/// <inheritdoc />
/// <exception cref="ArgumentNullException"> <paramref name="other" /> is <see langword="null" />. </exception>
/// <inheritdoc cref="DisposableBase.ThrowIfDisposed"/>
public async Task <bool> EqualsAsync(IReadOnlySafeString other)
{
ThrowIfDisposed();
if (other == null)
{
throw new ArgumentNullException(nameof(other));
}
if (other.Length == 0)
{
return(Length == 0);
}
if (this.GetHashCode() != other.GetHashCode())
{
return(false);
}
// Caution: Don't check length first and then fall out, since that leaks length info
var comparisonBit = (uint)Length ^ (uint)other.Length;
for (var i = 0; i < Length && i < other.Length; i++)
{
var ownBytes = GetAsSafeBytes(i);
var otherBytes = other.GetAsSafeBytes(i);
var areSameBytes = await ownBytes.EqualsAsync(otherBytes)
.ConfigureAwait(false);
comparisonBit |= (uint)(areSameBytes ? 0 : 1);
}
return(comparisonBit == 0);
}
private static Task DecryptAndCopyAsync(IReadOnlySafeString safeString, GCHandle handle)
{
var tasks = new Task[safeString.Length];
for (var i = 0; i < tasks.Length; i++)
{
var currentIndex = i;
tasks[currentIndex] = safeString.RevealDecryptedCharAsync(i)
.ContinueWith(charTask => CopyChar(handle, currentIndex, charTask.Result));
}
return(Task.WhenAll(tasks));
}
/// <summary>
/// Plain data of the <paramref name="safeString" /> will be available in
/// <see cref="String" /> property until this instance is disposed.
/// </summary>
/// <param name="safeString">The safe string to decrypt.</param>
/// <exception cref="ObjectDisposedException"><paramref name="safeString"/> is disposed</exception>
/// <exception cref="ArgumentNullException"> <paramref name="safeString" /> is <see langword="null" />. </exception>
/// <exception cref="InvalidOperationException">Already initialized</exception>
public async Task <IDisposableString> MarshalAsync(IReadOnlySafeString safeString)
{
if (safeString == null)
{
throw new ArgumentNullException(nameof(safeString));
}
if (safeString.IsDisposed)
{
throw new ObjectDisposedException(nameof(safeString));
}
if (safeString.IsEmpty)
{
return(new DisposableString(string.Empty, default));
}
var str = new string('\0', safeString.Length);
var handle = PinString(str);
await DecryptAndCopyAsync(safeString, handle).ConfigureAwait(false);
return(new DisposableString(str, handle));
}
/// <summary>
/// Indicates whether the specified <see cref="ISafeString"/> is null or an empty string ("").
/// </summary>
/// <param name="safeString">The string to test.</param>
/// <returns><see langword="true" /> if the value parameter is <see langword="null" /> or an empty string (""); otherwise, <see langword="false" />.</returns>
public static bool IsNullOrEmpty(IReadOnlySafeString safeString)
=> safeString == null || safeString.IsEmpty;