From af264cdc58c9d076bf83477cbdbfe7a5dad282b7 Mon Sep 17 00:00:00 2001
From: Daniel Nash <dnash2k@gmail.com>
Date: Mon, 3 Jun 2019 13:18:34 -0400
Subject: [PATCH] Return a bounded substream when data descriptors are used in
 seekable zips

---
 .../Common/Zip/SeekableZipFilePart.cs         |  12 ++++++++++
 .../SharpCompress.Test/Zip/ZipArchiveTests.cs |  21 +++++++++++++++++-
 .../Archives/Zip.none.datadescriptors.zip     | Bin 0 -> 744 bytes
 3 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 tests/TestArchives/Archives/Zip.none.datadescriptors.zip

diff --git a/src/SharpCompress/Common/Zip/SeekableZipFilePart.cs b/src/SharpCompress/Common/Zip/SeekableZipFilePart.cs
index d06b34aa..c7ac7de7 100644
--- a/src/SharpCompress/Common/Zip/SeekableZipFilePart.cs
+++ b/src/SharpCompress/Common/Zip/SeekableZipFilePart.cs
@@ -1,5 +1,6 @@
 using System.IO;
 using SharpCompress.Common.Zip.Headers;
+using SharpCompress.IO;
 
 namespace SharpCompress.Common.Zip
 {
@@ -7,11 +8,13 @@ namespace SharpCompress.Common.Zip
     {
         private bool _isLocalHeaderLoaded;
         private readonly SeekableZipHeaderFactory _headerFactory;
+        private readonly DirectoryEntryHeader _directoryEntryHeader;
 
         internal SeekableZipFilePart(SeekableZipHeaderFactory headerFactory, DirectoryEntryHeader header, Stream stream)
             : base(header, stream)
         {
             _headerFactory = headerFactory;
+            _directoryEntryHeader = header;
         }
 
         internal override Stream GetCompressedStream()
@@ -36,6 +39,15 @@ namespace SharpCompress.Common.Zip
         protected override Stream CreateBaseStream()
         {
             BaseStream.Position = Header.DataStartPosition.Value;
+
+            if ((Header.CompressedSize == 0)
+                && FlagUtility.HasFlag(Header.Flags, HeaderFlags.UsePostDataDescriptor)
+                && (_directoryEntryHeader?.HasData == true)
+                && (_directoryEntryHeader?.CompressedSize != 0))
+            {
+                return new ReadOnlySubStream(BaseStream, _directoryEntryHeader.CompressedSize);
+            }
+
             return BaseStream;
         }
     }
diff --git a/tests/SharpCompress.Test/Zip/ZipArchiveTests.cs b/tests/SharpCompress.Test/Zip/ZipArchiveTests.cs
index f76b380d..5238d5df 100644
--- a/tests/SharpCompress.Test/Zip/ZipArchiveTests.cs
+++ b/tests/SharpCompress.Test/Zip/ZipArchiveTests.cs
@@ -536,5 +536,24 @@ namespace SharpCompress.Test.Zip
                 Assert.Null(ex);
             }
         }
-    }
+
+        [Fact]
+        public void Zip_NoCompression_DataDescriptors_Read()
+        {
+            string zipPath = Path.Combine(TEST_ARCHIVES_PATH, "Zip.none.datadescriptors.zip");
+
+            using (ZipArchive za = ZipArchive.Open(zipPath))
+            {
+                var firstEntry = za.Entries.First(x => x.Key == "first.txt");
+                var buffer = new byte[4096];
+
+                using (var memoryStream = new MemoryStream())
+                using (var firstStream = firstEntry.OpenEntryStream())
+                {
+                    firstStream.CopyTo(memoryStream);
+                    Assert.Equal(199, memoryStream.Length);
+                }
+            }
+        }
+   }
 }
diff --git a/tests/TestArchives/Archives/Zip.none.datadescriptors.zip b/tests/TestArchives/Archives/Zip.none.datadescriptors.zip
new file mode 100644
index 0000000000000000000000000000000000000000..62d72a4f4b0015d2ba8116e1a12ec5edc66587ff
GIT binary patch
literal 744
zcmWIWW@h1H;9$T6oD4DyX_-aEC3+<lC7~gl49x2*Z^kfH-Ha)%;AUWCdBM!U04Cf(
ziWG)A$ra$u&e6{Hf%!NC0|N--4jC>68HVE2<ovu8c+l*wycu($5+i7W!KxI7GzAWr
z*T>_p9%W!)0O0^{MkYCCNTS&ku+|Sb&^Q?+;3;WIBZ!HVgjgX-2rc;_8@D51tsk;g
lTqwp#F*2ZpJ1YY-DBLm3V`T$b%*4RNFrR^e!I%le0{{_W)B6Ab

literal 0
HcmV?d00001