[BUG] LiteFileStream SetReadStreamPosition causes incorrect seeking about litedb

[SpaceCheetah]

@alexbereznikov It shows up when you try to seek in a file read stream. Just downloading directly to a file or copying to a memory stream works fine, but if you try to seek there's a chance depending on the file for it to seek to the wrong position. I noticed it when I was getting exceptions where it was trying to read more data from a chunk than actually existed.

Seeking to the beginning still works, seeking anywhere else in the file can fail if any chunks are smaller than max length, which for me is fairly common.

[bnuzhouwei]

It also cause that The LiteFileStream can't be use for read documents with stream by ITextSharp or other document libs.
Hope this fix as soon as possible

[CSDSP]

On the write size, MemoryStream.Read isn't guaranteed to return the maximum available number of bytes. Currently, a chunk is written for every buffer read, so whenever it happens to read less then max chunk size bytes, it still writes a chunk. This could be fixed, though it would leave the read issue in place for all current databases.

[alexbereznikov]

@CSDSP @SpaceCheetah May I ask how this issue shows itself? We have some new db corruption issues after upgrading to v5.0.19 so just wanted to know whether your fix could help us :)

[bnuzhouwei]

The Seek get error, so the file can not be suport enableRangeProcessing in MVC file result. How to fix it.!