NOMMU re-exec trick shuld not depend on existence of "don't daemonize"

option for every affected applet (and dnsd, for example, don't have one).
Thus rework re-exec support to not require it. Code got smaller too.

10 files changed, 34 insertions, 30 deletions

diff --git a/applets/busybox.c b/applets/busybox.c
index 0387d79b7..5334827ca 100644
--- a/applets/busybox.c
+++ b/applets/busybox.c
@@ -7,6 +7,7 @@
 #include "busybox.h"
 
 const char *applet_name ATTRIBUTE_EXTERNALLY_VISIBLE;
+smallint re_execed;
 
 #ifdef CONFIG_FEATURE_INSTALLER
 /*
@@ -59,6 +60,12 @@ int main(int argc, char **argv)
 {
         const char *s;
 
+        /* NOMMU re-exec trick sets high-order bit in first byte of name */
+        if (argv[0][0] & 0x80) {
+                re_execed = 1;
+                argv[0][0] &= 0x7f;
+        }
+
         applet_name = argv[0];
         if (*applet_name == '-')
                 applet_name++;
diff --git a/applets/individual.c b/applets/individual.c
index 072168352..1667f188b 100644
--- a/applets/individual.c
+++ b/applets/individual.c
@@ -9,12 +9,11 @@ const char *applet_name;
 
 #include <stdio.h>
 #include <stdlib.h>
-//Ok to remove? #include "bb_config.h"
 #include "usage.h"
 
 int main(int argc, char *argv[])
 {
-        applet_name=argv[0];
+        applet_name = argv[0];
 
         return APPLET_main(argc,argv);
 }
diff --git a/include/libbb.h b/include/libbb.h
index 659bfcaa7..0cfc22018 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -616,9 +616,7 @@ extern int index_in_substr_array(const char * const string_array[], const char *
 extern void print_login_issue(const char *issue_file, const char *tty);
 extern void print_login_prompt(void);
 #ifdef BB_NOMMU
-extern void vfork_daemon(int nochdir, int noclose);
-extern void vfork_daemon_rexec(int nochdir, int noclose,
-                int argc, char **argv, char *foreground_opt);
+extern void vfork_daemon_rexec(int nochdir, int noclose, char **argv);
 #endif
 extern int get_terminal_width_height(const int fd, int *width, int *height);
 
@@ -763,6 +761,7 @@ enum {	/* DO NOT CHANGE THESE VALUES!  cp.c, mv.c, install.c depend on them. */
 };
 
 #define FILEUTILS_CP_OPTSTR "pdRfils" USE_SELINUX("c")
+extern smallint re_execed;
 extern const char *applet_name;
 extern const char BB_BANNER[];
 
diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index 26d1826e0..3185f2d39 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -19,19 +19,18 @@
 #include "libbb.h"
 
 #ifdef BB_NOMMU
-void vfork_daemon_rexec(int nochdir, int noclose,
-                int argc, char **argv, char *foreground_opt)
+void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
 {
         int fd;
-        char **vfork_args;
-        int a = 0;
 
         setsid();
 
         if (!nochdir)
                 xchdir("/");
 
-        if (!noclose && (fd = open(bb_dev_null, O_RDWR, 0)) != -1) {
+        if (!noclose) {
+                /* if "/dev/null" doesn't exist, bail out! */
+                fd = xopen(bb_dev_null, O_RDWR);
                 dup2(fd, STDIN_FILENO);
                 dup2(fd, STDOUT_FILENO);
                 dup2(fd, STDERR_FILENO);
@@ -39,21 +38,17 @@ void vfork_daemon_rexec(int nochdir, int noclose,
                         close(fd--);
         }
 
