[Group 3] Enable nullable annotations for Microsoft.Extensions.FileProviders.Physical

src/libraries/Microsoft.Extensions.FileProviders.Physical/ref/Microsoft.Extensions.FileProviders.Physical.cs

@@ -16,9 +16,9 @@ public PhysicalFileProvider(string root, Microsoft.Extensions.FileProviders.Phys
         public void Dispose() { }
         protected virtual void Dispose(bool disposing) { }
         ~PhysicalFileProvider() { }
-        public Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string subpath) { throw null; }
+        public Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string? subpath) { throw null; }
         public Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string subpath) { throw null; }
-        public Microsoft.Extensions.Primitives.IChangeToken Watch(string filter) { throw null; }
+        public Microsoft.Extensions.Primitives.IChangeToken Watch(string? filter) { throw null; }
     }
 }
 namespace Microsoft.Extensions.FileProviders.Internal
@@ -67,8 +67,8 @@ public PhysicalFileInfo(System.IO.FileInfo info) { }
     }
     public partial class PhysicalFilesWatcher : System.IDisposable
     {
-        public PhysicalFilesWatcher(string root, System.IO.FileSystemWatcher fileSystemWatcher, bool pollForChanges) { }
-        public PhysicalFilesWatcher(string root, System.IO.FileSystemWatcher fileSystemWatcher, bool pollForChanges, Microsoft.Extensions.FileProviders.Physical.ExclusionFilters filters) { }
+        public PhysicalFilesWatcher(string root, System.IO.FileSystemWatcher? fileSystemWatcher, bool pollForChanges) { }
+        public PhysicalFilesWatcher(string root, System.IO.FileSystemWatcher? fileSystemWatcher, bool pollForChanges, Microsoft.Extensions.FileProviders.Physical.ExclusionFilters filters) { }
         public Microsoft.Extensions.Primitives.IChangeToken CreateFileChangeToken(string filter) { throw null; }
         public void Dispose() { }
         protected virtual void Dispose(bool disposing) { }
@@ -79,14 +79,14 @@ public partial class PollingFileChangeToken : Microsoft.Extensions.Primitives.IC
         public PollingFileChangeToken(System.IO.FileInfo fileInfo) { }
         public bool ActiveChangeCallbacks { get { throw null; } }
         public bool HasChanged { get { throw null; } }
-        public System.IDisposable RegisterChangeCallback(System.Action<object> callback, object state) { throw null; }
+        public System.IDisposable RegisterChangeCallback(System.Action<object?> callback, object? state) { throw null; }
     }
     public partial class PollingWildCardChangeToken : Microsoft.Extensions.Primitives.IChangeToken
     {
         public PollingWildCardChangeToken(string root, string pattern) { }
         public bool ActiveChangeCallbacks { get { throw null; } }
         public bool HasChanged { get { throw null; } }
         protected virtual System.DateTime GetLastWriteUtc(string path) { throw null; }
-        System.IDisposable Microsoft.Extensions.Primitives.IChangeToken.RegisterChangeCallback(System.Action<object> callback, object state) { throw null; }
+        System.IDisposable Microsoft.Extensions.Primitives.IChangeToken.RegisterChangeCallback(System.Action<object?> callback, object? state) { throw null; }
     }
 }

src/libraries/Microsoft.Extensions.FileProviders.Physical/ref/Microsoft.Extensions.FileProviders.Physical.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);netstandard2.0;net461</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Microsoft.Extensions.FileProviders.Physical.cs" />

src/libraries/Microsoft.Extensions.FileProviders.Physical/src/IPollingChangeToken.cs

@@ -8,6 +8,6 @@ namespace Microsoft.Extensions.FileProviders
 {
     internal interface IPollingChangeToken : IChangeToken
     {
-        CancellationTokenSource CancellationTokenSource { get; }
+        CancellationTokenSource? CancellationTokenSource { get; }
     }
 }

src/libraries/Microsoft.Extensions.FileProviders.Physical/src/Internal/FileSystemInfoHelper.cs

