Fix remote wipe keychain storage (issue #1592)

The app password for the remote wipe was constantly being written in
WebFlowCredentials::slotFinished to the keychain, leading to unnecessary
write and log overhead on the system.

This fix introduces a check to only store the app password once in
a lifetime of the Account class. Also the method used to store the
password will be renamed from setAppPassword to writeAppPasswordOnce
to be more expressive.

Signed-off-by: Michael Schuster <michael@schuster.ms>

src/gui/creds/webflowcredentials.cpp

@@ -420,7 +420,7 @@ void WebFlowCredentials::slotFinished(QNetworkReply *reply) {
         _credentialsValid = true;
 
         /// Used later for remote wipe
-        _account->setAppPassword(_password);
+        _account->writeAppPasswordOnce(_password);
     }
 }
 

src/libsync/account.cpp

@@ -513,7 +513,10 @@ void Account::setNonShib(bool nonShib)
     }
 }
 
-void Account::setAppPassword(QString appPassword){
+void Account::writeAppPasswordOnce(QString appPassword){
+    if(_wroteAppPassword)
+        return;
+
     const QString kck = AbstractCredentials::keychainKey(
                 url().toString(),
                 davUser() + app_password,
@@ -524,8 +527,10 @@ void Account::setAppPassword(QString appPassword){
     job->setInsecureFallback(false);
     job->setKey(kck);
     job->setBinaryData(appPassword.toLatin1());
-    connect(job, &WritePasswordJob::finished, [](Job *) {
+    connect(job, &WritePasswordJob::finished, [this](Job *) {
         qCInfo(lcAccount) << "appPassword stored in keychain";
+
+        _wroteAppPassword = true;
     });
     job->start();
 }

src/libsync/account.h

@@ -243,7 +243,7 @@ class OWNCLOUDSYNC_EXPORT Account : public QObject
 
     /// Used in RemoteWipe
     void retrieveAppPassword();
-    void setAppPassword(QString appPassword);
+    void writeAppPasswordOnce(QString appPassword);
     void deleteAppPassword();
 
 public slots:
@@ -319,6 +319,9 @@ protected Q_SLOTS:
     QString _davPath; // defaults to value from theme, might be overwritten in brandings
     ClientSideEncryption _e2e;
 
+    /// Used in RemoteWipe
+    bool _wroteAppPassword = false;
+
     friend class AccountManager;
 };
 }