rust-agent: Remove unused code that has undefined behavior

Some functions have undefined behavior and are not actually used.

This addresses the following warning:
    warning: the type `oci::User` does not permit zero-initialization
      --> rustjail/src/lib.rs:99:18
       |
    99 |         unsafe { MaybeUninit::zeroed().assume_init() }
       |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |                  |
       |                  this code causes undefined behavior when executed
       |                  help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
       |
       = note: `#[warn(invalid_value)]` on by default
    note: `std::ptr::Unique<u32>` must be non-null (in this struct field)

    warning: the type `protocols::oci::Process` does not permit zero-initialization
       --> rustjail/src/lib.rs:146:14
        |
    146 |     unsafe { MaybeUninit::zeroed().assume_init() }
        |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        |              |
        |              this code causes undefined behavior when executed
        |              help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
        |
    note: `std::ptr::Unique<std::string::String>` must be non-null (in this struct field)

Fixes: #750

Signed-off-by: Christophe de Dinechin <dinechin@redhat.com>

src/agent/rustjail/src/lib.rs

@@ -69,7 +69,6 @@ use protocols::oci::{
     Root as grpcRoot, Spec as grpcSpec,
 };
 use std::collections::HashMap;
-use std::mem::MaybeUninit;
 
 pub fn process_grpc_to_oci(p: &grpcProcess) -> ociProcess {
     let console_size = if p.ConsoleSize.is_some() {
@@ -91,7 +90,12 @@ pub fn process_grpc_to_oci(p: &grpcProcess) -> ociProcess {
             username: u.Username.clone(),
         }
     } else {
-        unsafe { MaybeUninit::zeroed().assume_init() }
+        ociUser {
+            uid: 0,
+            gid: 0,
+            additional_gids: vec![],
+            username: String::from(""),
+        }
     };
 
     let capabilities = if p.Capabilities.is_some() {
@@ -136,11 +140,6 @@ pub fn process_grpc_to_oci(p: &grpcProcess) -> ociProcess {
     }
 }
 
-fn process_oci_to_grpc(_p: ociProcess) -> grpcProcess {
-    // dont implement it for now
-    unsafe { MaybeUninit::zeroed().assume_init() }
-}
-
 fn root_grpc_to_oci(root: &grpcRoot) -> ociRoot {
     ociRoot {
         path: root.Path.clone(),
@@ -148,10 +147,6 @@ fn root_grpc_to_oci(root: &grpcRoot) -> ociRoot {
     }
 }
 
-fn root_oci_to_grpc(_root: &ociRoot) -> grpcRoot {
-    unsafe { MaybeUninit::zeroed().assume_init() }
-}
-
 fn mount_grpc_to_oci(m: &grpcMount) -> ociMount {
     ociMount {
         destination: m.destination.clone(),
@@ -161,10 +156,6 @@ fn mount_grpc_to_oci(m: &grpcMount) -> ociMount {
     }
 }
 
-fn mount_oci_to_grpc(_m: &ociMount) -> grpcMount {
-    unsafe { MaybeUninit::zeroed().assume_init() }
-}
-
 use oci::Hook as ociHook;
 use protocols::oci::Hook as grpcHook;
 
@@ -195,10 +186,6 @@ fn hooks_grpc_to_oci(h: &grpcHooks) -> ociHooks {
     }
 }
 
-fn hooks_oci_to_grpc(_h: &ociHooks) -> grpcHooks {
-    unsafe { MaybeUninit::zeroed().assume_init() }
-}
-
 use oci::{
     LinuxDevice as ociLinuxDevice, LinuxIDMapping as ociLinuxIDMapping,
     LinuxIntelRdt as ociLinuxIntelRdt, LinuxNamespace as ociLinuxNamespace,
@@ -565,10 +552,6 @@ pub fn grpc_to_oci(grpc: &grpcSpec) -> ociSpec {
     }
 }
 
-pub fn oci_to_grpc(_oci: &ociSpec) -> grpcSpec {
-    unsafe { MaybeUninit::zeroed().assume_init() }
-}
-
 #[cfg(test)]
 mod tests {
     #[test]