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" /* for struct bb_applet */
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 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 xspawn(char **argv)
63 pid_t pid = spawn(argv);
65 bb_perror_msg_and_die("%s", *argv);
69 // Wait for the specified child PID to exit, returning child's error return.
75 /*errno = ECHILD; -- wrong. */
76 /* we expect errno to be already set from failed [v]fork/exec */
79 if (waitpid(pid, &status, 0) == -1)
81 if (WIFEXITED(status))
82 return WEXITSTATUS(status);
83 if (WIFSIGNALED(status))
84 return WTERMSIG(status) + 1000;
88 int wait_nohang(int *wstat)
90 return waitpid(-1, wstat, WNOHANG);
93 int wait_pid(int *wstat, int pid)
98 r = waitpid(pid, wstat, 0);
99 while ((r == -1) && (errno == EINTR));
103 #if ENABLE_FEATURE_PREFER_APPLETS
104 void save_nofork_data(struct nofork_save_area *save)
106 save->current_applet = current_applet;
107 save->xfunc_error_retval = xfunc_error_retval;
108 save->option_mask32 = option_mask32;
109 save->die_sleep = die_sleep;
113 void restore_nofork_data(struct nofork_save_area *save)
115 current_applet = save->current_applet;
116 xfunc_error_retval = save->xfunc_error_retval;
117 option_mask32 = save->option_mask32;
118 die_sleep = save->die_sleep;
120 applet_name = current_applet->name;
123 int run_nofork_applet_prime(struct nofork_save_area *old, const struct bb_applet *a, char **argv)
128 applet_name = a->name;
129 xfunc_error_retval = EXIT_FAILURE;
130 /*option_mask32 = 0; - not needed */
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. */
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 = a->main(argc, tmp_argv);
148 } else { /* xfunc died in NOFORK applet */
149 /* in case they meant to return 0... */
154 /* Restoring globals */
155 restore_nofork_data(old);
159 int run_nofork_applet(const struct bb_applet *a, char **argv)
161 struct nofork_save_area old;
163 save_nofork_data(&old);
164 return run_nofork_applet_prime(&old, a, argv);
166 #endif /* FEATURE_PREFER_APPLETS */
168 int spawn_and_wait(char **argv)
171 #if ENABLE_FEATURE_PREFER_APPLETS
172 const struct bb_applet *a = find_applet_by_name(argv[0]);
176 || a->noexec /* NOEXEC trick needs fork() */
183 return run_nofork_applet(a, argv);
187 /* a->noexec is true */
189 if (rc) /* parent or error */
192 xfunc_error_retval = EXIT_FAILURE;
194 run_current_applet_and_exit(argv);
197 #endif /* FEATURE_PREFER_APPLETS */
204 void forkexit_or_rexec(char **argv)
207 /* Maybe we are already re-execed and come here again? */
212 if (pid < 0) /* wtf? */
213 bb_perror_msg_and_die("vfork");
214 if (pid) /* parent */
216 /* child - re-exec ourself */
217 /* high-order bit of first char in argv[0] is a hidden
218 * "we have (alrealy) re-execed, don't do it again" flag */
220 execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
221 bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
224 /* Dance around (void)...*/
225 #undef forkexit_or_rexec
226 void forkexit_or_rexec(void)
230 if (pid < 0) /* wtf? */
231 bb_perror_msg_and_die("fork");
232 if (pid) /* parent */
236 #define forkexit_or_rexec(argv) forkexit_or_rexec()
239 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
240 * char **argv "vanishes" */
241 void bb_daemonize_or_rexec(int flags, char **argv)
245 fd = xopen(bb_dev_null, O_RDWR);
247 if (flags & DAEMON_CHDIR_ROOT)
250 if (flags & DAEMON_DEVNULL_STDIO) {
256 while ((unsigned)fd < 2)
257 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
259 if (!(flags & DAEMON_ONLY_SANITIZE)) {
260 forkexit_or_rexec(argv);
261 /* if daemonizing, make sure we detach from stdio */
269 if (flags & DAEMON_CLOSE_EXTRA_FDS)
271 close(fd--); /* close everything after fd#2 */
274 void bb_sanitize_stdio(void)
276 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);