Process: namespaces: Change from Vec to HashMap

This change breaks the API for process namespaces, but it provides
a more efficent way of working with the namespaces of a process.

Signed-off-by: Jon Doron <jond@wiz.io>

src/process/namespaces.rs

@@ -1,5 +1,6 @@
 use rustix::fs::AtFlags;
 use std::{
+    collections::HashMap,
     ffi::OsString,
     fs::{self},
     path::PathBuf,
@@ -12,22 +13,36 @@ use super::Process;
 impl Process {
     /// Describes namespaces to which the process with the corresponding PID belongs.
     /// Doc reference: https://man7.org/linux/man-pages/man7/namespaces.7.html
-    pub fn namespaces(&self) -> ProcResult<Vec<Namespace>> {
+    /// The namespace type is the key for the HashMap, i.e 'net', 'user', etc.
+    pub fn namespaces(&self) -> ProcResult<HashMap<OsString, Namespace>> {
         let ns = self.root.join("ns");
-        let mut namespaces = Vec::new();
+        let mut namespaces = HashMap::new();
         for entry in fs::read_dir(ns)? {
             let entry = entry?;
             let path = entry.path();
             let ns_type = entry.file_name();
             let stat = rustix::fs::statat(&rustix::fs::cwd(), &path, AtFlags::empty())
                 .map_err(|_| build_internal_error!(format!("Unable to stat {:?}", path)))?;
 
-            namespaces.push(Namespace {
-                ns_type,
-                path,
-                identifier: stat.st_ino,
-                device_id: stat.st_dev,
-            })
+            namespaces
+                .insert(
+                    ns_type.clone(),
+                    Namespace {
+                        ns_type,
+                        path,
+                        identifier: stat.st_ino,
+                        device_id: stat.st_dev,
+                    },
+                )
+                .map_or_else(
+                    || Ok(()),
+                    |n| {
+                        Err(build_internal_error!(format!(
+                            "NsType appears more than once {:?}",
+                            n.ns_type
+                        )))
+                    },
+                )?;
         }
 
         Ok(namespaces)