Add AllUsers and AllGroups

examples/mocking.rs

@@ -0,0 +1,40 @@
+extern crate uzers;
+
+use uzers::mock::MockUsers;
+use uzers::{AllGroups, Group, Groups, UsersCache, UsersSnapshot};
+
+fn iter_aware<G: Groups + AllGroups>(g: &G) {
+    println!("All groups:");
+    for group in g.get_all_groups() {
+        println!("- {group:?}");
+    }
+
+    no_iter(g);
+}
+
+fn no_iter<G: Groups>(g: &G) {
+    let me = g.get_current_groupname();
+    let root = g.get_group_by_gid(0);
+    println!("My group is {me:?}, gid 0 is {root:?}");
+}
+
+fn main() {
+    env_logger::init();
+
+    // UsersCache can only be used with `no_iter`
+    println!("\n--- UsersCache ---");
+    no_iter(&UsersCache::new());
+
+    // UsersSnapshot can be used with both `no_iter` and `iter_aware`
+    println!("\n--- UsersSnapshot: all groups ---");
+    no_iter(unsafe { &UsersSnapshot::new() });
+    println!("\n--- UsersSnapshot: primary groups of some system users ---");
+    iter_aware(unsafe { &UsersSnapshot::only_users(|u| u.uid() < 10) });
+
+    // MockUsers can be used with both `no_iter` and `iter_aware`
+    println!("\n--- MockUsers ---");
+    let mut mock = MockUsers::with_current_uid(1000);
+    mock.add_group(Group::new(1000, "fred"));
+    mock.add_group(Group::new(0, "r00t"));
+    iter_aware(&mock);
+}