Address review feedback

Author: layomia

src/libraries/System.Text.Json/src/System/Text/Json/JsonConstants.cs

@@ -67,6 +67,8 @@ internal static class JsonConstants
         // When transcoding from UTF8 -> UTF16, the byte count threshold where we rent from the array pool before performing a normal alloc.
         public const long ArrayPoolMaxSizeBeforeUsingNormalAlloc = 1024 * 1024;
 
+        public const int MaxRawValueLength = int.MaxValue / MaxExpansionFactorWhileTranscoding;
+
         public const int MaxEscapedTokenSize = 1_000_000_000;   // Max size for already escaped value.
         public const int MaxUnescapedTokenSize = MaxEscapedTokenSize / MaxExpansionFactorWhileEscaping;  // 166_666_666 bytes
         public const int MaxBase64ValueTokenSize = (MaxEscapedTokenSize >> 2) * 3 / MaxExpansionFactorWhileEscaping;  // 125_000_000 bytes

src/libraries/System.Text.Json/src/System/Text/Json/Writer/Utf8JsonWriter.WriteValues.Raw.cs

@@ -8,26 +8,93 @@ namespace System.Text.Json
     public sealed partial class Utf8JsonWriter
     {
         /// <summary>
-        /// Writes the input as JSON content.
+        /// Writes the input as JSON content. It is expected that the input content is a single complete JSON value.
         /// </summary>
         /// <param name="json">The raw JSON content to write.</param>
-        /// <param name="skipInputValidation">Whether to skip validation of the input JSON content.</param>
+        /// <param name="skipInputValidation">Whether to validate if the input is an RFC 8259-compliant JSON payload.</param>
+        /// <exception cref="ArgumentNullException">Thrown if <paramref name="json"/> is <see langword="null"/>.</exception>
+        /// <exception cref="ArgumentException">Thrown if the length of the input is zero or greater than 715,827,882.</exception>
+        /// <exception cref="JsonException">Thrown if <paramref name="skipInputValidation"/> is <see langword="false"/>, and the input is not  RFC 8259-compliant.</exception>
+        /// <remarks>
+        /// When writing untrused JSON values, do not set <paramref name="skipInputValidation"/> to <see langword="true"/> as this can result in invalid JSON
+        /// being written, and/or the overall payload being written to the writer instance being invalid.
+        ///
+        /// When using this method, the input content will be written to the writer destination as-is, unless validation fails.
+        ///
+        /// The <see cref="JsonWriterOptions.SkipValidation"/> value for the writer instance is honored when using this method.
+        ///
+        /// The <see cref="JsonWriterOptions.Indented"/> and <see cref="JsonWriterOptions.Encoder"/> values for the writer instance are not applied when using this method.
+        /// </remarks>
         public void WriteRawValue(string json, bool skipInputValidation = false)
         {
+            if (!_options.SkipValidation)
+            {
+                ValidateWritingValue();
+            }
+
             if (json == null)
             {
                 throw new ArgumentNullException(nameof(json));
             }
 
-            WriteRawValue(json.AsSpan(), skipInputValidation);
+            TranscodeAndWriteRawValue(json.AsSpan(), skipInputValidation);
         }
 
         /// <summary>
-        /// Writes the input as JSON content.
+        /// Writes the input as JSON content. It is expected that the input content is a single complete JSON value.
         /// </summary>
         /// <param name="json">The raw JSON content to write.</param>
-        /// <param name="skipInputValidation">Whether to skip validation of the input JSON content.</param>
+        /// <param name="skipInputValidation">Whether to validate if the input is an RFC 8259-compliant JSON payload.</param>
+        /// <exception cref="ArgumentException">Thrown if the length of the input is zero or greater than 715,827,882.</exception>
+        /// <exception cref="JsonException">Thrown if <paramref name="skipInputValidation"/> is <see langword="false"/>, and the input is not  RFC 8259-compliant.</exception>
+        /// <remarks>
+        /// When writing untrused JSON values, do not set <paramref name="skipInputValidation"/> to <see langword="true"/> as this can result in invalid JSON
+        /// being written, and/or the overall payload being written to the writer instance being invalid.
+        ///
+        /// When using this method, the input content will be written to the writer destination as-is, unless validation fails.
+        ///
+        /// The <see cref="JsonWriterOptions.SkipValidation"/> value for the writer instance is honored when using this method.
+        ///
+        /// The <see cref="JsonWriterOptions.Indented"/> and <see cref="JsonWriterOptions.Encoder"/> values for the writer instance are not applied when using this method.
+        /// </remarks>
         public void WriteRawValue(ReadOnlySpan<char> json, bool skipInputValidation = false)
+        {
+            if (!_options.SkipValidation)
+            {
+                ValidateWritingValue();
+            }
+
+            TranscodeAndWriteRawValue(json, skipInputValidation);
+        }
+
+        /// <summary>
+        /// Writes the input as JSON content. It is expected that the input content is a single complete JSON value.
+        /// </summary>
+        /// <param name="utf8Json">The raw JSON content to write.</param>
+        /// <param name="skipInputValidation">Whether to validate if the input is an RFC 8259-compliant JSON payload.</param>
+        /// <exception cref="ArgumentException">Thrown if the length of the input is zero or greater than 715,827,882.</exception>
+        /// <exception cref="JsonException">Thrown if <paramref name="skipInputValidation"/> is <see langword="false"/>, and the input is not  RFC 8259-compliant.</exception>
+        /// <remarks>
+        /// When writing untrused JSON values, do not set <paramref name="skipInputValidation"/> to <see langword="true"/> as this can result in invalid JSON
+        /// being written, and/or the overall payload being written to the writer instance being invalid.
+        ///
+        /// When using this method, the input content will be written to the writer destination as-is, unless validation fails.
+        ///
+        /// The <see cref="JsonWriterOptions.SkipValidation"/> value for the writer instance is honored when using this method.
+        ///
+        /// The <see cref="JsonWriterOptions.Indented"/> and <see cref="JsonWriterOptions.Encoder"/> values for the writer instance are not applied when using this method.
+        /// </remarks>
+        public void WriteRawValue(ReadOnlySpan<byte> utf8Json, bool skipInputValidation = false)
+        {
+            if (!_options.SkipValidation)
+            {
+                ValidateWritingValue();
+            }
+
+            WriteRawValueInternal(utf8Json, skipInputValidation);
+        }
+
+        private void TranscodeAndWriteRawValue(ReadOnlySpan<char> json, bool skipInputValidation)
         {
             byte[]? tempArray = null;
 
