Merge pull request #686 from Erior/477

Mitigation of problems

src/SharpCompress/Common/Zip/StreamingZipFilePart.cs

@@ -43,12 +43,38 @@ internal BinaryReader FixStreamedFileLocation(ref RewindableStream rewindableStr
             {
                 _decompressionStream ??= GetCompressedStream();
 
-                _decompressionStream.Skip();
+                if( Header.CompressionMethod != ZipCompressionMethod.None )
+                {
+                    _decompressionStream.Skip();
 
-                if (_decompressionStream is DeflateStream deflateStream)
+                    if (_decompressionStream is DeflateStream deflateStream)
+                    {
+                        rewindableStream.Rewind(deflateStream.InputBuffer);
+                    }
+                }
+                else
                 {
-                    rewindableStream.Rewind(deflateStream.InputBuffer);
+                    // We would need to search for the magic word
+                    rewindableStream.Position -= 4;
+                    var pos = rewindableStream.Position;
+                    while( Utility.Find(rewindableStream, new byte[] { 0x50,0x4b,0x07,0x08 } ) )
+                    {
+                        // We should probably check CRC32 for positive matching as well
+                        var size = rewindableStream.Position - pos;
+                        var br = new BinaryReader(rewindableStream);
+                        br.ReadUInt32();
+                        br.ReadUInt32(); // CRC32
+                        var compressed_size = br.ReadUInt32();
+                        var uncompressed_size = br.ReadUInt32();
+                        if (compressed_size == size && compressed_size == uncompressed_size )
+                        {
+                            rewindableStream.Position -= 16;
+                            break;
+                        }
+                        rewindableStream.Position -= 12;
+                    }
                 }
+
                 Skipped = true;
             }
             var reader = new BinaryReader(rewindableStream);

src/SharpCompress/Readers/AbstractReader.cs

@@ -132,7 +132,6 @@ private void SkipEntry()
         private void Skip()
         {
             var part = Entry.Parts.First();
-            part.Skipped = true;
 
             if (ArchiveType != ArchiveType.Rar
                 && !Entry.IsSolid
@@ -145,6 +144,7 @@ private void Skip()
                 {
                     var bytesToAdvance = Entry.CompressedSize;
                     rawStream.Skip(bytesToAdvance);
+                    part.Skipped = true;
                     return;
                 }
             }

src/SharpCompress/Utility.cs

@@ -165,6 +165,41 @@ public static void Skip(this Stream source)
             }
         }
 
+        public static bool Find(this Stream source, byte[] array)
+        {
+            byte[] buffer = GetTransferByteArray();
+            try
+            {
+                var pos = source.Position;
+                int count = 0;
+                var len = source.Read(buffer, 0, buffer.Length);
+                source.Position = pos + len;
+
+                do
+                {
+                    for (int i = 0; i < len; i++)
+                    {
+                        if (array[count] == buffer[i])
+                        {
+                            count++;
+                            if (count == array.Length)
+                            {
+                                source.Position = source.Position - len + i - array.Length +1;
+                                return true;
+                            }
+                        }
+                    }
+                }
+                while ((len = source.Read(buffer, 0, buffer.Length)) > 0);
+            }
+            finally
+            {
+                ArrayPool<byte>.Shared.Return(buffer);
+            }
+
+            return false;
+        }
+
         public static DateTime DosDateToDateTime(UInt16 iDate, UInt16 iTime)
         {
             int year = iDate / 512 + 1980;

tests/SharpCompress.Test/Zip/ZipArchiveTests.cs

@@ -738,13 +738,20 @@ public void Zip_Zip64_CompressedSizeExtraOnly_Read()
         [Fact]
         public void Zip_Uncompressed_Skip_All()
         {
-            string zipPath = Path.Combine(TEST_ARCHIVES_PATH, "Zip.uncompressed.zip");
+            var keys = new string[] { "Folder/File1.txt", "Folder/File2.rtf", "Folder2/File1.txt", "Folder2/File2.txt", "DEADBEEF" };
+            var zipPath = Path.Combine(TEST_ARCHIVES_PATH, "Zip.uncompressed.zip");
             using (var stream = File.Open(zipPath, FileMode.Open, FileAccess.Read))
             {
                 IArchive archive = ArchiveFactory.Open(stream);
                 IReader reader = archive.ExtractAllEntries();
+                int x = 0;
                 while (reader.MoveToNextEntry())
-                    ;
+                {
+                    Assert.Equal(keys[x], reader.Entry.Key);
+                    x++;
+                }
+
+                Assert.Equal(4, x);
             }
         }
     }

tests/SharpCompress.Test/Zip/ZipReaderTests.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.IO;
 using SharpCompress.Common;
 using SharpCompress.IO;
@@ -368,5 +368,21 @@ public void Zip_None_Issue86_Streamed_Read()
             }
         }
 
+        [Fact]
+        public void Zip_ReaderMoveToNextEntry()
+        {
+            var keys = new string[] { "version", "sizehint", "data/0/metadata", "data/0/records" };
+
+            using (var fileStream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, "test_477.zip")))
+            using (var reader = ZipReader.Open(fileStream))
+            {
+                foreach( var key in keys)
+                {
+                    reader.MoveToNextEntry();
+
+                    Assert.Equal(reader.Entry.Key, key);
+                }
+            }
+        }
     }
 }