refactor disconnectFromFtp to remove cached entries when necessary

In cases where a cached ftp connection fails to connect, or a file
transfer has failed, we should removed the cached connection. Since qnam
has an idea of a single internal QFtp per full operation, when file
transfers failed previously the cached connection would be reused for
subsequent connections and thus fail.

[ChangeLog][QtNetwork][QNetworkAccessManager] QNetworkAccessManager now
properly handles FTP transfer failures by removing failed cached ftp
connections.

Task-number: QTBUG-40797
(cherry picked and adapted from qtbase/45cbbe56bc13216b83215ea148590eccf81f420a)
Change-Id: Ie9eec5ec54af16a8d19e34d04bdd993cc7bbd0f5
Reviewed-by: Richard J. Moore <rich@kde.org>

2 files changed, 15 insertions, 12 deletions

diff --git a/src/network/access/qnetworkaccessftpbackend.cpp b/src/network/access/qnetworkaccessftpbackend.cpp
index 449a51e618..541f8f426f 100644
--- a/src/network/access/qnetworkaccessftpbackend.cpp
+++ b/src/network/access/qnetworkaccessftpbackend.cpp
@@ -205,7 +205,7 @@ void QNetworkAccessFtpBackend::ftpConnectionReady(QNetworkAccessCache::Cacheable
     // no, defer the actual operation until after we've logged in
 }
 
-void QNetworkAccessFtpBackend::disconnectFromFtp()
+void QNetworkAccessFtpBackend::disconnectFromFtp(CacheCleanupMode mode)
 {
     state = Disconnecting;
 
@@ -213,7 +213,12 @@ void QNetworkAccessFtpBackend::disconnectFromFtp()
         disconnect(ftp, 0, this, 0);
 
         QByteArray key = makeCacheKey(url());
-        QNetworkAccessManagerPrivate::getObjectCache(this)->releaseEntry(key);
+        if (mode == RemoveCachedConnection) {
+            QNetworkAccessManagerPrivate::getObjectCache(this)->removeEntry(key);
+            ftp->dispose();
+        } else {
+            QNetworkAccessManagerPrivate::getObjectCache(this)->releaseEntry(key);
+        }
 
         ftp = 0;
     }
@@ -263,14 +268,7 @@ void QNetworkAccessFtpBackend::ftpDone()
         }
 
         // we're not connected, so remove the cache entry:
-        QByteArray key = makeCacheKey(url());
-        QNetworkAccessManagerPrivate::getObjectCache(this)->removeEntry(key);
-
-        disconnect(ftp, 0, this, 0);
-        ftp->dispose();
-        ftp = 0;
-
-        state = Disconnecting;
+        disconnectFromFtp(RemoveCachedConnection);
         finished();
         return;
     }
@@ -290,7 +288,7 @@ void QNetworkAccessFtpBackend::ftpDone()
         else
             error(QNetworkReply::ContentAccessDenied, msg);
 
-        disconnectFromFtp();
+        disconnectFromFtp(RemoveCachedConnection);
         finished();
     }
 
diff --git a/src/network/access/qnetworkaccessftpbackend_p.h b/src/network/access/qnetworkaccessftpbackend_p.h
index e64e2b4222..ea5cda39e4 100644
--- a/src/network/access/qnetworkaccessftpbackend_p.h
+++ b/src/network/access/qnetworkaccessftpbackend_p.h
@@ -90,7 +90,12 @@ public:
 
     virtual void downstreamReadyWrite();
 
-    void disconnectFromFtp();
+    enum CacheCleanupMode {
+        ReleaseCachedConnection,
+        RemoveCachedConnection
+    };
+
+    void disconnectFromFtp(CacheCleanupMode mode = ReleaseCachedConnection);
 
 public slots:
     void ftpConnectionReady(QNetworkAccessCache::CacheableObject *object);