From 6a6bfa6da9ac4b2c54d0eba88e3d30c4147a2379 Mon Sep 17 00:00:00 2001
From: Bond_009 <bond.009@outlook.com>
Date: Sun, 24 Nov 2019 17:08:28 +0100
Subject: [PATCH] Fix possible nullref when updating packages

---
 .../Emby.Server.Implementations.csproj         |  1 +
 .../ScheduledTasks/Tasks/PluginUpdateTask.cs   |  4 +++-
 .../Updates/InstallationManager.cs             | 18 +++++++++++-------
 .../Updates/IInstallationManager.cs            |  2 +-
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/Emby.Server.Implementations/Emby.Server.Implementations.csproj b/Emby.Server.Implementations/Emby.Server.Implementations.csproj
index 214ea5aff..385664737 100644
--- a/Emby.Server.Implementations/Emby.Server.Implementations.csproj
+++ b/Emby.Server.Implementations/Emby.Server.Implementations.csproj
@@ -36,6 +36,7 @@
     <PackageReference Include="ServiceStack.Text.Core" Version="5.7.0" />
     <PackageReference Include="sharpcompress" Version="0.24.0" />
     <PackageReference Include="SQLitePCL.pretty.netstandard" Version="2.0.1" />
+    <PackageReference Include="System.Interactive.Async" Version="4.0.0" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/Emby.Server.Implementations/ScheduledTasks/Tasks/PluginUpdateTask.cs b/Emby.Server.Implementations/ScheduledTasks/Tasks/PluginUpdateTask.cs
index fe8deae59..909fffb1f 100644
--- a/Emby.Server.Implementations/ScheduledTasks/Tasks/PluginUpdateTask.cs
+++ b/Emby.Server.Implementations/ScheduledTasks/Tasks/PluginUpdateTask.cs
@@ -52,7 +52,9 @@ namespace Emby.Server.Implementations.ScheduledTasks
         {
             progress.Report(0);
 
-            var packagesToInstall = (await _installationManager.GetAvailablePluginUpdates(cancellationToken).ConfigureAwait(false)).ToList();
+            var packagesToInstall = await _installationManager.GetAvailablePluginUpdates(cancellationToken)
+                .ToListAsync(cancellationToken)
+                .ConfigureAwait(false);
 
             progress.Report(10);
 
diff --git a/Emby.Server.Implementations/Updates/InstallationManager.cs b/Emby.Server.Implementations/Updates/InstallationManager.cs
index 1c5402268..09a5a0dca 100644
--- a/Emby.Server.Implementations/Updates/InstallationManager.cs
+++ b/Emby.Server.Implementations/Updates/InstallationManager.cs
@@ -180,7 +180,7 @@ namespace Emby.Server.Implementations.Updates
             // Package not found.
             if (package == null)
             {
-                return null;
+                return Enumerable.Empty<PackageVersionInfo>();
             }
 
             return GetCompatibleVersions(
@@ -190,19 +190,23 @@ namespace Emby.Server.Implementations.Updates
         }
 
         /// <inheritdoc />
-        public async Task<IEnumerable<PackageVersionInfo>> GetAvailablePluginUpdates(CancellationToken cancellationToken = default)
+        public async IAsyncEnumerable<PackageVersionInfo> GetAvailablePluginUpdates(CancellationToken cancellationToken = default)
         {
             var catalog = await GetAvailablePackages(cancellationToken).ConfigureAwait(false);
 
             var systemUpdateLevel = _applicationHost.SystemUpdateLevel;
 
             // Figure out what needs to be installed
-            return _applicationHost.Plugins.Select(x =>
+            foreach (var plugin in _applicationHost.Plugins)
             {
-                var compatibleversions = GetCompatibleVersions(catalog, x.Name, x.Id, x.Version, systemUpdateLevel);
-                return compatibleversions.FirstOrDefault(y => y.Version > x.Version);
-            }).Where(x => x != null)
-            .Where(x => !CompletedInstallations.Any(y => string.Equals(y.AssemblyGuid, x.guid, StringComparison.OrdinalIgnoreCase)));
+                var compatibleversions = GetCompatibleVersions(catalog, plugin.Name, plugin.Id, plugin.Version, systemUpdateLevel);
+                var version = compatibleversions.FirstOrDefault(y => y.Version > plugin.Version);
+                if (version != null
+                    && !CompletedInstallations.Any(x => string.Equals(x.AssemblyGuid, version.guid, StringComparison.OrdinalIgnoreCase)))
+                {
+                    yield return version;
+                }
+            }
         }
 
         /// <inheritdoc />
diff --git a/MediaBrowser.Common/Updates/IInstallationManager.cs b/MediaBrowser.Common/Updates/IInstallationManager.cs
index 524d8f3c6..e49812f15 100644
--- a/MediaBrowser.Common/Updates/IInstallationManager.cs
+++ b/MediaBrowser.Common/Updates/IInstallationManager.cs
@@ -92,7 +92,7 @@ namespace MediaBrowser.Common.Updates
         /// </summary>
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>The available plugin updates.</returns>
-        Task<IEnumerable<PackageVersionInfo>> GetAvailablePluginUpdates(CancellationToken cancellationToken = default);
+        IAsyncEnumerable<PackageVersionInfo> GetAvailablePluginUpdates(CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Installs the package.