make group member list a hashset

vec::dedup() won't work if the input is not sorted.

rust/userborn/src/config.rs

@@ -1,3 +1,4 @@
+use std::collections::HashSet;
 use std::{fs::File, io::Read, path::Path};
 
 use anyhow::{Context, Result};
@@ -48,7 +49,7 @@ pub struct Group {
     pub gid: Option<u32>,
     /// The members of this group
     #[serde(default)]
-    pub members: Vec<String>,
+    pub members: HashSet<String>,
 }
 
 #[derive(Deserialize, Debug)]

rust/userborn/src/group.rs

@@ -1,3 +1,4 @@
+use std::collections::HashSet;
 use std::{
     collections::{BTreeMap, BTreeSet},
     fs,
@@ -13,12 +14,12 @@ pub struct Entry {
     name: String,
     password: String,
     gid: u32,
-    user_list: Vec<String>,
+    user_list: HashSet<String>,
 }
 
 impl Entry {
     /// Create a new /etc/group entry.
-    pub fn new(name: String, gid: u32, user_list: Vec<String>) -> Self {
+    pub fn new(name: String, gid: u32, user_list: HashSet<String>) -> Self {
         Self {
             name,
             password: "x".into(),
@@ -28,7 +29,7 @@ impl Entry {
     }
 
     /// Update an /etc/group entry.
-    pub fn update(&mut self, user_list: Vec<String>) {
+    pub fn update(&mut self, user_list: HashSet<String>) {
         if self.user_list != user_list {
             log::info!(
                 "Updating members of group {} from {:?} to {user_list:?}...",
@@ -76,16 +77,16 @@ impl Entry {
 }
 
 /// Split a string containing group members separated by `,` into a list.
-fn split_group_members(s: &str) -> Vec<String> {
+fn split_group_members(s: &str) -> HashSet<String> {
     if s.is_empty() {
-        return Vec::new();
+        return HashSet::new();
     }
     s.split(',').map(ToString::to_string).collect()
 }
 
 /// Join a list of group members into a string separating each group name with a `,`.
-fn join_group_members(v: &[String]) -> String {
-    v.join(",")
+fn join_group_members(v: &HashSet<String>) -> String {
+    v.clone().into_iter().collect::<Vec<_>>().join(",")
 }
 
 #[derive(Default)]

rust/userborn/src/main.rs

@@ -6,6 +6,7 @@ mod passwd;
 mod password;
 mod shadow;
 
+use std::collections::HashSet;
 use std::{collections::BTreeSet, io::Write, process::ExitCode};
 
 use anyhow::{anyhow, Context, Result};
@@ -98,9 +99,7 @@ fn update_users_and_groups(
 ) {
     for group_config in &config.groups {
         if let Some(existing_entry) = group_db.get_mut(&group_config.name) {
-            let mut members = group_config.members.clone();
-            members.dedup();
-            existing_entry.update(members);
+            existing_entry.update(group_config.members.clone());
         } else if let Err(e) = create_group(group_config, group_db) {
             log::error!("Failed to create group {}: {e:#}", group_config.name);
         };
@@ -187,7 +186,7 @@ fn create_user(
             is_normal: user_config.is_normal,
             name: user_config.name.clone(),
             gid,
-            members: vec![user_config.name.clone()],
+            members: HashSet::from([user_config.name.clone()]),
         };
 
         create_group(&group_config, group_db)