From bd9c6a64e39a2d1650c0040e4b03ab04915882e8 Mon Sep 17 00:00:00 2001
From: ridiculousfish <rf@fishshell.com>
Date: Sat, 16 Apr 2022 13:25:38 -0700
Subject: [PATCH] Be careful to not touch curses variables if cur_term is null

Curses variables like `enter_italics_mode` are secretly defined to
dereference through the `cur_term` variable. Be sure we do not read or
write these curses variables if cur_term is NULL. See #8873, #8875.

Add a regression test.
---
 src/env_dispatch.cpp       |  5 +++++
 tests/pexpects/nullterm.py | 17 +++++++++++++++++
 2 files changed, 22 insertions(+)
 create mode 100644 tests/pexpects/nullterm.py

diff --git a/src/env_dispatch.cpp b/src/env_dispatch.cpp
index 588dc90ee..f989dbe6c 100644
--- a/src/env_dispatch.cpp
+++ b/src/env_dispatch.cpp
@@ -491,6 +491,11 @@ static void initialize_curses_using_fallbacks(const environment_t &vars) {
 // Apply any platform-specific hacks to cur_term/
 static void apply_term_hacks(const environment_t &vars) {
     UNUSED(vars);
+    // Be careful, variables like "enter_italics_mode" are #defined to dereference through cur_term.
+    // See #8876.
+    if (!cur_term) {
+        return;
+    }
 #ifdef __APPLE__
     // Hack in missing italics and dim capabilities omitted from MacOS xterm-256color terminfo
     // Helps Terminal.app/iTerm
diff --git a/tests/pexpects/nullterm.py b/tests/pexpects/nullterm.py
new file mode 100644
index 000000000..1e87386d2
--- /dev/null
+++ b/tests/pexpects/nullterm.py
@@ -0,0 +1,17 @@
+#!/usr/bin/env python3
+import os
+from pexpect_helper import SpawnedProc
+
+# Regression test for #8873.
+# fish doesn't crash if TERM is unset.
+env = os.environ.copy()
+env.pop("TERM", None)
+
+sp = SpawnedProc(env=env)
+sendline, expect_prompt = sp.sendline, sp.expect_prompt
+
+expect_prompt()
+sendline("set_color --italics")
+expect_prompt()
+sendline("set_color normal")
+expect_prompt()