public OpenedReader(MetadataReaderProvider provider, MetadataReader reader)
{
Debug.Assert(provider != null);
Debug.Assert(reader != null);
Provider = provider;
Reader = reader;
}
/// <summary>
/// Creates a provider for a stream of the specified size beginning at its current position.
/// </summary>
/// <param name="stream">Stream.</param>
/// <param name="size">Size of the metadata blob in the stream. If not specified the metadata blob is assumed to span to the end of the stream.</param>
/// <param name="options">
/// Options specifying how sections of the image are read from the stream.
///
/// Unless <see cref="MetadataStreamOptions.LeaveOpen"/> is specified, ownership of the stream is transferred to the <see cref="MetadataReaderProvider"/>
/// upon successful argument validation. It will be disposed by the <see cref="MetadataReaderProvider"/> and the caller must not manipulate it.
///
/// Unless <see cref="MetadataStreamOptions.PrefetchMetadata"/> is specified no data
/// is read from the stream during the construction of the <see cref="MetadataReaderProvider"/>. Furthermore, the stream must not be manipulated
/// by caller while the <see cref="MetadataReaderProvider"/> is alive and undisposed.
///
/// If <see cref="MetadataStreamOptions.PrefetchMetadata"/>, the <see cref="MetadataReaderProvider"/>
/// will have read all of the data requested during construction. As such, if <see cref="MetadataStreamOptions.LeaveOpen"/> is also
/// specified, the caller retains full ownership of the stream and is assured that it will not be manipulated by the <see cref="MetadataReaderProvider"/>
/// after construction.
/// </param>
/// <exception cref="ArgumentNullException"><paramref name="stream"/> is null.</exception>
/// <exception cref="ArgumentException"><paramref name="stream"/> doesn't support read and seek operations.</exception>
/// <exception cref="ArgumentOutOfRangeException">Size is negative or extends past the end of the stream.</exception>
/// <exception cref="IOException">Error reading from the stream (only when <see cref="MetadataStreamOptions.PrefetchMetadata"/> is specified).</exception>
public static MetadataReaderProvider FromMetadataStream(Stream stream, MetadataStreamOptions options = MetadataStreamOptions.Default, int size = 0)
{
if (stream == null)
{
throw new ArgumentNullException(nameof(stream));
}
if (!stream.CanRead || !stream.CanSeek)
{
throw new ArgumentException(SR.StreamMustSupportReadAndSeek, nameof(stream));
}
if (!options.IsValid())
{
throw new ArgumentOutOfRangeException(nameof(options));
}
long start = stream.Position;
int actualSize = StreamExtensions.GetAndValidateSize(stream, size, nameof(stream));
MetadataReaderProvider result;
bool closeStream = true;
try
{
bool isFileStream = FileStreamReadLightUp.IsFileStream(stream);
if ((options & MetadataStreamOptions.PrefetchMetadata) == 0)
{
result = new MetadataReaderProvider(new StreamMemoryBlockProvider(stream, start, actualSize, isFileStream, (options & MetadataStreamOptions.LeaveOpen) != 0));
closeStream = false;
}
else
{
// Read in the entire image or metadata blob:
result = new MetadataReaderProvider(StreamMemoryBlockProvider.ReadMemoryBlockNoLock(stream, isFileStream, start, actualSize));
// We read all we need, the stream is going to be closed.
}
}
finally
{
if (closeStream && (options & MetadataStreamOptions.LeaveOpen) == 0)
{
stream.Dispose();
}
}
return result;
}
