1 // Copyright 2021, The Android Open Source Project
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //     http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 //! Command to run a VM.
16 
17 use crate::sync::AtomicFlag;
18 use android_system_virtmanager::aidl::android::system::virtmanager::IVirtManager::IVirtManager;
19 use android_system_virtmanager::aidl::android::system::virtmanager::IVirtualMachine::IVirtualMachine;
20 use android_system_virtmanager::aidl::android::system::virtmanager::IVirtualMachineCallback::{
21     BnVirtualMachineCallback, IVirtualMachineCallback,
22 };
23 use android_system_virtmanager::binder::{
24     BinderFeatures, DeathRecipient, IBinder, ParcelFileDescriptor, Strong,
25 };
26 use android_system_virtmanager::binder::{Interface, Result as BinderResult};
27 use anyhow::{Context, Error};
28 use std::fs::File;
29 use std::io;
30 use std::os::unix::io::{AsRawFd, FromRawFd};
31 use std::path::Path;
32 
33 /// Run a VM from the given configuration file.
34 pub fn command_run(
35     virt_manager: Strong<dyn IVirtManager>,
36     config_path: &Path,
37     daemonize: bool,
38 ) -> Result<(), Error> {
39     let config_filename = config_path.to_str().context("Failed to parse VM config path")?;
40     let config_file = ParcelFileDescriptor::new(
41         File::open(config_filename).context("Failed to open config file")?,
42     );
43     let stdout_file = ParcelFileDescriptor::new(duplicate_stdout()?);
44     let stdout = if daemonize { None } else { Some(&stdout_file) };
45     let vm = virt_manager.startVm(&config_file, stdout).context("Failed to start VM")?;
46 
47     let cid = vm.getCid().context("Failed to get CID")?;
48     println!("Started VM from {} with CID {}.", config_filename, cid);
49 
50     if daemonize {
51         // Pass the VM reference back to Virt Manager and have it hold it in the background.
52         virt_manager.debugHoldVmRef(&vm).context("Failed to pass VM to Virt Manager")
53     } else {
54         // Wait until the VM or VirtManager dies. If we just returned immediately then the
55         // IVirtualMachine Binder object would be dropped and the VM would be killed.
56         wait_for_vm(vm)
57     }
58 }
59 
60 /// Wait until the given VM or the VirtManager itself dies.
61 fn wait_for_vm(vm: Strong<dyn IVirtualMachine>) -> Result<(), Error> {
62     let dead = AtomicFlag::default();
63     let callback = BnVirtualMachineCallback::new_binder(
64         VirtualMachineCallback { dead: dead.clone() },
65         BinderFeatures::default(),
66     );
67     vm.registerCallback(&callback)?;
68     let death_recipient = wait_for_death(&mut vm.as_binder(), dead.clone())?;
69     dead.wait();
70     // Ensure that death_recipient isn't dropped before we wait on the flag, as it is removed
71     // from the Binder when it's dropped.
72     drop(death_recipient);
73     Ok(())
74 }
75 
76 /// Raise the given flag when the given Binder object dies.
77 ///
78 /// If the returned DeathRecipient is dropped then this will no longer do anything.
79 fn wait_for_death(binder: &mut impl IBinder, dead: AtomicFlag) -> Result<DeathRecipient, Error> {
80     let mut death_recipient = DeathRecipient::new(move || {
81         println!("VirtManager died");
82         dead.raise();
83     });
84     binder.link_to_death(&mut death_recipient)?;
85     Ok(death_recipient)
86 }
87 
88 #[derive(Debug)]
89 struct VirtualMachineCallback {
90     dead: AtomicFlag,
91 }
92 
93 impl Interface for VirtualMachineCallback {}
94 
95 impl IVirtualMachineCallback for VirtualMachineCallback {
96     fn onDied(&self, _cid: i32) -> BinderResult<()> {
97         println!("VM died");
98         self.dead.raise();
99         Ok(())
100     }
101 }
102 
103 /// Safely duplicate the standard output file descriptor.
104 fn duplicate_stdout() -> io::Result<File> {
105     let stdout_fd = io::stdout().as_raw_fd();
106     // Safe because this just duplicates a file descriptor which we know to be valid, and we check
107     // for an error.
108     let dup_fd = unsafe { libc::dup(stdout_fd) };
109     if dup_fd < 0 {
110         Err(io::Error::last_os_error())
111     } else {
112         // Safe because we have just duplicated the file descriptor so we own it, and `from_raw_fd`
113         // takes ownership of it.
114         Ok(unsafe { File::from_raw_fd(dup_fd) })
115     }
116 }
117