remove global "jmp_buf die_jmp" from !FEATURE_PREFER_APPLETS builds

function                                             old     new   delta
xfunc_has_died                                         -      21     +21
sleep_much                                             -      12     +12
sleep10                                                -       9      +9
die_func                                               -       4      +4
fflush_stdout_and_exit                                35      36      +1
builtin_type                                         121     119      -2
die_sleep                                              4       -      -4
xfunc_die                                             60      24     -36
hush_main                                           1128    1011    -117
die_jmp                                              156       -    -156
------------------------------------------------------------------------------
(add/remove: 4/2 grow/shrink: 1/3 up/down: 47/-315)          Total: -268 bytes
   text	   data	    bss	    dec	    hex	filename
 939992	    992	  17652	 958636	  ea0ac	busybox_old
 939880	    992	  17496	 958368	  e9fa0	busybox_unstripped

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

include/libbb.h

@@ -1127,9 +1127,8 @@ enum {
 extern const char *msg_eol;
 extern smallint syslog_level;
 extern smallint logmode;
-extern int die_sleep;
 extern uint8_t xfunc_error_retval;
-extern jmp_buf die_jmp;
+extern void (*die_func)(void);
 extern void xfunc_die(void) NORETURN FAST_FUNC;
 extern void bb_show_usage(void) NORETURN FAST_FUNC;
 extern void bb_error_msg(const char *s, ...) __attribute__ ((format (printf, 1, 2))) FAST_FUNC;

init/init.c

@@ -1015,6 +1015,11 @@ void handle_sigsegv(int sig, siginfo_t *info, void *ucontext)
 }
 #endif
 
+static void sleep_much(void)
+{
+        sleep(30 * 24*60*60);
+}
+
 int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int init_main(int argc UNUSED_PARAM, char **argv)
 {
@@ -1051,12 +1056,12 @@ int init_main(int argc UNUSED_PARAM, char **argv)
 
 	/* If, say, xmalloc would ever die, we don't want to oops kernel
 	 * by exiting.
-	 * NB: we set die_sleep *after* PID 1 check and bb_show_usage.
+	 * NB: we set die_func *after* PID 1 check and bb_show_usage.
 	 * Otherwise, for example, "init u" ("please rexec yourself"
 	 * command for sysvinit) will show help text (which isn't too bad),
 	 * *and sleep forever* (which is bad!)
 	 */
-	die_sleep = 30 * 24*60*60;
+	die_func = sleep_much;
 
 	/* Figure out where the default console should be */
 	console_init();

libbb/fflush_stdout_and_exit.c

@@ -15,15 +15,10 @@
 
 void FAST_FUNC fflush_stdout_and_exit(int retval)
 {
+	xfunc_error_retval = retval;
 	if (fflush(stdout))
 		bb_perror_msg_and_die(bb_msg_standard_output);
-
+	/* In case we are in NOFORK applet. Do not exit() directly,
-	if (ENABLE_FEATURE_PREFER_APPLETS && die_sleep < 0) {
-		/* We are in NOFORK applet. Do not exit() directly,
 	 * but use xfunc_die() */
-		xfunc_error_retval = retval;
 	xfunc_die();
 }
-
-	exit(retval);
-}

libbb/vfork_daemon_rexec.c

@@ -69,28 +69,44 @@ pid_t FAST_FUNC xspawn(char **argv)
 }
 
 #if ENABLE_FEATURE_PREFER_APPLETS
+static jmp_buf die_jmp;
+static void jump(void)
+{
+	/* Special case. We arrive here if NOFORK applet
+	 * calls xfunc, which then decides to die.
+	 * We don't die, but jump instead back to caller.
+	 * NOFORK applets still cannot carelessly call xfuncs:
+	 * p = xmalloc(10);
+	 * q = xmalloc(10); // BUG! if this dies, we leak p!
+	 */
+	/* | 0x100 allows to pass zero exitcode (longjmp can't pass 0).
+	 * This works because exitcodes are bytes,
+	 * run_nofork_applet() ensures that by "& 0xff" */
+	longjmp(die_jmp, xfunc_error_retval | 0x100);
+}
+
 struct nofork_save_area {
 	jmp_buf die_jmp;
+	void (*die_func)(void);
 	const char *applet_name;
 	uint32_t option_mask32;
-	int die_sleep;
 	uint8_t xfunc_error_retval;
 };
 static void save_nofork_data(struct nofork_save_area *save)
 {
 	memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
+	save->die_func = die_func;
 	save->applet_name = applet_name;
-	save->xfunc_error_retval = xfunc_error_retval;
 	save->option_mask32 = option_mask32;
-	save->die_sleep = die_sleep;
+	save->xfunc_error_retval = xfunc_error_retval;
 }
 static void restore_nofork_data(struct nofork_save_area *save)
 {
 	memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp));
+	die_func = save->die_func;
 	applet_name = save->applet_name;
-	xfunc_error_retval = save->xfunc_error_retval;
 	option_mask32 = save->option_mask32;
-	die_sleep = save->die_sleep;
+	xfunc_error_retval = save->xfunc_error_retval;
 }
 
 int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
@@ -133,11 +149,8 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
 	while (argv[argc])
 		argc++;
 