@@ -53,7 +53,7 @@ public static bool IsExcluded(FileSystemInfo fileSystemInfo, ExclusionFilters fi
             {
                 try
                 {
-                    FileSystemInfo targetInfo = fileInfo.ResolveLinkTarget(returnFinalTarget: true);
+                    FileSystemInfo? targetInfo = fileInfo.ResolveLinkTarget(returnFinalTarget: true);
                     if (targetInfo != null && targetInfo.Exists)
                     {
                         return targetInfo.LastWriteTimeUtc;

src/libraries/Microsoft.Extensions.FileProviders.Physical/src/Internal/PhysicalDirectoryContents.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using Microsoft.Extensions.FileProviders.Physical;
@@ -15,7 +16,7 @@ namespace Microsoft.Extensions.FileProviders.Internal
     /// </summary>
     public class PhysicalDirectoryContents : IDirectoryContents
     {
-        private IEnumerable<IFileInfo> _entries;
+        private IEnumerable<IFileInfo>? _entries;
         private readonly string _directory;
         private readonly ExclusionFilters _filters;
 
@@ -54,6 +55,7 @@ IEnumerator IEnumerable.GetEnumerator()
             return _entries.GetEnumerator();
         }
 
+        [MemberNotNull(nameof(_entries))]
         private void EnsureInitialized()
         {
             try

src/libraries/Microsoft.Extensions.FileProviders.Physical/src/Microsoft.Extensions.FileProviders.Physical.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <RootNamespace>Microsoft.Extensions.FileProviders</RootNamespace>
     <TargetFrameworks>$(NetCoreAppCurrent);netstandard2.0;net461</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <EnableDefaultItems>true</EnableDefaultItems>
     <PackageDescription>File provider for physical files for Microsoft.Extensions.FileProviders.</PackageDescription>

src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFileProvider.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Threading;
 using Microsoft.Extensions.FileProviders.Internal;
@@ -28,7 +29,7 @@ public class PhysicalFileProvider : IFileProvider, IDisposable
         private readonly ExclusionFilters _filters;
 
         private readonly Func<PhysicalFilesWatcher> _fileWatcherFactory;
-        private PhysicalFilesWatcher _fileWatcher;
+        private PhysicalFilesWatcher? _fileWatcher;
         private bool _fileWatcherInitialized;
         private object _fileWatcherLock = new object();
 
@@ -145,7 +146,7 @@ internal PhysicalFilesWatcher FileWatcher
                     ref _fileWatcher,
                     ref _fileWatcherInitialized,
                     ref _fileWatcherLock,
-                    _fileWatcherFactory);
+                    _fileWatcherFactory) ?? throw new NullReferenceException(nameof(_fileWatcher));
             }
             set
             {
@@ -160,7 +161,7 @@ internal PhysicalFilesWatcher CreateFileWatcher()
         {
             string root = PathUtils.EnsureTrailingSlash(Path.GetFullPath(Root));
 
-            FileSystemWatcher watcher;
+            FileSystemWatcher? watcher;
 #if NETCOREAPP
             //  For browser we will proactively fallback to polling since FileSystemWatcher is not supported.
             if (OperatingSystem.IsBrowser())
@@ -182,9 +183,11 @@ internal PhysicalFilesWatcher CreateFileWatcher()
             };
         }
 
+        [MemberNotNull(nameof(_usePollingFileWatcher))]
+        [MemberNotNull(nameof(_useActivePolling))]
         private void ReadPollingEnvironmentVariables()
         {
-            string environmentValue = Environment.GetEnvironmentVariable(PollingEnvironmentKey);
+            string? environmentValue = Environment.GetEnvironmentVariable(PollingEnvironmentKey);
             bool pollForChanges = string.Equals(environmentValue, "1", StringComparison.Ordinal) ||
                 string.Equals(environmentValue, "true", StringComparison.OrdinalIgnoreCase);
 
@@ -222,7 +225,7 @@ protected virtual void Dispose(bool disposing)
         /// </summary>
         public string Root { get; }
 
