From 2a3b4221375235fb94aa083fec3ccfed06a96d0c Mon Sep 17 00:00:00 2001
From: Joachim Nilsson <troglobit@gmail.com>
Date: Wed, 29 Nov 2017 14:53:14 +0100
Subject: [PATCH] Fix negative array index triggered by i-search

This is a fix to a bug reported by Claus Fischer.  When doing a reversed
i-search on the history, clear_line() sets rl_point to a negative value,
which is later used by ceol().  The intention is to clear the whole line
for the new Search: prompt, but indexing an array with a negative value
is strongly discouraged.

To prevent this negative indexing from happening we check in ceol() for
rl_point < 0, but we quickly notice another side effect: one lingering
character at the end of line when returning from i-search.  The problem
manifests itself more cleary when having a looooo000ooonong prompt.

The fix is to rub out the extra space, insert the i-search string, and
*then* call ceol() again.

Thanks to Claus for pointing this out!

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
---
 src/editline.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/editline.c b/src/editline.c
index 9b549db..0142a81 100644
--- a/src/editline.c
+++ b/src/editline.c
@@ -431,11 +431,17 @@ static el_status_t case_cap_word(void)
 
 static void ceol(void)
 {
-    int         extras;
+    int         extras = 0;
     int         i;
     char        *p;
 
-    for (extras = 0, i = rl_point, p = &rl_line_buffer[i]; i <= rl_end; i++, p++) {
+    while (rl_point < 0) {
+        tty_put(' ');
+	rl_point++;
+	extras++;
+    }
+
+    for (i = rl_point, p = &rl_line_buffer[i]; i <= rl_end; i++, p++) {
         tty_put(' ');
         if (ISMETA(*p)) {
 	    if (rl_meta_chars) {
@@ -443,7 +449,7 @@ static void ceol(void)
 		tty_put(' ');
 		extras += 2;
 	    }
-	} if (ISCTL(*p)) {
+	} else if (ISCTL(*p)) {
             tty_put(' ');
             extras++;
         }
@@ -525,15 +531,19 @@ static const char *prev_hist(void)
 
 static el_status_t do_insert_hist(const char *p)
 {
+    el_status_t ret;
+
     if (p == NULL)
         return el_ring_bell();
 
     rl_point = 0;
     reposition();
-    ceol();
     rl_end = 0;
 
-    return insert_string(p);
+    ret = insert_string(p);
+    ceol();
+
+    return ret;
 }
 
 static el_status_t do_hist(const char *(*move)(void))