ProfileService: Rework handling of updates, again

Prefer updating an object instead of replacing it. This preserves the
selection in the UI list. Also make renaming atomic as it should be. Now
the only possibility for data loss is if the old file can be opened but
not written to.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/ProfileService.java

@@ -54,46 +54,6 @@ public class ProfileService extends Service {
         return START_STICKY;
     }
 
-    private class ProfileAdder extends AsyncTask<Void, Void, Boolean> {
-        private final Profile profile;
-        private final boolean shouldConnect;
-
-        private ProfileAdder(Profile profile, boolean shouldConnect) {
-            super();
-            if (profiles.get(profile.getName()) != null)
-                throw new IllegalStateException("Profile already exists: " + profile.getName());
-            this.profile = profile;
-            this.shouldConnect = shouldConnect;
-        }
-
-        @Override
-        protected Boolean doInBackground(Void... voids) {
-            Log.i(TAG, "Adding profile " + profile.getName());
-            try {
-                final String configFile = profile.getName() + ".conf";
-                if (new File(getFilesDir(), configFile).exists())
-                    throw new IOException("Refusing to overwrite existing profile configuration");
-                final FileOutputStream stream = openFileOutput(configFile, MODE_PRIVATE);
-                stream.write(profile.toString().getBytes(StandardCharsets.UTF_8));
-                stream.close();
-                return true;
-            } catch (IOException e) {
-                Log.e(TAG, "Could not create profile " + profile.getName(), e);
-                return false;
-            }
-        }
-
-        @Override
-        protected void onPostExecute(Boolean result) {
-            if (!result)
-                return;
-            profile.setIsConnected(false);
-            profiles.put(profile.getName(), profile);
-            if (shouldConnect)
-                new ProfileConnecter(profile).execute();
-        }
-    }
-
     private class ProfileConnecter extends AsyncTask<Void, Void, Boolean> {
         private final Profile profile;
 
@@ -184,14 +144,10 @@ public class ProfileService extends Service {
 
     private class ProfileRemover extends AsyncTask<Void, Void, Boolean> {
         private final Profile profile;
-        private final Profile replaceWith;
-        private final boolean shouldConnect;
 
-        private ProfileRemover(Profile profile, Profile replaceWith, Boolean shouldConnect) {
+        private ProfileRemover(Profile profile) {
             super();
             this.profile = profile;
-            this.replaceWith = replaceWith;
-            this.shouldConnect = shouldConnect != null ? shouldConnect : false;
         }
 
         @Override
@@ -211,8 +167,70 @@ public class ProfileService extends Service {
             if (!result)
                 return;
             profiles.remove(profile.getName());
-            if (replaceWith != null)
-                new ProfileAdder(replaceWith, shouldConnect).execute();
+        }
+    }
+
+    private class ProfileUpdater extends AsyncTask<Void, Void, Boolean> {
+        private final String newName;
+        private Profile newProfile;
+        private final String oldName;
+        private final Boolean shouldConnect;
+
+        private ProfileUpdater(String oldName, Profile newProfile, Boolean shouldConnect) {
+            super();
+            this.newName = newProfile.getName();
+            this.newProfile = newProfile;
+            this.oldName = oldName;
+            this.shouldConnect = shouldConnect;
+            if (profiles.values().contains(newProfile))
+                throw new IllegalArgumentException("Profile " + newName + " modified directly");
+            if (!newName.equals(oldName) && profiles.get(newName) != null)
+                throw new IllegalStateException("Profile " + newName + " already exists");
+        }
+
+        @Override
+        protected Boolean doInBackground(Void... voids) {
+            Log.i(TAG, (oldName == null ? "Adding" : "Updating") + " profile " + newName);
+            final File newFile = new File(getFilesDir(), newName + ".conf");
+            final File oldFile = new File(getFilesDir(), oldName + ".conf");
+            if (!newName.equals(oldName) && newFile.exists()) {
+                Log.w(TAG, "Refusing to overwrite existing profile configuration");
+                return false;
+            }
+            try {
+                final FileOutputStream stream = openFileOutput(oldFile.getName(), MODE_PRIVATE);
+                stream.write(newProfile.toString().getBytes(StandardCharsets.UTF_8));
+                stream.close();
+            } catch (IOException e) {
+                Log.e(TAG, "Could not save configuration for profile " + oldName, e);
+                return false;
+            }
+            if (!newName.equals(oldName) && !oldFile.renameTo(newFile)) {
+                Log.e(TAG, "Could not rename " + oldFile.getName() + " to " + newFile.getName());
+                return false;
+            }
+            return true;
+        }
+
+        @Override
+        protected void onPostExecute(Boolean result) {
+            if (!result)
+                return;
+            final Profile oldProfile = profiles.remove(oldName);
+            if (oldProfile != null) {
+                try {
+                    oldProfile.parseFrom(newProfile);
+                    oldProfile.setName(newName);
+                    newProfile = oldProfile;
+                } catch (IOException e) {
+                    Log.e(TAG, "Could not replace profile " + oldName + " with " + newName, e);
+                    return;
+                }
+            }
+            newProfile.setIsConnected(false);
+            profiles.put(newName, newProfile);
+            if (shouldConnect)
+                new ProfileConnecter(newProfile).execute();
         }
     }
 
@@ -251,7 +269,7 @@ public class ProfileService extends Service {
                 return;
             if (profile.getIsConnected())
                 new ProfileDisconnecter(profile).execute();
-            new ProfileRemover(profile, null, null).execute();
+            new ProfileRemover(profile).execute();
         }
 
         @Override
@@ -263,9 +281,9 @@ public class ProfileService extends Service {
                 final boolean wasConnected = oldProfile.getIsConnected();
                 if (wasConnected)
                     new ProfileDisconnecter(oldProfile).execute();
-                new ProfileRemover(oldProfile, newProfile, wasConnected).execute();
+                new ProfileUpdater(oldName, newProfile, wasConnected).execute();
             } else {
-                new ProfileAdder(newProfile, false).execute();
+                new ProfileUpdater(null, newProfile, false).execute();
             }
         }
     }