Pass file descriptors rather than filenames to Virt Manager.
This requires using a parcelable rather than a JSON file for the config.
Bug: 187181124
Test: atest VirtualizationTestCases
Change-Id: I1636010f5ed55da165f5acd82f1bd8b924e09b41
diff --git a/vm/src/config.rs b/vm/src/config.rs
new file mode 100644
index 0000000..a6f48ce
--- /dev/null
+++ b/vm/src/config.rs
@@ -0,0 +1,114 @@
+// Copyright 2021, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Struct for VM configuration.
+
+use android_system_virtmanager::{
+ aidl::android::system::virtmanager::DiskImage::DiskImage as AidlDiskImage,
+ aidl::android::system::virtmanager::VirtualMachineConfig::VirtualMachineConfig,
+ binder::ParcelFileDescriptor,
+};
+use anyhow::{bail, Context, Error};
+use serde::{Deserialize, Serialize};
+use std::fs::{File, OpenOptions};
+use std::io::BufReader;
+use std::path::{Path, PathBuf};
+
+/// Configuration for a particular VM to be started.
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct VmConfig {
+ /// The filename of the kernel image, if any.
+ pub kernel: Option<PathBuf>,
+ /// The filename of the initial ramdisk for the kernel, if any.
+ pub initrd: Option<PathBuf>,
+ /// Parameters to pass to the kernel. As far as the VMM and boot protocol are concerned this is
+ /// just a string, but typically it will contain multiple parameters separated by spaces.
+ pub params: Option<String>,
+ /// The bootloader to use. If this is supplied then the kernel and initrd must not be supplied;
+ /// the bootloader is instead responsibly for loading the kernel from one of the disks.
+ pub bootloader: Option<PathBuf>,
+ /// Disk images to be made available to the VM.
+ #[serde(default)]
+ pub disks: Vec<DiskImage>,
+}
+
+impl VmConfig {
+ /// Ensure that the configuration has a valid combination of fields set, or return an error if
+ /// not.
+ pub fn validate(&self) -> Result<(), Error> {
+ if self.bootloader.is_none() && self.kernel.is_none() {
+ bail!("VM must have either a bootloader or a kernel image.");
+ }
+ if self.bootloader.is_some() && (self.kernel.is_some() || self.initrd.is_some()) {
+ bail!("Can't have both bootloader and kernel/initrd image.");
+ }
+ Ok(())
+ }
+
+ /// Load the configuration for a VM from the given JSON file, and check that it is valid.
+ pub fn load(file: &File) -> Result<VmConfig, Error> {
+ let buffered = BufReader::new(file);
+ let config: VmConfig = serde_json::from_reader(buffered)?;
+ config.validate()?;
+ Ok(config)
+ }
+
+ /// Convert the `VmConfig` to a [`VirtualMachineConfig`] which can be passed to the Virt
+ /// Manager.
+ pub fn to_parcelable(&self) -> Result<VirtualMachineConfig, Error> {
+ Ok(VirtualMachineConfig {
+ kernel: maybe_open_parcel_file(&self.kernel)?,
+ initrd: maybe_open_parcel_file(&self.initrd)?,
+ params: self.params.clone(),
+ bootloader: maybe_open_parcel_file(&self.bootloader)?,
+ disks: self
+ .disks
+ .iter()
+ .map(|disk| {
+ Ok(AidlDiskImage {
+ writable: disk.writable,
+ image: Some(open_parcel_file(&disk.image, disk.writable)?),
+ })
+ })
+ .collect::<Result<_, Error>>()?,
+ })
+ }
+}
+
+/// A disk image to be made available to the VM.
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct DiskImage {
+ /// The filename of the disk image.
+ pub image: PathBuf,
+ /// Whether this disk should be writable by the VM.
+ pub writable: bool,
+}
+
+/// Try to open the given file and wrap it in a [`ParcelFileDescriptor`].
+fn open_parcel_file(filename: &Path, writable: bool) -> Result<ParcelFileDescriptor, Error> {
+ Ok(ParcelFileDescriptor::new(
+ OpenOptions::new()
+ .read(true)
+ .write(writable)
+ .open(filename)
+ .with_context(|| format!("Failed to open {:?}", filename))?,
+ ))
+}
+
+/// If the given filename is `Some`, try to open it and wrap it in a [`ParcelFileDescriptor`].
+fn maybe_open_parcel_file(
+ filename: &Option<PathBuf>,
+) -> Result<Option<ParcelFileDescriptor>, Error> {
+ filename.as_deref().map(|filename| open_parcel_file(filename, false)).transpose()
+}