fix(dotnet#27769): Fix regression of "System.Text.Json".

Maximys · Jul 28, 2023 · 0040924 · 0040924
1 parent ff8699f
commit 0040924
Showing 1 changed file with 3 additions and 14 deletions.
diff --git a/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.MultiSegment.cs b/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.MultiSegment.cs
@@ -68,28 +68,17 @@ public Utf8JsonReader(ReadOnlySequence<byte> jsonData, bool isFinalBlock, JsonRe
                 bool firstSegmentIsEmpty = _buffer.Length == 0;
                 if (firstSegmentIsEmpty)
                 {
-                    // Once we find a non-empty segment, we need to set current position to it.
-                    // Therefore, track the next position in a copy before it gets advanced to the next segment.
-                    SequencePosition previousNextPosition = _nextPosition;
-                    while (jsonData.TryGet(ref _nextPosition, out ReadOnlyMemory<byte> memory, advance: true))
+                    if (jsonData.TryGet(ref _currentPosition, out ReadOnlyMemory<byte> memory, advance: true))
                     {
-                        // _currentPosition should point to the segment right befor the segment that _nextPosition points to.
-                        _currentPosition = previousNextPosition;
                         if (memory.Length != 0)
                         {
                             _buffer = memory.Span;
-                            break;
                         }
-                        previousNextPosition = _nextPosition;
                     }
+                    _nextPosition = _currentPosition;
                 }
 
-                // If firstSegmentIsEmpty is true,
-                //    only check if we have reached the last segment but do not advance _nextPosition. The while loop above already advanced it.
-                //    Otherwise, we would end up skipping a segment (i.e. advance = false).
-                // If firstSegmentIsEmpty is false,
-                //    make sure to advance _nextPosition so that it is no longer the same as _currentPosition (i.e. advance = true).
-                _isLastSegment = !jsonData.TryGet(ref _nextPosition, out _, advance: !firstSegmentIsEmpty) && isFinalBlock; // Don't re-order to avoid short-circuiting
+                _isLastSegment = !jsonData.TryGet(ref _nextPosition, out _, advance: true) && isFinalBlock; // Don't re-order to avoid short-circuiting
 
                 Debug.Assert(!_nextPosition.Equals(_currentPosition));