2 files changed, 152 insertions, 2 deletions
diff --git a/MediaBrowser.Providers/Books/ComicBookInfo/ComicBookInfoProvider.cs b/MediaBrowser.Providers/Books/ComicBookInfo/ComicBookInfoProvider.cs
index a06de95fce..61615b288a 100644
--- a/MediaBrowser.Providers/Books/ComicBookInfo/ComicBookInfoProvider.cs
+++ b/MediaBrowser.Providers/Books/ComicBookInfo/ComicBookInfoProvider.cs
@@ -54,9 +54,10 @@ public class ComicBookInfoProvider : IComicProvider
                 var archive = await ZipArchive.CreateAsync(stream, ZipArchiveMode.Read, false, null, cancellationToken).ConfigureAwait(false);
                 await using (archive.ConfigureAwait(false))
                 {
-                    if (archive.Comment is null)
+                    // ZipArchive.Comment is an empty string, not null, when the archive has no comment
+                    if (string.IsNullOrWhiteSpace(archive.Comment))
                     {
-                        _logger.LogInformation("missing ComicBookInfo in archive comment: {Path}", info.Path);
+                        _logger.LogDebug("missing ComicBookInfo in archive comment: {Path}", info.Path);
                         return new MetadataResult<Book> { HasMetadata = false };
                     }
 
@@ -71,6 +72,12 @@ public class ComicBookInfoProvider : IComicProvider
                 }
             }
         }
+        catch (JsonException ex)
+        {
+            // the archive comment is not reserved for ComicBookInfo, so any other content is not an error
+            _logger.LogDebug("archive comment is not valid ComicBookInfo metadata: {Path}: {Message}", info.Path, ex.Message);
+            return new MetadataResult<Book> { HasMetadata = false };
+        }
         catch (Exception ex)
         {
             _logger.LogError(ex, "failed to load ComicBookInfo metadata: {Path}", info.Path);
diff --git a/tests/Jellyfin.Providers.Tests/Books/ComicBookInfoProviderTests.cs b/tests/Jellyfin.Providers.Tests/Books/ComicBookInfoProviderTests.cs
new file mode 100644
index 0000000000..f7f29d9768
--- /dev/null
+++ b/tests/Jellyfin.Providers.Tests/Books/ComicBookInfoProviderTests.cs
@@ -0,0 +1,143 @@
+using System;
+using System.IO;
+using System.IO.Compression;
+using System.Threading;
+using System.Threading.Tasks;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Providers;
+using MediaBrowser.Model.IO;
+using MediaBrowser.Providers.Books.ComicBookInfo;
+using Microsoft.Extensions.Logging;
+using Moq;
+using Xunit;
+
+namespace Jellyfin.Providers.Tests.Books;
+
+public sealed class ComicBookInfoProviderTests : IDisposable
+{
+    private const string ValidComment = """
+        {"appID":"test","ComicBookInfo/1.0":{"series":"Jungle Juice","title":"Episode 36","issue":175}}
+        """;
+
+    private readonly string _directory;
+
+    public ComicBookInfoProviderTests()
+    {
+        _directory = Path.Combine(Path.GetTempPath(), "jf-cbz-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(_directory);
+    }
+
+    public void Dispose()
+    {
+        Directory.Delete(_directory, true);
+    }
+
+    [Theory]
+    [InlineData(null)] // archive written without ever touching Comment
+    [InlineData("")]
+    [InlineData("   ")]
+    public async Task ReadMetadata_EmptyArchiveComment_SkipsWithoutDeserializing(string? comment)
+    {
+        var logger = new Mock<ILogger<ComicBookInfoProvider>>();
+        var path = CreateArchive(comment);
+        var provider = new ComicBookInfoProvider(CreateFileSystem(path), logger.Object);
+
+        var result = await provider.ReadMetadata(new ItemInfo(new Book { Path = path }), Mock.Of<IDirectoryService>(), CancellationToken.None);
+
+        Assert.False(result.HasMetadata);
