MDEV-8014 MariaDB client can hang in an infinite loop

On EOF vio_read returns 0, it's not an error so the errno
is not reset. If the previous error was EINTR the client
will loop forever. See also man recv.

1 files changed, 3 insertions, 0 deletions

diff --git a/vio/viosocket.c b/vio/viosocket.c
index 5576dfc48d8..e724165612c 100644
--- a/vio/viosocket.c
+++ b/vio/viosocket.c
@@ -137,6 +137,9 @@ int vio_socket_io_wait(Vio *vio, enum enum_vio_io_event event)
 #define VIO_DONTWAIT 0
 #endif
 
+/*
+  returns number of bytes read or -1 in case of an error
+*/
 size_t vio_read(Vio *vio, uchar *buf, size_t size)
 {
   ssize_t ret;