Fixed: Error messages when config file is empty or contains invalid characters

Closes #1104

src/NzbDrone.Common.Test/ConfigFileProviderTest.cs

@@ -17,17 +17,18 @@ namespace NzbDrone.Common.Test
     public class ConfigFileProviderTest : TestBase<ConfigFileProvider>
     {
         private string _configFileContents;
+        private string _configFilePath;
 
         [SetUp]
         public void SetUp()
         {
             WithTempAsAppPath();
 
-            var configFile = Mocker.Resolve<IAppFolderInfo>().GetConfigPath();
+            _configFilePath = Mocker.Resolve<IAppFolderInfo>().GetConfigPath();
 
             _configFileContents = null;
 
-            WithMockConfigFile(configFile);
+            WithMockConfigFile(_configFilePath);
         }
 
         protected void WithMockConfigFile(string configFile)
@@ -187,5 +188,30 @@ namespace NzbDrone.Common.Test
             Subject.SslPort.Should().Be(sslPort);
         }
 
+        [Test]
+        public void should_throw_if_config_file_is_empty()
+        {
+            Mocker.GetMock<IDiskProvider>()
+                  .Setup(v => v.FileExists(_configFilePath))
+                  .Returns(true);
+
+            Assert.Throws<InvalidConfigFileException>(() => Subject.GetValue("key", "value"));
+        }
+
+        [Test]
+        public void should_throw_if_config_file_contains_only_null_character()
+        {
+            _configFileContents = "\0";
+
+            Assert.Throws<InvalidConfigFileException>(() => Subject.GetValue("key", "value"));
+        }
+
+        [Test]
+        public void should_throw_if_config_file_contains_invalid_xml()
+        {
+            _configFileContents = "{ \"key\": \"value\" }";
+
+            Assert.Throws<InvalidConfigFileException>(() => Subject.GetValue("key", "value"));
+        }
     }
 }

src/NzbDrone.Core/Configuration/ConfigFileProvider.cs

@@ -348,6 +348,18 @@ namespace NzbDrone.Core.Configuration
                 {
                     if (_diskProvider.FileExists(_configFile))
                     {
+                        var contents = _diskProvider.ReadAllText(_configFile);
+
+                        if (contents.IsNullOrWhiteSpace())
+                        {
+                            throw new InvalidConfigFileException($"{_configFile} is empty. Please delete the config file and Sonarr will recreate it.");
+                        }
+
+                        if (contents.All(char.IsControl))
+                        {
+                            throw new InvalidConfigFileException($"{_configFile} is corrupt. Please delete the config file and Sonarr will recreate it.");
+                        }
+
                         return XDocument.Parse(_diskProvider.ReadAllText(_configFile));
                     }
 
@@ -360,7 +372,7 @@ namespace NzbDrone.Core.Configuration
 
             catch (XmlException ex)
             {
-                throw new InvalidConfigFileException(_configFile + " is invalid, please see the http://wiki.sonarr.tv for steps to resolve this issue.", ex);
+                throw new InvalidConfigFileException($"{_configFile} is corrupt is invalid. Please delete the config file and Sonarr will recreate it.", ex);
             }
         }
 

src/NzbDrone.Core/Configuration/InvalidConfigFileException.cs

@@ -5,6 +5,10 @@ namespace NzbDrone.Core.Configuration
 {
     public class InvalidConfigFileException : NzbDroneException
     {
+        public InvalidConfigFileException(string message) : base(message)
+        {
+        }
+
         public InvalidConfigFileException(string message, Exception innerException) : base(message, innerException)
         {
         }