rar5 read FHEXTRA_REDIR and expose via RarEntry

NOTE: api user should skip entries where RarEntry.IsRedir is true and not call OpenEntryStream()
adamhathcock · Mar 14, 2024 · c8683e5 · c8683e5
1 parent ab5535e
commit c8683e5
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Showing 5 changed files with 48 additions and 7 deletions.
diff --git a/src/SharpCompress/Common/Rar/Headers/FileHeader.cs b/src/SharpCompress/Common/Rar/Headers/FileHeader.cs
@@ -109,7 +109,7 @@ private void ReadFromReaderV5(MarkingBinaryReader reader)
         const ushort FHEXTRA_HASH = 0x02;
         const ushort FHEXTRA_HTIME = 0x03;
         // const ushort FHEXTRA_VERSION = 0x04;
-        // const ushort FHEXTRA_REDIR = 0x05;
+        const ushort FHEXTRA_REDIR = 0x05;
         // const ushort FHEXTRA_UOWNER = 0x06;
         // const ushort FHEXTRA_SUBDATA = 0x07;
 
@@ -120,7 +120,6 @@ private void ReadFromReaderV5(MarkingBinaryReader reader)
             var type = reader.ReadRarVIntUInt16();
             switch (type)
             {
-                //TODO
                 case FHEXTRA_CRYPT: // file encryption
 
                     {
@@ -171,11 +170,17 @@ private void ReadFromReaderV5(MarkingBinaryReader reader)
                 //
                 //                        }
                 //                        break;
-                //                    case FHEXTRA_REDIR: // file system redirection
-                //                        {
-                //
-                //                        }
-                //                        break;
+                case FHEXTRA_REDIR: // file system redirection
+
+                    {
+                        RedirType = reader.ReadRarVIntByte();
+                        RedirFlags = reader.ReadRarVIntByte();
+                        var nn = reader.ReadRarVIntUInt16();
+                        var bb = reader.ReadBytes(nn);
+                        RedirTargetName = ConvertPathV5(Encoding.UTF8.GetString(bb, 0, bb.Length));
+                    }
+                    break;
+                //TODO
                 //                    case FHEXTRA_UOWNER: // unix owner
                 //                        {
                 //
@@ -189,6 +194,7 @@ private void ReadFromReaderV5(MarkingBinaryReader reader)
 
                 default:
                     // skip unknown record types to allow new record types to be added in the future
+                    //Console.WriteLine($"unhandled rar header field type {type}");
                     break;
             }
             // drain any trailing bytes of extra record
@@ -437,6 +443,12 @@ internal byte[] FileCrc
 
     public bool IsSolid { get; private set; }
 
+    public byte RedirType { get; private set; }
+    public bool IsRedir => RedirType != 0;
+    public byte RedirFlags { get; private set; }
+    public bool IsRedirDirectory => (RedirFlags & RedirFlagV5.DIRECTORY) != 0;
+    public string RedirTargetName { get; private set; }
+
     // unused for UnpackV1 implementation (limitation)
     internal size_t WindowSize { get; private set; }
 

diff --git a/src/SharpCompress/Common/Rar/Headers/Flags.cs b/src/SharpCompress/Common/Rar/Headers/Flags.cs
@@ -157,3 +157,17 @@ internal static class EndArchiveFlagsV5
 {
     public const ushort HAS_NEXT_VOLUME = 0x0001;
 }
+
+internal static class RedirTypeV5
+{
+    public const byte UNIX_SYMLINK = 0x0001;
+    public const byte WIN_SYMLINK = 0x0002;
+    public const byte WIN_JUNCTION = 0x0003;
+    public const byte HARD_LINK = 0x0004;
+    public const byte FILE_COPY = 0x0005;
+}
+
+internal static class RedirFlagV5
+{
+    public const byte DIRECTORY = 0x0001;
+}
diff --git a/src/SharpCompress/Common/Rar/RarEntry.cs b/src/SharpCompress/Common/Rar/RarEntry.cs
@@ -66,6 +66,10 @@ public abstract class RarEntry : Entry
 
     public override bool IsSplitAfter => FileHeader.IsSplitAfter;
 
+    public bool IsRedir => FileHeader.IsRedir;
+
+    public string RedirTargetName => FileHeader.RedirTargetName;
+
     public override string ToString() =>
         string.Format(
             "Entry Path: {0} Compressed Size: {1} Uncompressed Size: {2} CRC: {3}",

diff --git a/src/SharpCompress/Compressors/Rar/RarStream.cs b/src/SharpCompress/Compressors/Rar/RarStream.cs
@@ -86,6 +86,11 @@ public override int Read(byte[] buffer, int offset, int count)
             fetch = false;
         }
         _position += outTotal;
+        if (count > 0 && outTotal == 0 && _position != Length)
+        {
+            // sanity check, eg if we try to decompress a redir entry
+            throw new InvalidOperationException($"unpacked file size does not match header: expected {Length} found {_position}");
+        }
         return outTotal;
     }
 

diff --git a/src/SharpCompress/Readers/Rar/RarReader.cs b/src/SharpCompress/Readers/Rar/RarReader.cs
@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -64,6 +65,11 @@ protected virtual IEnumerable<FilePart> CreateFilePartEnumerableForCurrentEntry(
 
     protected override EntryStream GetEntryStream()
     {
+        if (Entry.IsRedir)
+        {
+            throw new InvalidOperationException("no stream for redirect entry");
+        }
+
         var stream = new MultiVolumeReadOnlyStream(
             CreateFilePartEnumerableForCurrentEntry().Cast<RarFilePart>(),
             this