Eagerly close temporary init script file

Various of my qemu instances have hung and I had to kill them
forcefully. As a result, I ended up with 10+ vmtest-initGDllO.sh files
in my /tmp/ folder.
I think we don't have to rely on destructor based clean up in this
instance: after the end of the setup phase the init script should no
longer be accessed via file system path and so we can just unlink it.
This way, no matter how the process dies after that point, the temporary
file will always be gone as well.

Signed-off-by: Daniel Müller <deso@posteo.net>

src/qemu.rs

@@ -65,7 +65,10 @@ pub struct Qemu {
     rootfs: PathBuf,
     arch: String,
     mounts: HashMap<String, Mount>,
-    _init: NamedTempFile,
+    /// A reference to the temporary file representing the init script.
+    ///
+    /// This object will be cleared as part of the `run` invocation.
+    init: Option<NamedTempFile>,
     updates: Sender<Output>,
     /// Whether or not we are running an image target
     image: bool,
@@ -687,7 +690,7 @@ impl Qemu {
             rootfs: target.rootfs.clone(),
             arch: target.arch.clone(),
             mounts: target.vm.mounts.clone(),
-            _init: init,
+            init: Some(init),
             updates,
             image: target.image.is_some(),
         };
@@ -1070,6 +1073,12 @@ impl Qemu {
             return;
         }
 
+        // We can safely remove our init script temporary file at this
+        // point and stop relying on destructor based clean up. Doing so
+        // prevents leakage of the file in case Qemu hangs and has to be
+        // killed forcefully or is just exited early via Ctrl-C.
+        drop(self.init.take());
+
         // At this stage qemu should be prompting us with a shell prompt if running
         // in interactive mode.
         // Once the child has returned, we are done and can exit.
@@ -1102,7 +1111,7 @@ impl Qemu {
                 Err(e) => warn!("Failed to wait on child: {}", e),
             },
             // TODO(dxu): debug why we are getting errors here
-            Err(e) => debug!("Failed to gracefull quit QEMU: {e}"),
+            Err(e) => debug!("Failed to gracefully quit QEMU: {e}"),
         }
     }
 }