hush: fix nofork + ctrl-Z clobbering of globals

3 files changed, 58 insertions, 37 deletions

diff --git a/include/libbb.h b/include/libbb.h
index fce10f310..9950c61f2 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -509,10 +509,20 @@ int wait_nohang(int *wstat);
 #define wait_exitcode(w) ((w) >> 8)
 #define wait_stopsig(w) ((w) >> 8)
 #define wait_stopped(w) (((w) & 127) == 127)
-/* Does NOT check that applet is NOFORK, just blindly runs it */
-int run_nofork_applet(const struct bb_applet *a, char **argv);
 /* wait4pid(spawn(argv)) + NOFORK/NOEXEC (if configured) */
 int spawn_and_wait(char **argv);
+struct nofork_save_area {
+        const struct bb_applet *current_applet;
+        int xfunc_error_retval;
+        uint32_t option_mask32;
+        int die_sleep;
+        smallint saved;
+};
+void save_nofork_data(struct nofork_save_area *save);
+void restore_nofork_data(struct nofork_save_area *save);
+/* Does NOT check that applet is NOFORK, just blindly runs it */
+int run_nofork_applet(const struct bb_applet *a, char **argv);
+int run_nofork_applet_prime(struct nofork_save_area *old, const struct bb_applet *a, char **argv);
 
 /* Helpers for daemonization.
  *
diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index 78f3c4ad4..aef74e994 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -100,15 +100,28 @@ int wait_pid(int *wstat, int pid)
         return r;
 }
 
-int run_nofork_applet(const struct bb_applet *a, char **argv)
+void save_nofork_data(struct nofork_save_area *save)
 {
-        int rc, argc;
+        save->current_applet = current_applet;
+        save->xfunc_error_retval = xfunc_error_retval;
+        save->option_mask32 = option_mask32;
+        save->die_sleep = die_sleep;
+        save->saved = 1;
+}
 
-        /* Save some shared globals */
-        const struct bb_applet *old_a = current_applet;
-        int old_x = xfunc_error_retval;
-        uint32_t old_m = option_mask32;
-        int old_sleep = die_sleep;
+void restore_nofork_data(struct nofork_save_area *save)
+{
+        current_applet = save->current_applet;
+        xfunc_error_retval = save->xfunc_error_retval;
+        option_mask32 = save->option_mask32;
+        die_sleep = save->die_sleep;
+
+        applet_name = current_applet->name;
+}
+
+int run_nofork_applet_prime(struct nofork_save_area *old, const struct bb_applet *a, char **argv)
+{
+        int rc, argc;
 
         current_applet = a;
         applet_name = a->name;
@@ -138,14 +151,18 @@ int run_nofork_applet(const struct bb_applet *a, char **argv)
         }
 
         /* Restoring globals */
-        current_applet = old_a;
-        applet_name = old_a->name;
-        xfunc_error_retval = old_x;
-        option_mask32 = old_m;
-        die_sleep = old_sleep;
+        restore_nofork_data(old);
         return rc;
 }
 
+int run_nofork_applet(const struct bb_applet *a, char **argv)
+{
+        struct nofork_save_area old;
+        /* Saving globals */
+        save_nofork_data(&old);
+        return run_nofork_applet_prime(&old, a, argv);
+}
+
 int spawn_and_wait(char **argv)
 {
         int rc;
diff --git a/shell/hush.c b/shell/hush.c
index c87f3b566..b2ff0cb2e 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -441,30 +441,28 @@ static void signal_SA_RESTART(int sig, void (*handler)(int))
         sigaction(sig, &sa, NULL);
 }
 
+struct nofork_save_area nofork_save;
 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;
+        debug_jobs_printf("got tty sig %d\n", sig);
         pid = fork();
         if (pid < 0) /* can't fork. Pretend there were no Ctrl-Z */
                 return;
-        fprintf(stderr, "bg'ing nofork\n");
-        nofork_flag = 0;
+        debug_jobs_printf("bg'ing nofork\n");
+        nofork_save.saved = 0; /* flag the fact that Ctrl-Z was handled */
         nofork_pipe->running_progs = 1;
         nofork_pipe->stopped_progs = 0;
         if (!pid) { /* child */
-                fprintf(stderr, "setting pgrp for child\n");
+                debug_jobs_printf("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");
+                signal(SIGTSTP, SIG_DFL); /* make child do default action (stop) */
+                raise(SIGTSTP); /* resend TSTP so that child will be stopped */
+                debug_jobs_printf("returning to child\n");
                 /* return to nofork, it will eventually exit now,
                  * not return back to shell */
                 return;
@@ -1588,25 +1586,23 @@ static int run_pipe_real(struct pipe *pi)
                         const struct bb_applet *a = find_applet_by_name(argv[i]);
                         if (a && a->nofork) {
                                 setup_redirects(child, squirrel);
+                                /* TSTP handler will store pid etc in pi */
+                                nofork_pipe = pi;
+                                save_nofork_data(&nofork_save);
                                 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)
+                                        signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
+                                        rcode = run_nofork_applet_prime(&nofork_save, a, argv + i);
+                                        if (--nofork_save.saved != 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...
+                                        signal(SIGTSTP, SIG_IGN);
+                                        debug_jobs_printf("Exiting nofork early\n");
+                                        restore_nofork_data(&nofork_save);
                                         restore_redirects(squirrel);
                                         insert_bg_job(pi);
                                         return 0;
@@ -3021,8 +3017,6 @@ 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);