hush: add ctrl-Z handling for nofork'ed case

1 files changed, 82 insertions, 13 deletions

diff --git a/shell/hush.c b/shell/hush.c
index e2ce3676d..c87f3b566 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -431,6 +431,56 @@ static const struct built_in_command bltins[] = {
         { NULL, NULL, NULL }
 };
 
+/* move to libbb? */
+static void signal_SA_RESTART(int sig, void (*handler)(int))
+{
+        struct sigaction sa;
+        sa.sa_handler = handler;
+        sa.sa_flags = SA_RESTART;
+        sigemptyset(&sa.sa_mask);
+        sigaction(sig, &sa, NULL);
+}
+
+static sigjmp_buf nofork_jb;
+static smallint nofork_flag;
+static struct pipe *nofork_pipe;
+
+static void handler_ctrl_z(int sig)
+{
+        pid_t pid;
+
+        fprintf(stderr, "got tty sig %d\n", sig);
+        if (!nofork_flag)
+                return;
+        pid = fork();
+        if (pid < 0) /* can't fork. Pretend there were no Ctrl-Z */
+                return;
+        fprintf(stderr, "bg'ing nofork\n");
+        nofork_flag = 0;
+        nofork_pipe->running_progs = 1;
+        nofork_pipe->stopped_progs = 0;
+        if (!pid) { /* child */
+                fprintf(stderr, "setting pgrp for child\n");
+                setpgrp();
+                signal(sig, SIG_DFL); /* make child do default action (stop) */
+                raise(sig); /* resend TSTP so that child will be stopped */
+                fprintf(stderr, "returning to child\n");
+                /* return to nofork, it will eventually exit now,
+                 * not return back to shell */
+                return;
+        }
+        /* parent */
+        /* finish filling up pipe info */
+        nofork_pipe->pgrp = pid; /* child is in its own pgrp */
+        nofork_pipe->progs[0].pid = pid;
+        nofork_pipe->running_progs = 1;
+        nofork_pipe->stopped_progs = 0;
+        /* parent needs to longjmp out of running nofork.
+         * we will "return" exitcode 0, with child put in background */
+// as usual we can have all kinds of nasty problems with leaked malloc data here
+        siglongjmp(nofork_jb, 1);
+}
+
 /* Restores tty foreground process group, and exits.
  * May be called as signal handler for fatal signal
  * (will faithfully resend signal to itself, producing correct exit state)
@@ -1535,14 +1585,32 @@ static int run_pipe_real(struct pipe *pi)
                 }
 #if ENABLE_FEATURE_SH_STANDALONE
                 {
-// FIXME: applet runs like part of shell - for example, it ignores
-// SIGINT! Try to Ctrl-C out of "rm -i"... doesn't work
                         const struct bb_applet *a = find_applet_by_name(argv[i]);
                         if (a && a->nofork) {
                                 setup_redirects(child, squirrel);
-                                rcode = run_nofork_applet(a, argv + i);
-                                restore_redirects(squirrel);
-                                return rcode;
+                                if (sigsetjmp(nofork_jb, 1) == 0) {
+// enable ctrl_z here, not globally?
+                                        nofork_flag = 1;
+                                        /* TSTP handler will store pid there etc */
+                                        nofork_pipe = pi;
+                                        rcode = run_nofork_applet(a, argv + i);
+                                        if (--nofork_flag != 0)
+                                                /* Ctrl-Z! forked, we are child */
+                                                exit(rcode);
+                                        restore_redirects(squirrel);
+                                        return rcode;
+                                } else {
+                                        fprintf(stderr, "Exiting nofork early\n");
+                                        /* Ctrl-Z, forked, we are parent.
+                                         * Sighandler has longjmped us here */
+//problem: run_nofork_applet did not do the
+// "restore" trick and globals are trashed:
+// for one, applet_name is not "hush" :)
+// need to split run_nofork_applet into setup/run/restore...
+                                        restore_redirects(squirrel);
+                                        insert_bg_job(pi);
+                                        return 0;
+                                }
                         }
                 }
 #endif
@@ -1585,7 +1653,7 @@ static int run_pipe_real(struct pipe *pi)
                                 /* Don't do pgrp restore anymore on fatal signals */
                                 set_fatal_sighandler(SIG_DFL);
                         }
-
+                        // in non-interactive case fatal sigs are already SIG_DFL
                         close_all();
                         if (nextin != 0) {
                                 dup2(nextin, 0);
@@ -2927,17 +2995,16 @@ static void setup_job_control(void)
 {
         pid_t shell_pgrp;
 
-        saved_task_pgrp = getpgrp();
+        saved_task_pgrp = shell_pgrp = getpgrp();
         debug_printf("saved_task_pgrp=%d\n", saved_task_pgrp);
         fcntl(interactive_fd, F_SETFD, FD_CLOEXEC);
 
-        /* Loop until we are in the foreground.  */
-        while (1) {
-                shell_pgrp = getpgrp();
-                if (tcgetpgrp(interactive_fd) == shell_pgrp)
-                        break;
-// and this does... what? need a comment here
+        /* If we were ran as 'hush &',
+         * sleep until we are in the foreground.  */
+        while (tcgetpgrp(interactive_fd) != shell_pgrp) {
+                /* Send TTIN to ourself (will stop us) */
                 kill(- shell_pgrp, SIGTTIN);
+                shell_pgrp = getpgrp();
         }
 
         /* Ignore job-control and misc signals.  */
@@ -2954,6 +3021,8 @@ static void setup_job_control(void)
 
         /* Grab control of the terminal.  */
         tcsetpgrp(interactive_fd, shell_pgrp);
+
+        signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
 }
 
 int hush_main(int argc, char **argv);