[PATCH] openssl_client: avoid undefined SSL_write behavior

[Eric Wong <e@80x24.org>]

Sometimes apps may trigger zero-byte chunks in the response
body for whatever reason.  We should maintain consistent
behavior with the rest of kgio; and Ruby OpenSSL::SSL::SSLSocket
should maintain consistent behavior with the core IO class:

	https://bugs.ruby-lang.org/issues/12660
---
 *sigh*  The pain of being an early adopter; it feels like
 nobody deployed non-blocking servers using Ruby OpenSSL
 to production before me :x

 c.f. https://bugs.ruby-lang.org/issues/12126

 lib/yahns/openssl_client.rb | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/yahns/openssl_client.rb b/lib/yahns/openssl_client.rb
index 439bc75..0d376bd 100644
--- a/lib/yahns/openssl_client.rb
+++ b/lib/yahns/openssl_client.rb
@@ -38,12 +38,14 @@ def yahns_init_ssl(ssl_ctx)
   end
 
   def kgio_trywrite(buf)
+    len = buf.bytesize
+    return if len == 0
     buf = @ssl_blocked = buf.dup
     case rv = @ssl.write_nonblock(buf, exception: false)
     when :wait_readable, :wait_writable
       return rv # do not clear ssl_blocked
     when Integer
-      rv = buf.bytesize == rv ? nil : buf.byteslice(rv, buf.bytesize - rv)
+      rv = len == rv ? nil : buf.byteslice(rv, len - rv)
     end
     @ssl_blocked = nil
     rv
-- 
EW