protected override void Dispose(bool disposing)
{
LibZra.ZraDeleteDecompressor(_decompressor);
if (!_leaveOpen)
{
_baseStream?.Dispose();
}
base.Dispose(disposing);
}
/**
* <summary>
* Reads a sequence of bytes from the current stream and decompresses it, then advances the position within the stream by the number of bytes read.
* </summary>
* <param name="buffer">An array of bytes. When this method returns,
* the buffer contains the specified byte array with the values between offset and (offset + count - 1)
* replaced by the bytes decompressed from the current source.</param>
* <param name="offset">The zero-based byte offset in buffer at which to begin storing the data decompressed from the current stream.</param>
* <param name="count">The maximum number of bytes to be read and decompressed from the current stream.</param>
* <returns>The total number of bytes read and decompressed into the buffer.
* This can be less than the number of bytes requested if that many bytes are not currently available,
* or zero (0) if the end of the stream has been reached.</returns>
*/
public override int Read(byte[] buffer, int offset, int count)
{
long readOffset = Position + offset;
if (readOffset + count > Length)
{
count = (int)(Length - readOffset);
}
LibZra.ZraDecompressWithDecompressor(_decompressor, (ulong)readOffset, (ulong)count, buffer).ThrowIfError();
Position += count;
return(count);
}
/**
* <summary>
* Creates a <see cref="ZraDecompressionStream"/> used to stream-decompress data.
* </summary>
* <param name="baseStream">The underlying stream where the compressed data will be read from.</param>
* <param name="maxCacheSize">The maximum size of the file cache, if the uncompressed segment read goes above this then it'll be read into it's own buffer</param>
* <param name="leaveOpen">Whether to leave the underlying stream open or not when the <see cref="ZraDecompressionStream"/> is disposed.</param>
* <remarks>The cache is to preallocate buffers that are passed into readFunction, so that there isn't constant reallocation.</remarks>
* <returns><see cref="ZraDecompressionStream"/></returns>
*/
public ZraDecompressionStream(Stream baseStream, ulong maxCacheSize = 1024 * 1024 * 20, bool leaveOpen = false)
{
_baseStream = baseStream;
_leaveOpen = leaveOpen;
unsafe
{
_readFunction = (ulong offset, ulong size, byte *buffer) =>
{
_baseStream.Seek((long)offset, SeekOrigin.Begin);
_baseStream.Read(new Span <byte>(buffer, (int)size));
};
}
LibZra.ZraCreateDecompressor(out _decompressor, _readFunction, maxCacheSize).ThrowIfError();
_header = LibZra.ZraGetHeaderWithDecompressor(_decompressor);
Length = (long)LibZra.ZraGetUncompressedSizeWithHeader(_header);
}