From 620fe8e76427a3cc5783c0e632a395c9b9752c43 Mon Sep 17 00:00:00 2001
From: Craig Barnes <craigbarnes@protonmail.com>
Date: Tue, 8 Jun 2021 16:52:00 +0100
Subject: [PATCH] vt: fix buggy chains of ternary expressions in
 action_esc_dispatch()

Only the first character in the chain was being compared with `priv`
and the rest were just being evaluated as simple expressions. This
was causing the G2 and G3 operations to erroneously use the G1 index.

Since the characters are a contiguous range, we can just subtract the
start of the range to get the appropriate index. The outer switch
statement already ensures the values are in range.
---
 vt.c | 27 +++++++++------------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/vt.c b/vt.c
index fc6f8749..d0d215f1 100644
--- a/vt.c
+++ b/vt.c
@@ -442,32 +442,23 @@ action_esc_dispatch(struct terminal *term, uint8_t final)
         }
         break;  /* private[0] == 0 */
 
-    case '(':
-    case ')':
-    case '*':
-    case '+':
+    // Designate character set
+    case '(': // G0
+    case ')': // G1
+    case '*': // G2
+    case '+': // G3
         switch (final) {
         case '0': {
-            char priv = term->vt.private;
-            ssize_t idx = priv ==
-                '(' ? 0 :
-                ')' ? 1 :
-                '*' ? 2 :
-                '+' ? 3 : -1;
-            xassert(idx != -1);
+            size_t idx = term->vt.private - '(';
+            xassert(idx <= 3);
             term->charsets.set[idx] = CHARSET_GRAPHIC;
             term_update_ascii_printer(term);
             break;
         }
 
         case 'B': {
-            char priv = term->vt.private;
-            ssize_t idx = priv ==
-                '(' ? 0 :
-                ')' ? 1 :
-                '*' ? 2 :
-                '+' ? 3 : -1;
-            xassert(idx != -1);
+            size_t idx = term->vt.private - '(';
+            xassert(idx <= 3);
             term->charsets.set[idx] = CHARSET_ASCII;
             term_update_ascii_printer(term);
             break;