-        private string GetFullPath(string path)
+        private string? GetFullPath(string path)
         {
             if (PathUtils.PathNavigatesAboveRoot(path))
             {
@@ -273,7 +276,7 @@ public IFileInfo GetFileInfo(string subpath)
                 return new NotFoundFileInfo(subpath);
             }
 
-            string fullPath = GetFullPath(subpath);
+            string? fullPath = GetFullPath(subpath);
             if (fullPath == null)
             {
                 return new NotFoundFileInfo(subpath);
@@ -297,7 +300,7 @@ public IFileInfo GetFileInfo(string subpath)
         /// <paramref name="subpath" /> is absolute, if the directory does not exist, or <paramref name="subpath" /> has invalid
         /// characters.
         /// </returns>
-        public IDirectoryContents GetDirectoryContents(string subpath)
+        public IDirectoryContents GetDirectoryContents(string? subpath)
         {
             try
             {
@@ -315,7 +318,7 @@ public IDirectoryContents GetDirectoryContents(string subpath)
                     return NotFoundDirectoryContents.Singleton;
                 }
 
-                string fullPath = GetFullPath(subpath);
+                string? fullPath = GetFullPath(subpath);
                 if (fullPath == null || !Directory.Exists(fullPath))
                 {
                     return NotFoundDirectoryContents.Singleton;
@@ -346,7 +349,7 @@ public IDirectoryContents GetDirectoryContents(string subpath)
         /// characters or if <paramref name="filter" /> is an absolute path or outside the root directory specified in the
         /// constructor <seealso cref="PhysicalFileProvider(string)" />.
         /// </returns>
-        public IChangeToken Watch(string filter)
+        public IChangeToken Watch(string? filter)
         {
             if (filter == null || PathUtils.HasInvalidFilterChars(filter))
             {

src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFilesWatcher.cs

@@ -25,7 +25,7 @@ namespace Microsoft.Extensions.FileProviders.Physical
     /// </summary>
     public class PhysicalFilesWatcher : IDisposable
     {
-        private static readonly Action<object> _cancelTokenSource = state => ((CancellationTokenSource)state).Cancel();
+        private static readonly Action<object?> _cancelTokenSource = state => ((CancellationTokenSource?)state)?.Cancel();
 
         internal static TimeSpan DefaultPollingInterval = TimeSpan.FromSeconds(4);
 
@@ -34,12 +34,12 @@ public class PhysicalFilesWatcher : IDisposable
         private readonly ConcurrentDictionary<string, ChangeTokenInfo> _wildcardTokenLookup =
             new ConcurrentDictionary<string, ChangeTokenInfo>(StringComparer.OrdinalIgnoreCase);
 
-        private readonly FileSystemWatcher _fileWatcher;
+        private readonly FileSystemWatcher? _fileWatcher;
         private readonly object _fileWatcherLock = new object();
         private readonly string _root;
         private readonly ExclusionFilters _filters;
 
-        private Timer _timer;
+        private Timer? _timer;
         private bool _timerInitialzed;
         private object _timerLock = new object();
         private Func<Timer> _timerFactory;
@@ -57,7 +57,7 @@ public class PhysicalFilesWatcher : IDisposable
         /// </param>
         public PhysicalFilesWatcher(
             string root,
-            FileSystemWatcher fileSystemWatcher,
+            FileSystemWatcher? fileSystemWatcher,
             bool pollForChanges)
             : this(root, fileSystemWatcher, pollForChanges, ExclusionFilters.Sensitive)
         {
@@ -76,7 +76,7 @@ public PhysicalFilesWatcher(
         /// <param name="filters">Specifies which files or directories are excluded. Notifications of changes to are not raised to these.</param>
         public PhysicalFilesWatcher(
             string root,
-            FileSystemWatcher fileSystemWatcher,
+            FileSystemWatcher? fileSystemWatcher,
             bool pollForChanges,
             ExclusionFilters filters)
         {
@@ -369,8 +369,9 @@ private void ReportChangeForMatchedEntries(string path)
 
