Tar: Add processing for the LongLink header type

Fixes #846
adamhathcock · Jun 3, 2024 · 24aedfb · 24aedfb
1 parent 6fc4b04
commit 24aedfb
Showing 1 changed file with 30 additions and 14 deletions.
diff --git a/src/SharpCompress/Common/Tar/Headers/TarHeader.cs b/src/SharpCompress/Common/Tar/Headers/TarHeader.cs
@@ -101,57 +101,73 @@ private void WriteLongFilenameHeader(Stream output)
 
     internal bool Read(BinaryReader reader)
     {
+        string? longName = null;
+        string? longLinkName = null;
+
+read_next_block:
         var buffer = ReadBlock(reader);
+
         if (buffer.Length == 0)
         {
             return false;
         }
 
-        // for symlinks, additionally read the linkname
-        if (ReadEntryType(buffer) == EntryType.SymLink)
-        {
-            LinkName = ArchiveEncoding.Decode(buffer, 157, 100).TrimNulls();
-        }
+        var entryType = ReadEntryType(buffer);
 
-        if (ReadEntryType(buffer) == EntryType.LongName)
+        // LongName and LongLink headers can follow each other and need
+        // to apply to the header that follows them.
+        if (entryType == EntryType.LongName)
         {
-            Name = ReadLongName(reader, buffer);
-            buffer = ReadBlock(reader);
+            longName = ReadLongName(reader, buffer);
+            goto read_next_block;
         }
-        else
+        else if (entryType == EntryType.LongLink)
         {
-            Name = ArchiveEncoding.Decode(buffer, 0, 100).TrimNulls();
+            longLinkName = ReadLongName(reader, buffer);
+            goto read_next_block;
         }
 
-        EntryType = ReadEntryType(buffer);
+        Name = longName ?? ArchiveEncoding.Decode(buffer, 0, 100).TrimNulls();
+        EntryType = entryType;
         Size = ReadSize(buffer);
 
+        // for symlinks, additionally read the linkname
+        if (entryType == EntryType.SymLink
+            || entryType == EntryType.HardLink)
+        {
+            LinkName = longLinkName ?? ArchiveEncoding.Decode(buffer, 157, 100).TrimNulls();
+        }
+
         Mode = ReadAsciiInt64Base8(buffer, 100, 7);
+
         if (EntryType == EntryType.Directory)
         {
             Mode |= 0b1_000_000_000;
         }
 
         UserId = ReadAsciiInt64Base8oldGnu(buffer, 108, 7);
         GroupId = ReadAsciiInt64Base8oldGnu(buffer, 116, 7);
+
         var unixTimeStamp = ReadAsciiInt64Base8(buffer, 136, 11);
-        LastModifiedTime = EPOCH.AddSeconds(unixTimeStamp).ToLocalTime();
 
+        LastModifiedTime = EPOCH.AddSeconds(unixTimeStamp).ToLocalTime();
         Magic = ArchiveEncoding.Decode(buffer, 257, 6).TrimNulls();
 
         if (!string.IsNullOrEmpty(Magic) && "ustar".Equals(Magic))
         {
-            var namePrefix = ArchiveEncoding.Decode(buffer, 345, 157);
-            namePrefix = namePrefix.TrimNulls();
+            var namePrefix = ArchiveEncoding.Decode(buffer, 345, 157).TrimNulls();
+
             if (!string.IsNullOrEmpty(namePrefix))
             {
                 Name = namePrefix + "/" + Name;
             }
         }
+
         if (EntryType != EntryType.LongName && Name.Length == 0)
         {
             return false;
         }
+
         return true;
     }