mirror of https://github.com/SixLabors/ImageSharp
James Jackson-South
3 weeks ago
18 changed files with 440 additions and 264 deletions
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using SixLabors.ImageSharp.IO; |
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namespace SixLabors.ImageSharp; |
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/// <summary>
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/// Extension methods for the <see cref="BufferedReadStream"/> type.
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/// </summary>
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internal static class BufferedReadStreamExtensions |
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{ |
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/// <summary>
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/// Determines whether the complete read range is contained in the stream.
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/// </summary>
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/// <param name="stream">The stream containing the data.</param>
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/// <param name="offset">The absolute start of the range.</param>
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/// <param name="length">The number of bytes in the range.</param>
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/// <returns>Whether the range is contained in the stream.</returns>
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public static bool IsReadRangeValid(this BufferedReadStream stream, long offset, ulong length) |
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{ |
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// Compare the offset first so subtraction cannot underflow, and avoid
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// adding an untrusted length to the offset where it could wrap around.
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ulong streamLength = (ulong)stream.Length; |
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return (ulong)offset <= streamLength && length <= streamLength - (ulong)offset; |
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} |
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/// <summary>
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/// Gets a buffer length when the complete read fits in both the stream and an integer-sized buffer.
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/// </summary>
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/// <param name="stream">The stream containing the data.</param>
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/// <param name="length">The declared length in bytes.</param>
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/// <param name="bufferLength">The validated length, or zero when the range is invalid.</param>
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/// <returns>Whether the complete read is valid.</returns>
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public static bool TryGetReadLength(this BufferedReadStream stream, ulong length, out int bufferLength) |
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{ |
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if (length > int.MaxValue || !stream.IsReadRangeValid(stream.Position, length)) |
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{ |
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bufferLength = 0; |
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return false; |
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} |
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bufferLength = (int)length; |
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return true; |
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} |
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/// <summary>
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/// Reads data from the stream into a slice of the provided buffer.
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/// </summary>
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/// <param name="stream">The stream.</param>
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/// <param name="buffer">The buffer.</param>
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/// <param name="offset">The offset within the buffer where bytes are read into.</param>
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/// <param name="count">The number of bytes, if available, to read.</param>
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/// <returns>The actual number of bytes read.</returns>
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public static int Read(this BufferedReadStream stream, Span<byte> buffer, int offset, int count) |
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=> stream.Read(buffer.Slice(offset, count)); |
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/// <summary>
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/// Advances the stream by the specified number of bytes. Nonpositive counts are ignored.
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/// </summary>
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/// <param name="stream">The stream.</param>
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/// <param name="count">The number of bytes to skip.</param>
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public static void Skip(this BufferedReadStream stream, int count) |
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{ |
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if (count > 0) |
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{ |
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// BufferedReadStream is always seekable; its position setter preserves
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// buffered data when the destination is inside the current buffer.
