From 82ba55b8f994ab30ff561a347b82ea340ba7075c Mon Sep 17 00:00:00 2001
From: "Thomas E. Dickey" <dickey@invisible-island.net>
Date: Tue, 9 Feb 2021 23:04:41 +0000
Subject: [PATCH] snapshot of project "xterm", label xterm-365d

--- a/button.c
+++ b/button.c
@@ -4323,6 +4323,7 @@ SaltTextAway(XtermWidget xw,
     int i;
     int eol;
     int need = 0;
+    size_t have = 0;
     Char *line;
     Char *lp;
     CELL first = *cellc;
@@ -4357,7 +4358,11 @@ SaltTextAway(XtermWidget xw,
 
     /* UTF-8 may require more space */
     if_OPT_WIDE_CHARS(screen, {
-	need *= 4;
+	if (need > 0) {
+	    if (screen->max_combining > 0)
+		need += screen->max_combining;
+	    need *= 6;
+	}
     });
 
     /* now get some memory to save it in */
@@ -4395,10 +4400,20 @@ SaltTextAway(XtermWidget xw,
     }
     *lp = '\0';			/* make sure we have end marked */
 
-    TRACE(("Salted TEXT:%u:%s\n", (unsigned) (lp - line),
-	   visibleChars(line, (unsigned) (lp - line))));
+    have = (size_t) (lp - line);
+    /*
+     * Scanning the buffer twice is unnecessary.  Discard unwanted memory if
+     * the estimate is too-far off.
+     */
+    if ((have * 2) < (size_t) need) {
+	scp->data_limit = have + 1;
+	line = realloc(line, scp->data_limit);
+    }
+
+    TRACE(("Salted TEXT:%u:%s\n", (unsigned) have,
+	   visibleChars(line, (unsigned) have)));
 
-    scp->data_length = (size_t) (lp - line);
+    scp->data_length = have;
 }
 
 #if OPT_PASTE64
