Use external mode for term when running key bindings

Prior to this fix, when key binding is a script command (i.e. not a
readline command), fish would run that key binding using fish's shell
tty modes. Switch to using the external tty modes. This re-fixes
issue #2214.

src/fish_test_helper.cpp

@@ -113,6 +113,23 @@ static void print_ignored_signals() {
     }
 }
 
+static void print_stop_cont() {
+    signal(SIGTSTP, [](int) {
+        write(STDOUT_FILENO, "SIGTSTP\n", strlen("SIGTSTP\n"));
+        kill(getpid(), SIGSTOP);
+    });
+    signal(SIGCONT, [](int) {
+        write(STDOUT_FILENO, "SIGCONT\n", strlen("SIGCONT\n"));
+    });
+    char buff[1];
+    for (;;) {
+        if (read(STDIN_FILENO, buff, sizeof buff) >= 0) {
+            exit(0);
+        }
+    }
+
+}
+
 static void show_help();
 
 /// A thing that fish_test_helper can do.
@@ -142,6 +159,7 @@ static fth_command_t s_commands[] = {
      "Print to stdout the name(s) of blocked signals"},
     {"print_ignored_signals", print_ignored_signals,
      "Print to stdout the name(s) of ignored signals"},
+    {"print_stop_cont", print_stop_cont, "Print when we get SIGTSTP and SIGCONT, exiting on input"},
     {"help", show_help, "Print list of fish_test_helper commands"},
 };
 

src/reader.cpp

@@ -2720,11 +2720,14 @@ struct readline_loop_state_t {
 
 /// Run a sequence of commands from an input binding.
 void reader_data_t::run_input_command_scripts(const wcstring_list_t &cmds) {
+    // Need to donate/steal the tty - see #2214.
+    term_donate(outputter_t::stdoutput());
     auto last_statuses = parser().get_last_statuses();
     for (const wcstring &cmd : cmds) {
         parser().eval(cmd, io_chain_t{});
     }
     parser().set_last_statuses(std::move(last_statuses));
+    term_steal();
 }
 
 /// Read normal characters, inserting them into the command line.

tests/pexpects/fg2.py

@@ -43,3 +43,31 @@ expect_prompt("has stopped")
 sendline("fg")
 sleep(0.1) # allow tty to transfer
 send("\x03")  # control-c to cancel it
+
+expect_prompt()
+sendline("jobs")
+expect_prompt("jobs: There are no jobs")
+
+# Regression test for #2214: foregrounding from a key binding works!
+sendline(r"bind \cr 'fg >/dev/null 2>/dev/null'")
+expect_prompt()
+sendline("$fish_test_helper print_stop_cont");
+sleep(0.2)
+
+send("\x1A") # ctrl-z
+expect_prompt("SIGTSTP")
+sleep(0.1)
+send("\x12") # ctrl-r, placing fth in foreground
+expect_str("SIGCONT")
+
+# Do it again.
+send("\x1A")
+expect_str("SIGTSTP")
+sleep(0.1)
+send("\x12")
+expect_str("SIGCONT")
+
+# End fth by sending it anything.
+send("\x12")
+sendline("derp")
+expect_prompt()