From 045b2a9f59be88ddf14f855f60e2a3e807a349c7 Mon Sep 17 00:00:00 2001
From: Mathew Sutcliffe <oktal3700@gmail.com>
Date: Fri, 23 Dec 2016 02:25:05 +0000
Subject: [PATCH] refs #815 When a cache/settings file has errors, back it up
 before it can be overwritten.

---
 src/blackmisc/valuecache.cpp | 22 +++++++++++++++++++++-
 src/blackmisc/valuecache.h   |  2 ++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/blackmisc/valuecache.cpp b/src/blackmisc/valuecache.cpp
index fc3c99da2..d626eb979 100644
--- a/src/blackmisc/valuecache.cpp
+++ b/src/blackmisc/valuecache.cpp
@@ -22,7 +22,6 @@
 #include <QCoreApplication>
 #include <QDBusMetaType>
 #include <QDir>
-#include <QFile>
 #include <QFileInfo>
 #include <QFlags>
 #include <QIODevice>
@@ -450,6 +449,7 @@ namespace BlackMisc
             if (! messages.isEmpty())
             {
                 ok = false;
+                backupFile(file);
                 CLogMessage::preformatted(messages);
             }
             temp.removeDuplicates(currentValues);
@@ -459,6 +459,26 @@ namespace BlackMisc
             (keysMessage.isEmpty() ? o_values.keys().to<QStringList>().join(",") : keysMessage) << dir << (ok ? "successfully" : "with errors");
     }
 
+    void CValueCache::backupFile(QFile &file) const
+    {
+        QDir dir = getCacheRootDirectory();
+        QString relative = "backups/" + dir.relativeFilePath(file.fileName());
+        QString absolute = dir.absoluteFilePath(relative);
+        absolute += "." + QDateTime::currentDateTime().toString(QStringLiteral("yyMMddhhmmss"));
+        if (QFile::exists(absolute)) { return; }
+        if (! dir.mkpath(QFileInfo(relative).path()))
+        {
+            CLogMessage(this).error("Failed to create %1") << QFileInfo(absolute).path();
+            return;
+        }
+        if (! file.copy(absolute))
+        {
+            CLogMessage(this).error("Failed to back up %1: %2") << QFileInfo(file).fileName() << file.errorString();
+            return;
+        }
+        CLogMessage(this).info("Backed up %1 to %2") << QFileInfo(file).fileName() << dir.absoluteFilePath("backups");
+    }
+
     void CValueCache::markAllAsSaved(const QString &keyPrefix)
     {
         QMutexLocker lock(&m_mutex);
diff --git a/src/blackmisc/valuecache.h b/src/blackmisc/valuecache.h
index 12c3f3755..defff18c4 100644
--- a/src/blackmisc/valuecache.h
+++ b/src/blackmisc/valuecache.h
@@ -29,6 +29,7 @@
 #include <QChar>
 #include <QDBusArgument>
 #include <QDateTime>
+#include <QFile>
 #include <QJsonObject>
 #include <QMap>
 #include <QMetaType>
@@ -320,6 +321,7 @@ namespace BlackMisc
         Element &getElement(const QString &key);
         Element &getElement(const QString &key, QMap<QString, ElementPtr>::const_iterator pos);
         std::tuple<CVariant, qint64, bool> getValue(const QString &key);
+        void backupFile(QFile &file) const;
 
         virtual void connectPage(Private::CValuePage *page);