Example File Systems — pyfuse3 3.2.0 documentation

# Example File Systems

pyfuse3 comes with several example file systems in the `examples` directory of the release tarball. For completeness, these examples are also included here.

## Single-file, Read-only File System

(shipped as `examples/lltest.py`)

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    #!/usr/bin/env python3
    # -*- coding: utf-8 -*-
    '''
    hello.py - Example file system for pyfuse3.

    This program presents a static file system containing a single file.

    Copyright © 2015 Nikolaus Rath <Nikolaus.org>
    Copyright © 2015 Gerion Entrup.

    Permission is hereby granted, free of charge, to any person obtaining a copy of
    this software and associated documentation files (the "Software"), to deal in
    the Software without restriction, including without limitation the rights to
    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
    the Software, and to permit persons to whom the Software is furnished to do so.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
    FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
    COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    '''

    import os
    import sys

    # If we are running from the pyfuse3 source directory, try
    # to load the module from there first.
    basedir = os.path.abspath(os.path.join(os.path.dirname(sys.argv[0]), '..'))
    if (os.path.exists(os.path.join(basedir, 'setup.py')) and
        os.path.exists(os.path.join(basedir, 'src', 'pyfuse3.pyx'))):
        sys.path.insert(0, os.path.join(basedir, 'src'))

    from argparse import ArgumentParser
    import stat
    import logging
    import errno
    import pyfuse3
    import trio

    try:
        import faulthandler
    except ImportError:
        pass
    else:
        faulthandler.enable()

    log = logging.getLogger(__name__)

    class TestFs(pyfuse3.Operations):
        def __init__(self):
            super(TestFs, self).__init__()
            self.hello_name = b"message"
            self.hello_inode = pyfuse3.ROOT_INODE+1
            self.hello_data = b"hello world\n"

        async def getattr(self, inode, ctx=None):
            entry = pyfuse3.EntryAttributes()
            if inode == pyfuse3.ROOT_INODE:
                entry.st_mode = (stat.S_IFDIR | 0o755)
                entry.st_size = 0
            elif inode == self.hello_inode:
                entry.st_mode = (stat.S_IFREG | 0o644)
                entry.st_size = len(self.hello_data)
            else:
                raise pyfuse3.FUSEError(errno.ENOENT)

            stamp = int(1438467123.985654 * 1e9)
            entry.st_atime_ns = stamp
            entry.st_ctime_ns = stamp
            entry.st_mtime_ns = stamp
            entry.st_gid = os.getgid()
            entry.st_uid = os.getuid()
            entry.st_ino = inode

            return entry

        async def lookup(self, parent_inode, name, ctx=None):
            if parent_inode != pyfuse3.ROOT_INODE or name != self.hello_name:
                raise pyfuse3.FUSEError(errno.ENOENT)
            return self.getattr(self.hello_inode)

        async def opendir(self, inode, ctx):
            if inode != pyfuse3.ROOT_INODE:
                raise pyfuse3.FUSEError(errno.ENOENT)
            return inode

        async def readdir(self, fh, start_id, token):
            assert fh == pyfuse3.ROOT_INODE

            # only one entry
            if start_id == 0:
                pyfuse3.readdir_reply(
                    token, self.hello_name, await self.getattr(self.hello_inode), 1)
            return

        async def open(self, inode, flags, ctx):
            if inode != self.hello_inode:
                raise pyfuse3.FUSEError(errno.ENOENT)
            if flags & os.O_RDWR or flags & os.O_WRONLY:
                raise pyfuse3.FUSEError(errno.EACCES)
            return pyfuse3.FileInfo(fh=inode)

        async def read(self, fh, off, size):
            assert fh == self.hello_inode
            return self.hello_data[off:off+size]

    def init_logging(debug=False):
        formatter = logging.Formatter('%(asctime)s.%(msecs)03d %(threadName)s: '
                                      '[%(name)s] %(message)s', datefmt="%Y-%m-%d %H:%M:%S")
        handler = logging.StreamHandler()
        handler.setFormatter(formatter)
        root_logger = logging.getLogger()
        if debug:
            handler.setLevel(logging.DEBUG)
            root_logger.setLevel(logging.DEBUG)
        else:
            handler.setLevel(logging.INFO)
            root_logger.setLevel(logging.INFO)
        root_logger.addHandler(handler)

    def parse_args():
        '''Parse command line'''

        parser = ArgumentParser()

        parser.add_argument('mountpoint', type=str,
                            help='Where to mount the file system')
        parser.add_argument('--debug', action='store_true', default=False,
                            help='Enable debugging output')
        parser.add_argument('--debug-fuse', action='store_true', default=False,
                            help='Enable FUSE debugging output')
        return parser.parse_args()

    def main():
        options = parse_args()
        init_logging(options.debug)

        testfs = TestFs()
        fuse_options = set(pyfuse3.default_options)
        fuse_options.add('fsname=hello')
        if options.debug_fuse:
            fuse_options.add('debug')
        pyfuse3.init(testfs, options.mountpoint, fuse_options)
        try:
            trio.run(pyfuse3.main)
        except:
            pyfuse3.close(unmount=False)
            raise

        pyfuse3.close()

    if __name__ == '__main__':
        main()

## In-memory File System

(shipped as `examples/tmpfs.py`)

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    #!/usr/bin/env python3
    # -*- coding: utf-8 -*-
    '''
    tmpfs.py - Example file system for pyfuse3.

