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 tarball for details.
19 #include "busybox.h" /* uses applet tables */
21 /* This does a fork/exec in one call, using vfork(). Returns PID of new child,
22 * -1 for failure. Runs argv[0], searching path if that has no / in it. */
23 pid_t FAST_FUNC spawn(char **argv)
25 /* Compiler should not optimize stores here */
29 // Ain't it a good place to fflush(NULL)?
31 /* Be nice to nommu machines. */
34 if (pid < 0) /* error */
36 if (!pid) { /* child */
37 /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */
38 BB_EXECVP(argv[0], argv);
40 /* We are (maybe) sharing a stack with blocked parent,
41 * let parent know we failed and then exit to unblock parent
42 * (but don't run atexit() stuff, which would screw up parent.)
48 /* Unfortunately, this is not reliable: according to standards
49 * vfork() can be equivalent to fork() and we won't see value
51 * Interested party can wait on pid and learn exit code.
52 * If 111 - then it (most probably) failed to exec */
60 /* Die with an error message if we can't spawn a child process. */
61 pid_t FAST_FUNC xspawn(char **argv)
63 pid_t pid = spawn(argv);
65 bb_simple_perror_msg_and_die(*argv);
69 pid_t FAST_FUNC safe_waitpid(pid_t pid, int *wstat, int options)
74 r = waitpid(pid, wstat, options);
75 while ((r == -1) && (errno == EINTR));
79 pid_t FAST_FUNC wait_any_nohang(int *wstat)
81 return safe_waitpid(-1, wstat, WNOHANG);
84 // Wait for the specified child PID to exit, returning child's error return.
85 int FAST_FUNC wait4pid(pid_t pid)
90 /*errno = ECHILD; -- wrong. */
91 /* we expect errno to be already set from failed [v]fork/exec */
94 if (safe_waitpid(pid, &status, 0) == -1)
96 if (WIFEXITED(status))
97 return WEXITSTATUS(status);
98 if (WIFSIGNALED(status))
99 return WTERMSIG(status) + 1000;
103 #if ENABLE_FEATURE_PREFER_APPLETS
104 void FAST_FUNC save_nofork_data(struct nofork_save_area *save)
106 memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
107 save->applet_name = applet_name;
108 save->xfunc_error_retval = xfunc_error_retval;
109 save->option_mask32 = option_mask32;
110 save->die_sleep = die_sleep;
114 void FAST_FUNC restore_nofork_data(struct nofork_save_area *save)
116 memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp));
117 applet_name = save->applet_name;
118 xfunc_error_retval = save->xfunc_error_retval;
119 option_mask32 = save->option_mask32;
120 die_sleep = save->die_sleep;
123 int FAST_FUNC run_nofork_applet_prime(struct nofork_save_area *old, int applet_no, char **argv)
127 applet_name = APPLET_NAME(applet_no);
129 xfunc_error_retval = EXIT_FAILURE;
131 /* Special flag for xfunc_die(). If xfunc will "die"
132 * in NOFORK applet, xfunc_die() sees negative
133 * die_sleep and longjmp here instead. */
136 /* In case getopt() or getopt32() was already called:
137 * reset the libc getopt() function, which keeps internal state.
139 * BSD-derived getopt() functions require that optind be set to 1 in
140 * order to reset getopt() state. This used to be generally accepted
141 * way of resetting getopt(). However, glibc's getopt()
142 * has additional getopt() state beyond optind, and requires that
143 * optind be set to zero to reset its state. So the unfortunate state of
144 * affairs is that BSD-derived versions of getopt() misbehave if
145 * optind is set to 0 in order to reset getopt(), and glibc's getopt()
146 * will core dump if optind is set 1 in order to reset getopt().
148 * More modern versions of BSD require that optreset be set to 1 in
149 * order to reset getopt(). Sigh. Standards, anyone?
