libutil/terminal: cache isTTY()

NixOS · Mar 2, 2024 · c6f0407 · c6f0407
1 parent 8c1eeb4
commit c6f0407
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/src/libutil/terminal.cc b/src/libutil/terminal.cc
@@ -9,9 +9,12 @@ namespace nix {
 
 bool isTTY()
 {
-    return isatty(STDERR_FILENO)
+    static const bool tty =
+        isatty(STDERR_FILENO)
         && getEnv("TERM").value_or("dumb") != "dumb"
         && !(getEnv("NO_COLOR").has_value() || getEnv("NOCOLOR").has_value());
+
+    return tty;
 }
 
 std::string filterANSIEscapes(std::string_view s, bool filterAll, unsigned int width)