rustjail: add mock implementation for cgroup manager

Only root is able to create and manipulate cgroups, this mock
implementation of a cgroup manager can used in unit testing.

Signed-off-by: Julio Montes <julio.montes@intel.com>

src/agent/rustjail/src/cgroups/mock.rs

@@ -0,0 +1,74 @@
+// Copyright (c) 2020 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+use protobuf::{CachedSize, SingularPtrField, UnknownFields};
+
+use crate::cgroups::Manager as CgroupManager;
+use crate::protocols::agent::{BlkioStats, CgroupStats, CpuStats, MemoryStats, PidsStats};
+use anyhow::Result;
+use cgroups::freezer::FreezerState;
+use libc::{self, pid_t};
+use oci::LinuxResources;
+use std::collections::HashMap;
+use std::string::String;
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct Manager {
+    pub paths: HashMap<String, String>,
+    pub mounts: HashMap<String, String>,
+    pub cpath: String,
+}
+
+impl CgroupManager for Manager {
+    fn apply(&self, _: pid_t) -> Result<()> {
+        Ok(())
+    }
+
+    fn set(&self, _: &LinuxResources, _: bool) -> Result<()> {
+        Ok(())
+    }
+
+    fn get_stats(&self) -> Result<CgroupStats> {
+        Ok(CgroupStats {
+            cpu_stats: SingularPtrField::some(CpuStats::default()),
+            memory_stats: SingularPtrField::some(MemoryStats::new()),
+            pids_stats: SingularPtrField::some(PidsStats::new()),
+            blkio_stats: SingularPtrField::some(BlkioStats::new()),
+            hugetlb_stats: HashMap::new(),
+            unknown_fields: UnknownFields::default(),
+            cached_size: CachedSize::default(),
+        })
+    }
+
+    fn freeze(&self, _: FreezerState) -> Result<()> {
+        Ok(())
+    }
+
+    fn destroy(&mut self) -> Result<()> {
+        Ok(())
+    }
+
+    fn get_pids(&self) -> Result<Vec<pid_t>> {
+        Ok(Vec::new())
+    }
+}
+
+impl Manager {
+    pub fn new(cpath: &str) -> Result<Self> {
+        Ok(Self {
+            paths: HashMap::new(),
+            mounts: HashMap::new(),
+            cpath: cpath.to_string(),
+        })
+    }
+
+    pub fn update_cpuset_path(&self, _: &str) -> Result<()> {
+        Ok(())
+    }
+
+    pub fn get_cg_path(&self, _: &str) -> Option<String> {
+        Some("".to_string())
+    }
+}

src/agent/rustjail/src/cgroups/mod.rs

@@ -10,6 +10,7 @@ use protocols::agent::CgroupStats;
 use cgroups::freezer::FreezerState;
 
 pub mod fs;
+pub mod mock;
 pub mod notifier;
 pub mod systemd;