Fix problem on SerialPort ReadBufferAsync

[AdrianSoundy]

Description

This fixes a problem which caused the ReadBufferAsync etc to get in a tight loop. Trying to read data but finding the device handle is invalid which creates an exception. The calling code will try to connect again but picks up invalid handle as it thinks it still connected then tries to do a read again.

The original problem is that LoadAsync(32) initially only returns 19 bytes when the ESP32 is rebooting after a deploy.

Because it created a buffer of 32 bytes the ReadBytes tries to read 32 bytes from stream but there are only 19 available so we get an exception, data out of range.

This never ending loop also causes the Visual Studio to not close properly and processes are left in the background using lots of CPU time.

Types of changes

• [] Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Signed-off-by: adriansoundyadriansoundy@gmail.com

[nfbot]

Hi @AdrianSoundy,

I'm nanoFramework bot.
Thank you for your contribution!

A human will be reviewing it shortly. 😉

[AdrianSoundy]

Nice to get this released soon as it causes a lot of problems with Esp32

[josesimoes]

Nice finding!! 👍

[josesimoes]

Published with release following nanoframework/nf-Visual-Studio-extension#220.