Create backup of OpenVPN log file

Delete previous backup if it already exists.

1 files changed, 33 insertions, 4 deletions

diff --git a/mullvad-daemon/src/main.rs b/mullvad-daemon/src/main.rs
index 821206636d..78daca509b 100644
--- a/mullvad-daemon/src/main.rs
+++ b/mullvad-daemon/src/main.rs
@@ -643,10 +643,7 @@ impl Daemon {
 
         self.set_security_policy()?;
 
-        if let Some(ref file) = self.tunnel_log {
-            let _ = fs::remove_file(file);
-            fs::File::create(file).chain_err(|| "Unable to create the tunnel log file")?;
-        }
+        self.prepare_tunnel_log_file()?;
 
         let tunnel_monitor =
             self.spawn_tunnel_monitor(self.tunnel_endpoint.unwrap(), &account_token)?;
@@ -657,6 +654,38 @@ impl Daemon {
         Ok(())
     }
 
+    fn prepare_tunnel_log_file(&self) -> Result<()> {
+        if let Some(ref file) = self.tunnel_log {
+            if file.exists() {
+                Self::backup_existing_tunnel_log_file(file);
+            }
+
+            let _ = fs::remove_file(file);
+            fs::File::create(file).chain_err(|| "Unable to create the tunnel log file")?;
+        }
+
+        Ok(())
+    }
+
+    fn backup_existing_tunnel_log_file(log_file: &PathBuf) {
+        let mut backup = log_file.clone();
+        backup.set_extension("old.log");
+
+        if backup.exists() {
+            // Try to remove file first, in case rename fails to overwrite it
+            fs::remove_file(&backup).unwrap_or_else(|error| {
+                warn!("Failed to remove old backup of tunnel log file ({})", error);
+            });
+        }
+
+        fs::rename(log_file, backup).unwrap_or_else(|error| {
+            warn!(
+                "Failed to create backup of previous tunnel log file ({})",
+                error
+            );
+        });
+    }
+
     fn spawn_tunnel_monitor(
         &self,
         tunnel_endpoint: TunnelEndpoint,