This regressed in fcf25833bc. 0 return code on
unclean shutdown means the underlying BIO returned EOF, didn't push any error
code, but we haven't seen close_notify yet. The intent seems to be that you go
check errno or some BIO-specific equivalent if you care about close_notify.
Make sure test code routes all SSL_read return codes through SSL_get_error
since that's supposed to work in all cases.
(Note that rv == 0 can still give SSL_ERROR_SSL if the error queue is not
empty.)
Change-Id: I45bf9614573f876d93419ce169a4e0d9ceea9052
Reviewed-on: https://boringssl-review.googlesource.com/2981
Reviewed-by: Adam Langley <agl@google.com>
9a38e924aa