153 #else /* BSD style */
157 /* optarg = NULL; opterr = 1; optopt = 63; - do we need this too? */
158 /* (values above are what they initialized to in glibc and uclibc) */
159 /* option_mask32 = 0; - not needed, no applet depends on it being 0 */
165 rc = setjmp(die_jmp);
167 /* Some callers (xargs)
168 * need argv untouched because they free argv[i]! */
169 char *tmp_argv[argc+1];
170 memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0]));
171 /* Finally we can call NOFORK applet's main() */
172 rc = applet_main[applet_no](argc, tmp_argv);
174 /* The whole reason behind nofork_save_area is that <applet>_main
175 * may exit non-locally! For example, in hush Ctrl-Z tries
176 * (modulo bugs) to dynamically create a child (backgrounded task)
177 * if it detects that Ctrl-Z was pressed when a NOFORK was running.
178 * Testcase: interactive "rm -i".
179 * Don't fool yourself into thinking "and <applet>_main() returns
180 * quickly here" and removing "useless" nofork_save_area code. */
182 } else { /* xfunc died in NOFORK applet */
183 /* in case they meant to return 0... */
188 /* Restoring some globals */
189 restore_nofork_data(old);
191 /* Other globals can be simply reset to defaults */
194 #else /* BSD style */
198 return rc & 0xff; /* don't confuse people with "exitcodes" >255 */
201 int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
203 struct nofork_save_area old;
206 save_nofork_data(&old);
207 return run_nofork_applet_prime(&old, applet_no, argv);
209 #endif /* FEATURE_PREFER_APPLETS */
211 int FAST_FUNC spawn_and_wait(char **argv)
214 #if ENABLE_FEATURE_PREFER_APPLETS
215 int a = find_applet_by_name(argv[0]);
217 if (a >= 0 && (APPLET_IS_NOFORK(a)
219 || APPLET_IS_NOEXEC(a) /* NOEXEC trick needs fork() */
223 if (APPLET_IS_NOFORK(a))
226 return run_nofork_applet(a, argv);
230 /* a->noexec is true */
232 if (rc) /* parent or error */
235 xfunc_error_retval = EXIT_FAILURE;
236 run_applet_no_and_exit(a, argv);
239 #endif /* FEATURE_PREFER_APPLETS */
245 void FAST_FUNC re_exec(char **argv)
247 /* high-order bit of first char in argv[0] is a hidden
248 * "we have (already) re-execed, don't do it again" flag */
250 execv(bb_busybox_exec_path, argv);
251 bb_perror_msg_and_die("exec %s", bb_busybox_exec_path);
254 pid_t FAST_FUNC fork_or_rexec(char **argv)
257 /* Maybe we are already re-execed and come here again? */
259 return 0; /* child */
262 if (pid < 0) /* wtf? */
263 bb_perror_msg_and_die("vfork");
264 if (pid) /* parent */
266 /* child - re-exec ourself */
270 /* Dance around (void)...*/
272 pid_t FAST_FUNC fork_or_rexec(void)
276 if (pid < 0) /* wtf? */
277 bb_perror_msg_and_die("fork");
280 #define fork_or_rexec(argv) fork_or_rexec()
283 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
284 * char **argv "vanishes" */
285 void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
289 if (flags & DAEMON_CHDIR_ROOT)
292 if (flags & DAEMON_DEVNULL_STDIO) {
298 fd = open(bb_dev_null, O_RDWR);
300 /* NB: we can be called as bb_sanitize_stdio() from init
301 * or mdev, and there /dev/null may legitimately not (yet) exist!
302 * Do not use xopen above, but obtain _ANY_ open descriptor,
303 * even bogus one as below. */
304 fd = xopen("/", O_RDONLY); /* don't believe this can fail */
307 while ((unsigned)fd < 2)
308 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
310 if (!(flags & DAEMON_ONLY_SANITIZE)) {
311 if (fork_or_rexec(argv))
312 exit(EXIT_SUCCESS); /* parent */
313 /* if daemonizing, make sure we detach from stdio & ctty */
321 if (!(flags & DAEMON_CLOSE_EXTRA_FDS))
323 /* else close everything after fd#2 */
327 void FAST_FUNC bb_sanitize_stdio(void)
329 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);