    This file system stores all data in memory.

    Copyright © 2013 Nikolaus Rath <Nikolaus.org>

    Permission is hereby granted, free of charge, to any person obtaining a copy of
    this software and associated documentation files (the "Software"), to deal in
    the Software without restriction, including without limitation the rights to
    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
    the Software, and to permit persons to whom the Software is furnished to do so.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
    FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
    COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    '''

    import os
    import sys

    # If we are running from the pyfuse3 source directory, try
    # to load the module from there first.
    basedir = os.path.abspath(os.path.join(os.path.dirname(sys.argv[0]), '..'))
    if (os.path.exists(os.path.join(basedir, 'setup.py')) and
        os.path.exists(os.path.join(basedir, 'src', 'pyfuse3.pyx'))):
        sys.path.insert(0, os.path.join(basedir, 'src'))

    import pyfuse3
    import errno
    import stat
    from time import time
    import sqlite3
    import logging
    from collections import defaultdict
    from pyfuse3 import FUSEError
    from argparse import ArgumentParser
    import trio

    try:
        import faulthandler
    except ImportError:
        pass
    else:
        faulthandler.enable()

    log = logging.getLogger()

    class Operations(pyfuse3.Operations):
        '''An example filesystem that stores all data in memory

        This is a very simple implementation with terrible performance.
        Don't try to store significant amounts of data. Also, there are
        some other flaws that have not been fixed to keep the code easier
        to understand:

        * atime, mtime and ctime are not updated
        * generation numbers are not supported
        * lookup counts are not maintained
        '''

        enable_writeback_cache = True

        def __init__(self):
            super(Operations, self).__init__()
            self.db = sqlite3.connect(':memory:')
            self.db.text_factory = str
            self.db.row_factory = sqlite3.Row
            self.cursor = self.db.cursor()
            self.inode_open_count = defaultdict(int)
            self.init_tables()

        def init_tables(self):
            '''Initialize file system tables'''

            self.cursor.execute("""
            CREATE TABLE inodes (
                id        INTEGER PRIMARY KEY,
                uid       INT NOT NULL,
                gid       INT NOT NULL,
                mode      INT NOT NULL,
                mtime_ns  INT NOT NULL,
                atime_ns  INT NOT NULL,
                ctime_ns  INT NOT NULL,
                target    BLOB(256) ,
                size      INT NOT NULL DEFAULT 0,
                rdev      INT NOT NULL DEFAULT 0,
                data      BLOB
            )
            """)

            self.cursor.execute("""
            CREATE TABLE contents (
                rowid     INTEGER PRIMARY KEY AUTOINCREMENT,
                name      BLOB(256) NOT NULL,
                inode     INT NOT NULL REFERENCES inodes(id),
                parent_inode INT NOT NULL REFERENCES inodes(id),

                UNIQUE (name, parent_inode)
            )""")

            # Insert root directory
            now_ns = int(time() * 1e9)
            self.cursor.execute("INSERT INTO inodes (id,mode,uid,gid,mtime_ns,atime_ns,ctime_ns) "
                                "VALUES (?,?,?,?,?,?,?)",
                                (pyfuse3.ROOT_INODE, stat.S_IFDIR | stat.S_IRUSR | stat.S_IWUSR
                                  | stat.S_IXUSR | stat.S_IRGRP | stat.S_IXGRP | stat.S_IROTH
                                  | stat.S_IXOTH, os.getuid(), os.getgid(), now_ns, now_ns, now_ns))
            self.cursor.execute("INSERT INTO contents (name, parent_inode, inode) VALUES (?,?,?)",
                                (b'..', pyfuse3.ROOT_INODE, pyfuse3.ROOT_INODE))

        def get_row(self, *a, **kw):
            self.cursor.execute(*a, **kw)
            try:
                row = next(self.cursor)
            except StopIteration:
                raise NoSuchRowError()
            try:
                next(self.cursor)
            except StopIteration:
                pass
            else:
                raise NoUniqueValueError()