-        vfork_args = xzalloc(sizeof(char *) * (argc + 3));
-        vfork_args[a++] = CONFIG_BUSYBOX_EXEC_PATH;
-        while (*argv) {
-                vfork_args[a++] = *argv;
-                argv++;
-        }
-        vfork_args[a] = foreground_opt;
         switch (vfork()) {
         case 0: /* child */
                 /* Make certain we are not a session leader, or else we
                  * might reacquire a controlling terminal */
                 if (vfork())
                         _exit(0);
-                execv(vfork_args[0], vfork_args);
-                bb_perror_msg_and_die("execv %s", vfork_args[0]);
+                /* High-order bit of first char in argv[0] is a hidden
+                 * "we have (alrealy) re-execed, don't do it again" flag */
+                argv[0][0] |= 0x80;
+                execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
+                bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
         case -1: /* error */
                 bb_perror_msg_and_die("vfork");
         default: /* parent */
diff --git a/miscutils/crond.c b/miscutils/crond.c
index d237a677e..1ab0038e0 100644
--- a/miscutils/crond.c
+++ b/miscutils/crond.c
@@ -191,8 +191,8 @@ int crond_main(int ac, char **av)
 
         if (!(opt & 4)) {
 #ifdef BB_NOMMU
-                /* reexec for vfork() do continue parent */
-                vfork_daemon_rexec(1, 0, ac, av, "-f");
+                if (!re_execed)
+                        vfork_daemon_rexec(1, 0, av);
 #else
                 xdaemon(1, 0);
 #endif
diff --git a/miscutils/watchdog.c b/miscutils/watchdog.c
index ed9026d9e..e3d77d17e 100644
--- a/miscutils/watchdog.c
+++ b/miscutils/watchdog.c
@@ -38,12 +38,14 @@ int watchdog_main(int argc, char **argv)
         if (optind < argc - 1 || argc == 1)
                 bb_show_usage();
 
+        if (!(opts & OPT_FOREGROUND)) {
 #ifdef BB_NOMMU
-        if (!(opts & OPT_FOREGROUND))
-                vfork_daemon_rexec(0, 1, argc, argv, "-F");
+                if (!re_execed)
+                        vfork_daemon_rexec(0, 1, argv);
 #else
-        xdaemon(0, 1);
+                xdaemon(0, 1);
 #endif
+        }
 
         signal(SIGHUP, watchdog_shutdown);
         signal(SIGINT, watchdog_shutdown);
diff --git a/networking/dnsd.c b/networking/dnsd.c
index 78722d6f6..fb0c56cce 100644
--- a/networking/dnsd.c
+++ b/networking/dnsd.c
@@ -357,8 +357,8 @@ int dnsd_main(int argc, char **argv)
         if (OPT_daemon) {
 //FIXME: NOMMU will NOT set LOGMODE_SYSLOG!
 #ifdef BB_NOMMU
-                /* reexec for vfork() do continue parent */
-                vfork_daemon_rexec(1, 0, argc, argv, "-d");
+                if (!re_execed)
+                        vfork_daemon_rexec(1, 0, argv);
 #else
                 xdaemon(1, 0);
 #endif
diff --git a/networking/inetd.c b/networking/inetd.c
index 8016823c0..48e23db2e 100644
--- a/networking/inetd.c
+++ b/networking/inetd.c
@@ -1289,8 +1289,8 @@ int inetd_main(int argc, char *argv[])
 
 #ifdef BB_NOMMU
         if (!(opt & 2)) {
-                /* reexec for vfork() do continue parent */
-                vfork_daemon_rexec(0, 0, argc, argv, "-f");
+                if (!re_execed)
+                        vfork_daemon_rexec(0, 0, argv);
         }
         bb_sanitize_stdio();
 #else
diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c
index cca6f5671..fc0ed3037 100644
--- a/sysklogd/klogd.c
+++ b/sysklogd/klogd.c
@@ -51,7 +51,8 @@ int klogd_main(int argc, char **argv)
 
         if (!(option_mask32 & OPT_FOREGROUND)) {
 #ifdef BB_NOMMU
-                vfork_daemon_rexec(0, 1, argc, argv, "-n");
+                if (!re_execed)
+                        vfork_daemon_rexec(0, 1, argv);
 #else
                 bb_daemonize();
 #endif
diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 2a2b20c8b..437212372 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -643,7 +643,8 @@ int syslogd_main(int argc, char **argv)
 
         if (!(option_mask32 & OPT_nofork)) {
 #ifdef BB_NOMMU
-                vfork_daemon_rexec(0, 1, argc, argv, "-n");
+                if (!re_execed)
+                        vfork_daemon_rexec(0, 1, argv);
 #else
                 bb_daemonize();
 #endif