Appending text to an SPFile in document library (creating file if necessary)

Question

Here is the setup. On error i want to write (append) the error message to an SPFile in a document library. If the file doesn't already exist i want to create it. Searching around this is what i came up with. However, when it attempts to create the file using SPFolder.Files.Add it throws an I/O Error exception (no inner exception/better description during debug). If the file is already there, however, all is well and the file is updated as expected. So first question would be what am i doing wrong. Second would be is there a better way to do what i am doing (no doubt there is).....any help appreciated

System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
UnicodeEncoding uniEncoding = new UnicodeEncoding();
StringBuilder errors = new StringBuilder();

foreach (Exception e in cc.aggregatedException.m_InnerExceptionsList)
{
    errors.Append(e.Message + Environment.NewLine);
}

SPFile logFile = csvList.Items.Cast<SPListItem>()
                              .Where(x => x.Name.Equals(logFileName))
                              .Select(x => x.File)
                              .FirstOrDefault();

if (logFile == null)
{
    using (MemoryStream ms = new MemoryStream())
    {
         using (StreamWriter sw = new StreamWriter(ms, uniEncoding))
         {
              sw.Write(errors.ToString());
         }

         SPFolder csvLibraryFolder = SPContext.Current.Web.Folders[libraryName];
         csvLibraryFolder.Files.Add(logFileName, ms, false);
    }
}
else
{
    byte[] fileContents = logFile.OpenBinary();
    string newContents = enc.GetString(fileContents) + 
                             Environment.NewLine + errors.ToString();
    logFile.SaveBinary(enc.GetBytes(newContents));
}                

Answer 1

Add the MemoryStream as a byte[]:

folder.Files.Add(fileName, memoryStream.ToArray(), bool);

Answer 2

This is a simple approach I have used in the past with a try/catch so maybe you could revamp for your needs:

string myResponse = "whatever needs to be written to the file...";
        string filename = "C:\\splogs\\" + (DateTime.Now).ToString("yyyyMMdd") + "_customlog.log";
        FileStream logStream = new FileStream(@filename, FileMode.Append);
        StreamWriter logfile = new StreamWriter(logStream);
        logfile.WriteLine(myResponse.ToString());
        logfile.Close();