            return row

        async def lookup(self, inode_p, name, ctx=None):
            if name == '.':
                inode = inode_p
            elif name == '..':
                inode = self.get_row("SELECT * FROM contents WHERE inode=?",
                                     (inode_p,))['parent_inode']
            else:
                try:
                    inode = self.get_row("SELECT * FROM contents WHERE name=? AND parent_inode=?",
                                         (name, inode_p))['inode']
                except NoSuchRowError:
                    raise(pyfuse3.FUSEError(errno.ENOENT))

            return await self.getattr(inode, ctx)

        async def getattr(self, inode, ctx=None):
            row = self.get_row('SELECT * FROM inodes WHERE id=?', (inode,))

            entry = pyfuse3.EntryAttributes()
            entry.st_ino = inode
            entry.generation = 0
            entry.entry_timeout = 300
            entry.attr_timeout = 300
            entry.st_mode = row['mode']
            entry.st_nlink = self.get_row("SELECT COUNT(inode) FROM contents WHERE inode=?",
                                         (inode,))[0]
            entry.st_uid = row['uid']
            entry.st_gid = row['gid']
            entry.st_rdev = row['rdev']
            entry.st_size = row['size']

            entry.st_blksize = 512
            entry.st_blocks = 1
            entry.st_atime_ns = row['atime_ns']
            entry.st_mtime_ns = row['mtime_ns']
            entry.st_ctime_ns = row['ctime_ns']

            return entry

        async def readlink(self, inode, ctx):
            return self.get_row('SELECT * FROM inodes WHERE id=?', (inode,))['target']

        async def opendir(self, inode, ctx):
            return inode

        async def readdir(self, inode, off, token):
            if off == 0:
                off = -1

            cursor2 = self.db.cursor()
            cursor2.execute("SELECT * FROM contents WHERE parent_inode=? "
                            'AND rowid > ? ORDER BY rowid', (inode, off))

            for row in cursor2:
                pyfuse3.readdir_reply(
                    token, row['name'], await self.getattr(row['inode']), row['rowid'])

        async def unlink(self, inode_p, name,ctx):
            entry = await self.lookup(inode_p, name)

            if stat.S_ISDIR(entry.st_mode):
                raise pyfuse3.FUSEError(errno.EISDIR)

            self._remove(inode_p, name, entry)

        async def rmdir(self, inode_p, name, ctx):
            entry = await self.lookup(inode_p, name)

            if not stat.S_ISDIR(entry.st_mode):
                raise pyfuse3.FUSEError(errno.ENOTDIR)

            self._remove(inode_p, name, entry)

        def _remove(self, inode_p, name, entry):
            if self.get_row("SELECT COUNT(inode) FROM contents WHERE parent_inode=?",
                            (entry.st_ino,))[0] > 0:
                raise pyfuse3.FUSEError(errno.ENOTEMPTY)

            self.cursor.execute("DELETE FROM contents WHERE name=? AND parent_inode=?",
                            (name, inode_p))

            if entry.st_nlink == 1 and entry.st_ino not in self.inode_open_count:
                self.cursor.execute("DELETE FROM inodes WHERE id=?", (entry.st_ino,))

        async def symlink(self, inode_p, name, target, ctx):
            mode = (stat.S_IFLNK | stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR |
                    stat.S_IRGRP | stat.S_IWGRP | stat.S_IXGRP |
                    stat.S_IROTH | stat.S_IWOTH | stat.S_IXOTH)
            return await self._create(inode_p, name, mode, ctx, target=target)

        async def rename(self, inode_p_old, name_old, inode_p_new, name_new,
                         flags, ctx):
            if flags != 0:
                raise FUSEError(errno.EINVAL)

            entry_old = await self.lookup(inode_p_old, name_old)

            try:
                entry_new = await self.lookup(inode_p_new, name_new)
            except pyfuse3.FUSEError as exc:
                if exc.errno != errno.ENOENT:
                    raise
                target_exists = False
            else:
                target_exists = True

            if target_exists:
                self._replace(inode_p_old, name_old, inode_p_new, name_new,
                              entry_old, entry_new)
            else:
                self.cursor.execute("UPDATE contents SET name=?, parent_inode=? WHERE name=? "
                                    "AND parent_inode=?", (name_new, inode_p_new,
                                                           name_old, inode_p_old))

        def _replace(self, inode_p_old, name_old, inode_p_new, name_new,
                     entry_old, entry_new):

            if self.get_row("SELECT COUNT(inode) FROM contents WHERE parent_inode=?",
                            (entry_new.st_ino,))[0] > 0:
                raise pyfuse3.FUSEError(errno.ENOTEMPTY)

            self.cursor.execute("UPDATE contents SET inode=? WHERE name=? AND parent_inode=?",
                                (entry_old.st_ino, name_new, inode_p_new))
            self.db.execute('DELETE FROM contents WHERE name=? AND parent_inode=?',
                            (name_old, inode_p_old))

