xref: /openbmc/qemu/scripts/qmp/qom-fuse (revision 2aa10179) 
1#!/usr/bin/env python3
2"""
3QEMU Object Model FUSE filesystem tool
4
5This script offers a simple FUSE filesystem within which the QOM tree
6may be browsed, queried and edited using traditional shell tooling.
7
8This script requires the 'fusepy' python package.
9
10
11usage: qom-fuse [-h] [--socket SOCKET] <mount>
12
13Mount a QOM tree as a FUSE filesystem
14
15positional arguments:
16  <mount>               Mount point
17
18optional arguments:
19  -h, --help            show this help message and exit
20  --socket SOCKET, -s SOCKET
21                        QMP socket path or address (addr:port). May also be
22                        set via QMP_SOCKET environment variable.
23"""
24##
25# Copyright IBM, Corp. 2012
26# Copyright (C) 2020 Red Hat, Inc.
27#
28# Authors:
29#  Anthony Liguori   <aliguori@us.ibm.com>
30#  Markus Armbruster <armbru@redhat.com>
31#
32# This work is licensed under the terms of the GNU GPL, version 2 or later.
33# See the COPYING file in the top-level directory.
34##
35
36import argparse
37from errno import ENOENT, EPERM
38import os
39import stat
40import sys
41from typing import Dict
42
43import fuse
44from fuse import FUSE, FuseOSError, Operations
45
46
47sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'python'))
48from qemu.qmp import QMPResponseError
49from qemu.qmp.qom_common import QOMCommand
50
51
52fuse.fuse_python_api = (0, 2)
53
54
55class QOMFuse(QOMCommand, Operations):
56    """
57    QOMFuse implements both fuse.Operations and QOMCommand.
58
59    Operations implements the FS, and QOMCommand implements the CLI command.
60    """
61    name = 'fuse'
62    help = 'Mount a QOM tree as a FUSE filesystem'
63    fuse: FUSE
64
65    @classmethod
66    def configure_parser(cls, parser: argparse.ArgumentParser) -> None:
67        super().configure_parser(parser)
68        parser.add_argument(
69            'mount',
70            metavar='<mount>',
71            action='store',
72            help="Mount point",
73        )
74
75    def __init__(self, args: argparse.Namespace):
76        super().__init__(args)
77        self.mount = args.mount
78        self.ino_map: Dict[str, int] = {}
79        self.ino_count = 1
80
81    def run(self) -> int:
82        print(f"Mounting QOMFS to '{self.mount}'", file=sys.stderr)
83        self.fuse = FUSE(self, self.mount, foreground=True)
84        return 0
85
86    def get_ino(self, path):
87        """Get an inode number for a given QOM path."""
88        if path in self.ino_map:
89            return self.ino_map[path]
90        self.ino_map[path] = self.ino_count
91        self.ino_count += 1
92        return self.ino_map[path]
93
94    def is_object(self, path):
95        """Is the given QOM path an object?"""
96        try:
97            self.qmp.command('qom-list', path=path)
98            return True
99        except QMPResponseError:
100            return False
101
102    def is_property(self, path):
103        """Is the given QOM path a property?"""
104        path, prop = path.rsplit('/', 1)
105        if path == '':
106            path = '/'
107        try:
108            for item in self.qmp.command('qom-list', path=path):
109                if item['name'] == prop:
110                    return True
111            return False
112        except QMPResponseError:
113            return False
114
115    def is_link(self, path):
116        """Is the given QOM path a link?"""
117        path, prop = path.rsplit('/', 1)
118        if path == '':
119            path = '/'
120        try:
121            for item in self.qmp.command('qom-list', path=path):
122                if item['name'] == prop:
123                    if item['type'].startswith('link<'):
124                        return True
125                    return False
126            return False
127        except QMPResponseError:
128            return False
129
130    def read(self, path, size, offset, fh):
131        if not self.is_property(path):
132            return -ENOENT
133
134        path, prop = path.rsplit('/', 1)
135        if path == '':
136            path = '/'
137        try:
138            data = self.qmp.command('qom-get', path=path, property=prop)
139            data += '\n'  # make values shell friendly
140        except QMPResponseError as err:
141            raise FuseOSError(EPERM) from err
142
143        if offset > len(data):
144            return ''
145
146        return bytes(data[offset:][:size], encoding='utf-8')
147
148    def readlink(self, path):
149        if not self.is_link(path):
150            return False
151        path, prop = path.rsplit('/', 1)
152        prefix = '/'.join(['..'] * (len(path.split('/')) - 1))
153        return prefix + str(self.qmp.command('qom-get', path=path,
154                                             property=prop))
155
156    def getattr(self, path, fh=None):
157        if self.is_link(path):
158            value = {
159                'st_mode': 0o755 | stat.S_IFLNK,
160                'st_ino': self.get_ino(path),
161                'st_dev': 0,
162                'st_nlink': 2,
163                'st_uid': 1000,
164                'st_gid': 1000,
165                'st_size': 4096,
166                'st_atime': 0,
167                'st_mtime': 0,
168                'st_ctime': 0
169            }
170        elif self.is_object(path):
171            value = {
172                'st_mode': 0o755 | stat.S_IFDIR,
173                'st_ino': self.get_ino(path),
174                'st_dev': 0,
175                'st_nlink': 2,
176                'st_uid': 1000,
177                'st_gid': 1000,
178                'st_size': 4096,
179                'st_atime': 0,
180                'st_mtime': 0,
181                'st_ctime': 0
182            }
183        elif self.is_property(path):
184            value = {
185                'st_mode': 0o644 | stat.S_IFREG,
186                'st_ino': self.get_ino(path),
187                'st_dev': 0,
188                'st_nlink': 1,
189                'st_uid': 1000,
190                'st_gid': 1000,
191                'st_size': 4096,
192                'st_atime': 0,
193                'st_mtime': 0,
194                'st_ctime': 0
195            }
196        else:
197            raise FuseOSError(ENOENT)
198        return value
199
200    def readdir(self, path, fh):
201        yield '.'
202        yield '..'
203        for item in self.qmp.command('qom-list', path=path):
204            yield str(item['name'])
205
206
207if __name__ == '__main__':
208    sys.exit(QOMFuse.entry_point())
209