propagateupload: Save the mtime given by the server in the reply to GET

There could be a race condition if the file was updated on the server
between the discovery and the propagate phase. By taking the mtime from
the server, we make sure that we do not have a race.

This is tested by t6.pl with BIG3.file because the script was modifying
the file between the two phases

csync/tests/ownCloud/t6.pl

@@ -125,6 +125,10 @@ while(readdir $dh) {
 closedir $dh;
 assert( $seen == 1, "No conflict file created on precondition failed!" );
 unlink($script);
+$ENV{'OWNCLOUD_POST_UPDATE_SCRIPT'} = "";
+
+assertLocalAndRemoteDir( '', 1);
+
 
 # Set a custom chunk size in environment.
 my $ChunkSize = 1*1024*1024;

src/libsync/propagatedownload.cpp

@@ -37,7 +37,7 @@ GETFileJob::GETFileJob(AccountPtr account, const QString& path, QFile *device,
   _device(device), _headers(headers), _expectedEtagForResume(expectedEtagForResume)
 , _resumeStart(resumeStart) , _errorStatus(SyncFileItem::NoStatus)
 , _bandwidthLimited(false), _bandwidthChoked(false), _bandwidthQuota(0), _bandwidthManager(0)
-, _hasEmittedFinishedSignal(false)
+, _hasEmittedFinishedSignal(false), _lastModified()
 {
 }
 
@@ -49,7 +49,7 @@ GETFileJob::GETFileJob(AccountPtr account, const QUrl& url, QFile *device,
   _device(device), _headers(headers), _expectedEtagForResume(expectedEtagForResume)
 , _resumeStart(resumeStart), _errorStatus(SyncFileItem::NoStatus), _directDownloadUrl(url)
 , _bandwidthLimited(false), _bandwidthChoked(false), _bandwidthQuota(0), _bandwidthManager(0)
-, _hasEmittedFinishedSignal(false)
+, _hasEmittedFinishedSignal(false), _lastModified()
 {
 }
 
@@ -160,6 +160,10 @@ void GETFileJob::slotMetaDataChanged()
         }
     }
 
+    auto lastModified = reply()->header(QNetworkRequest::LastModifiedHeader);
+    if (!lastModified.isNull()) {
+        _lastModified = Utility::qDateTimeToTime_t(lastModified.toDateTime());
+    }
 }
 
 void GETFileJob::setBandwidthManager(BandwidthManager *bwm)
@@ -410,6 +414,11 @@ void PropagateDownloadFileQNAM::slotGetFinished()
         // (If it was really empty by the server, the GETFileJob will have errored
         _item._etag = parseEtag(job->etag());
     }
+    if (job->lastModified()) {
+        // It is possible that the file was modified on the server since we did the discovery phase
+        // so make sure we have the up-to-date time
+        _item._modtime = job->lastModified();
+    }
     _item._requestDuration = job->duration();
     _item._responseTimeStamp = job->responseTimestamp();
 

src/libsync/propagatedownload.h

@@ -36,6 +36,7 @@ class GETFileJob : public AbstractNetworkJob {
     qint64 _bandwidthQuota;
     QPointer<BandwidthManager> _bandwidthManager;
     bool _hasEmittedFinishedSignal;
+    time_t _lastModified;
 public:
 
     // DOES NOT take owncership of the device.
@@ -86,6 +87,7 @@ public:
 
     QByteArray &etag() { return _etag; }
     quint64 resumeStart() { return _resumeStart; }
+    time_t lastModified() { return _lastModified; }
 
 
 signals:

src/libsync/syncengine.cpp

@@ -726,7 +726,7 @@ void SyncEngine::slotDiscoveryJobFinished(int discoveryResult)
         qDebug() << "OOO => Post Update Script: " << script;
         QProcess::execute(script.toUtf8());
 #else
-    qDebug() << "**** Attention: POST_UPDATE_SCRIPT installed, but not executed because compiled with NDEBUG";
+    qWarning() << "**** Attention: POST_UPDATE_SCRIPT installed, but not executed because compiled with NDEBUG";
 #endif
     }