            if entry_new.st_nlink == 1 and entry_new.st_ino not in self.inode_open_count:
                self.cursor.execute("DELETE FROM inodes WHERE id=?", (entry_new.st_ino,))

        async def link(self, inode, new_inode_p, new_name, ctx):
            entry_p = await self.getattr(new_inode_p)
            if entry_p.st_nlink == 0:
                log.warn('Attempted to create entry %s with unlinked parent %d',
                         new_name, new_inode_p)
                raise FUSEError(errno.EINVAL)

            self.cursor.execute("INSERT INTO contents (name, inode, parent_inode) VALUES(?,?,?)",
                                (new_name, inode, new_inode_p))

            return await self.getattr(inode)

        async def setattr(self, inode, attr, fields, fh, ctx):

            if fields.update_size:
                data = self.get_row('SELECT data FROM inodes WHERE id=?', (inode,))[0]
                if data is None:
                    data = b''
                if len(data) < attr.st_size:
                    data = data + b'\0' * (attr.st_size - len(data))
                else:
                    data = data[:attr.st_size]
                self.cursor.execute('UPDATE inodes SET data=?, size=? WHERE id=?',
                                    (memoryview(data), attr.st_size, inode))
            if fields.update_mode:
                self.cursor.execute('UPDATE inodes SET mode=? WHERE id=?',
                                    (attr.st_mode, inode))

            if fields.update_uid:
                self.cursor.execute('UPDATE inodes SET uid=? WHERE id=?',
                                    (attr.st_uid, inode))

            if fields.update_gid:
                self.cursor.execute('UPDATE inodes SET gid=? WHERE id=?',
                                    (attr.st_gid, inode))

            if fields.update_atime:
                self.cursor.execute('UPDATE inodes SET atime_ns=? WHERE id=?',
                                    (attr.st_atime_ns, inode))

            if fields.update_mtime:
                self.cursor.execute('UPDATE inodes SET mtime_ns=? WHERE id=?',
                                    (attr.st_mtime_ns, inode))

            if fields.update_ctime:
                self.cursor.execute('UPDATE inodes SET ctime_ns=? WHERE id=?',
                                    (attr.st_ctime_ns, inode))
            else:
                self.cursor.execute('UPDATE inodes SET ctime_ns=? WHERE id=?',
                                    (int(time()*1e9), inode))

            return await self.getattr(inode)

        async def mknod(self, inode_p, name, mode, rdev, ctx):
            return await self._create(inode_p, name, mode, ctx, rdev=rdev)

        async def mkdir(self, inode_p, name, mode, ctx):
            return await self._create(inode_p, name, mode, ctx)

        async def statfs(self, ctx):
            stat_ = pyfuse3.StatvfsData()

            stat_.f_bsize = 512
            stat_.f_frsize = 512

            size = self.get_row('SELECT SUM(size) FROM inodes')[0]
            stat_.f_blocks = size // stat_.f_frsize
            stat_.f_bfree = max(size // stat_.f_frsize, 1024)
            stat_.f_bavail = stat_.f_bfree

            inodes = self.get_row('SELECT COUNT(id) FROM inodes')[0]
            stat_.f_files = inodes
            stat_.f_ffree = max(inodes , 100)
            stat_.f_favail = stat_.f_ffree

            return stat_

        async def open(self, inode, flags, ctx):
            # Yeah, unused arguments
            #pylint: disable=W0613
            self.inode_open_count[inode] += 1

            # Use inodes as a file handles
            return pyfuse3.FileInfo(fh=inode)

        async def access(self, inode, mode, ctx):
            # Yeah, could be a function and has unused arguments
            #pylint: disable=R0201,W0613
            return True

        async def create(self, inode_parent, name, mode, flags, ctx):
            #pylint: disable=W0612
            entry = await self._create(inode_parent, name, mode, ctx)
            self.inode_open_count[entry.st_ino] += 1
            return (pyfuse3.FileInfo(fh=entry.st_ino), entry)

        async def _create(self, inode_p, name, mode, ctx, rdev=0, target=None):
            if (await self.getattr(inode_p)).st_nlink == 0:
                log.warn('Attempted to create entry %s with unlinked parent %d',
                         name, inode_p)
                raise FUSEError(errno.EINVAL)

            now_ns = int(time() * 1e9)
            self.cursor.execute('INSERT INTO inodes (uid, gid, mode, mtime_ns, atime_ns, '
                                'ctime_ns, target, rdev) VALUES(?, ?, ?, ?, ?, ?, ?, ?)',
                                (ctx.uid, ctx.gid, mode, now_ns, now_ns, now_ns, target, rdev))

            inode = self.cursor.lastrowid
            self.db.execute("INSERT INTO contents(name, inode, parent_inode) VALUES(?,?,?)",
                            (name, inode, inode_p))
            return await self.getattr(inode)

