Lucene.Net.Store.CompoundFileDirectory.ReadLegacyEntries C# (CSharp) Method

        private static IDictionary<string, FileEntry> ReadLegacyEntries(IndexInput stream, int firstInt)
        {
            IDictionary<string, FileEntry> entries = new Dictionary<string, FileEntry>();
            int count;
            bool stripSegmentName;
            if (firstInt < CompoundFileWriter.FORMAT_PRE_VERSION)
            {
                if (firstInt < CompoundFileWriter.FORMAT_NO_SEGMENT_PREFIX)
                {
                    throw new CorruptIndexException("Incompatible format version: " + firstInt + " expected >= " + CompoundFileWriter.FORMAT_NO_SEGMENT_PREFIX + " (resource: " + stream + ")");
                }
                // It's a post-3.1 index, read the count.
                count = stream.ReadVInt();
                stripSegmentName = false;
            }
            else
            {
                count = firstInt;
                stripSegmentName = true;
            }

            // read the directory and init files
            long streamLength = stream.Length();
            FileEntry entry = null;
            for (int i = 0; i < count; i++)
            {
                long offset = stream.ReadLong();
                if (offset < 0 || offset > streamLength)
                {
                    throw new CorruptIndexException("Invalid CFS entry offset: " + offset + " (resource: " + stream + ")");
                }
                string id = stream.ReadString();

                if (stripSegmentName)
                {
                    // Fix the id to not include the segment names. this is relevant for
                    // pre-3.1 indexes.
                    id = IndexFileNames.StripSegmentName(id);
                }

                if (entry != null)
                {
                    // set length of the previous entry
                    entry.Length = offset - entry.Offset;
                }

                entry = new FileEntry();
                entry.Offset = offset;

                FileEntry previous;
                if (entries.TryGetValue(id, out previous))
                {
                    throw new CorruptIndexException("Duplicate cfs entry id=" + id + " in CFS: " + stream);
                }
                else
                {
                    entries[id] = entry;
                }
            }

            // set the length of the final entry
            if (entry != null)
            {
                entry.Length = streamLength - entry.Offset;
            }

            return entries;
        }