Remove a bunch more clones

We the Qemu::new() constructor might as well just consume the Target
object, given that it won't be used afterwards. Adjust the signature and
then just pull out the members we need instead of cloning them, removing
a bunch of unnecessary allocations.
Similarly, the CommandContext that we instantiate just for the sake of
conveying some data to the template does not need to contain any owned
objects. So just work with references to existing ones, eliminating a
bunch of more clones.

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

src/qemu.rs

@@ -76,15 +76,15 @@ pub struct Qemu {
 
 /// Used by templating engine to render command
 #[derive(Serialize)]
-struct CommandContext {
+struct CommandContext<'data> {
     /// True if command should change working directory before executing.
     should_cd: bool,
     /// Path to directory shared between guest/host
-    host_shared: PathBuf,
+    host_shared: &'data Path,
     /// User supplied command to run
-    command: String,
+    command: &'data str,
     /// virtio-serial output port name
-    command_output_port_name: String,
+    command_output_port_name: &'data str,
 }
 
 /// Used by templating engine to render init.sh
@@ -173,7 +173,7 @@ fn init_script() -> String {
 fn gen_init(rootfs: &Path) -> Result<(NamedTempFile, PathBuf)> {
     let guest_temp_dir = std::env::temp_dir();
     let mut host_dest_dir = rootfs.to_path_buf().into_os_string();
-    host_dest_dir.push(guest_temp_dir.clone().into_os_string());
+    host_dest_dir.push(&guest_temp_dir);
 
     let mut host_init = Builder::new()
         .prefix("vmtest-init")
@@ -651,7 +651,7 @@ impl Qemu {
     /// Construct a QEMU instance backing a vmtest target.
     ///
     /// Does not run anything yet.
-    pub fn new(updates: Sender<Output>, target: &Target, host_shared: &Path) -> Result<Self> {
+    pub fn new(updates: Sender<Output>, target: Target, host_shared: &Path) -> Result<Self> {
         let qga_sock = gen_sock("qga");
         let qmp_sock = gen_sock("qmp");
         let command_sock = gen_sock("cmdout");
@@ -715,12 +715,12 @@ impl Qemu {
             process: c,
             qga_sock,
             qmp_sock,
-            command: target.command.to_string(),
+            command: target.command,
             command_sock,
             host_shared: host_shared.to_owned(),
-            rootfs: target.rootfs.clone(),
-            arch: target.arch.clone(),
-            mounts: target.vm.mounts.clone(),
+            rootfs: target.rootfs,
+            arch: target.arch,
+            mounts: target.vm.mounts,
             init: Some(init),
             updates,
             image: target.image.is_some(),
@@ -777,9 +777,9 @@ impl Qemu {
         let context = CommandContext {
             // Only `cd` for kernel targets that share userspace with host
             should_cd: !self.image && self.rootfs == Target::default_rootfs(),
-            host_shared: self.host_shared.clone(),
-            command: self.command.clone(),
-            command_output_port_name: COMMAND_OUTPUT_PORT_NAME.into(),
+            host_shared: &self.host_shared,
+            command: &self.command,
+            command_output_port_name: COMMAND_OUTPUT_PORT_NAME,
         };
 
         // Ignore errors cuz only trivial bugs are possible

src/vmtest.rs

@@ -120,7 +120,7 @@ impl Vmtest {
         target.rootfs = self.resolve_path(target.rootfs.as_path());
         target.vm.bios = target.vm.bios.map(|s| self.resolve_path(s.as_path()));
 
-        Qemu::new(updates, &target, &self.base).context("Failed to setup QEMU")
+        Qemu::new(updates, target, &self.base).context("Failed to setup QEMU")
     }
 
     /// Run a single target