        async def read(self, fh, offset, length):
            data = self.get_row('SELECT data FROM inodes WHERE id=?', (fh,))[0]
            if data is None:
                data = b''
            return data[offset:offset+length]

        async def write(self, fh, offset, buf):
            data = self.get_row('SELECT data FROM inodes WHERE id=?', (fh,))[0]
            if data is None:
                data = b''
            data = data[:offset] + buf + data[offset+len(buf):]

            self.cursor.execute('UPDATE inodes SET data=?, size=? WHERE id=?',
                                (memoryview(data), len(data), fh))
            return len(buf)

        async def release(self, fh):
            self.inode_open_count[fh] -= 1

            if self.inode_open_count[fh] == 0:
                del self.inode_open_count[fh]
                if (await self.getattr(fh)).st_nlink == 0:
                    self.cursor.execute("DELETE FROM inodes WHERE id=?", (fh,))

    class NoUniqueValueError(Exception):
        def __str__(self):
            return 'Query generated more than 1 result row'

    class NoSuchRowError(Exception):
        def __str__(self):
            return 'Query produced 0 result rows'

    def init_logging(debug=False):
        formatter = logging.Formatter('%(asctime)s.%(msecs)03d %(threadName)s: '
                                      '[%(name)s] %(message)s', datefmt="%Y-%m-%d %H:%M:%S")
        handler = logging.StreamHandler()
        handler.setFormatter(formatter)
        root_logger = logging.getLogger()
        if debug:
            handler.setLevel(logging.DEBUG)
            root_logger.setLevel(logging.DEBUG)
        else:
            handler.setLevel(logging.INFO)
            root_logger.setLevel(logging.INFO)
        root_logger.addHandler(handler)

    def parse_args():
        '''Parse command line'''

        parser = ArgumentParser()

        parser.add_argument('mountpoint', type=str,
                            help='Where to mount the file system')
        parser.add_argument('--debug', action='store_true', default=False,
                            help='Enable debugging output')
        parser.add_argument('--debug-fuse', action='store_true', default=False,
                            help='Enable FUSE debugging output')

        return parser.parse_args()

    if __name__ == '__main__':

        options = parse_args()
        init_logging(options.debug)
        operations = Operations()

        fuse_options = set(pyfuse3.default_options)
        fuse_options.add('fsname=tmpfs')
        fuse_options.discard('default_permissions')
        if options.debug_fuse:
            fuse_options.add('debug')
        pyfuse3.init(operations, options.mountpoint, fuse_options)

        try:
            trio.run(pyfuse3.main)
        except:
            pyfuse3.close(unmount=False)
            raise

        pyfuse3.close()

## Passthrough / Overlay File System

(shipped as `examples/passthroughfs.py`)

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    #!/usr/bin/env python3
    '''
    passthroughfs.py - Example file system for pyfuse3

    This file system mirrors the contents of a specified directory tree.

    Caveats:

     * Inode generation numbers are not passed through but set to zero.

     * Block size (st_blksize) and number of allocated blocks (st_blocks) are not
       passed through.

     * Performance for large directories is not good, because the directory
       is always read completely.

     * There may be a way to break-out of the directory tree.

     * The readdir implementation is not fully POSIX compliant. If a directory
       contains hardlinks and is modified during a readdir call, readdir()
       may return some of the hardlinked files twice or omit them completely.

     * If you delete or rename files in the underlying file system, the
       passthrough file system will get confused.

    Copyright ©  Nikolaus Rath <Nikolaus.org>

    Permission is hereby granted, free of charge, to any person obtaining a copy of
    this software and associated documentation files (the "Software"), to deal in
    the Software without restriction, including without limitation the rights to
    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
    the Software, and to permit persons to whom the Software is furnished to do so.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
    FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
    COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    '''

    import os
    import sys

    # If we are running from the pyfuse3 source directory, try
    # to load the module from there first.
    basedir = os.path.abspath(os.path.join(os.path.dirname(sys.argv[0]), '..'))
    if (os.path.exists(os.path.join(basedir, 'setup.py')) and
        os.path.exists(os.path.join(basedir, 'src', 'pyfuse3.pyx'))):
        sys.path.insert(0, os.path.join(basedir, 'src'))

    import pyfuse3
    from argparse import ArgumentParser
    import errno
    import logging
    import stat as stat_m
    from pyfuse3 import FUSEError
    from os import fsencode, fsdecode
    from collections import defaultdict
    import trio

    import faulthandler
    faulthandler.enable()

    log = logging.getLogger(__name__)

    class Operations(pyfuse3.Operations):

        enable_writeback_cache = True

        def __init__(self, source):
            super().__init__()
            self._inode_path_map = { pyfuse3.ROOT_INODE: source }
            self._lookup_cnt = defaultdict(lambda : 0)
            self._fd_inode_map = dict()
            self._inode_fd_map = dict()
            self._fd_open_count = dict()

        def _inode_to_path(self, inode):
            try:
                val = self._inode_path_map[inode]
            except KeyError:
                raise FUSEError(errno.ENOENT)

            if isinstance(val, set):
                # In case of hardlinks, pick any path
                val = next(iter(val))
            return val

        def _add_path(self, inode, path):
            log.debug('_add_path for %d, %s', inode, path)
            self._lookup_cnt[inode] += 1

