Security: NULL pointer dereference in writer due to pipe function result handling.

Security: NULL pointer dereference in writer due to pipe function result handling.

The GCC -fanalyzer parameter helped me discover this one.

The status_pipe is being read and processed.
There is a case where the status_pipe is being set but it is not being reset after handling.
In a later loop the pipe does not get read but the previously set state is used bringing the code into a bad state.
Then the loop doesn't do the block buffer used check and this results in the eventual NULL dereference.