[PATCH 3.16 096/370] kconfig/nconf: Fix hang when editing symbol with a long prompt

Ben Hutchings
2017-03-10T14:08:36Z

From: Ben Hutchings <ben.hutchings@codethink.co.uk>

commit 79e51b5c2deea542b3bb8c66e0d502230b017dde upstream.

Currently it is impossible to edit the value of a config symbol with a
prompt longer than (terminal width - 2) characters. dialog_inputbox()
calculates a negative x-offset for the input window and newwin() fails
as this is invalid. It also doesn't check for this failure, so it
busy-loops calling wgetch(NULL) which immediately returns -1.

The additions in the offset calculations also don't match the intended
size of the window.

Limit the window size and calculate the offset similarly to
show_scroll_win().

Fixes: 692d97c380c6 ("kconfig: new configuration interface (nconfig)")
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
scripts/kconfig/nconf.gui.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

--- a/scripts/kconfig/nconf.gui.c
+++ b/scripts/kconfig/nconf.gui.c
@@ -364,12 +364,14 @@ int dialog_inputbox(WINDOW *main_window,
WINDOW *prompt_win;
WINDOW *form_win;
PANEL *panel;
- int i, x, y;
+ int i, x, y, lines, columns, win_lines, win_cols;
int res = -1;
int cursor_position = strlen(init);
int cursor_form_win;
char *result = *resultp;

+ getmaxyx(stdscr, lines, columns);
+
if (strlen(init)+1 > *result_len) {
*result_len = strlen(init)+1;
*resultp = result = realloc(result, *result_len);
@@ -386,14 +388,19 @@ int dialog_inputbox(WINDOW *main_window,
if (title)
prompt_width = max(prompt_width, strlen(title));

+ win_lines = min(prompt_lines+6, lines-2);
+ win_cols = min(prompt_width+7, columns-2);
+ prompt_lines = max(win_lines-6, 0);
+ prompt_width = max(win_cols-7, 0);
+
/* place dialog in middle of screen */
- y = (getmaxy(stdscr)-(prompt_lines+4))/2;
- x = (getmaxx(stdscr)-(prompt_width+4))/2;
+ y = (lines-win_lines)/2;
+ x = (columns-win_cols)/2;

strncpy(result, init, *result_len);

/* create the windows */
- win = newwin(prompt_lines+6, prompt_width+7, y, x);
+ win = newwin(win_lines, win_cols, y, x);
prompt_win = derwin(win, prompt_lines+1, prompt_width, 2, 2);
form_win = derwin(win, 1, prompt_width, prompt_lines+3, 2);
keypad(form_win, TRUE);