Victor Hsieh | f393a72 | 2021-12-08 13:04:27 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2021 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | use log::error; |
| 18 | use nix::sys::stat::{mode_t, Mode, SFlag}; |
| 19 | use std::io; |
| 20 | |
| 21 | use super::VirtFdService; |
| 22 | |
| 23 | /// Default/assumed mode of files not created by authfs. |
| 24 | /// |
| 25 | /// For files that are given to authfs as FDs (i.e. not created through authfs), their mode is |
| 26 | /// unknown (or untrusted) until it is ever set. The default mode is just to make it |
| 27 | /// readable/writable to VFS. When the mode is set, the value on fd_server is supposed to become |
| 28 | /// consistent. |
| 29 | const DEFAULT_FILE_MODE: Mode = |
| 30 | Mode::from_bits_truncate(Mode::S_IRUSR.bits() | Mode::S_IWUSR.bits()); |
| 31 | |
| 32 | /// Default/assumed mode of directories not created by authfs. |
| 33 | /// |
| 34 | /// See above. |
| 35 | const DEFAULT_DIR_MODE: Mode = Mode::S_IRWXU; |
| 36 | |
| 37 | /// `Attr` maintains the local truth for attributes (e.g. mode and type) while allowing setting the |
| 38 | /// remote attribute for the file description. |
| 39 | pub struct Attr { |
| 40 | service: VirtFdService, |
| 41 | mode: Mode, |
| 42 | remote_fd: i32, |
| 43 | is_dir: bool, |
| 44 | } |
| 45 | |
| 46 | impl Attr { |
| 47 | pub fn new_file(service: VirtFdService, remote_fd: i32) -> Attr { |
| 48 | Attr { service, mode: DEFAULT_FILE_MODE, remote_fd, is_dir: false } |
| 49 | } |
| 50 | |
| 51 | pub fn new_dir(service: VirtFdService, remote_fd: i32) -> Attr { |
| 52 | Attr { service, mode: DEFAULT_DIR_MODE, remote_fd, is_dir: true } |
| 53 | } |
| 54 | |
| 55 | pub fn new_file_with_mode(service: VirtFdService, remote_fd: i32, mode: mode_t) -> Attr { |
| 56 | Attr { service, mode: Mode::from_bits_truncate(mode), remote_fd, is_dir: false } |
| 57 | } |
| 58 | |
| 59 | pub fn new_dir_with_mode(service: VirtFdService, remote_fd: i32, mode: mode_t) -> Attr { |
| 60 | Attr { service, mode: Mode::from_bits_truncate(mode), remote_fd, is_dir: true } |
| 61 | } |
| 62 | |
| 63 | pub fn mode(&self) -> u32 { |
| 64 | self.mode.bits() |
| 65 | } |
| 66 | |
| 67 | /// Sets the file mode. |
| 68 | /// |
| 69 | /// In addition to the actual file mode, `encoded_mode` also contains information of the file |
| 70 | /// type. |
| 71 | pub fn set_mode(&mut self, encoded_mode: u32) -> io::Result<()> { |
| 72 | let new_sflag = SFlag::from_bits_truncate(encoded_mode); |
| 73 | let new_mode = Mode::from_bits_truncate(encoded_mode); |
| 74 | |
| 75 | let type_flag = if self.is_dir { SFlag::S_IFDIR } else { SFlag::S_IFREG }; |
| 76 | if !type_flag.contains(new_sflag) { |
| 77 | return Err(io::Error::from_raw_os_error(libc::EINVAL)); |
| 78 | } |
| 79 | |
| 80 | // Request for update only if changing. |
| 81 | if new_mode != self.mode { |
| 82 | self.service.chmod(self.remote_fd, new_mode.bits() as i32).map_err(|e| { |
| 83 | error!( |
| 84 | "Failed to chmod (fd: {}, mode: {:o}) on fd_server: {:?}", |
| 85 | self.remote_fd, new_mode, e |
| 86 | ); |
| 87 | io::Error::from_raw_os_error(libc::EIO) |
| 88 | })?; |
| 89 | self.mode = new_mode; |
| 90 | } |
| 91 | Ok(()) |
| 92 | } |
| 93 | } |