public async Task <string> LoadFirstLinesFromDiskAsync(string fileName, int lineCount, SecureString passphrase)
{
using (var inputStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read, 4096, true))
{
using (var outputStream = new MemoryStream())
{
var password = SecureStringCredentialStore.SecureStringToString(passphrase);
using (var cryptoStream = CipherStream.Open(inputStream, password))
{
while (cryptoStream.CanRead)
{
var buffer = new byte[4096];
await cryptoStream.ReadAsync(buffer, 0, 4096);
await outputStream.WriteAsync(buffer, 0, 4096);
char[] chunk = Encoding.UTF8.GetChars(buffer);
var occurances = chunk.Count(c => c == '\n');
if (occurances >= lineCount)
{
break;
}
}
}
outputStream.Position = 0;
using (var reader = new StreamReader(outputStream))
{
return(await reader.ReadToEndAsync());
}
}
}
}