< Summary

Information
Class: System.IO.Compression.Deflater
Assembly: System.IO.Compression
File(s): D:\runner\runtime\src\libraries\System.IO.Compression\src\System\IO\Compression\DeflateZLib\Deflater.cs
Line coverage
86%
Covered lines: 95
Uncovered lines: 15
Coverable lines: 110
Total lines: 208
Line coverage: 86.3%
Branch coverage
50%
Covered branches: 10
Total branches: 20
Branch coverage: 50%
Method coverage

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Metrics

MethodBranch coverage Cyclomatic complexity NPath complexity Sequence coverage
.ctor(...)100%11100%
Finalize()100%110%
Dispose()100%11100%
Dispose(...)50%44100%
NeedsInput()100%11100%
SetInput(...)100%11100%
SetInput(...)100%11100%
GetDeflateOutput(...)100%22100%
ReadDeflateOutput(...)50%22100%
Finish(...)100%11100%
Flush(...)100%110%
DeallocateInputBufferHandle(...)100%22100%
Deflate(...)25%8853.84%
CreateDeflater(...)50%22100%

File(s)

D:\runner\runtime\src\libraries\System.IO.Compression\src\System\IO\Compression\DeflateZLib\Deflater.cs

#LineLine coverage
 1// Licensed to the .NET Foundation under one or more agreements.
 2// The .NET Foundation licenses this file to you under the MIT license.
 3
 4using System.Buffers;
 5using System.Diagnostics;
 6
 7using ZErrorCode = System.IO.Compression.ZLibNative.ErrorCode;
 8using ZFlushCode = System.IO.Compression.ZLibNative.FlushCode;
 9
 10namespace System.IO.Compression
 11{
 12    /// <summary>
 13    /// Provides a wrapper around the ZLib compression API.
 14    /// </summary>
 15    internal sealed class Deflater : IDisposable
 16    {
 17        private readonly ZLibNative.ZLibStreamHandle _zlibStream;
 18        private MemoryHandle _inputBufferHandle;
 19        private bool _isDisposed;
 20        private const int minWindowBits = -15;  // WindowBits must be between -8..-15 to write no header, 8..15 for a
 21        private const int maxWindowBits = 31;   // zlib header, or 24..31 for a GZip header
 22
 23        // Note, DeflateStream or the deflater do not try to be thread safe.
 24        // The lock is just used to make writing to unmanaged structures atomic to make sure
 25        // that they do not get inconsistent fields that may lead to an unmanaged memory violation.
 26        // To prevent *managed* buffer corruption or other weird behavior users need to synchronize
 27        // on the stream explicitly.
 409028        private object SyncLock => this;
 29
 81830        private Deflater(ZLibNative.ZLibStreamHandle zlibStream)
 81831        {
 81832            _zlibStream = zlibStream;
 81833        }
 34
 35        ~Deflater()
 036        {
 037            Dispose(false);
 038        }
 39
 40        public void Dispose()
 81841        {
 81842            Dispose(true);
 81843            GC.SuppressFinalize(this);
 81844        }
 45
 46        private void Dispose(bool disposing)
 81847        {
 81848            if (!_isDisposed)
 81849            {
 81850                if (disposing)
 81851                {
 81852                    _zlibStream.Dispose();
 81853                }
 54
 55                // Unpin the input buffer, but avoid modifying the ZLibStreamHandle (which may have been disposed of).
 81856                DeallocateInputBufferHandle(resetStreamHandle: false);
 81857                _isDisposed = true;
 81858            }
 81859        }
 60
 490861        public bool NeedsInput() => 0 == _zlibStream.AvailIn;
 62
 63        internal unsafe void SetInput(ReadOnlyMemory<byte> inputBuffer)
 40964        {
 40965            Debug.Assert(NeedsInput(), "We have something left in previous input!");
 40966            Debug.Assert(!inputBuffer.IsEmpty);
 67
 40968            lock (SyncLock)
 40969            {
 40970                _inputBufferHandle = inputBuffer.Pin();
 71
 40972                _zlibStream.NextIn = (IntPtr)_inputBufferHandle.Pointer;
 40973                _zlibStream.AvailIn = (uint)inputBuffer.Length;
 40974            }
 40975        }
 76
 77        internal unsafe void SetInput(byte* inputBufferPtr, int count)
 40978        {
 40979            Debug.Assert(NeedsInput(), "We have something left in previous input!");
 40980            Debug.Assert(inputBufferPtr != null);
 40981            Debug.Assert(count > 0);
 82
 40983            lock (SyncLock)
 40984            {
 40985                _zlibStream.NextIn = (IntPtr)inputBufferPtr;
 40986                _zlibStream.AvailIn = (uint)count;
 40987            }
 40988        }
 89
 90        internal int GetDeflateOutput(byte[] outputBuffer)
 81891        {
 81892            Debug.Assert(null != outputBuffer, "Can't pass in a null output buffer!");
 81893            Debug.Assert(!NeedsInput(), "GetDeflateOutput should only be called after providing input");
 94
 95            try
 81896            {
 97                int bytesRead;
 81898                ReadDeflateOutput(outputBuffer, ZFlushCode.NoFlush, out bytesRead);
 81899                return bytesRead;
 100            }
 101            finally
 818102            {
 103                // Before returning, make sure to release input buffer if necessary:
