From b8f4094a77ff077b8bcf616e8fadd25693abe689 Mon Sep 17 00:00:00 2001
From: winscripter <142818255+winscripter@users.noreply.github.com>
Date: Tue, 25 Aug 2026 00:12:11 +0400
Subject: [PATCH] Reduce errors

---
 .../Formats/Jxl/Fields/JxlReadVisitor.cs      | 12 ----
 .../Jxl/Processing/Decoder/JxlBitReader.cs    | 65 +++++++++----------
 .../Jxl/Processing/Decoder/JxlDecoderCore.cs  | 15 ++---
 3 files changed, 36 insertions(+), 56 deletions(-)

diff --git a/src/ImageSharp/Formats/Jxl/Fields/JxlReadVisitor.cs b/src/ImageSharp/Formats/Jxl/Fields/JxlReadVisitor.cs
index c60e5985e..d54dba670 100644
--- a/src/ImageSharp/Formats/Jxl/Fields/JxlReadVisitor.cs
+++ b/src/ImageSharp/Formats/Jxl/Fields/JxlReadVisitor.cs
@@ -116,18 +116,6 @@ internal sealed class JxlReadVisitor(JxlBitReader reader) : JxlVisitorBase
             reader.SkipBits64((uint)remainingBits);
         }
 
-        return this.ThrowIfEndOfStreamOrReturnTrue();
-    }
-
-    private bool ThrowIfEndOfStreamOrReturnTrue()
-    {
-        if (reader.IsEndOfStream)
-        {
-            DebugGuard.IsTrue(false, "Got an invalid end-of-stream");
-            this.notEnoughBytes = true;
-            return true;
-        }
-
         return true;
     }
 }
diff --git a/src/ImageSharp/Formats/Jxl/Processing/Decoder/JxlBitReader.cs b/src/ImageSharp/Formats/Jxl/Processing/Decoder/JxlBitReader.cs
index 9dbc090ae..33b7307d3 100644
--- a/src/ImageSharp/Formats/Jxl/Processing/Decoder/JxlBitReader.cs
+++ b/src/ImageSharp/Formats/Jxl/Processing/Decoder/JxlBitReader.cs
@@ -8,56 +8,61 @@ namespace SixLabors.ImageSharp.Formats.Jxl.Processing.Decoder;
 /// <summary>
 /// Represents a bitstream reader.
 /// </summary>
-internal ref struct JxlBitReader(ReadOnlySpan<byte> bytes)
+internal sealed class JxlBitReader(Stream stream)
 {
-    private readonly ReadOnlySpan<byte> data = bytes;
-
     private ulong buffer;
     private uint bufferRemainingBits;
     private int pointer;
 
-    /// <summary>
-    /// Gets a value indicating whether this marks an end of stream.
-    /// </summary>
-    public bool IsEndOfStream { get; private set; }
-
     /// <summary>
     /// Gets the total number of bits consumed.
     /// </summary>
-    public readonly long TotalBitsConsumed => ((long)this.pointer * 8) + (64 - this.bufferRemainingBits);
+    public long TotalBitsConsumed => ((long)this.pointer * 8) + (64 - this.bufferRemainingBits);
 
     /// <summary>
     /// Fetches a new buffer.
     /// </summary>
     private void RefillCore()
     {
-        int remaining = this.data.Length - this.pointer;
-        if (remaining <= 0)
-        {
-            // we don't have any more data... mark an end of stream
-            this.buffer = 0;
-            this.bufferRemainingBits = 0;
-            this.IsEndOfStream = true;
-            return;
-        }
-
-        if (remaining >= 8)
+        Span<byte> temp = stackalloc byte[8];
+        int bytesRead = stream.Read(temp);
+        if (bytesRead == 8)
         {
-            this.buffer = BinaryPrimitives.ReadUInt64LittleEndian(this.data[this.pointer..]);
+            this.buffer = BinaryPrimitives.ReadUInt64LittleEndian(temp);
             this.bufferRemainingBits = 64u;
             this.pointer += 8;
         }
         else
         {
+            if (bytesRead == 0)
+            {
+                throw new EndOfStreamException();
+            }
+
             ulong value = 0;
-            for (int i = 0; i < remaining; i++)
+            for (int i = 0; i < bytesRead; i++)
             {
-                value |= (ulong)this.data[this.pointer + i] << (8 * i);
+                value |= (ulong)temp[i] << (8 * i);
             }
 
