Pass VM config by FD rather than filename.

Bug: 184131756
Test: atest VirtualizationTestCases
Change-Id: Iba739bc8de941b68a88090438743d9f54ba0380c
diff --git a/virtmanager/aidl/android/system/virtmanager/IVirtManager.aidl b/virtmanager/aidl/android/system/virtmanager/IVirtManager.aidl
index ab03c18..c2fc719 100644
--- a/virtmanager/aidl/android/system/virtmanager/IVirtManager.aidl
+++ b/virtmanager/aidl/android/system/virtmanager/IVirtManager.aidl
@@ -23,7 +23,8 @@
      * Start the VM with the given config file, and return a handle to it. If `logFd` is provided
      * then console logs from the VM will be sent to it.
      */
-    IVirtualMachine startVm(String configPath, in @nullable ParcelFileDescriptor logFd);
+    IVirtualMachine startVm(
+            in ParcelFileDescriptor configFd, in @nullable ParcelFileDescriptor logFd);
 
     /**
      * Get a list of all currently running VMs. This method is only intended for debug purposes,
diff --git a/virtmanager/aidl/android/system/virtmanager/VirtualMachineDebugInfo.aidl b/virtmanager/aidl/android/system/virtmanager/VirtualMachineDebugInfo.aidl
index d877a56..9003bc3 100644
--- a/virtmanager/aidl/android/system/virtmanager/VirtualMachineDebugInfo.aidl
+++ b/virtmanager/aidl/android/system/virtmanager/VirtualMachineDebugInfo.aidl
@@ -19,10 +19,4 @@
 parcelable VirtualMachineDebugInfo {
     /** The CID assigned to the VM. */
     int cid;
-
-    /**
-     * The filename of the config file used to start the VM. This may have changed since it was
-     * read so it shouldn't be trusted; it is only stored for debugging purposes.
-     */
-    String configPath;
 }
diff --git a/virtmanager/src/aidl.rs b/virtmanager/src/aidl.rs
index 8c963d2..ff8ab30 100644
--- a/virtmanager/src/aidl.rs
+++ b/virtmanager/src/aidl.rs
@@ -50,7 +50,7 @@
     /// Returns a binder `IVirtualMachine` object referring to it, as a handle for the client.
     fn startVm(
         &self,
-        config_path: &str,
+        config_fd: &ParcelFileDescriptor,
         log_fd: Option<&ParcelFileDescriptor>,
     ) -> binder::Result<Strong<dyn IVirtualMachine>> {
         let state = &mut *self.state.lock().unwrap();
@@ -58,7 +58,7 @@
         let log_fd = log_fd
             .map(|fd| fd.as_ref().try_clone().map_err(|_| StatusCode::UNKNOWN_ERROR))
             .transpose()?;
-        let instance = Arc::new(start_vm(config_path, cid, log_fd)?);
+        let instance = Arc::new(start_vm(config_fd.as_ref(), cid, log_fd)?);
         // TODO(qwandor): keep track of which CIDs are currently in use so that we can reuse them.
         state.next_cid = state.next_cid.checked_add(1).ok_or(StatusCode::UNKNOWN_ERROR)?;
         state.add_vm(Arc::downgrade(&instance));
@@ -74,13 +74,8 @@
 
         let state = &mut *self.state.lock().unwrap();
         let vms = state.vms();
-        let cids = vms
-            .into_iter()
-            .map(|vm| VirtualMachineDebugInfo {
-                cid: vm.cid as i32,
-                configPath: vm.config_path.clone(),
-            })
-            .collect();
+        let cids =
+            vms.into_iter().map(|vm| VirtualMachineDebugInfo { cid: vm.cid as i32 }).collect();
         Ok(cids)
     }
 
@@ -193,13 +188,13 @@
 
 /// Start a new VM instance from the given VM config filename. This assumes the VM is not already
 /// running.
-fn start_vm(config_path: &str, cid: Cid, log_fd: Option<File>) -> binder::Result<VmInstance> {
-    let config = VmConfig::load(config_path).map_err(|e| {
-        error!("Failed to load VM config {}: {:?}", config_path, e);
+fn start_vm(config_file: &File, cid: Cid, log_fd: Option<File>) -> binder::Result<VmInstance> {
+    let config = VmConfig::load(config_file).map_err(|e| {
+        error!("Failed to load VM config from {:?}: {:?}", config_file, e);
         StatusCode::BAD_VALUE
     })?;
-    Ok(VmInstance::start(&config, cid, config_path, log_fd).map_err(|e| {
-        error!("Failed to start VM {}: {:?}", config_path, e);
+    Ok(VmInstance::start(&config, cid, log_fd).map_err(|e| {
+        error!("Failed to start VM from {:?}: {:?}", config_file, e);
         StatusCode::UNKNOWN_ERROR
     })?)
 }
diff --git a/virtmanager/src/config.rs b/virtmanager/src/config.rs
index d8cb06f..0b12c0b 100644
--- a/virtmanager/src/config.rs
+++ b/virtmanager/src/config.rs
@@ -14,7 +14,7 @@
 
 //! Function and types for VM configuration.
 
-use anyhow::{bail, Context, Error};
+use anyhow::{bail, Error};
 use serde::{Deserialize, Serialize};
 use std::fs::File;
 use std::io::BufReader;
@@ -51,8 +51,7 @@
     }
 
     /// Load the configuration for a VM from the given JSON file.
-    pub fn load(path: &str) -> Result<VmConfig, Error> {
-        let file = File::open(path).with_context(|| format!("Failed to open {}", path))?;
+    pub fn load(file: &File) -> Result<VmConfig, Error> {
         let buffered = BufReader::new(file);
         Ok(serde_json::from_reader(buffered)?)
     }
diff --git a/virtmanager/src/crosvm.rs b/virtmanager/src/crosvm.rs
index 814a1a7..c865357 100644
--- a/virtmanager/src/crosvm.rs
+++ b/virtmanager/src/crosvm.rs
@@ -30,27 +30,19 @@
     child: Child,
     /// The CID assigned to the VM for vsock communication.
     pub cid: Cid,
-    /// The filename of the config file that was used to start the VM. This may have changed since
-    /// it was read so it shouldn't be trusted; it is only stored for debugging purposes.
-    pub config_path: String,
 }
 
 impl VmInstance {
     /// Create a new `VmInstance` for the given process.
-    fn new(child: Child, cid: Cid, config_path: &str) -> VmInstance {
-        VmInstance { child, cid, config_path: config_path.to_owned() }
+    fn new(child: Child, cid: Cid) -> VmInstance {
+        VmInstance { child, cid }
     }
 
     /// Start an instance of `crosvm` to manage a new VM. The `crosvm` instance will be killed when
     /// the `VmInstance` is dropped.
-    pub fn start(
-        config: &VmConfig,
-        cid: Cid,
-        config_path: &str,
-        log_fd: Option<File>,
-    ) -> Result<VmInstance, Error> {
+    pub fn start(config: &VmConfig, cid: Cid, log_fd: Option<File>) -> Result<VmInstance, Error> {
         let child = run_vm(config, cid, log_fd)?;
-        Ok(VmInstance::new(child, cid, config_path))
+        Ok(VmInstance::new(child, cid))
     }
 }