPGETRC['contents'][row[1]] = ''.join(['%s %s\n' % (OUTPUT_HEADERS[n],
    row[(n << 1) + 1]) for n in range(len(OUTPUT_HEADERS))])

if __name__=='__main__':
 main()