noexec: consolidate code

function                                             old     new   delta
run_noexec_applet_and_exit                             -      61     +61
find_applet_by_name                                  128     124      -4
run_applet_no_and_exit                               441     434      -7
tryexec                                              169     152     -17
pseudo_exec_argv                                     338     321     -17
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/6 up/down: 61/-48)             Total: 13 bytes

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

include/libbb.h

@@ -1112,9 +1112,10 @@ int wait_for_exitstatus(pid_t pid) FAST_FUNC;
 int spawn_and_wait(char **argv) FAST_FUNC;
 /* Does NOT check that applet is NOFORK, just blindly runs it */
 int run_nofork_applet(int applet_no, char **argv) FAST_FUNC;
+void run_noexec_applet_and_exit(int a, const char *name, char **argv) NORETURN FAST_FUNC;
 #ifndef BUILD_INDIVIDUAL
-extern int find_applet_by_name(const char *name) FAST_FUNC;
+int find_applet_by_name(const char *name) FAST_FUNC;
-extern void run_applet_no_and_exit(int a, const char *name, char **argv) NORETURN FAST_FUNC;
+void run_applet_no_and_exit(int a, const char *name, char **argv) NORETURN FAST_FUNC;
 #endif
 #if defined(__linux__)
 void set_task_comm(const char *comm) FAST_FUNC;

libbb/appletlib.c

@@ -924,8 +924,6 @@ void FAST_FUNC run_applet_no_and_exit(int applet_no, const char *name, char **ar
 {
 	int argc = string_array_len(argv);
 
-	/* Reinit some shared global data */
-	xfunc_error_retval = EXIT_FAILURE;
 	/*
 	 * We do not use argv[0]: do not want to repeat massaging of
 	 * "-/sbin/halt" -> "halt", for example.

libbb/vfork_daemon_rexec.c

@@ -158,6 +158,26 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
 }
 #endif /* FEATURE_PREFER_APPLETS || FEATURE_SH_NOFORK */
 
+#if (NUM_APPLETS > 1) && (ENABLE_FEATURE_PREFER_APPLETS || ENABLE_FEATURE_SH_STANDALONE)
+void FAST_FUNC run_noexec_applet_and_exit(int a, const char *name, char **argv)
+{
+	/* reset some state and run without execing */
+	/* msg_eol = "\n"; - no caller needs this reinited yet */
+	logmode = LOGMODE_STDIO;
+	xfunc_error_retval = EXIT_FAILURE;
+	die_func = NULL;
+	GETOPT_RESET();
+
+//TODO: think pidof, pgrep, pkill!
+//set_task_comm() makes our pidof find NOEXECs (e.g. "yes >/dev/null"),
+//but one from procps-ng-3.3.10 needs more!
+//Rewrite /proc/PID/cmdline? (need to save argv0 and length at init for this to work!)
+	set_task_comm(name);
+	/* xfunc_error_retval and applet_name are init by: */
+	run_applet_no_and_exit(a, name, argv);
+}
+#endif
+
 int FAST_FUNC spawn_and_wait(char **argv)
 {
 	int rc;
@@ -175,22 +195,7 @@ int FAST_FUNC spawn_and_wait(char **argv)
 				return wait4pid(rc);
 
 			/* child */
-			/* reset some state and run without execing */
+			run_noexec_applet_and_exit(a, argv[0], argv);
-			GETOPT_RESET();
-
-			/* msg_eol = "\n"; - no caller needs this reinited yet */
-			logmode = LOGMODE_STDIO;
-			/* die_func = NULL; - needed if the caller is a shell,
-			 * init, or a NOFORK applet. But none of those call us
-			 * as of yet (and that should probably always stay true).
-			 */
-//TODO: think pidof, pgrep, pkill!
-//set_task_comm() makes our pidof find NOEXECs (e.g. "yes >/dev/null"),
-//but one from procps-ng-3.3.10 needs more!
-//Rewrite /proc/PID/cmdline? (need to save argv0 and length at init for this to work!)
-			set_task_comm(argv[0]);
-			/* xfunc_error_retval and applet_name are init by: */
-			run_applet_no_and_exit(a, argv[0], argv);
 		}
 # endif
 	}

shell/ash.c

@@ -7803,13 +7803,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
 			while (*envp)
 				putenv(*envp++);
 			popredir(/*drop:*/ 1);
-			GETOPT_RESET();
+			run_noexec_applet_and_exit(applet_no, cmd, argv);
-//TODO: think pidof, pgrep, pkill!
-//set_task_comm() makes our pidof find NOEXECs (e.g. "yes >/dev/null"),
-//but one from procps-ng-3.3.10 needs more!
-//Rewrite /proc/PID/cmdline? (need to save argv0 and length at init for this to work!)
-			set_task_comm(argv[0]);
-			run_applet_no_and_exit(applet_no, cmd, argv);
 		}
 		/* re-exec ourselves with the new arguments */
 		execve(bb_busybox_exec_path, argv, envp);

shell/hush.c

@@ -7386,14 +7386,8 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
 //FIXME: should also close saved redir fds
 				/* Without this, "rm -i FILE" can't be ^C'ed: */
 				switch_off_special_sigs(G.special_sig_mask);
-				GETOPT_RESET();
-//TODO: think pidof, pgrep, pkill!
-//set_task_comm() makes our pidof find NOEXECs (e.g. "yes >/dev/null"),
-//but one from procps-ng-3.3.10 needs more!
-//Rewrite /proc/PID/cmdline? (need to save argv0 and length at init for this to work!)
-				set_task_comm(argv[0]);
 				debug_printf_exec("running applet '%s'\n", argv[0]);
-				run_applet_no_and_exit(a, argv[0], argv);
+				run_noexec_applet_and_exit(a, argv[0], argv);
 			}
 # endif
 			/* Re-exec ourselves */