Improve handling of BIO_read()/BIO_write() failures in the TLSv1.3 stack.

When BIO returns a failure, it does not always add an error to the error
stack. In the case of the legacy stack, this was generally handled by the
guesswork performed by SSL_get_error(). However, in the case of the new
stack we push an 'unknown' error onto the stack.

Improve this situation by specifically checking errno in the case of a
BIO_read() or BIO_write() failure. If the error stack is empty then push
a SYSerror() with the errno which is preferable to the 'unknown' error
later.

Noted by bluhm@ via syslogd regress.

ok beck@ tb@

0 files changed, 0 insertions, 0 deletions