CClash.HashUtil.DigestFile C# (CSharp) Method

        DataHash DigestFile( MD5 provider, string filepath, Regex findDateTime)
        {
            var rv = new DataHash() {
                Result = DataHashResult.FileNotFound,
                InputName = filepath,
            };

            if (!FileUtils.Exists(filepath)) return rv;
            provider.Initialize();
            var fs = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.Read);
            using (var bs = new BufferedStream(fs))
            {
                Logging.Emit("digest {0}", filepath);
                rv.Hash = new SoapHexBinary(provider.ComputeHash(bs)).ToString();
                rv.Result = DataHashResult.Ok;
                
                if (findDateTime != null) {
                    // check include cache for this file
                    
                    if (includeCache.ContainsEntry(rv.Hash, F_NotDateTime)) 
                    {
                        return rv;
                    }
                    if (includeCache.ContainsEntry(rv.Hash, F_HasDateTime)) 
                    {
                        rv.Result = DataHashResult.ContainsTimeOrDate;
                        return rv;
                    }

                    bs.Seek(0, SeekOrigin.Begin);
                    using (var ts = new StreamReader(bs))
                    {
                        string line = null;
                        do
                        {
                            line = ts.ReadLine();
                            if (line == null) 
                            {
                                includeCache.WaitOne();
                                try
                                {
                                    includeCache.AddTextFileContent(rv.Hash, F_NotDateTime, "");
                                }
                                finally
                                {
                                    includeCache.ReleaseMutex();
                                }
                                break;
                            }

                            if (findDateTime.IsMatch(line))
                            {
                                rv.Result = DataHashResult.ContainsTimeOrDate;

                                includeCache.WaitOne();
                                try
                                {
                                    includeCache.AddTextFileContent(rv.Hash, F_HasDateTime, "");
                                }
                                finally
                                {
                                    includeCache.ReleaseMutex();
                                }
                                
                                break;
                            }

                        } while (true);
                    }
                }
            }
            rv.Result = DataHashResult.Ok;
            
            return rv;
        }
    }