Remove a few instances of unsafe code (#116111)

Co-authored-by: Stephen Toub <[email protected]>

Author: EgorBo

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

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Buffers.Binary;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
@@ -178,14 +179,8 @@ private void ComputeHash(IncrementalHash sha256, string path, DateTime lastChang
             sha256.AppendData(_byteBuffer, 0, length);
             sha256.AppendData(Separator, 0, Separator.Length);
 
-            Debug.Assert(_byteBuffer.Length > sizeof(long));
-            unsafe
-            {
-                fixed (byte* b = _byteBuffer)
-                {
-                    *((long*)b) = lastChangedUtc.Ticks;
-                }
-            }
+            BinaryPrimitives.WriteInt64LittleEndian(_byteBuffer, lastChangedUtc.Ticks);
+
             sha256.AppendData(_byteBuffer, 0, sizeof(long));
             sha256.AppendData(Separator, 0, Separator.Length);
         }

src/libraries/System.Collections.Immutable/src/System/Collections/Frozen/String/Hashing.cs

@@ -139,7 +139,7 @@ public static unsafe int GetHashCodeOrdinalIgnoreCaseAscii(ReadOnlySpan<char> s)
             }
         }
 
-        public static unsafe int GetHashCodeOrdinalIgnoreCase(ReadOnlySpan<char> s)
+        public static int GetHashCodeOrdinalIgnoreCase(ReadOnlySpan<char> s)
         {
 #if NET
             return string.GetHashCode(s, StringComparison.OrdinalIgnoreCase);

src/libraries/System.Data.Odbc/src/Common/System/Data/ProviderBase/DbBuffer.cs

@@ -362,7 +362,7 @@ internal IntPtr ReadIntPtr(int offset)
             return value;
         }
 
-        internal unsafe float ReadSingle(int offset)
+        internal float ReadSingle(int offset)
         {
             int value = ReadInt32(offset);
             return BitConverter.Int32BitsToSingle(value);
@@ -634,7 +634,7 @@ internal void WriteIntPtr(int offset, IntPtr value)
             }
         }
 
-        internal unsafe void WriteSingle(int offset, float value)
+        internal void WriteSingle(int offset, float value)
         {
             WriteInt32(offset, BitConverter.SingleToInt32Bits(value));
         }

src/libraries/System.Data.OleDb/src/System/Data/ProviderBase/DbBuffer.cs

@@ -607,7 +607,7 @@ internal void WriteIntPtr(int offset, IntPtr value)
             }
         }
 
-        internal unsafe void WriteSingle(int offset, float value)
+        internal void WriteSingle(int offset, float value)
         {
             WriteInt32(offset, BitConverter.SingleToInt32Bits(value));
         }

src/libraries/System.IO.Pipes/src/System/IO/Pipes/PipeStream.Unix.cs

@@ -253,7 +253,7 @@ internal virtual void DisposeCore(bool disposing)
             // nop
         }
 
-        private unsafe int ReadCore(Span<byte> buffer)
+        private int ReadCore(Span<byte> buffer)
         {
             Debug.Assert(_handle != null);
             DebugAssertHandleValid(_handle);
@@ -277,7 +277,7 @@ private unsafe int ReadCore(Span<byte> buffer)
             }
         }
 
-        private unsafe void WriteCore(ReadOnlySpan<byte> buffer)
+        private void WriteCore(ReadOnlySpan<byte> buffer)
         {
             Debug.Assert(_handle != null);
             DebugAssertHandleValid(_handle);

src/libraries/System.IO.Pipes/src/System/IO/Pipes/PipeStream.cs

@@ -110,15 +110,15 @@ private static void DebugAssertHandleValid(SafePipeHandle handle)
 
         // Reads a byte from the pipe stream.  Returns the byte cast to an int
         // or -1 if the connection has been broken.
-        public override unsafe int ReadByte()
+        public override int ReadByte()
         {
-            byte b;
-            return Read(new Span<byte>(&b, 1)) > 0 ? b : -1;
+            byte b = 0;
+            return Read(new Span<byte>(ref b)) > 0 ? b : -1;
         }
 