             foreach (System.Collections.Generic.KeyValuePair<string, ChangeTokenInfo> wildCardEntry in _wildcardTokenLookup)
             {
-                PatternMatchingResult matchResult = wildCardEntry.Value.Matcher.Match(path);
-                if (matchResult.HasMatches &&
+                PatternMatchingResult? matchResult = wildCardEntry.Value.Matcher?.Match(path);
+                if (matchResult != null &&
+                    matchResult.HasMatches &&
                     _wildcardTokenLookup.TryRemove(wildCardEntry.Key, out matchInfo))
                 {
                     CancelToken(matchInfo);
@@ -443,8 +444,13 @@ private static void CancelToken(ChangeTokenInfo matchInfo)
                 TaskScheduler.Default);
         }
 
-        internal static void RaiseChangeEvents(object state)
+        internal static void RaiseChangeEvents(object? state)
         {
+            if (state == null)
+            {
+                throw new ArgumentNullException(nameof(state));
+            }
+
             // Iterating over a concurrent bag gives us a point in time snapshot making it safe
             // to remove items from it.
             var changeTokens = (ConcurrentDictionary<IPollingChangeToken, IPollingChangeToken>)state;
@@ -466,7 +472,7 @@ internal static void RaiseChangeEvents(object state)
                 // We're already on a background thread, don't need to spawn a background Task to cancel the CTS
                 try
                 {
-                    token.CancellationTokenSource.Cancel();
+                    token.CancellationTokenSource?.Cancel();
                 }
                 catch
                 {
@@ -487,7 +493,7 @@ public ChangeTokenInfo(
             public ChangeTokenInfo(
                 CancellationTokenSource tokenSource,
                 CancellationChangeToken changeToken,
-                Matcher matcher)
+                Matcher? matcher)
             {
                 TokenSource = tokenSource;
                 ChangeToken = changeToken;
@@ -498,7 +504,7 @@ public ChangeTokenInfo(
 
             public CancellationChangeToken ChangeToken { get; }
 
-            public Matcher Matcher { get; }
+            public Matcher? Matcher { get; }
         }
     }
 }

src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PollingFileChangeToken.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Threading;
 using Microsoft.Extensions.Primitives;
@@ -28,8 +29,8 @@ public class PollingFileChangeToken : IPollingChangeToken
         private DateTime _previousWriteTimeUtc;
         private DateTime _lastCheckedTimeUtc;
         private bool _hasChanged;
-        private CancellationTokenSource _tokenSource;
-        private CancellationChangeToken _changeToken;
+        private CancellationTokenSource? _tokenSource;
+        private CancellationChangeToken? _changeToken;
 
         /// <summary>
         /// Initializes a new instance of <see cref="PollingFileChangeToken" /> that polls the specified file for changes as
@@ -73,7 +74,8 @@ private DateTime GetLastWriteTimeUtc()
         /// </summary>
         public bool ActiveChangeCallbacks { get; internal set; }
 
-        internal CancellationTokenSource CancellationTokenSource
+        [DisallowNull]
+        internal CancellationTokenSource? CancellationTokenSource
         {
             get => _tokenSource;
             set
@@ -85,7 +87,7 @@ internal CancellationTokenSource CancellationTokenSource
             }
         }
 
-        CancellationTokenSource IPollingChangeToken.CancellationTokenSource => CancellationTokenSource;
+        CancellationTokenSource? IPollingChangeToken.CancellationTokenSource => CancellationTokenSource;
 
         /// <summary>
         /// True when the file has changed since the change token was created. Once the file changes, this value is always true
@@ -127,9 +129,9 @@ public bool HasChanged
         /// <param name="callback">This parameter is ignored</param>
         /// <param name="state">This parameter is ignored</param>
         /// <returns>A disposable object that noops when disposed</returns>
-        public IDisposable RegisterChangeCallback(Action<object> callback, object state)
+        public IDisposable RegisterChangeCallback(Action<object?> callback, object? state)
         {
-            if (!ActiveChangeCallbacks)
+            if (!ActiveChangeCallbacks || _changeToken == null)
             {
                 return EmptyDisposable.Instance;
             }