            # With hardlinks, one inode may map to multiple paths.
            if inode not in self._inode_path_map:
                self._inode_path_map[inode] = path
                return

            val = self._inode_path_map[inode]
            if isinstance(val, set):
                val.add(path)
            elif val != path:
                self._inode_path_map[inode] = { path, val }

        async def forget(self, inode_list):
            for (inode, nlookup) in inode_list:
                if self._lookup_cnt[inode] > nlookup:
                    self._lookup_cnt[inode] -= nlookup
                    continue
                log.debug('forgetting about inode %d', inode)
                assert inode not in self._inode_fd_map
                del self._lookup_cnt[inode]
                try:
                    del self._inode_path_map[inode]
                except KeyError: # may have been deleted
                    pass

        async def lookup(self, inode_p, name, ctx=None):
            name = fsdecode(name)
            log.debug('lookup for %s in %d', name, inode_p)
            path = os.path.join(self._inode_to_path(inode_p), name)
            attr = self._getattr(path=path)
            if name != '.' and name != '..':
                self._add_path(attr.st_ino, path)
            return attr

        async def getattr(self, inode, ctx=None):
            if inode in self._inode_fd_map:
                return self._getattr(fd=self._inode_fd_map[inode])
            else:
                return self._getattr(path=self._inode_to_path(inode))

        def _getattr(self, path=None, fd=None):
            assert fd is None or path is None
            assert not(fd is None and path is None)
            try:
                if fd is None:
                    stat = os.lstat(path)
                else:
                    stat = os.fstat(fd)
            except OSError as exc:
                raise FUSEError(exc.errno)

            entry = pyfuse3.EntryAttributes()
            for attr in ('st_ino', 'st_mode', 'st_nlink', 'st_uid', 'st_gid',
                         'st_rdev', 'st_size', 'st_atime_ns', 'st_mtime_ns',
                         'st_ctime_ns'):
                setattr(entry, attr, getattr(stat, attr))
            entry.generation = 0
            entry.entry_timeout = 0
            entry.attr_timeout = 0
            entry.st_blksize = 512
            entry.st_blocks = ((entry.st_size+entry.st_blksize-1) // entry.st_blksize)

            return entry

        async def readlink(self, inode, ctx):
            path = self._inode_to_path(inode)
            try:
                target = os.readlink(path)
            except OSError as exc:
                raise FUSEError(exc.errno)
            return fsencode(target)

        async def opendir(self, inode, ctx):
            return inode

        async def readdir(self, inode, off, token):
            path = self._inode_to_path(inode)
            log.debug('reading %s', path)
            entries = []
            for name in os.listdir(path):
                if name == '.' or name == '..':
                    continue
                attr = self._getattr(path=os.path.join(path, name))
                entries.append((attr.st_ino, name, attr))

            log.debug('read %d entries, starting at %d', len(entries), off)

            # This is not fully posix compatible. If there are hardlinks
            # (two names with the same inode), we don't have a unique
            # offset to start in between them. Note that we cannot simply
            # count entries, because then we would skip over entries
            # (or return them more than once) if the number of directory
            # entries changes between two calls to readdir().
            for (ino, name, attr) in sorted(entries):
                if ino <= off:
                    continue
                if not pyfuse3.readdir_reply(
                    token, fsencode(name), attr, ino):
                    break
                self._add_path(attr.st_ino, os.path.join(path, name))

        async def unlink(self, inode_p, name, ctx):
            name = fsdecode(name)
            parent = self._inode_to_path(inode_p)
            path = os.path.join(parent, name)
            try:
                inode = os.lstat(path).st_ino
                os.unlink(path)
            except OSError as exc:
                raise FUSEError(exc.errno)
            if inode in self._lookup_cnt:
                self._forget_path(inode, path)

        async def rmdir(self, inode_p, name, ctx):
            name = fsdecode(name)
            parent = self._inode_to_path(inode_p)
            path = os.path.join(parent, name)
            try:
                inode = os.lstat(path).st_ino
                os.rmdir(path)
            except OSError as exc:
                raise FUSEError(exc.errno)
            if inode in self._lookup_cnt:
                self._forget_path(inode, path)

