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 // 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);
64 if (pid < 0) bb_perror_msg_and_die("%s", *argv);
71 // Die with an error message if we can't daemonize.
72 void xdaemon(int nochdir, int noclose)
74 if (daemon(nochdir, noclose))
75 bb_perror_msg_and_die("daemon");
80 void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
84 /* Maybe we are already re-execed and come here again? */
94 /* if "/dev/null" doesn't exist, bail out! */
95 fd = xopen(bb_dev_null, O_RDWR);
96 dup2(fd, STDIN_FILENO);
97 dup2(fd, STDOUT_FILENO);
98 dup2(fd, STDERR_FILENO);
105 /* Make certain we are not a session leader, or else we
106 * might reacquire a controlling terminal */
109 /* High-order bit of first char in argv[0] is a hidden
110 * "we have (alrealy) re-execed, don't do it again" flag */
112 execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
113 bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
115 bb_perror_msg_and_die("vfork");
116 default: /* parent */
120 #endif /* BB_NOMMU */
123 void forkexit_or_rexec(char **argv)
126 /* Maybe we are already re-execed and come here again? */
131 if (pid < 0) /* wtf? */
132 bb_perror_msg_and_die("vfork");
133 if (pid) /* parent */
135 /* child - re-exec ourself */
136 /* high-order bit of first char in argv[0] is a hidden
137 * "we have (alrealy) re-execed, don't do it again" flag */
139 execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
140 bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
143 /* Dance around (void)...*/
144 #undef forkexit_or_rexec
145 void forkexit_or_rexec(void)
149 if (pid < 0) /* wtf? */
150 bb_perror_msg_and_die("fork");
151 if (pid) /* parent */
155 #define forkexit_or_rexec(argv) forkexit_or_rexec()
159 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
160 * char **argv "vanishes" */
161 void bb_daemonize_or_rexec(int flags, char **argv)
165 fd = xopen(bb_dev_null, O_RDWR);
167 if (flags & DAEMON_CHDIR_ROOT)
170 if (flags & DAEMON_DEVNULL_STDIO) {
176 while ((unsigned)fd < 2)
177 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
179 if (!(flags & DAEMON_ONLY_SANITIZE)) {
180 forkexit_or_rexec(argv);
181 /* if daemonizing, make sure we detach from stdio */
189 if (flags & DAEMON_CLOSE_EXTRA_FDS)
191 close(fd--); /* close everything after fd#2 */
194 void bb_sanitize_stdio(void)
196 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);