protected override async Task <ViewFileObjectInitUnderlayFileResultParam> CreateUnderlayFileImplAsync(FileParameters option, CancellationToken cancel = default)
{
checked
{
ViewFileObjectInitUnderlayFileResultParam underlayFileObjectResult = await base.CreateUnderlayFileImplAsync(option, cancel);
try
{
HasBom = false;
long fileSize = underlayFileObjectResult.InitialSize;
if (fileSize == 0)
{
if (option.Access.Bit(FileAccess.Write))
{
await underlayFileObjectResult.FileObject.WriteRandomAsync(0, Str.BOM_UTF_8, cancel);
HasBom = true;
fileSize = 3;
}
}
else if (fileSize >= 3)
{
Memory <byte> tmp = new byte[3];
if (await underlayFileObjectResult.FileObject.ReadRandomAsync(0, tmp, cancel) == tmp.Length)
{
if (tmp.Span.SequenceEqual(Str.BOM_UTF_8.Span))
{
HasBom = true;
}
}
}
HeaderOffset = HasBom ? 3 : 0;
fileSize -= HeaderOffset;
long currentPosition = 0;
if (FileParams.Mode == FileMode.Append)
{
currentPosition = fileSize;
}
return(new ViewFileObjectInitUnderlayFileResultParam(underlayFileObjectResult.FileObject, currentPosition, fileSize));
}
catch
{
await underlayFileObjectResult.FileObject.CloseAsync();
underlayFileObjectResult.FileObject._DisposeSafe();
throw;
}
}
}
protected virtual async Task <ViewFileObjectInitUnderlayFileResultParam> CreateUnderlayFileImplAsync(FileParameters option, CancellationToken cancel = default)
{
FileObject obj = await UnderlayFileSystem.CreateFileAsync(option, cancel);
try
{
ViewFileObjectInitUnderlayFileResultParam result = new ViewFileObjectInitUnderlayFileResultParam(
obj,
obj.FileParams.Flags.Bit(FileFlags.RandomAccessOnly) ? 0 : obj.Position,
obj.Size);
return(result);
}
catch
{
obj._DisposeSafe();
throw;
}
}
internal async Task _InternalCreateFileAsync(CancellationToken cancel = default)
{
if (UnderlayFile != null)
{
throw new ApplicationException("Already inited.");
}
ViewFileObjectInitUnderlayFileResultParam createResult = await CreateUnderlayFileImplAsync(this.FileParams, cancel);
try
{
InitAndCheckFileSizeAndPosition(createResult.InitialPositon, createResult.InitialSize, cancel);
}
catch
{
createResult.FileObject._DisposeSafe();
throw;
}
this.UnderlayFile = createResult.FileObject;
}