ReadWriteVerifyTest - big file naive remaining space error checking test

gistfile1.txt

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.IO;
using System.Windows.Forms;

namespace ReadWriteVerifyTest
{
    class Program
    {
        static long ExamineBlock(FileStream fs, long startPos, long length, byte pattern)
        {
            long errors = 0;
            fs.Seek(startPos, SeekOrigin.Begin);
            // Write
            for (long l = 0; l < length; l++)
            {
                fs.WriteByte(pattern);
            }
            fs.Seek(-length, SeekOrigin.Current);
            for (long l = 0; l < length; l++)
            {
                int i = fs.ReadByte();
                if (i != pattern) { errors++; }
            }
            return errors;
        }

        static long TestBlock(FileStream fs, long block, long blockSize, long maxSize)
        {
            long blockStart = block * blockSize;
            long blockEnd = blockStart + blockSize;
            if (blockEnd > maxSize) { blockEnd = maxSize; }
            if (blockStart > maxSize) { blockStart = maxSize; }
            long testBlockSize = blockEnd - blockStart;
            if (testBlockSize <= 0) { return 0; }

            long errors = 0;
            long subErrors = 0;
            byte testPattern = 0;
            
            subErrors = 0;
            testPattern = 0xFF;
            subErrors = ExamineBlock(fs, blockStart, testBlockSize, testPattern);
            if (subErrors > 0)
            {
                Console.WriteLine("block {0} failed on test pattern 0x{1:X2} with {2} errors.", block, testPattern, subErrors);
            }
            errors += subErrors;

            subErrors = 0;
            testPattern = 0x00;
            subErrors = ExamineBlock(fs, blockStart, testBlockSize, testPattern);
            if (subErrors > 0)
            {
                Console.WriteLine("block {0} failed on test pattern 0x{1:X2} with {2} errors.", block, testPattern, subErrors);
            }
            errors += subErrors;

            subErrors = 0;
            testPattern = 0x55;
            subErrors = ExamineBlock(fs, blockStart, testBlockSize, testPattern);
            if (subErrors > 0)
            {
                Console.WriteLine("block {0} failed on test pattern 0x{1:X2} with {2} errors.", block, testPattern, subErrors);
            }
            errors += subErrors;

            subErrors = 0;
            testPattern = 0xAA;
            subErrors = ExamineBlock(fs, blockStart, testBlockSize, testPattern);
            if (subErrors > 0)
            {
                Console.WriteLine("block {0} failed on test pattern 0x{1:X2} with {2} errors.", block, testPattern, subErrors);
            }
            errors += subErrors;

            return errors;
        }

        static void DoTest(string location, long maxSize, long blockSize)
        {
            string filename = Path.Combine(location, Path.GetRandomFileName());

            using (FileStream fs = File.Create(filename))
            {
                //fs.SetLength(maxSize);
                fs.Flush();

                long blocks = (maxSize / blockSize) + ((maxSize % blockSize) > 0 ? 1 : 0);
                for (long block = 0; block < blocks; block++)
                {
                    TestBlock(fs, block, blockSize, maxSize);
                }

                fs.Close();
            }
        }

        [STAThread]
        static void Main(string[] args)
        {
            FolderBrowserDialog dlg = new FolderBrowserDialog();
            if(DialogResult.OK != dlg.ShowDialog()){return;}
            string location = dlg.SelectedPath;
            string root = Path.GetPathRoot(location);
            DriveInfo inf = new DriveInfo(root);
            long space = inf.AvailableFreeSpace;

            long blockSize = 128 * 1024;

            DoTest(location, space, blockSize);
        }
    }
}