fix(network): fall back to unlimited bandwidth in case the legacy global limit is still set

src/libsync/account.cpp

@@ -1426,7 +1426,14 @@ void Account::setUploadLimitSetting(const AccountNetworkTransferLimitSetting set
         return;
     }
 
-    _uploadLimitSetting = setting;
+    auto targetSetting = setting;
+
+    if (setting == AccountNetworkTransferLimitSetting::LegacyGlobalLimit) {
+        qCInfo(lcAccount) << "Upload limit setting was requested to be set to the legacy global limit, falling back to unlimited";
+        targetSetting = AccountNetworkTransferLimitSetting::NoLimit;
+    }
+
+    _uploadLimitSetting = targetSetting;
     emit uploadLimitSettingChanged();
 }
 
@@ -1440,8 +1447,15 @@ void Account::setDownloadLimitSetting(const AccountNetworkTransferLimitSetting s
     if (setting == _downloadLimitSetting) {
         return;
     }
-
-    _downloadLimitSetting = setting;
+
+    auto targetSetting = setting;
+
+    if (setting == AccountNetworkTransferLimitSetting::LegacyGlobalLimit) {
+        qCInfo(lcAccount) << "Download limit setting was requested to be set to the legacy global limit, falling back to unlimited";
+        targetSetting = AccountNetworkTransferLimitSetting::NoLimit;
+    }
+
+    _downloadLimitSetting = targetSetting;
     emit downloadLimitSettingChanged();
 }
 

src/libsync/account.h

@@ -1,3 +1,3 @@
 /*
  * SPDX-FileCopyrightText: 2017 Nextcloud GmbH and Nextcloud contributors
  * SPDX-FileCopyrightText: 2013 ownCloud GmbH
@@ -99,6 +99,7 @@
 
 public:
     enum class AccountNetworkTransferLimitSetting {
+        LegacyGlobalLimit = -2, // Until 3.17.0 a value of -2 was interpreted as "Use global network settings", it's now used to fall back to "No limit".  See also GH#8743
         AutoLimit = -1, // Value under 0 is interpreted as auto in general
         NoLimit,
         ManualLimit,

test/testaccount.cpp

@@ -8,7 +8,7 @@
  * any purpose.
  */
 
 #include <qglobal.h>
 #include <QTemporaryDir>
 #include <QtTest>
 
@@ -69,6 +69,37 @@
         QCOMPARE(account->isPublicShareLink(), expectedResult);
         QCOMPARE(account->davUser(), expectedDavUser);
     }
+
+    void testAccount_setLimitSettings_globalNetworkLimitFallback()
+    {
+        using LimitSetting = Account::AccountNetworkTransferLimitSetting;
+        AccountPtr account = Account::create();
+
+        const auto setLimitSettings = [account](const LimitSetting setting) -> void {
+            account->setDownloadLimitSetting(setting);
+            account->setUploadLimitSetting(setting);
+        };
+
+        const auto verifyLimitSettings = [account](const LimitSetting expectedSetting) -> void {
+            QCOMPARE_EQ(expectedSetting, account->downloadLimitSetting());
+            QCOMPARE_EQ(expectedSetting, account->uploadLimitSetting());
+        };
+
+        // the default setting should be NoLimit
+        verifyLimitSettings(LimitSetting::NoLimit);
+
+        // changing it to ManualLimit should succeed
+        setLimitSettings(LimitSetting::ManualLimit);
+        verifyLimitSettings(LimitSetting::ManualLimit);
+
+        // changing it to AutoLimit should succeed
+        setLimitSettings(LimitSetting::AutoLimit);
+        verifyLimitSettings(LimitSetting::AutoLimit);
+
+        // changing it to LegacyGlobalLimit (-2) should fall back to NoLimit
+        setLimitSettings(LimitSetting::LegacyGlobalLimit);
+        verifyLimitSettings(LimitSetting::NoLimit);
+    }
 };
 
 QTEST_APPLESS_MAIN(TestAccount)