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: according to standards
47 * vfork() can be equivalent to fork() and we won't see value
49 * Interested party can wait on pid and learn exit code.
50 * If 111 - then it (most probably) failed to exec */
58 /* Die with an error message if we can't spawn a child process. */
59 pid_t xspawn(char **argv)
61 pid_t pid = spawn(argv);
62 if (pid < 0) bb_perror_msg_and_die("%s", *argv);
69 // Die with an error message if we can't daemonize.
70 void xdaemon(int nochdir, int noclose)
72 if (daemon(nochdir, noclose))
73 bb_perror_msg_and_die("daemon");
78 void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
82 /* Maybe we are already re-execed and come here again? */
92 /* if "/dev/null" doesn't exist, bail out! */
93 fd = xopen(bb_dev_null, O_RDWR);
94 dup2(fd, STDIN_FILENO);
95 dup2(fd, STDOUT_FILENO);
96 dup2(fd, STDERR_FILENO);
103 /* Make certain we are not a session leader, or else we
104 * might reacquire a controlling terminal */
107 /* High-order bit of first char in argv[0] is a hidden
108 * "we have (alrealy) re-execed, don't do it again" flag */
110 execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
111 bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
113 bb_perror_msg_and_die("vfork");
114 default: /* parent */
118 #endif /* BB_NOMMU */
121 void forkexit_or_rexec(char **argv)
124 /* Maybe we are already re-execed and come here again? */
129 if (pid < 0) /* wtf? */
130 bb_perror_msg_and_die("vfork");
131 if (pid) /* parent */
133 /* child - re-exec ourself */
134 /* high-order bit of first char in argv[0] is a hidden
135 * "we have (alrealy) re-execed, don't do it again" flag */
137 execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
138 bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
141 /* Dance around (void)...*/
142 #undef forkexit_or_rexec
143 void forkexit_or_rexec(void)
147 if (pid < 0) /* wtf? */
148 bb_perror_msg_and_die("fork");
149 if (pid) /* parent */
153 #define forkexit_or_rexec(argv) forkexit_or_rexec()
157 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
158 * char **argv "vanishes" */
159 void bb_daemonize_or_rexec(int flags, char **argv)
163 fd = xopen(bb_dev_null, O_RDWR);
165 if (flags & DAEMON_CHDIR_ROOT)
168 if (flags & DAEMON_DEVNULL_STDIO) {
174 while ((unsigned)fd < 2)
175 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
177 if (!(flags & DAEMON_ONLY_SANITIZE)) {
178 forkexit_or_rexec(argv);
179 /* if daemonizing, make sure we detach from stdio */
187 if (flags & DAEMON_CLOSE_EXTRA_FDS)
189 close(fd--); /* close everything after fd#2 */
192 void bb_sanitize_stdio(void)
194 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);