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stream.Position += count; |
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} |
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} |
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} |
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@ -0,0 +1,60 @@ |
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using SixLabors.ImageSharp.IO; |
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namespace SixLabors.ImageSharp.Tests.Common; |
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public class BufferedReadStreamExtensionsTests |
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{ |
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[Theory] |
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[InlineData(0L, 8UL, true)] |
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[InlineData(8L, 0UL, true)] |
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[InlineData(7L, 2UL, false)] |
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[InlineData(9L, 0UL, false)] |
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[InlineData(-1L, 1UL, false)] |
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[InlineData(long.MaxValue, ulong.MaxValue, false)] |
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[InlineData(0L, ulong.MaxValue, false)] |
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public void IsReadRangeValid_ChecksCompleteExtent(long offset, ulong length, bool expected) |
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{ |
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using MemoryStream input = new(new byte[8]); |
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using BufferedReadStream stream = new(Configuration.Default, input); |
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Assert.Equal(expected, stream.IsReadRangeValid(offset, length)); |
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Assert.Equal(0, stream.Position); |
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} |
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[Theory] |
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[InlineData(0UL, true, 0)] |
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[InlineData(6UL, true, 6)] |
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[InlineData(7UL, false, 0)] |
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[InlineData(1073741824UL, false, 0)] |
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[InlineData(4294967294UL, false, 0)] |
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[InlineData(4294967296UL, false, 0)] |
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[InlineData(ulong.MaxValue, false, 0)] |
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public void TryGetReadLength_ReturnsResultWithoutMovingStream(ulong length, bool expected, int expectedLength) |
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{ |
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using MemoryStream input = new(new byte[8]); |
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using BufferedReadStream stream = new(Configuration.Default, input); |
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stream.Position = 2; |
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Assert.Equal(expected, stream.TryGetReadLength(length, out int bufferLength)); |
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Assert.Equal(expectedLength, bufferLength); |
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Assert.Equal(2, stream.Position); |
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} |
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[Theory] |
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[InlineData(0)] |
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[InlineData(-1)] |
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public void Skip_CountZeroOrLower_PositionNotChanged(int count) |
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{ |
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using MemoryStream input = new(new byte[8]); |
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using BufferedReadStream stream = new(Configuration.Default, input); |
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stream.Position = 4; |
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stream.Skip(count); |
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Assert.Equal(4, stream.Position); |
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Assert.Equal(0, stream.ReadByte()); |
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} |
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} |
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@ -1,111 +0,0 @@ |
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// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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namespace SixLabors.ImageSharp.Tests.Common; |
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public class StreamExtensionsTests |
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{ |
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[Theory] |
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[InlineData(0)] |
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[InlineData(-1)] |
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public void Skip_CountZeroOrLower_PositionNotChanged(int count) |
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{ |
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using (MemoryStream memStream = new(5)) |
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{ |
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memStream.Position = 4; |
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memStream.Skip(count); |
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Assert.Equal(4, memStream.Position); |
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} |
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} |
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[Fact] |
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public void Skip_SeekableStream_SeekIsCalled() |
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{ |
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using (SeekableStream seekableStream = new(4)) |
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{ |
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seekableStream.Skip(4); |
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Assert.Equal(4, seekableStream.Offset); |
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Assert.Equal(SeekOrigin.Current, seekableStream.Loc); |
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} |
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} |
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[Fact] |
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public void Skip_NonSeekableStream_BytesAreRead() |
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{ |
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using (NonSeekableStream nonSeekableStream = new()) |
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{ |
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nonSeekableStream.Skip(5); |
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Assert.Equal(3, nonSeekableStream.Counts.Count); |
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Assert.Equal(5, nonSeekableStream.Counts[0]); |
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Assert.Equal(3, nonSeekableStream.Counts[1]); |
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Assert.Equal(1, nonSeekableStream.Counts[2]); |
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} |
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} |
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[Fact] |
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public void Skip_EofStream_NoExceptionIsThrown() |
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{ |
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using (EofStream eofStream = new(7)) |
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{ |
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eofStream.Skip(7); |
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Assert.Equal(0, eofStream.Position); |
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} |
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} |
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private class SeekableStream : MemoryStream |
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{ |
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public long Offset; |
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public SeekOrigin Loc; |
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public SeekableStream(int capacity) |
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: base(capacity) |
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{ |
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} |
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public override long Seek(long offset, SeekOrigin loc) |
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{ |
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this.Offset = offset; |
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this.Loc = loc; |
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return base.Seek(offset, loc); |
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} |
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} |
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private class NonSeekableStream : MemoryStream |
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{ |
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public override bool CanSeek => false; |
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public List<int> Counts = new(); |
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public NonSeekableStream() |
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: base(4) |
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{ |
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} |
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public override int Read(byte[] buffer, int offset, int count) |
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{ |
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this.Counts.Add(count); |
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return Math.Min(2, count); |
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} |
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} |
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private class EofStream : MemoryStream |
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{ |
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public override bool CanSeek => false; |
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public EofStream(int capacity) |
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: base(capacity) |
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{ |
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} |
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public override int Read(byte[] buffer, int offset, int count) |
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{ |
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return 0; |
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} |
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} |
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} |
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