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 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_simple_perror_msg_and_die(*argv);
69 int safe_waitpid(int pid, int *wstat, int options)
74 r = waitpid(pid, wstat, options);
75 while ((r == -1) && (errno == EINTR));
79 int 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.
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;
101 if (WIFEXITED(status))
102 return WEXITSTATUS(status);
103 if (WIFSIGNALED(status))
104 return WTERMSIG(status) + 1000;
108 #if ENABLE_FEATURE_PREFER_APPLETS
109 void save_nofork_data(struct nofork_save_area *save)
111 memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
112 save->applet_name = applet_name;
113 save->xfunc_error_retval = xfunc_error_retval;
114 save->option_mask32 = option_mask32;
115 save->die_sleep = die_sleep;
119 void restore_nofork_data(struct nofork_save_area *save)
121 memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp));
122 applet_name = save->applet_name;
123 xfunc_error_retval = save->xfunc_error_retval;
124 option_mask32 = save->option_mask32;
125 die_sleep = save->die_sleep;
128 int run_nofork_applet_prime(struct nofork_save_area *old, int applet_no, char **argv)
132 applet_name = APPLET_NAME(applet_no);
133 xfunc_error_retval = EXIT_FAILURE;
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 /* Reset the libc getopt() function, which keeps internal state.
142 * BSD-derived getopt() functions require that optind be reset to 1 in
143 * order to reset getopt() state. This used to be generally accepted
144 * way of resetting getopt(). However, glibc's getopt()
145 * has additional getopt() state beyond optind, and requires that
146 * optind be set zero to reset its state. So the unfortunate state of
147 * affairs is that BSD-derived versions of getopt() misbehave if
148 * optind is set to 0 in order to reset getopt(), and glibc's getopt()
149 * will core ump if optind is set 1 in order to reset getopt().
151 * More modern versions of BSD require that optreset be set to 1 in
152 * order to reset getopt(). Sigh. Standards, anyone?
156 #else /* BSD style */
160 /* option_mask32 = 0; - not needed */
166 rc = setjmp(die_jmp);
168 /* Some callers (xargs)
169 * need argv untouched because they free argv[i]! */
170 char *tmp_argv[argc+1];
171 memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0]));
172 /* Finally we can call NOFORK applet's main() */
173 rc = applet_main[applet_no](argc, tmp_argv);
174 } else { /* xfunc died in NOFORK applet */
175 /* in case they meant to return 0... */
180 /* Restoring globals */
181 restore_nofork_data(old);
185 int run_nofork_applet(int applet_no, char **argv)
187 struct nofork_save_area old;
190 save_nofork_data(&old);
191 return run_nofork_applet_prime(&old, applet_no, argv);
193 #endif /* FEATURE_PREFER_APPLETS */
195 int spawn_and_wait(char **argv)
198 #if ENABLE_FEATURE_PREFER_APPLETS
199 int a = find_applet_by_name(argv[0]);
201 if (a >= 0 && (APPLET_IS_NOFORK(a)
203 || APPLET_IS_NOEXEC(a) /* NOEXEC trick needs fork() */
207 if (APPLET_IS_NOFORK(a))
210 return run_nofork_applet(a, argv);
214 /* a->noexec is true */
216 if (rc) /* parent or error */
219 xfunc_error_retval = EXIT_FAILURE;
220 run_applet_no_and_exit(a, argv);
223 #endif /* FEATURE_PREFER_APPLETS */
229 void re_exec(char **argv)
231 /* high-order bit of first char in argv[0] is a hidden
232 * "we have (already) re-execed, don't do it again" flag */
234 execv(bb_busybox_exec_path, argv);
235 bb_perror_msg_and_die("exec %s", bb_busybox_exec_path);
238 void forkexit_or_rexec(char **argv)
241 /* Maybe we are already re-execed and come here again? */
246 if (pid < 0) /* wtf? */
247 bb_perror_msg_and_die("vfork");
248 if (pid) /* parent */
250 /* child - re-exec ourself */
254 /* Dance around (void)...*/
255 #undef forkexit_or_rexec
256 void forkexit_or_rexec(void)
260 if (pid < 0) /* wtf? */
261 bb_perror_msg_and_die("fork");
262 if (pid) /* parent */
266 #define forkexit_or_rexec(argv) forkexit_or_rexec()
269 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
270 * char **argv "vanishes" */
271 void bb_daemonize_or_rexec(int flags, char **argv)
275 if (flags & DAEMON_CHDIR_ROOT)
278 if (flags & DAEMON_DEVNULL_STDIO) {
284 fd = xopen(bb_dev_null, O_RDWR);
286 while ((unsigned)fd < 2)
287 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
289 if (!(flags & DAEMON_ONLY_SANITIZE)) {
290 forkexit_or_rexec(argv);
291 /* if daemonizing, make sure we detach from stdio & ctty */
299 if (!(flags & DAEMON_CLOSE_EXTRA_FDS))
301 /* else close everything after fd#2 */
305 void bb_sanitize_stdio(void)
307 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);