+        VerifyLogged(logger, LogLevel.Debug, "missing ComicBookInfo in archive comment");
+        VerifyNothingLoggedAbove(logger, LogLevel.Debug);
+    }
+
+    [Fact]
+    public async Task ReadMetadata_ArchiveCommentIsNotComicBookInfo_SkipsWithoutError()
+    {
+        var logger = new Mock<ILogger<ComicBookInfoProvider>>();
+        var path = CreateArchive("Created by some packer");
+        var provider = new ComicBookInfoProvider(CreateFileSystem(path), logger.Object);
+
+        var result = await provider.ReadMetadata(new ItemInfo(new Book { Path = path }), Mock.Of<IDirectoryService>(), CancellationToken.None);
+
+        Assert.False(result.HasMetadata);
+        VerifyLogged(logger, LogLevel.Debug, "archive comment is not valid ComicBookInfo metadata");
+        VerifyNothingLoggedAbove(logger, LogLevel.Debug);
+    }
+
+    [Fact]
+    public async Task ReadMetadata_ValidComicBookInfoComment_ReturnsMetadata()
+    {
+        var logger = new Mock<ILogger<ComicBookInfoProvider>>();
+        var path = CreateArchive(ValidComment);
+        var provider = new ComicBookInfoProvider(CreateFileSystem(path), logger.Object);
+
+        var result = await provider.ReadMetadata(new ItemInfo(new Book { Path = path }), Mock.Of<IDirectoryService>(), CancellationToken.None);
+
+        Assert.True(result.HasMetadata);
+        Assert.NotNull(result.Item);
+        Assert.Equal("Episode 36", result.Item.Name);
+        Assert.Equal("Jungle Juice", result.Item.SeriesName);
+        Assert.Equal(175, result.Item.IndexNumber);
+        VerifyNothingLoggedAbove(logger, LogLevel.Debug);
+    }
+
+    private static void VerifyLogged(Mock<ILogger<ComicBookInfoProvider>> logger, LogLevel level, string message)
+    {
+        logger.Verify(
+            x => x.Log(
+                level,
+                It.IsAny<EventId>(),
+                It.Is<It.IsAnyType>((state, _) => state.ToString()!.Contains(message, StringComparison.Ordinal)),
+                It.IsAny<Exception>(),
+                It.IsAny<Func<It.IsAnyType, Exception?, string>>()),
+            Times.Once);
+    }
+
+    private static void VerifyNothingLoggedAbove(Mock<ILogger<ComicBookInfoProvider>> logger, LogLevel level)
+    {
+        // a comment that holds no ComicBookInfo is normal, so it must not reach the log of a default install
+        logger.Verify(
+            x => x.Log(
+                It.Is<LogLevel>(actual => actual > level),
+                It.IsAny<EventId>(),
+                It.IsAny<It.IsAnyType>(),
+                It.IsAny<Exception>(),
+                It.IsAny<Func<It.IsAnyType, Exception?, string>>()),
+            Times.Never);
+    }
+
+    private static IFileSystem CreateFileSystem(string path)
+    {
+        var fileSystem = new Mock<IFileSystem>();
+        fileSystem.Setup(x => x.GetFileSystemInfo(path))
+            .Returns(new FileSystemMetadata
+            {
+                Exists = true,
+                FullName = path,
+                Name = Path.GetFileName(path),
+                Extension = ".cbz",
+                IsDirectory = false
+            });
+
+        return fileSystem.Object;
+    }
+
+    private string CreateArchive(string? comment)
+    {
+        var path = Path.Combine(_directory, Guid.NewGuid().ToString("N") + ".cbz");
+
+        using (var stream = File.Create(path))
+        using (var archive = new ZipArchive(stream, ZipArchiveMode.Create))
+        {
+            if (comment is not null)
+            {
+                archive.Comment = comment;
+            }
+
+            var entry = archive.CreateEntry("ComicInfo.xml");
+            using var writer = new StreamWriter(entry.Open());
+            writer.Write("<ComicInfo />");
+        }
+
+        return path;
+    }
+}