[CIT-402] Fix the condition to look at the default system location in tedge_mapper (#279)

* [CIT-402] Fix the condition to look at the default system location when tedge_mapper is running as the tedge-mapper user

- Add UserManager::running_as(desired_user)
- Add the same fix to collectd_mapper

Signed-off-by: Rina Fujino <18257209+rina23q@users.noreply.github.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/common/tedge_users/src/unix.rs b/common/tedge_users/src/unix.rs
index 6ac81194..aef224cf 100644
--- a/common/tedge_users/src/unix.rs
+++ b/common/tedge_users/src/unix.rs
@@ -59,6 +59,22 @@ impl UserManager {
         users::get_current_uid() == 0
     }
 
+    /// Check if the process has been launched using a desired user or not.
+    ///
+    /// # Example
+    ///
+    /// ```
+    ///     # use tedge_users::UserManager;
+    ///     let path = if UserManager::running_as("tedge-mapper") {
+    ///          "/etc/tedge/tedge.toml"
+    ///      } else {
+    ///          ".tedge/tedge.toml"
+    ///      };
+    /// ```
+    pub fn running_as(desired_user: &str) -> bool {
+        users::get_current_username() == Some(desired_user.into())
+    }
+
     /// Switch the effective user of the running process.
     ///
     /// This method returns a guard. As long as the guard is owned by the caller,