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.
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 // Be nice to nommu machines.
32 if (pid < 0) /* error */
34 if (!pid) { /* child */
35 /* Don't use BB_EXECVP tricks here! */
36 execvp(argv[0], argv);
38 /* We are (maybe) sharing a stack with blocked parent,
39 * let parent know we failed and then exit to unblock parent
40 * (but don't run atexit() stuff, which would screw up parent.)
46 /* Unfortunately, this is not reliable: vfork()
47 * can be equivalent to fork() according to standards */
55 /* Die with an error message if we can't spawn a child process. */
56 pid_t xspawn(char **argv)
58 pid_t pid = spawn(argv);
59 if (pid < 0) bb_perror_msg_and_die("%s", *argv);
66 // Die with an error message if we can't daemonize.
67 void xdaemon(int nochdir, int noclose)
69 if (daemon(nochdir, noclose))
70 bb_perror_msg_and_die("daemon");
75 void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
79 /* Maybe we are already re-execed and come here again? */
89 /* if "/dev/null" doesn't exist, bail out! */
90 fd = xopen(bb_dev_null, O_RDWR);
91 dup2(fd, STDIN_FILENO);
92 dup2(fd, STDOUT_FILENO);
93 dup2(fd, STDERR_FILENO);
100 /* Make certain we are not a session leader, or else we
101 * might reacquire a controlling terminal */
104 /* High-order bit of first char in argv[0] is a hidden
105 * "we have (alrealy) re-execed, don't do it again" flag */
107 execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
108 bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
110 bb_perror_msg_and_die("vfork");
111 default: /* parent */
115 #endif /* BB_NOMMU */
118 void forkexit_or_rexec(char **argv)
121 /* Maybe we are already re-execed and come here again? */
126 if (pid < 0) /* wtf? */
127 bb_perror_msg_and_die("vfork");
128 if (pid) /* parent */
130 /* child - re-exec ourself */
131 /* high-order bit of first char in argv[0] is a hidden
132 * "we have (alrealy) re-execed, don't do it again" flag */
134 execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
135 bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
138 /* Dance around (void)...*/
139 #undef forkexit_or_rexec
140 void forkexit_or_rexec(void)
144 if (pid < 0) /* wtf? */
145 bb_perror_msg_and_die("fork");
146 if (pid) /* parent */
150 #define forkexit_or_rexec(argv) forkexit_or_rexec()
154 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
155 * char **argv "vanishes" */
156 void bb_daemonize_or_rexec(int flags, char **argv)
160 fd = xopen(bb_dev_null, O_RDWR);
162 if (flags & DAEMON_CHDIR_ROOT)
165 if (flags & DAEMON_DEVNULL_STDIO) {
171 while ((unsigned)fd < 2)
172 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
174 if (!(flags & DAEMON_ONLY_SANITIZE)) {
175 forkexit_or_rexec(argv);
176 /* if daemonizing, make sure we detach from stdio */
184 if (flags & DAEMON_CLOSE_EXTRA_FDS)
186 close(fd--); /* close everything after fd#2 */
189 void bb_sanitize_stdio(void)
191 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);