        def _forget_path(self, inode, path):
            log.debug('forget %s for %d', path, inode)
            val = self._inode_path_map[inode]
            if isinstance(val, set):
                val.remove(path)
                if len(val) == 1:
                    self._inode_path_map[inode] = next(iter(val))
            else:
                del self._inode_path_map[inode]

        async def symlink(self, inode_p, name, target, ctx):
            name = fsdecode(name)
            target = fsdecode(target)
            parent = self._inode_to_path(inode_p)
            path = os.path.join(parent, name)
            try:
                os.symlink(target, path)
                os.chown(path, ctx.uid, ctx.gid, follow_symlinks=False)
            except OSError as exc:
                raise FUSEError(exc.errno)
            stat = os.lstat(path)
            self._add_path(stat.st_ino, path)
            return await self.getattr(stat.st_ino)

        async def rename(self, inode_p_old, name_old, inode_p_new, name_new,
                         flags, ctx):
            if flags != 0:
                raise FUSEError(errno.EINVAL)

            name_old = fsdecode(name_old)
            name_new = fsdecode(name_new)
            parent_old = self._inode_to_path(inode_p_old)
            parent_new = self._inode_to_path(inode_p_new)
            path_old = os.path.join(parent_old, name_old)
            path_new = os.path.join(parent_new, name_new)
            try:
                os.rename(path_old, path_new)
                inode = os.lstat(path_new).st_ino
            except OSError as exc:
                raise FUSEError(exc.errno)
            if inode not in self._lookup_cnt:
                return

            val = self._inode_path_map[inode]
            if isinstance(val, set):
                assert len(val) > 1
                val.add(path_new)
                val.remove(path_old)
            else:
                assert val == path_old
                self._inode_path_map[inode] = path_new

        async def link(self, inode, new_inode_p, new_name, ctx):
            new_name = fsdecode(new_name)
            parent = self._inode_to_path(new_inode_p)
            path = os.path.join(parent, new_name)
            try:
                os.link(self._inode_to_path(inode), path, follow_symlinks=False)
            except OSError as exc:
                raise FUSEError(exc.errno)
            self._add_path(inode, path)
            return await self.getattr(inode)

        async def setattr(self, inode, attr, fields, fh, ctx):
            # We use the f* functions if possible so that we can handle
            # a setattr() call for an inode without associated directory
            # handle.
            if fh is None:
                path_or_fh = self._inode_to_path(inode)
                truncate = os.truncate
                chmod = os.chmod
                chown = os.chown
                stat = os.lstat
            else:
                path_or_fh = fh
                truncate = os.ftruncate
                chmod = os.fchmod
                chown = os.fchown
                stat = os.fstat

            try:
                if fields.update_size:
                    truncate(path_or_fh, attr.st_size)

                if fields.update_mode:
                    # Under Linux, chmod always resolves symlinks so we should
                    # actually never get a setattr() request for a symbolic
                    # link.
                    assert not stat_m.S_ISLNK(attr.st_mode)
                    chmod(path_or_fh, stat_m.S_IMODE(attr.st_mode))

                if fields.update_uid:
                    chown(path_or_fh, attr.st_uid, -1, follow_symlinks=False)

                if fields.update_gid:
                    chown(path_or_fh, -1, attr.st_gid, follow_symlinks=False)

                if fields.update_atime and fields.update_mtime:
                    if fh is None:
                        os.utime(path_or_fh, None, follow_symlinks=False,
                                 ns=(attr.st_atime_ns, attr.st_mtime_ns))
                    else:
                        os.utime(path_or_fh, None,
                                 ns=(attr.st_atime_ns, attr.st_mtime_ns))
                elif fields.update_atime or fields.update_mtime:
                    # We can only set both values, so we first need to retrieve the
                    # one that we shouldn't be changing.
                    oldstat = stat(path_or_fh)
                    if not fields.update_atime:
                        attr.st_atime_ns = oldstat.st_atime_ns
                    else:
                        attr.st_mtime_ns = oldstat.st_mtime_ns
                    if fh is None:
                        os.utime(path_or_fh, None, follow_symlinks=False,
                                 ns=(attr.st_atime_ns, attr.st_mtime_ns))
                    else:
                        os.utime(path_or_fh, None,
                                 ns=(attr.st_atime_ns, attr.st_mtime_ns))

            except OSError as exc:
                raise FUSEError(exc.errno)

            return await self.getattr(inode)

        async def mknod(self, inode_p, name, mode, rdev, ctx):
            path = os.path.join(self._inode_to_path(inode_p), fsdecode(name))
            try:
                os.mknod(path, mode=(mode & ~ctx.umask), device=rdev)
                os.chown(path, ctx.uid, ctx.gid)
            except OSError as exc:
                raise FUSEError(exc.errno)
            attr = self._getattr(path=path)
            self._add_path(attr.st_ino, path)
            return attr

