kconfig/nconf: Fix hang when editing symbol with a long prompt

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().

Cc: stable <stable@vger.kernel.org>
Fixes: 692d97c380c6 ("kconfig: new configuration interface (nconfig)")
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>

diff --git a/scripts/kconfig/nconf.gui.c b/scripts/kconfig/nconf.gui.c
index 8275f0e55106bc0055d0a1adfe2a169ad1b54193..4b2f44c20caf8941d150f261074b40d589a10376 100644 (file)
--- 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);