@@ -55,33 +122,40 @@ public void WriteRawValue(ReadOnlySpan<char> json, bool skipInputValidation = fa
             }
         }
 
-        /// <summary>
-        /// Writes the input as JSON content.
-        /// </summary>
-        /// <param name="utf8Json">The raw JSON content to write.</param>
-        /// <param name="skipInputValidation">Whether to skip validation of the input JSON content.</param>
-        public void WriteRawValue(ReadOnlySpan<byte> utf8Json, bool skipInputValidation = false)
+        private void WriteRawValueInternal(ReadOnlySpan<byte> utf8Json, bool skipInputValidation)
         {
-            if (utf8Json.Length == 0)
+            int len = utf8Json.Length;
+
+            if (len == 0)
             {
                 ThrowHelper.ThrowArgumentException(SR.ExpectedJsonTokens);
             }
-
-            if (!skipInputValidation)
+            else if (len > JsonConstants.MaxRawValueLength)
             {
-                Utf8JsonReader reader = new Utf8JsonReader(utf8Json);
+                ThrowHelper.ThrowArgumentException_ValueTooLarge(len);
+            }
 
-                try
-                {
-                    while (reader.Read());
-                }
-                catch (JsonReaderException ex)
+            if (skipInputValidation)
+            {
+                // Treat all unvalidated raw JSON value writes as string. If the payload is valid, this approach does
+                // not affect structural validation since a string token is equivalent to a complete object, array,
+                // or other complete JSON tokens when considering structural validation on subsequent writer calls.
+                // If the payload is not valid, then we make no guarantees about the structural validation of the final payload.
+                _tokenType = JsonTokenType.String;
+            }
+            else
+            {
+                // Utilize reader validation.
+                Utf8JsonReader reader = new(utf8Json);
+                while (reader.Read())
                 {
-                    ThrowHelper.ThrowArgumentException(ex.Message);
+                    _tokenType = reader.TokenType;
                 }
             }
 
-            int maxRequired = utf8Json.Length + 1; // Optionally, 1 list separator
+            // TODO (https://github.com/dotnet/runtime/issues/29293):
+            // investigate writing this in chunks, rather than requesting one potentially long, contiguous buffer.
+            int maxRequired = len + 1; // Optionally, 1 list separator
 
             if (_memory.Length - BytesPending < maxRequired)
             {
@@ -96,12 +170,10 @@ public void WriteRawValue(ReadOnlySpan<byte> utf8Json, bool skipInputValidation
             }
 
             utf8Json.CopyTo(output.Slice(BytesPending));
-            BytesPending += utf8Json.Length;
+            BytesPending += len;
 
-            SetFlagToAddListSeparatorBeforeNextItem();
 
-            // Treat all raw JSON value writes as string.
-            _tokenType = JsonTokenType.String;
+            SetFlagToAddListSeparatorBeforeNextItem();
         }
     }
 }

src/libraries/System.Text.Json/tests/System.Text.Json.Tests/System.Text.Json.Tests.csproj

@@ -186,10 +186,10 @@
     <Compile Include="Utf8JsonReaderTests.TryGet.Date.cs" />
     <Compile Include="Utf8JsonReaderTests.ValueTextEquals.cs" />
     <Compile Include="Utf8JsonWriterTests.cs" />
+    <Compile Include="Utf8JsonWriterTests.WriteRaw.cs" />
   </ItemGroup>
   <ItemGroup>
     <Compile Include="..\..\src\System\Text\Json\BitStack.cs" Link="BitStack.cs" />
-    <Compile Include="Utf8JsonWriterTests.WriteRaw.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' != '$(NetCoreAppCurrent)'">
     <Compile Include="$(CommonPath)System\Runtime\CompilerServices\IsExternalInit.cs" Link="Common\System\Runtime\CompilerServices\IsExternalInit.cs" />