Hi,
I found a very annoying bug in the authentication feature of grub
(grub-core/normal/auth.c). The feature uses the function grub_printf to
print backspaces to the screen, but the function fails to remove/override
the last printed character and setting the cursor one step back (printing
backspace). It simply moves the cursor one step forward, when it reveives a
backspace character. Therfore the username entered by user is not displayed
correctly, if the user used the backspace key (this problem has no effect
on the input buffer; it only affects the display of the user input).
The patch I attached this mail should fix this bug. It manipulates the
cursor directly, if the user pressed the backspace key.
--- a/grub-core/normal/auth.c
+++ b/grub-core/normal/auth.c
@@ -159,10 +159,13 @@ grub_username_get (char buf[], unsigned buf_size)
{
unsigned cur_len = 0;
int key;
+ struct grub_term_output *term;
+ struct grub_term_coordinate coords;
while (1)
{
- key = grub_getkey ();
+ key = grub_getkey ();
+
if (key == '\n' || key == '\r')
break;
@@ -177,7 +180,19 @@ grub_username_get (char buf[], unsigned buf_size)
if (cur_len)
{
cur_len--;
- grub_printf ("\b \b");
+ FOR_ACTIVE_TERM_OUTPUTS(term)
+ {
+ coords=grub_term_getxy (term);
+ if (coords.x) coords.x--;
+ else
+ {
+ coords.x = grub_term_width (term);
+ coords.y--;
+ }
+ grub_term_gotoxy (term, coords);
+ grub_puts_terminal (" ", term);
+ grub_term_gotoxy (term, coords);
+ }
}
continue;
}
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