io BUGFIX unset errno means EOF

Author: michalvasko

src/io.c

@@ -181,7 +181,7 @@ nc_read(struct nc_session *session, char *buf, size_t count, uint32_t inact_time
                     session->term_reason = NC_SESSION_TERM_DROPPED;
                     return -1;
                 case SSL_ERROR_SYSCALL:
-                    ERR(session, "SSL socket error (%s).", strerror(errno));
+                    ERR(session, "SSL socket error (%s).", errno ? strerror(errno) : "unexpected EOF");
                     session->status = NC_STATUS_INVALID;
                     session->term_reason = NC_SESSION_TERM_OTHER;
                     return -1;

src/session_client_tls.c

@@ -650,7 +650,7 @@ nc_connect_tls(const char *host, unsigned short port, struct ly_ctx *ctx)
     if (ret != 1) {
         switch (SSL_get_error(session->ti.tls, ret)) {
         case SSL_ERROR_SYSCALL:
-            ERR(NULL, "SSL_connect failed (%s).", strerror(errno));
+            ERR(NULL, "SSL_connect failed (%s).", errno ? strerror(errno) : "unexpected EOF");
             break;
         case SSL_ERROR_SSL:
             ERR(NULL, "SSL_connect failed (%s).", ERR_reason_error_string(ERR_get_error()));