        async def mkdir(self, inode_p, name, mode, ctx):
            path = os.path.join(self._inode_to_path(inode_p), fsdecode(name))
            try:
                os.mkdir(path, mode=(mode & ~ctx.umask))
                os.chown(path, ctx.uid, ctx.gid)
            except OSError as exc:
                raise FUSEError(exc.errno)
            attr = self._getattr(path=path)
            self._add_path(attr.st_ino, path)
            return attr

        async def statfs(self, ctx):
            root = self._inode_path_map[pyfuse3.ROOT_INODE]
            stat_ = pyfuse3.StatvfsData()
            try:
                statfs = os.statvfs(root)
            except OSError as exc:
                raise FUSEError(exc.errno)
            for attr in ('f_bsize', 'f_frsize', 'f_blocks', 'f_bfree', 'f_bavail',
                         'f_files', 'f_ffree', 'f_favail'):
                setattr(stat_, attr, getattr(statfs, attr))
            stat_.f_namemax = statfs.f_namemax - (len(root)+1)
            return stat_

        async def open(self, inode, flags, ctx):
            if inode in self._inode_fd_map:
                fd = self._inode_fd_map[inode]
                self._fd_open_count[fd] += 1
                return pyfuse3.FileInfo(fh=fd)
            assert flags & os.O_CREAT == 0
            try:
                fd = os.open(self._inode_to_path(inode), flags)
            except OSError as exc:
                raise FUSEError(exc.errno)
            self._inode_fd_map[inode] = fd
            self._fd_inode_map[fd] = inode
            self._fd_open_count[fd] = 1
            return pyfuse3.FileInfo(fh=fd)

        async def create(self, inode_p, name, mode, flags, ctx):
            path = os.path.join(self._inode_to_path(inode_p), fsdecode(name))
            try:
                fd = os.open(path, flags | os.O_CREAT | os.O_TRUNC)
            except OSError as exc:
                raise FUSEError(exc.errno)
            attr = self._getattr(fd=fd)
            self._add_path(attr.st_ino, path)
            self._inode_fd_map[attr.st_ino] = fd
            self._fd_inode_map[fd] = attr.st_ino
            self._fd_open_count[fd] = 1
            return (pyfuse3.FileInfo(fh=fd), attr)

        async def read(self, fd, offset, length):
            os.lseek(fd, offset, os.SEEK_SET)
            return os.read(fd, length)

        async def write(self, fd, offset, buf):
            os.lseek(fd, offset, os.SEEK_SET)
            return os.write(fd, buf)

        async def release(self, fd):
            if self._fd_open_count[fd] > 1:
                self._fd_open_count[fd] -= 1
                return

            del self._fd_open_count[fd]
            inode = self._fd_inode_map[fd]
            del self._inode_fd_map[inode]
            del self._fd_inode_map[fd]
            try:
                os.close(fd)
            except OSError as exc:
                raise FUSEError(exc.errno)

    def init_logging(debug=False):
        formatter = logging.Formatter('%(asctime)s.%(msecs)03d %(threadName)s: '
                                      '[%(name)s] %(message)s', datefmt="%Y-%m-%d %H:%M:%S")
        handler = logging.StreamHandler()
        handler.setFormatter(formatter)
        root_logger = logging.getLogger()
        if debug:
            handler.setLevel(logging.DEBUG)
            root_logger.setLevel(logging.DEBUG)
        else:
            handler.setLevel(logging.INFO)
            root_logger.setLevel(logging.INFO)
        root_logger.addHandler(handler)

    def parse_args(args):
        '''Parse command line'''

        parser = ArgumentParser()

        parser.add_argument('source', type=str,
                            help='Directory tree to mirror')
        parser.add_argument('mountpoint', type=str,
                            help='Where to mount the file system')
        parser.add_argument('--debug', action='store_true', default=False,
                            help='Enable debugging output')
        parser.add_argument('--debug-fuse', action='store_true', default=False,
                            help='Enable FUSE debugging output')

        return parser.parse_args(args)

    def main():
        options = parse_args(sys.argv[1:])
        init_logging(options.debug)
        operations = Operations(options.source)

        log.debug('Mounting...')
        fuse_options = set(pyfuse3.default_options)
        fuse_options.add('fsname=passthroughfs')
        if options.debug_fuse:
            fuse_options.add('debug')
        pyfuse3.init(operations, options.mountpoint, fuse_options)

        try:
            log.debug('Entering main loop..')
            trio.run(pyfuse3.main)
        except:
            pyfuse3.close(unmount=False)
            raise

        log.debug('Unmounting..')
        pyfuse3.close()

    if __name__ == '__main__':
        main()