用Python编写一个简单的FUSE文件系统的教程

#!/usr/bin/env python
 
from __future__ import with_statement
 
import os
import sys
import errno
 
from fuse import FUSE, FuseOSError, Operations
 
class Passthrough(Operations):
 def __init__(self, root):
 self.root = root
 
 # Helpers
 # =======
 
 def _full_path(self, partial):
 if partial.startswith("/"):
 partial = partial[1:]
 path = os.path.join(self.root, partial)
 return path
 
 # Filesystem methods
 # ==================
 
 def access(self, path, mode):
 full_path = self._full_path(path)
 if not os.access(full_path, mode):
 raise FuseOSError(errno.EACCES)
 
 def chmod(self, path, mode):
 full_path = self._full_path(path)
 return os.chmod(full_path, mode)
 
 def chown(self, path, uid, gid):
 full_path = self._full_path(path)
 return os.chown(full_path, uid, gid)
 
 def getattr(self, path, fh=None):
 full_path = self._full_path(path)
 st = os.lstat(full_path)
 return dict((key, getattr(st, key)) for key in ('st_atime', 'st_ctime',
 'st_gid', 'st_mode', 'st_mtime', 'st_nlink', 'st_size', 'st_uid'))
 
 def readdir(self, path, fh):
 full_path = self._full_path(path)
 
 dirents = ['.', '..']
 if os.path.isdir(full_path):
 dirents.extend(os.listdir(full_path))
 for r in dirents:
 yield r
 
 def readlink(self, path):
 pathname = os.readlink(self._full_path(path))
 if pathname.startswith("/"):
 # Path name is absolute, sanitize it.
 return os.path.relpath(pathname, self.root)
 else:
 return pathname
 
 def mknod(self, path, mode, dev):
 return os.mknod(self._full_path(path), mode, dev)
 
 def rmdir(self, path):
 full_path = self._full_path(path)
 return os.rmdir(full_path)
 
 def mkdir(self, path, mode):
 return os.mkdir(self._full_path(path), mode)
 
 def statfs(self, path):
 full_path = self._full_path(path)
 stv = os.statvfs(full_path)
 return dict((key, getattr(stv, key)) for key in ('f_bavail', 'f_bfree',
 'f_blocks', 'f_bsize', 'f_favail', 'f_ffree', 'f_files', 'f_flag',
 'f_frsize', 'f_namemax'))
 
 def unlink(self, path):
 return os.unlink(self._full_path(path))
 
 def symlink(self, target, name):
 return os.symlink(self._full_path(target), self._full_path(name))
 
 def rename(self, old, new):
 return os.rename(self._full_path(old), self._full_path(new))
 
 def link(self, target, name):
 return os.link(self._full_path(target), self._full_path(name))
 
 def utimens(self, path, times=None):
 return os.utime(self._full_path(path), times)
 
 # File methods
 # ============
 
 def open(self, path, flags):
 full_path = self._full_path(path)
 return os.open(full_path, flags)
 
 def create(self, path, mode, fi=None):
 full_path = self._full_path(path)
 return os.open(full_path, os.O_WRONLY | os.O_CREAT, mode)
 
 def read(self, path, length, offset, fh):
 os.lseek(fh, offset, os.SEEK_SET)
 return os.read(fh, length)
 
 def write(self, path, buf, offset, fh):
 os.lseek(fh, offset, os.SEEK_SET)
 return os.write(fh, buf)
 
 def truncate(self, path, length, fh=None):
 full_path = self._full_path(path)
 with open(full_path, 'r+') as f:
 f.truncate(length)
 
 def flush(self, path, fh):
 return os.fsync(fh)
 
 def release(self, path, fh):
 return os.close(fh)
 
 def fsync(self, path, fdatasync, fh):
 return self.flush(path, fh)
 
def main(mountpoint, root):
 FUSE(Passthrough(root), mountpoint, foreground=True)
 
if __name__ == '__main__':
 main(sys.argv[2], sys.argv[1])