[1.20.0] histfile can get emptied when CONFIG_FEATURE_EDITING_SAVE_ON_EXIT=y

[Dennis Groenen]

When CONFIG_FEATURE_EDITING_SAVE_ON_EXIT is set to y, the histfile will get cleared if the total amount of history lines is less than MAX_HISTORY. 
Only if the histfile is not empty _and_ the amount of lines currently in memory are equal to or greater than MAX_HISTORY, history saving will work as expected with this feature enabled.

Output from defconfig + CONFIG_FEATURE_EDITING_SAVE_ON_EXIT=y:
[dennis at i7-820qm ~/busybox/a]$ echo "foo" > ~/.ash_history 
[dennis at i7-820qm ~/busybox/a]$ ./busybox ash
~/busybox/a $ echo "bar" > /dev/null
~/busybox/a $ exit
[dennis at i7-820qm ~/busybox/a]$ cat ~/.ash_history 
[dennis at i7-820qm ~/busybox/a]$ 

Attached is a patch that resolves this issue. Output with the patch applied and same config as above:
[dennis at i7-820qm ~/busybox/b]$ echo "foo" > ~/.ash_history 
[dennis at i7-820qm ~/busybox/b]$ ./busybox ash
~/busybox/b $ echo "bar" > /dev/null
~/busybox/b $ exit
[dennis at i7-820qm ~/busybox/b]$ cat ~/.ash_history 
foo
echo "bar" > /dev/null
exit
[dennis at i7-820qm ~/busybox/b]$ 

--Dennis

Signed-off-by: Dennis Groenen <tj.groenen at gmail.com>
---
 libbb/lineedit.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index db84167..b89748a 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -1352,8 +1352,7 @@ static void load_history(line_input_t *st_parm)
 		/* fill temp_h[], retaining only last MAX_HISTORY lines */
 		memset(temp_h, 0, sizeof(temp_h));
 		idx = 0;
-		if (!ENABLE_FEATURE_EDITING_SAVE_ON_EXIT)
-			st_parm->cnt_history_in_file = 0;
+		st_parm->cnt_history_in_file = 0;
 		while ((line = xmalloc_fgetline(fp)) != NULL) {
 			if (line[0] == '\0') {
 				free(line);
@@ -1361,8 +1360,7 @@ static void load_history(line_input_t *st_parm)
 			}
 			free(temp_h[idx]);
 			temp_h[idx] = line;
-			if (!ENABLE_FEATURE_EDITING_SAVE_ON_EXIT)
-				st_parm->cnt_history_in_file++;
+			st_parm->cnt_history_in_file++;
 			idx++;
 			if (idx == st_parm->max_history)
 				idx = 0;
-- 
1.7.10