/// <summary>
/// Reads a tag's data from the file.
/// </summary>
/// <param name="stream">The stream to read from.</param>
/// <param name="tag">The tag to read.</param>
/// <returns>The data that was read.</returns>
public CachedTagData ExtractTag(Stream stream, CachedTagInstance tag)
{
if (tag == null)
{
throw new ArgumentNullException(nameof(tag));
}
else if (tag.HeaderOffset < 0)
{
throw new ArgumentException("The tag is not in the cache file");
}
// Build the description info and get the data offset
var data = BuildTagData(stream, tag, out uint dataOffset);
// Read the tag data
stream.Position = tag.HeaderOffset + dataOffset;
data.Data = new byte[tag.TotalSize - dataOffset];
stream.Read(data.Data, 0, data.Data.Length);
// Correct pointers
using (var dataWriter = new BinaryWriter(new MemoryStream(data.Data)))
{
foreach (var fixup in data.PointerFixups)
{
dataWriter.BaseStream.Position = fixup.WriteOffset;
dataWriter.Write(tag.OffsetToPointer(fixup.TargetOffset));
}
}
return(data);
}
/// <summary>
/// Overwrites a tag's data.
/// </summary>
/// <param name="stream">The stream to write to.</param>
/// <param name="tag">The tag to overwrite.</param>
/// <param name="data">The data to store.</param>
public void SetTagData(Stream stream, CachedTagInstance tag, CachedTagData data)
{
if (tag == null)
{
throw new ArgumentNullException(nameof(tag));
}
else if (data == null)
{
throw new ArgumentNullException(nameof(data));
}
else if (data.Group == TagGroup.None)
{
throw new ArgumentException("Cannot assign a tag to a null tag group");
}
else if (data.Data == null)
{
throw new ArgumentException("The tag data buffer is null");
}
// Ensure the data fits
var headerSize = CachedTagInstance.CalculateHeaderSize(data);
var alignedHeaderSize = (uint)((headerSize + 0xF) & ~0xF);
if (tag.HeaderOffset < 0)
{
tag.HeaderOffset = GetNewTagOffset(tag.Index);
}
var alignedLength = (data.Data.Length + 0xF) & ~0xF;
ResizeBlock(stream, tag, tag.HeaderOffset, tag.TotalSize, alignedHeaderSize + alignedLength);
tag.TotalSize = alignedHeaderSize + alignedLength;
tag.Update(data, alignedHeaderSize);
// Write in the new header and data
stream.Position = tag.HeaderOffset;
var writer = new BinaryWriter(stream);
tag.WriteHeader(writer);
StreamUtil.Fill(stream, 0, (int)(alignedHeaderSize - headerSize));
stream.Write(data.Data, 0, data.Data.Length);
StreamUtil.Fill(stream, 0, alignedLength - data.Data.Length);
// Correct pointers
foreach (var fixup in data.PointerFixups)
{
writer.BaseStream.Position = tag.HeaderOffset + alignedHeaderSize + fixup.WriteOffset;
writer.Write(tag.OffsetToPointer(alignedHeaderSize + fixup.TargetOffset));
}
UpdateTagOffsets(writer);
}
