Fix the checks of UI_add_input_string

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Todd Short <todd.short@me.com>
(Merged from https://github.com/openssl/openssl/pull/18424)

engines/e_loader_attic.c

@@ -70,8 +70,8 @@ static char *file_get_pass(const UI_METHOD *ui_method, char *pass,
     if ((prompt = UI_construct_prompt(ui, desc, info)) == NULL) {
         ATTICerr(0, ERR_R_MALLOC_FAILURE);
         pass = NULL;
-    } else if (!UI_add_input_string(ui, prompt, UI_INPUT_FLAG_DEFAULT_PWD,
-                                    pass, 0, maxsize - 1)) {
+    } else if (UI_add_input_string(ui, prompt, UI_INPUT_FLAG_DEFAULT_PWD,
+                                    pass, 0, maxsize - 1) <= 0) {
         ATTICerr(0, ERR_R_UI_LIB);
         pass = NULL;
     } else {

test/uitest.c

@@ -44,8 +44,8 @@ static int test_old(void)
     /* The wrapper passes the UI userdata as the callback userdata param */
     UI_add_user_data(ui, defpass);
 
-    if (!UI_add_input_string(ui, "prompt", UI_INPUT_FLAG_DEFAULT_PWD,
-                             pass, 0, sizeof(pass) - 1))
+    if (UI_add_input_string(ui, "prompt", UI_INPUT_FLAG_DEFAULT_PWD,
+                             pass, 0, sizeof(pass) - 1) <= 0)
         goto err;
 
     switch (UI_process(ui)) {