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 int spawn_and_wait(char **argv)
105 #if ENABLE_FEATURE_PREFER_APPLETS
107 const struct bb_applet *a = find_applet_by_name(argv[0]);
111 || a->noexec /* NOEXEC trick needs fork() */
122 int old_sleep = die_sleep;
123 int old_x = xfunc_error_retval;
124 uint32_t old_m = option_mask32;
126 xfunc_error_retval = EXIT_FAILURE;
127 /* special flag for xfunc_die(). If xfunc will "die"
128 * in NOFORK applet, xfunc_die() sees negative
129 * die_sleep and longjmp here instead. */
132 rc = setjmp(die_jmp);
134 const struct bb_applet *old_a = current_applet;
136 applet_name = a->name;
137 // what else should we save/restore?
138 // TODO: what if applet will mangle argv vector?
139 // xargs needs argv untouched because it frees argv[i]!
140 // shouldn't we pass a copy?
141 rc = a->main(argc, argv);
142 current_applet = old_a;
143 applet_name = old_a->name;
145 /* xfunc died in NOFORK applet */
150 die_sleep = old_sleep;
151 xfunc_error_retval = old_x;
152 option_mask32 = old_m;
157 /* a->noexec is true */
159 if (rc) /* parent or error */
162 xfunc_error_retval = EXIT_FAILURE;
164 run_current_applet_and_exit(argc, argv);
167 #endif /* FEATURE_PREFER_APPLETS */
174 void forkexit_or_rexec(char **argv)
177 /* Maybe we are already re-execed and come here again? */
182 if (pid < 0) /* wtf? */
183 bb_perror_msg_and_die("vfork");
184 if (pid) /* parent */
186 /* child - re-exec ourself */
187 /* high-order bit of first char in argv[0] is a hidden
188 * "we have (alrealy) re-execed, don't do it again" flag */
190 execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
191 bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
194 /* Dance around (void)...*/
195 #undef forkexit_or_rexec
196 void forkexit_or_rexec(void)
200 if (pid < 0) /* wtf? */
201 bb_perror_msg_and_die("fork");
202 if (pid) /* parent */
206 #define forkexit_or_rexec(argv) forkexit_or_rexec()
209 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
210 * char **argv "vanishes" */
211 void bb_daemonize_or_rexec(int flags, char **argv)
215 fd = xopen(bb_dev_null, O_RDWR);
217 if (flags & DAEMON_CHDIR_ROOT)
220 if (flags & DAEMON_DEVNULL_STDIO) {
226 while ((unsigned)fd < 2)
227 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
229 if (!(flags & DAEMON_ONLY_SANITIZE)) {
230 forkexit_or_rexec(argv);
231 /* if daemonizing, make sure we detach from stdio */
239 if (flags & DAEMON_CLOSE_EXTRA_FDS)
241 close(fd--); /* close everything after fd#2 */
244 void bb_sanitize_stdio(void)
246 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);