-	/* Special flag for xfunc_die(). If xfunc will "die"
+	/* If xfunc "dies" in NOFORK applet, die_func longjmp's here instead */
-	 * in NOFORK applet, xfunc_die() sees negative
+	die_func = jump;
-	 * die_sleep and longjmp here instead. */
-	die_sleep = -1;
-
 	rc = setjmp(die_jmp);
 	if (!rc) {
 		/* Some callers (xargs)
@@ -146,10 +159,8 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
 		memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0]));
 		/* Finally we can call NOFORK applet's main() */
 		rc = applet_main[applet_no](argc, tmp_argv);
-	} else { /* xfunc died in NOFORK applet */
+	} else {
-		/* in case they meant to return 0... */
+		/* xfunc died in NOFORK applet */
-		if (rc == -2222)
-			rc = 0;
 	}
 
 	/* Restoring some globals */

libbb/xfunc_die.c

@@ -7,34 +7,16 @@
  * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 
-/* Keeping it separate allows to NOT suck in stdio for VERY small applets.
+/* Keeping it separate allows to NOT pull in stdio for VERY small applets.
  * Try building busybox with only "true" enabled... */
 
 #include "libbb.h"
 
-int die_sleep;
+void (*die_func)(void);
-#if ENABLE_FEATURE_PREFER_APPLETS || ENABLE_HUSH
-jmp_buf die_jmp;
-#endif
 
 void FAST_FUNC xfunc_die(void)
 {
-	if (die_sleep) {
+	if (die_func)
-		if ((ENABLE_FEATURE_PREFER_APPLETS || ENABLE_HUSH)
+		die_func();
-		 && die_sleep < 0
-		) {
-			/* Special case. We arrive here if NOFORK applet
-			 * calls xfunc, which then decides to die.
-			 * We don't die, but jump instead back to caller.
-			 * NOFORK applets still cannot carelessly call xfuncs:
-			 * p = xmalloc(10);
-			 * q = xmalloc(10); // BUG! if this dies, we leak p!
-			 */
-			/* -2222 means "zero" (longjmp can't pass 0)
-			 * run_nofork_applet() catches -2222. */
-			longjmp(die_jmp, xfunc_error_retval ? xfunc_error_retval : -2222);
-		}
-		sleep(die_sleep);
-	}
 	exit(xfunc_error_retval);
 }

loginutils/getty.c

@@ -520,6 +520,11 @@ static void alarm_handler(int sig UNUSED_PARAM)
 	_exit(EXIT_SUCCESS);
 }
 
+static void sleep10(void)
+{
+	sleep(10);
+}
+
 int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int getty_main(int argc UNUSED_PARAM, char **argv)
 {
@@ -599,7 +604,7 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
 		close(n--);
 
 	/* Logging. We want special flavor of error_msg_and_die */
-	die_sleep = 10;
+	die_func = sleep10;
 	msg_eol = "\r\n";
 	/* most likely will internally use fd #3 in CLOEXEC mode: */
 	openlog(applet_name, LOG_PID, LOG_AUTH);

shell/hush.c

@@ -1479,10 +1479,11 @@ static sighandler_t install_sighandler(int sig, sighandler_t handler)
 
 #if ENABLE_HUSH_JOB
 
+static void xfunc_has_died(void);
 /* After [v]fork, in child: do not restore tty pgrp on xfunc death */
-# define disable_restore_tty_pgrp_on_exit() (die_sleep = 0)
+# define disable_restore_tty_pgrp_on_exit() (die_func = NULL)
 /* After [v]fork, in parent: restore tty pgrp on xfunc death */
-# define enable_restore_tty_pgrp_on_exit()  (die_sleep = -1)
+# define enable_restore_tty_pgrp_on_exit()  (die_func = xfunc_has_died)
 
 /* Restores tty foreground process group, and exits.
  * May be called as signal handler for fatal signal
@@ -1587,6 +1588,15 @@ static void hush_exit(int exitcode)
 #endif
 }
 
+static void xfunc_has_died(void) NORETURN;
+static void xfunc_has_died(void)
+{
+	/* xfunc has failed! die die die */
+	/* no EXIT traps, this is an escape hatch! */
+	G.exiting = 1;
+	hush_exit(xfunc_error_retval);
+}
+
 
 //TODO: return a mask of ALL handled sigs?
 static int check_and_run_traps(void)
@@ -7866,12 +7876,7 @@ int hush_main(int argc, char **argv)
 	/* Initialize some more globals to non-zero values */
 	cmdedit_update_prompt();
 
-	if (setjmp(die_jmp)) {
+	die_func = xfunc_has_died;
-		/* xfunc has failed! die die die */
-		/* no EXIT traps, this is an escape hatch! */
-		G.exiting = 1;
-		hush_exit(xfunc_error_retval);
-	}
 
 	/* Shell is non-interactive at first. We need to call
 	 * install_special_sighandlers() if we are going to execute "sh <script>",
@@ -8129,9 +8134,7 @@ int hush_main(int argc, char **argv)
 			/* Grab control of the terminal */
 			tcsetpgrp(G_interactive_fd, getpid());
 		}
-		/* -1 is special - makes xfuncs longjmp, not exit
+		enable_restore_tty_pgrp_on_exit();
-		 * (we reset die_sleep = 0 whereever we [v]fork) */
-		enable_restore_tty_pgrp_on_exit(); /* sets die_sleep = -1 */
 
 # if ENABLE_HUSH_SAVEHISTORY && MAX_HISTORY > 0
 		{