             this.buffer = value;
-            this.bufferRemainingBits = (uint)(remaining * 8);
-            this.pointer += remaining;
+            this.bufferRemainingBits = (uint)(bytesRead * 8);
+            this.pointer += bytesRead;
+        }
+    }
+
+    public void JumpToByteBoundary()
+    {
+        uint remainder = (uint)(this.TotalBitsConsumed % 8);
+
+        if (remainder == 0)
+        {
+            return;
+        }
+
+        if (this.ReadBits32(8u - remainder) != 0)
+        {
+            throw new InvalidDataException("Non-zero padding bits");
         }
     }
 
@@ -74,11 +79,6 @@ internal ref struct JxlBitReader(ReadOnlySpan<byte> bytes)
         DebugGuard.MustBeLessThanOrEqualTo(n, 64u, nameof(n));
         this.MaybeRefill();
 
-        if (this.IsEndOfStream)
-        {
-            JxlThrowHelper.ThrowEndOfStream();
-        }
-
         if (n <= this.bufferRemainingBits)
         {
             ulong result = this.buffer & ((1UL << (int)n) - 1);
@@ -119,11 +119,6 @@ internal ref struct JxlBitReader(ReadOnlySpan<byte> bytes)
         DebugGuard.MustBeLessThanOrEqualTo(n, 32u, nameof(n));
         this.MaybeRefill();
 
-        if (this.IsEndOfStream)
-        {
-            JxlThrowHelper.ThrowEndOfStream();
-        }
-
         if (n <= this.bufferRemainingBits)
         {
             uint result = (uint)(this.buffer & ((1UL << (int)n) - 1));
diff --git a/src/ImageSharp/Formats/Jxl/Processing/Decoder/JxlDecoderCore.cs b/src/ImageSharp/Formats/Jxl/Processing/Decoder/JxlDecoderCore.cs
index 0287760e4..0fe20686a 100644
--- a/src/ImageSharp/Formats/Jxl/Processing/Decoder/JxlDecoderCore.cs
+++ b/src/ImageSharp/Formats/Jxl/Processing/Decoder/JxlDecoderCore.cs
@@ -1753,11 +1753,6 @@ internal sealed class JxlDecoderCore : ImageDecoderCore, IDisposable
 
                 this.frameDecoder.InitializeFrame(reader, this.imageBundle!, this.previewFrame);
 
-                if (!reader.AllReadsWithinBounds)
-                {
-                    return this.TryRequestMoreInput() ? 1 : 0;
-                }
-
                 this.AdvanceCodeStream(reader.TotalBitsConsumed / JxlMath.BitsPerByte);
                 this.frameHeader = this.frameDecoder.GetFrameHeader();
 
@@ -2701,13 +2696,13 @@ internal sealed class JxlDecoderCore : ImageDecoderCore, IDisposable
 
         if (!this.gotSignature)
         {
-            JxlSignatureCheck status = CheckSignature(this.nextInput, this.availableInput);
-            if (status == JxlSignatureCheck.InvalidSignature)
+            JxlSignature signature = DetectSignature(this.nextInput, this.availableInput);
+            if (signature == JxlSignature.Invalid)
             {
                 throw new InvalidOperationException("The signature is invalid.");
             }
 
-            if (status == JxlSignatureCheck.NotEnoughBytes)
+            if (signature == JxlSignature.NotEnoughBytes)
             {
                 if (this.inputClosed)
                 {
@@ -2719,7 +2714,7 @@ internal sealed class JxlDecoderCore : ImageDecoderCore, IDisposable
 
             this.gotSignature = true;
 
-            if (status == JxlSignatureCheck.Container)
+            if (signature == JxlSignature.Container)
             {
                 this.haveContainer = true;
             }
@@ -2750,6 +2745,8 @@ internal sealed class JxlDecoderCore : ImageDecoderCore, IDisposable
         }
     }
 
+    private static void ThrowNotEnoughData() => throw new InvalidOperationException("Not enough data");
+
     protected override Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken) => throw new NotImplementedException();
 
     protected override ImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken) => throw new NotImplementedException();