Added check to see if mount folder is empty (#871)

* Added check for if mount folder is empty

* updating log message

* Adding unit test

API.Tests/Services/DirectoryServiceTests.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.IO.Abstractions;
@@ -373,6 +373,29 @@ namespace API.Tests.Services
         }
         #endregion
 
+        #region IsDirectoryEmpty
+        [Fact]
+        public void IsDirectoryEmpty_DirectoryIsEmpty()
+        {
+            const string testDirectory = "c:/manga/";
+            var fileSystem = new MockFileSystem();
+            var ds = new DirectoryService(Substitute.For<ILogger<DirectoryService>>(), fileSystem);
+
+            Assert.False(ds.IsDirectoryEmpty("c:/manga/"));
+        }
+
+        [Fact]
+        public void IsDirectoryEmpty_DirectoryIsNotEmpty()
+        {
+            const string testDirectory = "c:/manga/";
+            var fileSystem = new MockFileSystem();
+            fileSystem.AddFile($"{testDirectory}data-0.txt", new MockFileData("abc"));
+            var ds = new DirectoryService(Substitute.For<ILogger<DirectoryService>>(), fileSystem);
+
+            Assert.False(ds.IsDirectoryEmpty("c:/manga/"));
+        }
+        #endregion
+
         #region ExistOrCreate
         [Fact]
         public void ExistOrCreate_ShouldCreate()

API/Services/DirectoryService.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Immutable;
@@ -32,6 +32,7 @@ namespace API.Services
         void CopyFileToDirectory(string fullFilePath, string targetDirectory);
         int TraverseTreeParallelForEach(string root, Action<string> action, string searchPattern, ILogger logger);
         bool IsDriveMounted(string path);
+        bool IsDirectoryEmpty(string path);
         long GetTotalSize(IEnumerable<string> paths);
         void ClearDirectory(string directoryPath);
         void ClearAndDeleteDirectory(string directoryPath);
@@ -259,6 +260,17 @@ namespace API.Services
            return FileSystem.DirectoryInfo.FromDirectoryName(FileSystem.Path.GetPathRoot(path) ?? string.Empty).Exists;
        }
 
+
+        /// <summary>
+        /// Checks if the root path of a path is empty or not.
+        /// </summary>
+        /// <param name="path"></param>
+        /// <returns></returns>
+        public bool IsDirectoryEmpty(string path)
+        {
+            return Directory.EnumerateFileSystemEntries(path).Any();
+        }
+
         public string[] GetFilesWithExtension(string path, string searchPatternExpression = "")
        {
            // TODO: Use GitFiles instead

API/Services/Tasks/ScannerService.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
@@ -221,6 +221,13 @@ public class ScannerService : IScannerService
             return;
         }
 
+        // For Docker instances check if any of the folder roots are not available (ie disconnected volumes, etc) and fail if any of them are
+        if (library.Folders.Any(f => !_directoryService.IsDirectoryEmpty(f.Path)))
+        {
+            _logger.LogError("Some of the root folders for the library are empty. Either your mount has been disconnected or you are trying to delete all series in the library. Scan will be aborted. Check that your mount is connected or change the library's root folder and rescan.");
+            return;
+        }
+
         _logger.LogInformation("[ScannerService] Beginning file scan on {LibraryName}", library.Name);
         await _messageHub.Clients.All.SendAsync(SignalREvents.ScanLibraryProgress,
             MessageFactory.ScanLibraryProgressEvent(libraryId, 0));