-        public override unsafe void WriteByte(byte value)
+        public override void WriteByte(byte value)
         {
-            Write(new ReadOnlySpan<byte>(&value, 1));
+            Write([value]);
         }
 
         public override void Flush()

src/libraries/System.Memory/src/System/Buffers/SequenceReaderExtensions.Binary.cs

@@ -29,7 +29,7 @@ internal static unsafe bool TryRead<T>(ref this SequenceReader<byte> reader, out
             if (span.Length < sizeof(T))
                 return TryReadMultisegment(ref reader, out value);
 
-            value = Unsafe.ReadUnaligned<T>(ref MemoryMarshal.GetReference(span));
+            value = MemoryMarshal.Read<T>(span);
             reader.Advance(sizeof(T));
             return true;
         }
@@ -48,7 +48,7 @@ private static unsafe bool TryReadMultisegment<T>(ref SequenceReader<byte> reade
                 return false;
             }
 
-            value = Unsafe.ReadUnaligned<T>(ref MemoryMarshal.GetReference(tempSpan));
+            value = MemoryMarshal.Read<T>(tempSpan);
             reader.Advance(sizeof(T));
             return true;
         }

src/libraries/System.Net.ServerSentEvents/src/System/Net/ServerSentEvents/Helpers.cs

@@ -38,7 +38,7 @@ public static void WriteUtf8String(this IBufferWriter<byte> writer, ReadOnlySpan
             writer.Advance(value.Length);
         }
 
-        public static unsafe void WriteUtf8String(this IBufferWriter<byte> writer, ReadOnlySpan<char> value)
+        public static void WriteUtf8String(this IBufferWriter<byte> writer, ReadOnlySpan<char> value)
         {
             if (value.IsEmpty)
             {
@@ -52,10 +52,13 @@ public static unsafe void WriteUtf8String(this IBufferWriter<byte> writer, ReadO
 #if NET
             bytesWritten = Encoding.UTF8.GetBytes(value, buffer);
 #else
-            fixed (char* chars = value)
-            fixed (byte* bytes = buffer)
+            unsafe
             {
-                bytesWritten = Encoding.UTF8.GetBytes(chars, value.Length, bytes, maxByteCount);
+                fixed (char* chars = value)
+                fixed (byte* bytes = buffer)
+                {
+                    bytesWritten = Encoding.UTF8.GetBytes(chars, value.Length, bytes, maxByteCount);
+                }
             }
 #endif
             writer.Advance(bytesWritten);

src/libraries/System.Net.ServerSentEvents/src/System/Net/ServerSentEvents/SseParser.cs

@@ -50,16 +50,19 @@ public static SseParser<T> Create<T>(Stream sseStream, SseItemParser<T> itemPars
         }
 
         /// <summary>Encoding.UTF8.GetString(bytes)</summary>
-        internal static unsafe string Utf8GetString(ReadOnlySpan<byte> bytes)
+        internal static string Utf8GetString(ReadOnlySpan<byte> bytes)
         {
 #if NET
             return Encoding.UTF8.GetString(bytes);
 #else
-            fixed (byte* ptr = bytes)
+            unsafe
             {
-                return ptr is null ?
-                    string.Empty :
-                    Encoding.UTF8.GetString(ptr, bytes.Length);
+                fixed (byte* ptr = bytes)
+                {
+                    return ptr is null ?
+                        string.Empty :
+                        Encoding.UTF8.GetString(ptr, bytes.Length);
+                }
             }
 #endif
         }

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Regex.Replace.cs

@@ -216,7 +216,7 @@ private static string Replace(MatchEvaluator evaluator, Regex regex, string inpu
         }
 
         /// <summary>Creates a string from all the segments in the builder and then disposes of the builder.</summary>
-        internal static unsafe string SegmentsToStringAndDispose(ref StructListBuilder<ReadOnlyMemory<char>> segments)
+        internal static string SegmentsToStringAndDispose(ref StructListBuilder<ReadOnlyMemory<char>> segments)
         {
             Span<ReadOnlyMemory<char>> span = segments.AsSpan();