 818104                if (0 == _zlibStream.AvailIn)
 818105                {
 818106                    DeallocateInputBufferHandle(resetStreamHandle: true);
 818107                }
 818108            }
 818109        }
 110
 111        private unsafe ZErrorCode ReadDeflateOutput(byte[] outputBuffer, ZFlushCode flushCode, out int bytesRead)
 1636112        {
 1636113            Debug.Assert(outputBuffer?.Length > 0);
 114
 1636115            lock (SyncLock)
 1636116            {
 1636117                fixed (byte* bufPtr = &outputBuffer[0])
 1636118                {
 1636119                    _zlibStream.NextOut = (IntPtr)bufPtr;
 1636120                    _zlibStream.AvailOut = (uint)outputBuffer.Length;
 121
 1636122                    ZErrorCode errC = Deflate(flushCode);
 1636123                    bytesRead = outputBuffer.Length - (int)_zlibStream.AvailOut;
 124
 1636125                    return errC;
 126                }
 127            }
 1636128        }
 129
 130        internal bool Finish(byte[] outputBuffer, out int bytesRead)
 818131        {
 818132            Debug.Assert(null != outputBuffer, "Can't pass in a null output buffer!");
 818133            Debug.Assert(outputBuffer.Length > 0, "Can't pass in an empty output buffer!");
 134
 818135            ZErrorCode errC = ReadDeflateOutput(outputBuffer, ZFlushCode.Finish, out bytesRead);
 818136            return errC == ZErrorCode.StreamEnd;
 818137        }
 138
 139        /// <summary>
 140        /// Returns true if there was something to flush. Otherwise False.
 141        /// </summary>
 142        internal bool Flush(byte[] outputBuffer, out int bytesRead)
 0143        {
 0144            Debug.Assert(null != outputBuffer, "Can't pass in a null output buffer!");
 0145            Debug.Assert(outputBuffer.Length > 0, "Can't pass in an empty output buffer!");
 0146            Debug.Assert(NeedsInput(), "We have something left in previous input!");
 147
 148
 149            // Note: we require that NeedsInput() == true, i.e. that 0 == _zlibStream.AvailIn.
 150            // If there is still input left we should never be getting here; instead we
 151            // should be calling GetDeflateOutput.
 152
 0153            return ReadDeflateOutput(outputBuffer, ZFlushCode.SyncFlush, out bytesRead) == ZErrorCode.Ok;
 0154        }
 155
 156        private void DeallocateInputBufferHandle(bool resetStreamHandle)
 1636157        {
 1636158            lock (SyncLock)
 1636159            {
 1636160                if (resetStreamHandle)
 818161                {
 818162                    _zlibStream.AvailIn = 0;
 818163                    _zlibStream.NextIn = ZLibNative.ZNullPtr;
 818164                }
 165
 1636166                _inputBufferHandle.Dispose();
 1636167            }
 1636168        }
 169
 170        private ZErrorCode Deflate(ZFlushCode flushCode)
 1636171        {
 172            ZErrorCode errC;
 173            try
 1636174            {
 1636175                errC = _zlibStream.Deflate(flushCode);
 1636176            }
 0177            catch (Exception cause)
 0178            {
 0179                throw new ZLibException(SR.ZLibErrorDLLLoadError, cause);
 180            }
 181
 1636182            switch (errC)
 183            {
 184                case ZErrorCode.Ok:
 185                case ZErrorCode.StreamEnd:
 1636186                    return errC;
 187
 188                case ZErrorCode.BufError:
 0189                    return errC;  // This is a recoverable error
 190
 191                case ZErrorCode.StreamError:
 0192                    throw new ZLibException(SR.ZLibErrorInconsistentStream, "deflate", (int)errC, _zlibStream.GetErrorMe
 193
 194                default:
 0195                    throw new ZLibException(SR.ZLibErrorUnexpected, "deflate", (int)errC, _zlibStream.GetErrorMessage())
 196            }
 1636197        }
 198
 199        public static Deflater CreateDeflater(ZLibNative.CompressionLevel compressionLevel, ZLibNative.CompressionStrate
 818200        {
 818201            Debug.Assert(windowBits >= minWindowBits && windowBits <= maxWindowBits);
 202
 818203            ZLibNative.ZLibStreamHandle zlibStream = ZLibNative.ZLibStreamHandle.CreateForDeflate(compressionLevel, wind
 204
 818205            return new Deflater(zlibStream);
 818206        }
 207    }
 208}
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7/30/2026 - 1:54:58 PM
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Methods/Properties

SyncLock()
.ctor(System.IO.Compression.ZLibNative/ZLibStreamHandle)
Finalize()
Dispose()
Dispose(System.Boolean)
NeedsInput()
SetInput(System.ReadOnlyMemory`1<System.Byte>)
SetInput(System.Byte*,System.Int32)
GetDeflateOutput(System.Byte[])
ReadDeflateOutput(System.Byte[],System.IO.Compression.ZLibNative/FlushCode,System.Int32&)
Finish(System.Byte[],System.Int32&)
Flush(System.Byte[],System.Int32&)
DeallocateInputBufferHandle(System.Boolean)
Deflate(System.IO.Compression.ZLibNative/FlushCode)
CreateDeflater(System.IO.Compression.ZLibNative/CompressionLevel,System.IO.Compression.ZLibNative/CompressionStrategy,System.Int32,System.Int32)