1 /* vi: set sw=4 ts=4: */
3 * Rexec program for system have fork() as vfork() with foreground option
5 * Copyright (C) Vladimir N. Oleynik <dzo@simtreas.ru>
6 * Copyright (C) 2003 Russ Dill <Russ.Dill@asu.edu>
8 * daemon() portion taken from uClibc:
10 * Copyright (c) 1991, 1993
11 * The Regents of the University of California. All rights reserved.
13 * Modified for uClibc by Erik Andersen <andersee@debian.org>
15 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
18 #include "busybox.h" /* uses applet tables */
20 /* This does a fork/exec in one call, using vfork(). Returns PID of new child,
21 * -1 for failure. Runs argv[0], searching path if that has no / in it. */
22 pid_t FAST_FUNC spawn(char **argv)
24 /* Compiler should not optimize stores here */
30 /* Be nice to nommu machines. */
33 if (pid < 0) /* error */
35 if (!pid) { /* child */
36 /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */
37 BB_EXECVP(argv[0], argv);
39 /* We are (maybe) sharing a stack with blocked parent,
40 * let parent know we failed and then exit to unblock parent
41 * (but don't run atexit() stuff, which would screw up parent.)
44 /* mount, for example, does not want the message */
45 /*bb_perror_msg("can't execute '%s'", argv[0]);*/
49 /* Unfortunately, this is not reliable: according to standards
50 * vfork() can be equivalent to fork() and we won't see value
52 * Interested party can wait on pid and learn exit code.
53 * If 111 - then it (most probably) failed to exec */
61 /* Die with an error message if we can't spawn a child process. */
62 pid_t FAST_FUNC xspawn(char **argv)
64 pid_t pid = spawn(argv);
66 bb_simple_perror_msg_and_die(*argv);
70 #if ENABLE_FEATURE_PREFER_APPLETS
71 struct nofork_save_area {
73 const char *applet_name;
74 uint32_t option_mask32;
76 uint8_t xfunc_error_retval;
78 static void save_nofork_data(struct nofork_save_area *save)
80 memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
81 save->applet_name = applet_name;
82 save->xfunc_error_retval = xfunc_error_retval;
83 save->option_mask32 = option_mask32;
84 save->die_sleep = die_sleep;
86 static void restore_nofork_data(struct nofork_save_area *save)
88 memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp));
89 applet_name = save->applet_name;
90 xfunc_error_retval = save->xfunc_error_retval;
91 option_mask32 = save->option_mask32;
92 die_sleep = save->die_sleep;
95 int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
98 struct nofork_save_area old;
100 save_nofork_data(&old);
102 applet_name = APPLET_NAME(applet_no);
104 xfunc_error_retval = EXIT_FAILURE;
106 /* In case getopt() or getopt32() was already called:
107 * reset the libc getopt() function, which keeps internal state.
109 * BSD-derived getopt() functions require that optind be set to 1 in
110 * order to reset getopt() state. This used to be generally accepted
111 * way of resetting getopt(). However, glibc's getopt()
112 * has additional getopt() state beyond optind, and requires that
113 * optind be set to zero to reset its state. So the unfortunate state of
114 * affairs is that BSD-derived versions of getopt() misbehave if
115 * optind is set to 0 in order to reset getopt(), and glibc's getopt()
116 * will core dump if optind is set 1 in order to reset getopt().
118 * More modern versions of BSD require that optreset be set to 1 in
119 * order to reset getopt(). Sigh. Standards, anyone?
123 #else /* BSD style */
127 /* optarg = NULL; opterr = 1; optopt = 63; - do we need this too? */
128 /* (values above are what they initialized to in glibc and uclibc) */
129 /* option_mask32 = 0; - not needed, no applet depends on it being 0 */
135 /* Special flag for xfunc_die(). If xfunc will "die"
136 * in NOFORK applet, xfunc_die() sees negative
137 * die_sleep and longjmp here instead. */
140 rc = setjmp(die_jmp);
142 /* Some callers (xargs)
143 * need argv untouched because they free argv[i]! */
144 char *tmp_argv[argc+1];
145 memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0]));
146 /* Finally we can call NOFORK applet's main() */
147 rc = applet_main[applet_no](argc, tmp_argv);
148 } else { /* xfunc died in NOFORK applet */
149 /* in case they meant to return 0... */
154 /* Restoring some globals */
155 restore_nofork_data(&old);
157 /* Other globals can be simply reset to defaults */
160 #else /* BSD style */
164 return rc & 0xff; /* don't confuse people with "exitcodes" >255 */
166 #endif /* FEATURE_PREFER_APPLETS */
168 int FAST_FUNC spawn_and_wait(char **argv)
171 #if ENABLE_FEATURE_PREFER_APPLETS
172 int a = find_applet_by_name(argv[0]);
174 if (a >= 0 && (APPLET_IS_NOFORK(a)
176 || APPLET_IS_NOEXEC(a) /* NOEXEC trick needs fork() */
180 if (APPLET_IS_NOFORK(a))
183 return run_nofork_applet(a, argv);
187 /* a->noexec is true */
189 if (rc) /* parent or error */
192 xfunc_error_retval = EXIT_FAILURE;
193 run_applet_no_and_exit(a, argv);
196 #endif /* FEATURE_PREFER_APPLETS */
202 void FAST_FUNC re_exec(char **argv)
204 /* high-order bit of first char in argv[0] is a hidden
205 * "we have (already) re-execed, don't do it again" flag */
207 execv(bb_busybox_exec_path, argv);
208 bb_perror_msg_and_die("can't execute '%s'", bb_busybox_exec_path);
211 pid_t FAST_FUNC fork_or_rexec(char **argv)
214 /* Maybe we are already re-execed and come here again? */
218 if (pid) /* parent */
220 /* child - re-exec ourself */
225 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
226 * char **argv "vanishes" */
227 void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
231 if (flags & DAEMON_CHDIR_ROOT)
234 if (flags & DAEMON_DEVNULL_STDIO) {
240 fd = open(bb_dev_null, O_RDWR);
242 /* NB: we can be called as bb_sanitize_stdio() from init
243 * or mdev, and there /dev/null may legitimately not (yet) exist!
244 * Do not use xopen above, but obtain _ANY_ open descriptor,
245 * even bogus one as below. */
246 fd = xopen("/", O_RDONLY); /* don't believe this can fail */
249 while ((unsigned)fd < 2)
250 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
252 if (!(flags & DAEMON_ONLY_SANITIZE)) {
253 if (fork_or_rexec(argv))
254 exit(EXIT_SUCCESS); /* parent */
255 /* if daemonizing, make sure we detach from stdio & ctty */
263 if (!(flags & DAEMON_CLOSE_EXTRA_FDS))
265 /* else close everything after fd#2 */
269 void FAST_FUNC bb_sanitize_stdio(void)
271 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);