NOFORK fixes

"rm -i FILE" and "yes" can now be interrupted by ^C in hush.
This also now works:

$ usleep 19999999
^C
$ echo $?
130

function                                             old     new   delta
run_pipe                                            1668    1711     +43
pseudo_exec_argv                                     312     321      +9
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 52/0)               Total: 52 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 30 insertions, 1 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 7cceab30d..2e435cf9f 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -7063,6 +7063,8 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
                         if (APPLET_IS_NOEXEC(a)) {
                                 /* Do not leak open fds from opened script files etc */
                                 close_all_FILE_list();
+                                /* Without this, "rm -i FILE" can't be ^C'ed: */
+                                switch_off_special_sigs(G.special_sig_mask);
                                 debug_printf_exec("running applet '%s'\n", argv[0]);
                                 run_applet_no_and_exit(a, argv[0], argv);
                         }
@@ -7725,6 +7727,24 @@ static NOINLINE int run_pipe(struct pipe *pi)
                         add_vars(old_vars);
 /* clean_up_and_ret0: */
                         restore_redirects(squirrel);
+                        /*
+                         * Try "usleep 99999999" + ^C + "echo $?"
+                         * with FEATURE_SH_NOFORK=y.
+                         */
+                        if (!funcp) {
+                                /* It was builtin or nofork.
+                                 * if this would be a real fork/execed program,
+                                 * it should have died if a fatal sig was received.
+                                 * But OTOH, there was no separate process,
+                                 * the sig was sent to _shell_, not to non-existing
+                                 * child.
+                                 * Let's just handle ^C only, this one is obvious:
+                                 * we aren't ok with exitcode 0 when ^C was pressed
+                                 * during builtin/nofork.
+                                 */
+                                if (sigismember(&G.pending_set, SIGINT))
+                                        rcode = 128 + SIGINT;
+                        }
  clean_up_and_ret1:
                         free(argv_expanded);
                         IF_HAS_KEYWORDS(if (pi->pi_inverted) rcode = !rcode;)
@@ -7740,6 +7760,14 @@ static NOINLINE int run_pipe(struct pipe *pi)
                                 if (rcode == 0) {
                                         debug_printf_exec(": run_nofork_applet '%s' '%s'...\n",
                                                 argv_expanded[0], argv_expanded[1]);
+                                        /*
+                                         * Note: signals (^C) can't interrupt here.
+                                         * We remember them and they will be acted upon
+                                         * after applet returns.
+                                         * This makes applets which can run for a long time
+                                         * and/or wait for user input ineligible for NOFORK:
+                                         * for example, "yes" or "rm" (rm -i waits for input).
+                                         */
                                         rcode = run_nofork_applet(n, argv_expanded);
                                 }
                                 goto clean_up_and_ret;
@@ -8160,7 +8188,7 @@ static int run_list(struct pipe *pi)
                         /* Last command's pid goes to $! */
                         G.last_bg_pid = pi->cmds[pi->num_cmds - 1].pid;
                         debug_printf_exec(": cmd&: exitcode EXIT_SUCCESS\n");
-/* Check pi->pi_inverted? "! sleep 1 & echo $?": bash says 1. dash and ash says 0 */
+/* Check pi->pi_inverted? "! sleep 1 & echo $?": bash says 1. dash and ash say 0 */
                         rcode = EXIT_SUCCESS;
                         goto check_traps;
                 } else {
@@ -9791,6 +9819,7 @@ static int wait_for_child_or_signal(struct pipe *waitfor_pipe, pid_t waitfor_pid
                 /* So, did we get a signal? */
                 sig = check_and_run_traps();
                 if (sig /*&& sig != SIGCHLD - always true */) {
+                        /* Do this for any (non-ignored) signal, not only for ^C */
                         ret = 128 + sig;
                         break;
                 }